GRAIL

 

DATA PRODUCT

SOFTWARE INTERFACE SPECIFICATION

 

JPL D-76383

 

 

 

 

 

Version 1.8

May 3, 2016

Daniel Kahan

 

 

Copyright 2013 California Institute of Technology. Government sponsorship acknowledged.

Copyright 2013. All rights reserved.


 

TABLE OF CONTENTS

 

TABLES         5

DOCUMENT CHANGE LOG.......................................................................................................................................... 7

1        Purpose and Scope of Document......................................................................................................................... 8

2        Definitions of Data Processing Levels................................................................................................................ 9

3        Relationships with Other Interfaces.................................................................................................................... 9

4        Data Product Characteristics and Environment................................................................................................. 9

4.1         Instrument Overview....................................................................................................................... 9

4.2         Data Product Overview.................................................................................................................. 11

4.2.1               LGRS EDR (NASA Level 0 Products)........................................................ 11

4.2.2               LGRS CDR (NASA Level 1A and Level 1B Products)................................. 12

4.2.2.1      Timing [17]......................................................................................................................... 12

4.2.2.2      Position.............................................................................................................................. 13

4.2.2.3      Ka-band............................................................................................................................. 14

4.2.2.4      S-band................................................................................................................................ 14

4.2.2.5      Satellite Attitude.................................................................................................................. 14

4.2.2.6      Events................................................................................................................................ 15

4.2.2.7      Satellite Condition................................................................................................................ 15

4.2.2.8      DSN Tracking.................................................................................................................... 15

4.2.3               RSS EDR................................................................................................... 15

4.2.3.1      DSN Radio Data................................................................................................................. 15

4.2.3.2      Ancillary DSN Data............................................................................................................ 16

4.2.4               LGRS RDR (NASA Level 2 Products)........................................................ 17

4.2.5               Data Flow and Product Generation............................................................... 17

4.2.6               Labeling and Identification........................................................................... 18

4.2.6.1      LGRS EDR and LGRS CDR File Naming Convention........................................................... 18

4.2.6.2      RSS EDR File Naming Convention....................................................................................... 19

4.2.6.3      LGRS RDR File Naming Convention.................................................................................... 20

4.3         Standards Used in Generating Data Products................................................................................... 22

4.3.1               PDS Standards........................................................................................... 22

4.3.2               Time Standards........................................................................................... 22

4.3.2.1      LGRS clock........................................................................................................................ 23

4.3.2.2      Onboard spacecraft clocks.................................................................................................. 23

4.3.2.3      UTC clock used by DSN..................................................................................................... 23

4.3.3               Coordinate Systems..................................................................................... 24

4.4         Data Validation.............................................................................................................................. 27

5        Detailed Data Product Specifications................................................................................................................ 27

5.1         Data Product Structure and Organization......................................................................................... 27

5.2         Data Format Descriptions............................................................................................................... 31

5.2.1               LGRS EDR (Level 0) Products.................................................................... 31

5.2.2               LGRS CDR Products.................................................................................. 34

5.2.2.1      Level 1A............................................................................................................................ 34

5.2.2.2      Level 1B............................................................................................................................ 48

5.2.3               RSS EDR Products..................................................................................... 56

5.3         Header Descriptions....................................................................................................................... 57

5.3.1               Headers for LGRS EDR............................................................................. 57

5.3.2               Headers for LGRS CDR............................................................................. 57

5.3.3               Headers for LGRS RDR............................................................................. 58

5.3.4               Headers for RSS EDR................................................................................ 58

6        Applicable Software............................................................................................................................................. 59

6.1         Utility Programs............................................................................................................................. 59

7        Appendices........................................................................................................................................................... 59

7.1         Glossary........................................................................................................................................ 59

7.2         Acronyms...................................................................................................................................... 60

7.3         Example PDS Labels..................................................................................................................... 62

7.3.1               LGRS EDR................................................................................................ 62

7.3.2               LGRS CDR................................................................................................ 62

7.3.3               RSS EDR................................................................................................... 63

7.3.3.1      BTM, EOP, ION, TDM, TNF, TRO, WEA, & XFR............................................................. 63

7.3.3.2      ODF, OLF, and BOF.......................................................................................................... 64

7.3.3.3      RSR................................................................................................................................... 92

7.3.4               LGRS RDR.............................................................................................. 113

7.3.4.1      Radio Science Digital Map Products (RSDMAP)................................................................ 113

7.3.4.2      Spherical Harmonics ASCII Data Record (SHADR)........................................................... 114

7.3.4.3      Spherical Harmonics Binary Data Record (SHBDR)........................................................... 119

7.3.4.4      SPICE ephemeris files (SPK)............................................................................................ 124

8        Applicable Documents...................................................................................................................................... 124

 


FIGURES

 

Figure 1: View of GRAIL satellites. 10

Figure 2: Payload Block Diagram [26] 11

Figure 3. GRAIL Science Downlink Data Flow Diagram.. 18

Figure 4. GRAIL clocks, models, and measurements used for timing [17] 23

Figure 5: The GRAIL Mechanical Frame (MF) [23] 24

Figure 6: GRAIL thruster locations (XYZ is the same as XMYMZM in text) 25

Figure 7: GRAIL thruster locations (XYZ is the same as XMYMZM in text) 25

Figure 8: GRAIL primary science spacecraft configuration (XYZ is the same as XMYMZM in text) 26

Figure 9: GRAIL extended science spacecraft configuration (XYZ is the same as XMYMZM in text) 27


TABLES

 

Table 1.          Processing Levels. 9

Table 2.          Summary of Data Products. 28

Table 3.          DTC00 Record Format 31

Table 4.          EHK00 Record Format 31

Table 5.          LTB00 Record Format 32

Table 6.          MAS00 Record Format 32

Table 7.          SAE00 Record Format 32

Table 8.          SCA00 Record Format 32

Table 9.          TDE00 Record Format 33

Table 10.        THR00 Record Format 33

Table 11.        WRS00 Record Format 33

Table 12.        CLK1A Record Format 34

Table 13.        DEL1A Record Format 35

Table 14.        EHK1A Record Format 35

Table 15.        IHK1A Record Format 36

Table 16.        IHS1A Record Format 36

Table 17.        ILG1A Record Format 36

Table 18.        KBR1A Record Format 37

Table 19.        LTM1A Record Format 38

Table 20.        MAS1A Record Format 38

Table 21.        PCI1A Record Format 39

Table 22.        PLT1A Record Format 39

Table 23.        PPS1A Record Format 39

Table 24.        REL1A Record Format 39

Table 25.        SAE1A Record Format 40

Table 26.        SBR1A Record Format 40

Table 27.        SCA1A Record Format 41

Table 28.        SNV1A Record Format 42

Table 29.        TC11A Record Format 42

Table 30.        TC21A Record Format 43

Table 31.        TC31A Record Format 43

Table 32.        TC41A Record Format 44

Table 33.        TC51A Record Format 44

Table 34.        TC61A Record Format 45

Table 35.        THR1A Record Format 45

Table 36.        USO1A Record Format 46

Table 37.        VCM1A Record Format 46

Table 38.        WRS1A Record Format 46

Table 39.        CLK1B Record Format 48

Table 40.        EHK1B Record Format 48

Table 41.        GNI1B Record Format 49

Table 42.        GNV1B Record Format 49

Table 43.        KBR1C Record Format 50

Table 44.        MAS1B Record Format 50

Table 45.        SAE1B Record Format 51

Table 46.        SBR1B Record Format 51

Table 47.        SCA1B Record Format 52

Table 48.        THR1B Record Format 52

Table 49.        USO1B Record Format 53

Table 50.        VCM1B Record Format 53

Table 51.        VGS1B Record Format 55

Table 52.        VGX1B Record Format 55

Table 53.        VKB1B Record Format 55

Table 54.        WRS1B Record Format 56

Table 55.        BTM Record Format 56

Table 56.        TDM Record Format 56

Table 57.        XFR Record Format 57


 DOCUMENT CHANGE LOG

Change

Date (mm/dd/yy)

Affected Portions

Version 1.0 submitted for peer review.

09/21/12

All

Version 1.1 submitted for PDS release.

12/13/12

All

Version 1.2 initial team RDR review.

03/11/13

All

Version 1.3 release 2 updates.

06/11/13

All

Version 1.4 adjusted SHBDR file name. Submitted for RDR review.

06/18/13

4.2.6.3

Version 1.5 RDR peer review updates.

08/23/13

4.2.4, 7.3.4.1-7.3.4.4

Version 1.6 updated for Version 04 data.

04/01/14

All

Version 1.7 PDS release 5 updates.

06/18/14

4.2.6.3, 7.3.4.1

Version 1.8 PDS release 7 updates.

05/03/16

4.33, 8


1           Purpose and Scope of Document

 

This document provides a detailed description of data products at all levels for the Gravity Recovery and Interior Laboratory (GRAIL) Mission. The data products specified in this document are obtained from the science instruments and subsystems on board the twin GRAIL spacecraft; some include the results of ground data processing carried out by the GRAIL Science Data System (SDS).  Also included are data products from the NASA Deep Space Network (DSN) and products that resulted from processing by GRAIL Science Team members at their home institutions.

 

The GRAIL Science Data System (SDS) is defined as the infrastructure at NASA’s Jet Propulsion Laboratory (JPL) for the collection of all science and ancillary data relevant to the GRAIL mission. It includes hardware, software tools, procedures, and trained personnel. The SDS receives data from three sources (as described below) and carries out calibration, editing, and processing to produce NASA Level 1A and 1B GRAIL science data as described below.

 

The GRAIL archive comprises the following four separate volumes (also known as data sets):

 

GRAIL-L-LGRS-2-EDR-V1.0 – Raw science data, originating from spacecraft telemetry, in time order with duplicates and transmission errors removed. Also known as NASA Level 0 science data (NASA processing levels are described in section 2) and stored in this archive for historical purposes only. All Level 0 products have been processed to Level 1A by the GRAIL SDS.

 

GRAIL-L-LGRS-3-CDR-V1.0 – Calibrated and resampled engineering (e.g., star tracker data and timing) and science data acquired from the Lunar Gravity and Ranging System (LGRS). NASA Level 1A and 1B.

 

GRAIL-L-RSS-2-EDR-V1.0 – Raw Radio Science data acquired at the Deep Space Network.

 

GRAIL-L-LGRS-5-RDR-V1.0 – Lunar gravitational field, NASA Level 2 data. Includes SPICE geometry and navigation kernels created by the GRAIL SDS.  SPICE is the ephemeris, orientation, and event information system developed by the Navigation and Ancillary Information Facility (NAIF) at NASA’s JPL (see section 7.2).

                                                       

 

The above data set identifiers (IDs) may be abbreviated as LGRS EDR, LGRS CDR, RSS EDR, and LGRS RDR in the sections that follow. The first digit in each data set ID refers to the CODMAC processing level (see section 2).


2           Definitions of Data Processing Levels

 

The GRAIL Science Data System (SDS) uses NASA processing levels, which are defined in Table 1.  Data set IDs use the processing levels defined by the Committee on Data Management, Archiving, and Computation (CODMAC), which are also given in Table 1.

Table 1.               Processing Levels

NASA

CODMAC

Description

Packet data

Raw - Level 1

Telemetry with data embedded.

Level 0

Edited - Level 2

Corrected for telemetry errors and split or decommutated according to instrument. Sometimes called Experimental Data Record (EDR). Data are also tagged with time and location of acquisition.

Level 1A

Calibrated - Level 3

Edited data that are still in units produced by instrument, but that have been corrected so that values are expressed in or are proportional to some physical unit such as radiance. No resampling, so original values can be recovered.

Level 1B

Resampled - Level 4

Data that have been resampled in the time or space domains in such a way that the original edited data cannot be reconstructed. Could be calibrated in addition to being resampled.

Level 2

Derived - Level 5

Derived results, as maps, reports, graphics, etc.

 

Ancillary - Level 6

Non-science data needed to generate calibrated or resampled data sets. Consists of instrument gains and/or offsets, pointing information for scan platforms, etc.

 

 

3           Relationships with Other Interfaces

 

The descriptions of data products in this document are consistent with the corresponding descriptions in “dataset” catalog files in the CATALOG directory of each GRAIL volume. File/directory names are consistent with the conventions used in the GRAIL Archive Volume Software Interface Specification (SIS) [16].

 

 

4           Data Product Characteristics and Environment

 

4.1            Instrument Overview

 

Lockheed Martin built GRAIL-A and GRAIL-B as near-twins (Figure 1). Each satellite contains the following components:

 

1)       Rectangular bus

2)       Fixed solar panels

3)       Titanium diaphragm fuel tank

4)       Ultra stable oscillator (USO), which drives onboard LGRS clock and provides frequency reference for S-, X-, and Ka-Band radio systems

5)       Attitude control system (ACS) [23], consisting of:

a.        Four reaction wheels to change attitude

b.       Inertial Measurement Unit (IMU) to measure the rate components of angular rotation

c.        Star Tracker to measure the absolute attitude

d.       Sun Sensor

e.        Eight thrusters, coupled to allow applications of torque

f.         Main engine

6)       Ka-band carrier phase tracking inter-satellite receiver/transmitter

7)       S-band inter-satellite Time Transfer System (TTS)

8)       Two low-gain antennas (LGA) for S-band communication with the DSN

9)       Two Radio Science Beacons (RSB), which transmit X-band carriers to the DSN

 

For the mechanical and optical properties of the spacecraft, see GRAILCOMPONENTS.TXT in the CALIB directory [11].

 

Figure 1: View of GRAIL satellites

There are two payload elements on each GRAIL orbiter: the Lunar Gravity Ranging System (LGRS) which is the science instrument, and the MoonKAM lunar imager which is used for education and public outreach. The LGRS is based on the instrument used for the Gravity Recovery and Climate Experiment (GRACE) mission [32], which has been mapping Earth's gravity since 2002. The LGRS is responsible for sending and receiving the signals needed to accurately and precisely measure the changes in range between the two orbiters. The LGRS consists of an Ultra-Stable Oscillator (USO), Microwave Assembly (MWA), a Time-Transfer Assembly (TTA), and the Gravity Recovery Processor Assembly (GPA). See Figure 2.

Figure 2: Payload Block Diagram [26]

The USO provides a steady reference signal that is used by all of the instrument subsystems. Within the LGRS, the USO provides the reference frequency for the MWA and the TTA. The MWA converts the USO reference signal to the Ka-band frequency, which is transmitted to the other orbiter.

The function of the TTA is to provide a two-way time-transfer link between the spacecraft to both synchronize and measure the clock offset between the two LGRS clocks. The TTA generates an S-band signal from the USO reference frequency and sends a GPS-like ranging code to the other spacecraft. The GPA combines all the inputs received from the MWA and TTA to produce the radiometric data that are downlinked to the Deep Space Network. In addition to acquiring the inter-spacecraft measurements, the LGRS also provides a one-way signal to the DSN based on the USO, which is transmitted via the X-band Radio Science Beacon (RSB). The steady-state drift of the USO is measured via the one-way Doppler data provided by the RSB.

 

4.2            Data Product Overview

 

The scientific goals of the GRAIL project are achieved by measuring the lunar gravitational attraction on the two spacecraft; GRAIL’s instrumentation is specifically designed to sense this through relative motion between the two spacecraft and with DSN stations on Earth. The GRAIL payload on each spacecraft consists of a single science instrument called the Lunar Gravity Ranging System (LGRS), a Ka-band ranging system that determines the precise instantaneous relative range-rate of the two spacecraft. Also, as part of the LGRS, the GRAIL investigation requires a radio link from each spacecraft’s Radio Science Beacon to the stations of the NASA Deep Space Network (DSN).

 

The rest of this section gives an overview of the data products and the measurements GRAIL provides. Product name suffixes indicate NASA processing level. For example, the Level 1A S-band product is named SBR1A, and the Level 1B S-band product is SBR1B.

 

The Algorithm Theoretical Basis Document (ATBD) [15] in the DOCUMENT directory contains a detailed description of the processing flow from EDR to CDR as implemented by the GRAIL SDS.

 

 

                                                            

4.2.1            LGRS EDR (NASA Level 0 Products)

 

The GRAIL SDS receives science packets and engineering data from the JPL Ground Data System (GDS) (Figure 3).  The LGRS EDR data set contains the raw data in time order with duplicates and transmission errors removed.  These data are archived mainly for completeness, as they are immediately processed to Level 1A and/or 1B (the LGRS CDR data set) by the SDS.  There are twelve product types in the LGRS EDR data set:

 

DTC00 - Time Correlation Data Record File (DRF) (ASCII) – Clock correlation among RTC, BTC, and the 1-per-second pulse associated with LGRS time. See section 4.2.2.1.

EHK00 - Spacecraft Engineering Housekeeping data, including temperature sensor data for locations near the LGRS instrumentation (ASCII)

LTB00 - LGRS Time Bias of the Lunar Gravity Ranging System in BTC time (ASCII). Accumulated list of biases over the complete mission. Biases apply to the LGRS time tag of both spacecraft

MAS00 - Satellite Mass Data (ASCII). Accumulated list of center of mass and spacecraft mass over the complete mission.

S7200 - Engineering SFDU ID #72 (binary)

S7300 - Science SFDU ID #73 (binary)

SAE00 - Solar Array Eclipse data, including solar array short circuit currents and open circuit voltages, to identify eclipse events for spacecraft ephemeris models (ASCII)

SCA00 - Star Tracker Data. Including attitudes from an on-board Kalman filter that processes Star Tracker attitude data and Inertial Measurement Unit (IMU) angular rotation data (ASCII)

STC00 - Time Correlation SFDU (binary)

TDE00 - measured time correlation between LGRS time and UTC, using Time Transfer System (TTS) S-Band ranging collected at DSS-24 (ASCII)

THR00 - Thruster Activation Data, including time tags, counts of cumulative work cycles for each thruster, recent thruster ‘on’ time, and cumulative thruster ‘on’ time (ASCII)

WRS00 – Wheel Rotational Speed data, including time tags, measures rotational wheel speed of each of four reaction wheels as determined by a digital tachometer (ASCII)

 

The SFDU products — S7200, S7300, and STC00 — are binary and contain (besides the appropriate headers) the unscaled, binary encoded instrument communication packets. For information on extracting the SFDU data contents. see the following in the DOCUMENT directory:

 

0161_telecomm_L5_8.txt [8]

0171_telecomm_NJPL_L5.txt [20]

090_RevC_1.txt [1], and

0172_Telecomm_CHDO_RevE_L5.TXT [35]

 

Each telemetry packet generated by the LGRS flight software is wrapped inside a packet called a BlackJack Protocol Frame, which ensures the integrity of the data; Blackjack was inherited from the predecessor Gravity Recovery and Climate Experiment (GRACE) terrestrial gravity mission.  The documents GPA_TD_D_71987_REVE.TXT [14] and BlackJackDLP.txt [12] in the DOCUMENT directory describe the format of the Blackjack binary data for processing to Level 1A.

 

The remaining nine LGRS EDR product types are in ASCII format.

 

 

4.2.2            LGRS CDR (NASA Level 1A and Level 1B Products)

 

The LGRS CDR data set contains (calibrated and resampled) Level 1A and 1B science data from the Lunar Gravity Ranging System. All forty-three LGRS CDR file types are in ASCII format. Most of the file types apply to both spacecraft separately. A few apply to both spacecraft together, as they are indicative of a relationship between the two.

 

4.2.2.1        Timing [17]

 

GRAIL timing (discussed further in section 4.3.2) requires coordination of three clocks on each satellite, and two time standards:

1.        LGRS: Lunar Gravity Ranging System clock. Very stable clock for on-board Ka-band ranging (KBR), X-band (RSB), and S-band (TTS) instruments. Driven by an Ultra-Stable Oscillator (USO). Set to 0 when booted. Produces a pulse per second (pps) signal. LGRS time starts at 0 seconds when powered on. The SDS adds a bias to LGRS time to create an approximate UTC time tag. This time will be referred to as LGRS + bias.

2.        BTC: Base Time Clock. On-board satellite clock, comparable in stability to a wristwatch. Roughly synced to UTC at launch time.

3.        RTC: Real Time Clock. Flight software clock. Set to 0 when booted. Relatively unstable clock.

4.        UTC: Coordinated Universal Time.

5.        TDB: Barycentric Dynamical Time.

 

Seven Level 1A products establish the relationships among the clocks:

TC11A: LGRS to BTC, approximated by flight software.

TC21A: LGRS to BTC. more accurate mapping than TC11A, from BTC clock cycle counts.

TC31A: BTC to RTC.

TC41A: LGRS to RTC.

TC51A: RTC to UTC.

TC61A: UTC to TDB. One product applies to both spacecraft.

CLK1A: TDB toLGRS.

 

An approximation of the relativistic time correction from TDB to on-board satellite proper time is calculated in the REL1A product, treating the moon as a point mass, based on [17]:

where  t = proper time, t = coordinate time, U = gravitational potential, v = velocity, and L is a constant offset (1.550520e-8).

 

Measurements from the S-band time transfer system (TTS) are processed to produce DEL1A, which lists inter-satellite LGRS clock offset between spacecraft by TDB time.

 

Radio Science Receivers (RSR), located at DSN sites and discussed in section 4.2.3, record X-band Radio Science Beacon (RSB) signals. Since the LGRS clock drives the RSB, LGRS frequency at TDB can be estimated for USO1A.

 

A PPS1A product is also created, listing the LGRS time of PPS signals.

A least squares fit to DEL1A, CLK1A, and USO1A produces CLK1B and USO1B, best estimates of LGRS to TDB and LGRS frequency at TDB.

 

The TTS Direct-to-Earth (DTE) experiment was devised to independently measure the absolute clock offset between the GRAIL Moon orbiters and Earth. This experiment prompted the development of software for acquiring weak signals and extracting observables (i.e., phase, range, range rate). Data collected during TTS DTE tracks enabled SDS team to compute more accurately the delay in the spacecraft which led to a more accurate gravity field solutions. The TTS DTE activities were done about once per week due to limitations in geometry and equipment availability at the DSN. Specifically, only DSS-24 had the necessary equipment allocated to collect the data.

The TDE00 product is the result of the TTS DTE experiment. TDE00 data provide the only direct measurement of the absolute LGRS time tag. This measurement is used to calibrate the CLK1A product as part of the generation of the CLK1B product.

 

4.2.2.2        Position

 

As an improved estimate for the Moon’s gravity field is built, GRAIL-A and GRAIL-B orbital solutions are improved. Best estimates of the ephemerides are saved in two frames (further detailed in section 4.3.3):

 

GNI1B: EME 2000 Lunar-Centered Solar System Barycentric Frame

 

GNV1B: DE 421 Lunar Body-Fixed Frame

 

From the best ephemeris solution, spacecraft to DSN relative position and light time are computed in EME 2000 (LTM1A), and spacecraft to spacecraft relative position and light time are computed in DE 421 (PLT1A).

 

4.2.2.3        Ka-band

 

GRAIL science depends on estimating the relative movements of GRAIL-A and GRAIL-B. The estimate depends primarily on an inter-satellite Ka-band system: GRAIL-A carrier-phase-tracks a Ka-band signal from GRAIL-B, and GRAIL-B carrier-phase-tracks a Ka-band signal from GRAIL-A. In each continuous phase arc, carrier-phase gives a one-way range, biased by an unknown constant.

 

KBR1A records raw carrier-phase measurements, flagged for phase breaks. Gaps of up to 2 seconds are filled in by quadratic interpolation; longer gaps are classified as “missing data.”

 

KBR1C contains biased dual one-way range between GRAIL-A and GRAIL-B [17], digitally filtered, but not corrected for time of flight or antenna offset. After the dual one-way range combination has been formed, gaps of up to 20 seconds are filled in by quadratic interpolation. KBR1C also contains corrections for time of flight and antenna offset from center of mass.

 

In addition, KBR1C also contains the first and second derivatives of the biased dual one-way range between GRAIL-A and –B and associated time of flight and antenna offset corrections.

 

In general, the instantaneous range, range rate, and range acceleration is used for scientific analysis. The instantaneous range, range rate, and range acceleration are computed by adding the time of flight correction and antenna offset correction to the dual one-way range, range rate, or range acceleration measurement.

 

This (level 1B) product is designated as ‘1C’ to distinguish it from earlier versions of KBR1B which did not contain an additional four columns of information on the temperature range corrections. The raw temperature range correction, filtered temperature range correction, filtered temperature range rate correction, and filtered temperature range acceleration correction are the final four columns of the KBR1C product.

               

 

4.2.2.4        S-band

 

The S-band inter-satellite Time Transfer System (TTS) produces files in parallel to the Ka-band system mentioned above. Carrier phase and a modulating range code are tracked in products SBR1A and SBR1B, which are analogous to KBR1A and KBR1C. In SBR1B, a more accurate range is produced by carrier smoothing over each arc.

 

The SNV1A S-band navigation product contains ancillary information for TTS, which primarily serves to tell the ground whether GRAIL-A and GRAIL-B are communicating correctly with each other.

                                                                                                                                          

4.2.2.5        Satellite Attitude

 

Because GRAIL-A and GRAIL-B antennas are offset from the spacecraft center of mass, distance between GRAIL-A and GRAIL-B Ka-band antennas depends on spacecraft attitude. An on-board Kalman filter processes Star Tracker attitude data and Inertial Measurement Unit (IMU) angular rotation data. Filtered attitudes are saved in SCA1A, tagged by BTC time.

 

SCA1B contains the same results, tagged by TDB.

 

PCI1A lists Ka-band antenna range corrections, range rate corrections, and range acceleration corrections.

 

WRS1A lists rotational wheel speed data for each of the spacecraft’s four reaction wheels, as determined by digital tachometer. WRS1B lists the same information in TDB.

                                                                                                                                             

4.2.2.6        Events

 

GRAIL-A and GRAIL-B events are noted in a variety of files. ILG1A contains log messages from the LGRS.  SAE1A lists solar array short circuit currents and voltages, to identify eclipse events for spacecraft ephemeris models.  THR1A contains thruster activation data, including time tags, cumulative work cycles by thruster, current thruster on time, and cumulative thruster on time.

                                                                                

SAE1B and THR1B contain the same information as in SAE1A and THR1A, but time-tagged by TDB rather than UTC SCET.

 

4.2.2.7        Satellite Condition

 

On-board sensors and a priori information describe spacecraft condition. EHK1A contains temperature sensor data for locations near LGRS instruments. Housekeeping data for the LGRS in IHK1A includes voltage, temperature, and current measurements; IHS1A includes other LGRS status data. MAS1A lists spacecraft mass as a function of UTC time, while VCM1A describes center of mass displacement from the spacecraft mechanical frame origin.

 

EHK1B, MAS1B, and VCM1B list results relative to TDB rather than UTC SCET.

 

The VKB1B file is the Ka boresight vector, as a result of Ka-Band boresight calibration analysis and is stored in VKB1B format in TDB format. Therefore, no VKB1A file exists.

 

4.2.2.8        DSN Tracking

 

GRAIL transmits information to the Deep Space Network using S-band. S-band communication from each GRAIL spacecraft to the DSN depends on a pair of low-gain antennas (LGAs), located on opposite sides of the spacecraft. At a given TDB, only one antenna can communicate with the DSN. The VGS1B product contains a time history of the active S-Band antenna phase center location, in TDB time. The vector is described in the Mechanical Frame (MF).

 

Each GRAIL spacecraft also transmits an unmodulated X-band carrier to the DSN through one of a pair of Radio Science Beacons (RSB). The VGX1B product contains a time history of the active X-Band antenna phase center location, in TDB time, The vector is described in the Mechanical Frame (MF).

 

 

4.2.3            RSS EDR

 

The RSS EDR data set contains raw radio science data, which include DSN Doppler tracking data, open-loop data, media calibrations, and others.

 

4.2.3.1        DSN Radio Data

 

X-Band Open-Loop data, used in the creation of USO1A (LGRS CDR data set), are recorded at the DSN on the Radio Science Receiver (RSR). The RSR is a computer-controlled open loop receiver that digitally records a spacecraft signal using an analog-to-digital converter (ADC) and up to four digital filter sub-channels. The digital samples from each sub-channel are stored to disk in one-second records in real time. In near real time the one-second records are partitioned and formatted into a sequence of RSR Standard Format Data Units (SFDUs) which are transmitted to the Advanced Multi-Mission Operations System (AMMOS) at the Jet Propulsion Laboratory (JPL). Included in each RSR SFDU are the ancillary data necessary to reconstruct the signal represented by the recorded data samples. See 0159_science_l5.txt [9] in the document directory for more information on this data type.

 

S-Band closed-loop data are recorded at the DSN and stored as Orbit Data Files (ODFs). ODFs are produced by the NASA/JPL Multi-Mission Navigation Radio Metric Data Conditioning Team for use in determining spacecraft trajectories, gravity fields affecting them, and radio propagation conditions.  Each ODF consists of many 36-byte logical records, which fall into 7 primary groups plus an End-of-File Group.  An ODF usually contains most groups, but may not have all.  The first record in each of the 7 primary groups is a header record; depending on the group, there may be from zero to many data records following each header. See nav023_odf_2_18_rev3.htm [18] in the document directory for more information.

 

The SDS also archives the Tracking and Navigation File (TNF). The TNF data type captures radiometric tracking data for delivery to navigation and radio science users from the Telecommunications Services at JPL. The product replaces data types formerly known as Archival Tracking Data Files and others. See tnfsis.txt [6] in the document directory for information. Although the TNF is not used for processing by the SDS, it is saved in parallel with the ODF for this archive.

 

RSR data are processed by the SDS to determine the X-Band sky frequency (XFR, an ASCII file) at the DSN versus UTC-Earth Received Time. XFR data are converted into Tracking Data Messages (TDM, also ASCII [34]). From the TDM, the (binary) Open Loop File (OLF) is created. The OLF contains the sky frequency information derived from RSR data, but in the format of the ODF. Along with the closed-loop S-Band ODF, the X-Band OLF is used for orbit determination, which is recorded in the GNI, GNV, LTM, and PLT products in the LGRS CDR data set.

 

The "biased TDM" product (BTM, ASCII [34]) is in exactly the same format as the TDM. It is generated by subtracting off a one-way Doppler frequency bias at X-band from the TDM file containing the raw one-way Doppler measurement provided by the radio science team. The one-way Doppler frequency bias was estimated every orbit (approximately 2 hours) as part of the gravity field determination process and the estimates are reported in the USO1A data product. The one-way Doppler bias is computed by linearly interpolating the one-way Doppler bias time series in the USO1A product to the time tag of the one-way Doppler measurement. The computed one-way Doppler bias is then subtracted from the original raw TDM value and the result in stored in the "biased TDM" product. The "biased TDM" product is intended to remove non-linear drifts in the one-way Doppler bias induced by solar activity during the GRAIL mission.

The (binary) Biased Open Loop File (BOF) is the same format as the OLF and is converted from the BTM.

 

 

4.2.3.2        Ancillary DSN Data

 

To calibrate the radio data recorded at the DSN, several data types are also collected as listed below:

 

The DSN and flight projects use Earth Orientation Parameters (EOP), which include Universal Time and Polar Motion data, in the process of performing orbit determination and generating prediction data. See trk_2_21_950831.txt [21] in the document directory.

 

Ionospheric Media Calibrations (ION) are created by the Radio Metric Modeling and Calibration (RMC) Subsystem and delivered to a central repository on the flight operations network by the DSN Operations and Maintenance Contract (OMC) Media Analyst. Ionosphere calibration files are specific to one spacecraft or other user and provide one calibration per tracking pass or other time period of interest at each Deep Space Communications Complex (DSCC) or Deep Space Station (DSS). See dsn006_medialcal_rev2.htm [27] in the document directory.

 

Tropospheric Media Calibrations (TRO) are created by the Radio Metric Modeling and Calibration (RMC) Subsystem and delivered to a central repository on the flight operations network by the DSN Operations and Maintenance Contract (OMC) Media Analyst. Troposphere calibration files are spacecraft-independent; their calibrations collectively cover all 24 hours of each day at each Deep Space Communications Complex (DSCC) in contiguous “passes” of approximately six hours each. Two troposphere calibrations are provided for each such pass: a “dry” tropospheric delay calibration and a “wet” tropospheric delay calibration. See dsn006_medialcal_rev2.htm [27] in the document directory.

 

Weather data (WEA) provided by the Deep Space Network (DSN) are used by radio science teams and other investigators to estimate meteorological corrections to radio tracking and propagation data. Measurements are recorded at one-minute intervals, thinned to a sampling rate that is determined by the user accuracy requirements, and delivered post-real time at intervals that are determined by the timeliness requirement of the primary users and by negotiations with the various DSN users. There will be one file per weather station at each complex for each delivery interval. See t2_24_l5.htm [10] in the document directory.

 

 

4.2.4            LGRS RDR (NASA Level 2 Products)

 

The LGRS RDR data set contains Level 2 products resulting from analysis of the GRAIL science data.  The products include:

 

The Spherical Harmonics ASCII Data Record (SHADR), which contains ASCII coefficients and/or an ASCII covariance matrix for a spherical harmonic expansion of the lunar gravity field. See shadr.htm [29] in the document directory.

 

The Spherical Harmonics Binary Data Record (SHBDR), which contains binary coefficients and/or a binary covariance matrix for a spherical harmonic expansion of the lunar gravity fields. See shbdr.htm [30] in the document directory.

 

Radio Science Digital Map Products (RSDMAP), which are geoid, isostatic anomaly, Bouguer anomaly, or other digital maps derived primarily from GRAIL science results including the spherical harmonics models above. See rsdmap.htm [19] in the document directory.

 
SPICE Spacecraft and Planet Ephemeris Kernels (SPK), which are the physical realization of two logical elements of the SPICE system––the S-kernel (spacecraft ephemeris) and the ephemeris portion of the P-kernel (planet, satellite, asteroid and comet ephemerides). When read using an appropriate subroutine from the SPICE Toolkit, an SPK file will yield state vectors––Cartesian position and velocity––of one user-specified ephemeris object relative to another, at a specified epoch and in a specified reference frame. See SPK_MM_SIS.HTM [5] in the document directory.
 
The SPK products in this data set differ from those archived by GRAIL navigation; they are created by the GRAIL SDS and make use of the LGRS to provide a more refined solution than those produced by GRAIL Navigation.
 

4.2.5            Data Flow and Product Generation

 

As shown in the downlink data flow diagram (Figure 3), telemetry packets from the Deep Space Network (DSN) are placed on the Telemetry Delivery System (TDS).  Science data and engineering data packets are transferred from the TDS to the GRAIL SDS computers on a regular basis. The SDS also receives Level 1 Doppler (tracking) data from the Radio Science Group (X-band) and the Tracking Data System (S-band). Finally, the SDS receives high-rate telemetry data from the Multi-Mission Distributed Object Manager (MMDOM) servers, placed there by the Lockheed Mission Operations Center (MOC).

 

Figure 3. GRAIL Science Downlink Data Flow Diagram

 

 

4.2.6            Labeling and Identification

 

4.2.6.1        LGRS EDR and LGRS CDR File Naming Convention

 

For all LGRS data, the product identifier, in conjunction with either a date or a range of dates in a specified format, determines the filename containing the data product.

 

The file naming convention for most Level 0/1A/1B LGRS products is:

 

PRDID_YYYY_MM_DD_S_VV.EXT

 

where

 

                PRDID                    product identification label, e.g. CLK1B

                YYYY                     year

                MM                        month

                DD                          day of month

                S                              GRAIL satellite identifier:

                                                                A             GRAIL-A

                                                                B             GRAIL-B

                                                                X             combined product of GRAIL-A and GRAIL-B

                VV                           data product version number (starting from 00)

                EXT                        file extension indicating binary (DAT) or ASCII (ASC) files

 

The Product ID (PRDID) is of the form XXXLL, where:

                XXX                       is a three-character mnemonic, and

                LL                           specifies the data product Level (00, 1A, 1B).

 

The only exception to this naming convention is TDE00. To accommodate multiple direct-to-earth measurements within the same day, the convention is the same as above with the addition of the start time in seconds past midnight (NNNNN):

PRDID_YYYY_MM_DD_S_NNNNN_VV.EXT

 

 

4.2.6.2        RSS EDR File Naming Convention

 

Orbit Data Files (ODFs) and Tracking and Navigation Files (TNFs) are named, respectively, as follows:

 

sssttaayyyy_ddd_hhmmwuudV#.odf,

sssttaayyyy_ddd_hhmmwuudV#.tnf,

 

where

sss                          3-character spacecraft identifier

                                                GRA       GRAIL-A

                                                GRB        GRAIL-B

                                                GRX        both

tt                             Target ID, e.g., LU = Moon

aa                            Activity/Experiment ID, e.g. GF = gravity field

yyyy                       year

ddd                         day of year

hhmm                     hours/minutes

w                             Ground Transmitter Band(s):

N             none

M            multiple

S              S-band

X             X-band

uu                           Uplinking Station(s) = the DSN station number, or

NN          none

MM        multiple

d                              way

                                                1              one-way

                                                2              two-way

M            multiple

V#                           version number

 

Radio Science Receiver (RSR) data, Tracking Data Messages (TDM), Biased Tracking Data Messages (BTM), Sky Frequency Files (XFR), Open Loop Files (OLF), and Biased Open Loop Files (BOF) are named, respectively, as follows:

 

sssttaayyyyddd_hhmmxuudrrpD.rcs,

sssttaayyyyddd_hhmmxuudrrpD.tdm,

sssttaayyyyddd_hhmmxuudrrpD.btm,

sssttaayyyyddd_hhmmxuudrrpD.xfr,

sssttaayyyyddd_hhmmxuudrrpD.olf

sssttaayyyyddd_hhmmxuudrrpD.bof

 

 

where:

sss                          3-character spacecraft identifier

GRA       GRAIL-A

GRB        GRAIL-B

tt                             Target ID, e.g., LU = Moon

aa                            Activity/Experiment ID, e.g. GF = gravity field

yyyy                       year

ddd                         day of year

hhmm                     hours/minutes

xuu                          Uplink Transmitter Band (e.g., S, X) and 2-digit Uplinking Station number, or

"NNN" = 1-way

drr                           Downlink Band (e.g., X) and 2-digit Receiving Station number

p                              Polarization

L = left hand;

R = right hand;

M = mixed

D                             Open-loop data type

D             RSR data

V             VSR data

W            WVSR data

rcs                           RSR number + channel + subchannel

tdm                         Tracking Data Message

btm                         Biased Tracking Data Message

xfr                            Sky Frequency File

olf                           Open Loop File

bof                          Biased Open Loop File

 

Ionospheric Media Calibration (ION) files, Tropospheric Media Calibration (TRO) files, Earth Orientation Parameter (EOP) files, and weather (WEA) files are named, respectively, as follows:

 

sssttaaYYYY_DDD_yyyy_ddd.ion,

sssttaaYYYY_DDD_yyyy_ddd.tro,

sssttaaYYYY_DDD_yyyy_ddd.eop,

sssttaaYYYYDDDyyyyddd_##.wea,

 

where:

sss                          3-character spacecraft identifier

                                                GRA       GRAIL-A

                                                GRB        GRAIL-B

                                                GRX        both

tt                             Target ID, e.g., LU = Moon

aa                            Activity/Experiment ID, e.g. GF = gravity field

YYYY                     start year

DDD                       start day of year

yyyy                       end year

ddd                         end day of year

 ##                         DSN station number

 

 

4.2.6.3        LGRS RDR File Naming Convention

 

Spherical Harmonics ASCII Data Records (SHADR) and Spherical Harmonics Binary Data Records (SHBDR) are named, respectively, as follows:

 

GTsss_nnnnvv_SHA.TAB,

GTsss_nnnnvv_SHB_Lccc.DAT,

 

where

G             denotes the generating institution

J              Jet Propulsion Laboratory

G             Goddard Space Flight Center

M            Massachusetts Institute of Technology

T             indicates the type of data represented

G             gravity field

sss          a 3-character modifier specified by the data producer. This modifier is used to indicate the source spacecraft or project, such as GRX (the pair of GRAIL spacecraft).

nnnnvv  a 4- to 6-character modifier specified by the data producer. Among other things, this modifier may be used to indicate the target body, whether the SHADR contains primary data values as specified by "T" or uncertainties/errors, and/or the version number. For GRAIL, this modifier indicates the degree and order of the solution for the gravity field.

"SHA" or “SHB” denotes that this is an ASCII or binary file, respectively.

“Lccc” is a 2- to 4-character modifier specified by the data producer to indicate the degree and order to which degree (L) the gravity covariance has been truncated, if applicable.

"TAB" or “DAT” denotes that this is an ASCII or binary file, respectively.

 

Bouguer gravity data products will have the name "Bouguer" following the degree and order identifier, i.e. GTsss_nnnnvv_BOUGUER_SHA.TAB

 

Radio Science Digital Map Products (RSDMAP) are named as follows:

 

GTsss_ffff_nnnn_cccc.IMG,

 

where

G             denotes the generating institution:

J              Jet Propulsion Laboratory

G             Goddard Space Flight Center

M            Massachusetts Institute of Technology

T             indicates the type of mission data represented:

G             gravity field

sss          a 3-character modifier specified by the data producer. This modifier is used to indicate the source spacecraft or project, such as GRX (the pair of GRAIL spacecraft).

ffff           a 4- to 6-character modifier specified by the data producer to indicate the degree and order of the solution for the gravity field.

nnnn       a 4- to 8-character modifier indicating the type of data represented:

ANOM                   free air gravity anomalies

ANOMERR           free air gravity anomaly errors (1)

GEOID                    geoid heights

GEOIDERR            geoid height errors (1)

BOUG                     Bouguer anomaly

ISOS                       isostatic anomaly

TOPO                     topography

MAGF                    magnetic field

DIST                    gravity disturbances

DEGSTR             degree strength

(1) Geoid and gravity anomaly errors are computed from a mapping of the error covariance matrix of the gravity field solution.

cccc        a 2- to 4-character modifier specified by the data producer to indicate the degree and order to which the potential solution (gravity, topography or magnetic field) has been evaluated. In the case of the error maps for the gravity anomalies or geoid, this field indicates to which maximum degree and order the error covariance was used to propagate the spatial errors.

.IMG       the data is stored as an image.

 

 

Spacecraft and Planet Ephemeris Kernels (SPK) are named as follows:

 

sssttaaYYYY_DDD_yyyy_ddd.spk,

 

where:

sss                          3-character spacecraft identifier

GRA       GRAIL-A

GRB        GRAIL-B

GRX        both

tt                             Target ID, e.g., LU = Moon

aa                            Activity/Experiment ID, e.g. GF = gravity field

YYYY                     start year

DDD                       start day of year

yyyy                       end year

ddd                         end day of year

 

 

4.3            Standards Used in Generating Data Products

4.3.1            PDS Standards

All data products comply with Planetary Data System standards [25] for file formats and labels.

4.3.2            Time Standards

 

The objective of the GRAIL mission is to determine with high accuracy the lunar gravity field for scientific research. The input data for the gravity field determination process are Ka-Band phase measurements between the two GRAIL spacecraft; the phase measurements are used to compute the dual one-way range (DOWR). The DOWR measurement is then converted to instantaneous range, range rate and range acceleration measurements, which serve as inputs to the gravity field estimation process. Very accurate timing of the GRAIL measurements is crucial to achieving the high accuracy measurements needed for a high quality gravity field.

 

Science data from the GRAIL spacecraft are time tagged by onboard clocks. However, most of the SDS scientific computer programs process data with Barycentric Dynamic Time (TDB).  Timing data from the Deep Space Network (DSN) and the onboard Time Transfer System (TTS) and frequency observations from the Radio Science Receiver (RSR) are combined to estimate the time tag conversion for the GRAIL science data.  Figure 4 provides an overview of the relationships among the three timing systems; the three subsections which follow have additional detail.

 

 

 

 Figure 4. GRAIL clocks, models, and measurements used for timing [17]

 

 

 

4.3.2.1        LGRS clock

 

Each spacecraft has an LGRS clock; its USO frequency reference makes it very stable. The LGRS clock is used for timing of the LGRS Ka-Band phase measurement and the ranging data from the TTS. The LGRS clock has no notion of absolute time; instead, the LGRS clock reading is with respect to its startup epoch.

 

4.3.2.2        Onboard spacecraft clocks

 

The Onboard Spacecraft Clocks (OSC) are run by crystal oscillators, which have inferior stability characteristics compared to the USO (and LGRS clock). The two OSC clocks are the Real Time Clock (RTC) and the Base Time Clock (BTC). The real time clock starts at 0 at boot-up of the onboard computer, whereas the Base Time Clock is set at launch and is never reset. The OSCs are used for time tagging all spacecraft data and the arrival of the LGRS data packets (which include the LGRS 1 Pulse per Second (PPS) packets) by the onboard computer. By time tagging the arrival of LGRS data packets and the arrival of the LGRS 1 PPS, a time correlation can be established between the LGRS clock and the OSCs.

 

The RTC is used to time stamp spacecraft time correlation packets, which are then transmitted to a DSN station where the arrival time is recorded in UTC, thus providing a time correlation between the RTC and UTC. By combining LGRS/BTC, BTC/RTC, and RTC/UTC time correlation products, a time correlation between the LGRS and UTC can be determined, and the OSC clocks drop out.  Hence, the stability characteristics of the OSCs do not affect the LGRS and UTC time correlation because the OSC errors over short intervals (< 1 second) are less than 1 microsecond.

 

4.3.2.3        UTC clock used by DSN

 

The DSN uses very stable clocks which are based on the DSN Frequency and Timing Subsystem (FTS) [33]. The DSN time stamps the arrival of telemetry and radio metric tracking data in UTC. Based on FTS reports, the real-time timing performance is at the microsecond level and post processing analysis improves the performance to the nanosecond level.

 

4.3.3            Coordinate Systems

 

Four coordinate systems are used to define the various GRAIL data products; see [23] for detail. The definitions are summarized below.

 

1)       Mechanical Frame (MF) (Figure 5): This is defined by the spacecraft manufacturer. It is the reference frame for such things as KBR horn location, center of mass, and thruster locations (Figures 6 and 7).

                                                                                                                                   

+XM = Parallel to, and in opposite direction from, the solar array normal vector

+ZM = Normal to star tracker bus plate

+YM = +ZM ´ +XM

 

An onboard attitude control system approximately orients the mechanical frame with -ZM along the line of flight and -/+ YM pointed towards the moon. For the orientation of the mechanical frame, during the primary and extended missions, see figures 8 and 9.

 

2)       Science Reference Frame (SRF): This is the Mechanical Frame as realized by the Star Tracker. If the Star Tracker were perfectly aligned, MF would equal SRF. SRF is the reference frame for GRAIL science measurements.

 

3)       EME 2000 Lunar-Centered Solar System Barycentric Frame: This is the Earth Mean Equator 2000 inertial reference frame [31], re-centered at the moon using the DE 421 planetary ephemeris. It is the reference frame for ephemeris products.

 

4)       DE 421 Lunar Body-Fixed Frame: This is the lunar body-fixed frame as defined in the DE 421 planetary ephemeris [13].  It is the reference frame for gravity products.  GRGM1200A products use the DE 430 ephemeris [37].

 

Figure 5: The GRAIL Mechanical Frame (MF) [23]

Figure 6: GRAIL thruster locations (XYZ is the same as XMYMZM in text)

 

Figure 7: GRAIL thruster locations (XYZ is the same as XMYMZM in text)

Figure 8: GRAIL primary science spacecraft configuration (XYZ is the same as XMYMZM in text)

 

Figure 9: GRAIL extended science spacecraft configuration (XYZ is the same as XMYMZM in text)

 

 

4.4            Data Validation

 

Data validation occurs in three steps: validation of the data themselves, validation of the correctness and completeness of the data set documentation, and validation of the compliance of the archive with PDS standards. The primary method by which Science Team members will validate the various archive products is by using them for their own science. Calibrated data files (CDRs) will be derived from the raw data files (EDRs) in the archive; then reduced data records (RDRs) will be created from the archival CDRs. Errors in the raw and calibrated data products are likely to be caught by the science team in this process. The formal validation of data content, adequacy of documentation, and adherence to PDS archiving standards is finalized with an external peer review.

 

 

5           Detailed Data Product Specifications

 

5.1            Data Product Structure and Organization

 

The following table lists product identifiers and pointers to the corresponding format descriptions. Format descriptions can be found in the listed documents or in this document in section 5.2, Tables 3 through 53.  Some products have headers, which are discussed in Section 5.3; all products have PDS labels, which are also discussed in Section 5.3.

 

A summary of all data products, including their product identifiers, follows.

 


Table 2.               Summary of Data Products

Data

Set

Product

Identifier

(XXXLL)

S/C*

Clock

Product

Format Description in DOCUMENT Directory…

… or Section 5.2 Table

LGRS

EDR

DTC00

A/B

UTC SCET

Time Correlation Data Record File (DRF)

 

3

EHK00

A/B

UTC SCET

Spacecraft Engineering Housekeeping Data

 

4

LTB00

X

BTC

LGRS Time Bias

 

5

MAS00

A/B

UTC SCET

Satellite Mass Data

 

6

S7200

A/B

UTC SCET

Engineering SFDU (ID #72)

0161_TELECOMM_L5_8.LBL

0171_TELECOMM_NJPL_L5.LBL

090_REVC_1.LBL

0172_TELECOMM_CHDO_REVE_L5.LBL

GPA_TD_D_71987_REVE.LBL

BLACKJACKDLP.LBL

 

S7300

A/B

UTC SCET

Science SFDU (ID #73)

0161_TELECOMM_L5_8.LBL

0171_TELECOMM_NJPL_L5.LBL

090_REVC_1.LBL

0172_TELECOMM_CHDO_REVE_L5.LBL

GPA_TD_D_71987_REVE.LBL

BLACKJACKDLP.LBL

 

SAE00

A/B

UTC SCET

Solar Array Eclipse Data

 

7

SCA00

A/B

UTC SCET

Star Tracker Data

                       

8

STC00

A/B

UTC SCET

Time Correlation SFDU

0161_TELECOMM_L5_8.LBL

0171_TELECOMM_NJPL_L5.LBL

090_REVC_1.LBL

0172_TELECOMM_CHDO_REVE_L5.LBL

 

TDE00

A/B

UTC ERT

Time Transfer System Direct to Earth

 

9

THR00

A/B

UTC SCET

Thruster Activation Data

 

10

WRS00

A/B

UTC SCET

Wheel Rotational Speed Data

 

11

LGRS

CDR

CLK1A

A/B

TDB

TDB to LGRS time correlation

 

12

DEL1A

X

LGRS + Bias

Inter-satellite LGRS clock offset

 

13

EHK1A

A/B

UTC SCET

Spacecraft temperature sensor data from Engineering Housekeeping data

 

14

IHK1A

A/B

LGRS +Bias

LGRS Housekeeping Data

 

15

IHS1A

A/B

LGRS + Bias

Level 1A LGRS Health Status data

 

16

ILG1A

A/B

LGRS + Bias

LGRS log messages

 

17

KBR1A

A/B

LGRS + Bias

Ka-Band Ranging Data

 

18

LTM1A

A/B

TDB

Position vector and light time between one S/C and DSN station

 

19

MAS1A

A/B

UTC SCET

Satellite Mass Data

 

20

PCI1A

A/B

TDB

Phase Center to Center of Mass Correction

 

21

PLT1A

X

TDB

Position vector and light time between two spacecraft

 

22

PPS1A

A/B

LGRS + Bias

LGRS Pulse Per Second (PPS) Time Record

 

23

REL1A

A/B

TDB

Relativistic time correction (TDB to onboard satellite proper time)

 

24

SAE1A

A/B

UTC SCET

Solar Array Eclipse Data

 

25

SBR1A

A/B

LGRS + Bias

S-Band Ranging Data

 

26

SCA1A

A/B

BTC

Star Tracker Data

 

27

SNV1A

A/B

LGRS + Bias

S-Band navigation product

 

28

TC11A

A/B

LGRS + Bias

LGRS to BTC time correlation

 

29

TC21A

A/B

LGRS + Bias

LGRS to BTC time correlation from BTC clock cycle counts

 

30

TC31A

A/B

BTC

BTC to RTC time correlation

 

31

TC41A

A/B

LGRS + Bias

LGRS to RTC time correlation

 

32

TC51A

A/B

RTC

RTC to UTC time correlation

 

33

TC61A

X

UTC

UTC to TDB time correlation

 

34

THR1A

A/B

UTC SCET

Thruster Activation Data

 

35

USO1A

A/B

TDB

Oscillator frequency data

 

36

VCM1A

A/B

UTC SCET

center of mass displacement from spacecraft mechanical frame origin

 

37

WRS1A

A/B

UTC SCET

Wheel Rotational Speed Data

 

38

CLK1B

A/B

LGRS + Bias

Time correlation between LGRS time +Bias and TDB

 

39

EHK1B

A/B

TDB

Spacecraft temperature sensor data from Engineering Housekeeping Data

 

40

GNI1B

A/B

TDB

satellite orbit solution in Moon centered Inertial frame

 

41

GNV1B

A/B

TDB

satellite orbit Solution in lunar body fixed frame

 

42

KBR1C

X

TDB

Dual-One-Way Ka-Band Ranging Data

 

43

MAS1B

A/B

TDB

Satellite Mass Data

 

44

SAE1B

A/B

TDB

Solar Array Eclipse Data

 

45

SBR1B

X

TDB

Dual one-way S-Band Ranging data

 

46

SCA1B

A/B

TDB

Star Tracker Data

 

47

THR1B

A/B

TDB

Thruster Activation Data

 

48

USO1B

A/B

TDB

USO Frequency Estimate

 

49

VCM1B

A/B

TDB

center of mass displacement from spacecraft mechanical frame origin

 

50

VGS1B

A/B

TDB

S-Band antenna offset vector and switch time (TDB time)

 

51

VGX1B

A/B

TDB

X-Band antenna offset vector and switch time (TDB time)

 

52

VKB1B

A/B

TDB

Ka-Band Boresight Vector

 

53

WRS1B

A/B

TDB

Wheel Rotational Speed Data

 

54

RSS

EDR

BOF

A/B

UTC

Biased Open Loop File

SEE LABEL FILE

 

BTM

A/B

UTC

Biased Tracking Data Message Standard

 

55

EOP

X

TDB

Earth Orientation Parameters

TRK_2_21_950831.LBL

 

ION

A/B

UTC

Ionospheric Media Calibration

DSN006_MEDIACAL_REV2.LBL

 

ODF

A/B

UTC

Tracking Data, Orbit Data File

SEE LABEL FILE

 

OLF

A/B

UTC

Open Loop File

SEE LABEL FILE

 

RSR

A/B

UTC

Radio Science Receiver 0159

SEE LABEL FILE

 

TDM

A/B

UTC

Tracking Data Message Standard

 

56

TNF

A/B

UTC

Tracking and Navigation File

TNFSIS.LBL

 

TRO

X

UTC

Tropospheric Media Calibration

DSN006_MEDIACAL_REV2.LBL

 

WEA

X

UTC

Weather Files

TRK_2_24.LBL

 

XFR

A/B

UTC

X-Band sky frequency

 

57

LGRS RDR

RSDMAP

X

N/A

Radio Science Digital Map Products

RSDMAP.LBL

 

SHADR

X

N/A

Spherical Harmonics ASCII Data Record

SHADR.LBL

 

SHBDR

X

N/A

Spherical Harmonics Binary Data Record

SHBDR.LBL

 

SPK

A/B

TDB

Spacecraft Ephemeris Kernel

SPK_MM_SIS.LBL

 

* Spacecraft: Value “A/B” means that there is one file for GRAIL-A and a second file for GRAIL-B; value “X” means that GRAIL-A and GRAIL-B data are combined into a single file

 

 

5.2            Data Format Descriptions

 

For all LGRS RDR data, see documentation in Table 2 for format descriptions.

 

5.2.1            LGRS EDR (Level 0) Products

 

For S7200, S7300, and STC00 in LGRS EDR, see documentation in Table 2 for format descriptions. All other LGRS EDR (Level 0) products are in ASCII format and are delimited by a variable number of white spaces as described in Tables 3 through 10.

 

Table 3.               DTC00 Record Format

Column #

DTC00

Time Correlation (DRF) Record

Data may be missing in fields 2 through 7

1

UTC SCET (YY/DDD-HH:MM:SS.sss)

2.

Clock BTC fractional second counter (1/65536 seconds)

3.

Clock BTC second counter

4.

Clock USO fractional seconds count (1/65536 seconds) since last 1 PPS arrival at on board computer

5.

Clock USO seconds counter since last 1 PPS arrival at on board computer

6.

BTC Bias (seconds)

7.

RTC Seconds

8.

Application Packet ID

 

Table 4.               EHK00 Record Format

Column #

EHK00

Level 0 Space temperature sensors for KBR data correction

1.

UTC SCET Time YY/DDD-HH:MM:SS.sss

2.

(Microwave Assembly T1 Temperature in C + 273.0718) / 0.1220652

3.

(Microwave Assembly T2 Temperature in C + 273.0718) / 0.1220652

4.

(Waveguide Transmit Module Ka-Band Assembly temperature in C + 273.0718) / 0.1220652

5.

(Waveguide Transmit Module Microwave Assembly temperature in C + 273.0718) / 0.1220652

6.

(Waveguide Receive Module Middle of Span temperature in C + 273.0718) / 0.1220652

7.

(Waveguide Transmit Module Middle of Span temperature in C + 273.0718) / 0.1220652

8.

(Aperture temperature in C + 273.0718) / 0.1220652

9.

(Radome temperature in C + 273.0718) / 0.1220652

10.

(Horn Base temperature in C + 273.0718) / 0.1220652

11.

(Midway on Horn temperature in C + 273.0718) / 0.1220652

12.

(Orthomode transducer (where transmit and receive modules are split off at base of horn) temperature + 273.0718) / 0.1220652 in C

13.

Ground Data System Application Packet Identification

 

Table 5.               LTB00 Record Format

Column #

LTB00

LGRS Time Bias

1

BTC time (seconds)

2.

LGRS Bias (seconds)

 

Table 6.               MAS00 Record Format

Column #

MAS00

Level 0 Spacecraft  Mass Data

1.

Spacecraft Event name

2.

UTC SCET Date MM/DD/YYYY

3.

UTC SCET Day of Year YY-DDD

4.

UTC SCET Maneuver End Time HH:MM:SS.sss

5.

Fuel Mass Remaining Book Keeping (kg)

6.

Fuel Mass Remaining Book Keeping Uncertainty (kg)

7.

Post Maneuver Spacecraft Mass

8.

Post Maneuver Center of Mass X coordinate (meters) in mechanical reference frame

9.

Post Maneuver Center of Mass Y coordinate (meters) in mechanical reference frame

10.

Post Maneuver Center of Mass Z coordinate (meters) in mechanical reference frame

11.

Post Maneuver Boresight Vector X coordinate

12.

Post Maneuver Boresight Vector Y coordinate

13.

Post Maneuver Boresight Vector Z coordinate

 

Table 7.               SAE00 Record Format

Column #

SAE00

Level 0 Solar array eclipse data

1.

UTC SCET Time YY/DDD-HH:MM:SS.sss

2.

Solar array short circuit current (Amperes / 2.442000E-04), as reported by the Solar Array Battery Control

3.

Solar array open circuit voltage (Volts / 9.760000E-04), as reported by the Solar Array Battery Control

4.

GDS Application Packet Identification

 

Table 8.               SCA00 Record Format

Column #

SCA00

Level 0 Star Tracker Data

1.

UTC SCET Time YY/DDD-HH:MM:SS.sss

2.

1st element of current spacecraft attitude quaternion based on the onboard filter, phased as inertial to body.

3.

2nd element of current spacecraft attitude quaternion based on the onboard filter, phased as inertial to body.

4.

ADS (quat_body(3)).  3rd element of current spacecraft attitude quaternion based on the onboard filter, phased as inertial to body.

5.

ADS (quat_body(4)).  Scalar component of current spacecraft attitude quaternion based on the onboard filter, phased as inertial to body.

6.

Star tracker time stamp (SCLK) of current spacecraft attitude quaternion based on the onboard filter

7.

GDS Application Packet Identification number

 

Table 9.               TDE00 Record Format

Column #

TDE00

Time Transfer System Direct to Earth Data

1.

DERT = UTC-ERT: Seconds past initial start time in header (Data Date), indicating the time at which measurements in columns 2-4 were made

2.

Range (seconds), integrated carrier phase measurement with N-cycle ambiguity unresolved

3.

Pseudo range (seconds). Equal to Column 1 minus Column 4 plus a constant to set the pseudo range equal to zero at the start of the first observation of the primary and extended mission

4.

Transmit Time of the TTS range code in LGRS time (seconds). Computed by decoding the GRAIL data message and adding fractional timing information from the Code Delay Lock Loop

 

Table 10.            THR00 Record Format

Column #

THR00

Level 0 Thruster Activation Data

1.

UTC SCET Time YY/DDD-HH:MM:SS.sss

2.

The cumulative on time for thruster Attitude Control System 1 (milliseconds).

3.

The cumulative on time for thruster Attitude Control System 2 (milliseconds).

4.

The cumulative on time for thruster Attitude Control System 3 (milliseconds).

5.

The cumulative on time for thruster Attitude Control System 4 (milliseconds).

6.

The cumulative on time for thruster Attitude Control System 5 (milliseconds).

7.

The cumulative on time for thruster Attitude Control System 6 (milliseconds).

8.

The cumulative on time for thruster Attitude Control System 7 (milliseconds).

9.

The cumulative on time for thruster Attitude Control System 8 (milliseconds).

10.

GDS Application Packet Identification

 

Table 11.            WRS00 Record Format

Column #

WRS00

Level 0 Wheel Rotational Speed Data

1.

UTC SCET Activation Time YY/DDD-HH:MM:SS.sss

2.

Reaction wheel 1 rotational speed as determined by digital tachometer (radians/sec)

3.

Reaction wheel 2 rotational speed as determined by digital tachometer (radians/sec)

4.

Reaction wheel 3 rotational speed as determined by digital tachometer (radians/sec)

5.

Reaction wheel 4 rotational speed as determined by digital tachometer (radians/sec)

 

 

 


5.2.2            LGRS CDR Products

 

All LGRS CDR (Level 1A & 1B) products are in ASCII format and are delimited by a variable number of white spaces as described in Tables 11 through 51.

 

Many of the following data types contain data product flags. Read right to left, the data product flags indicate, with a 1, the presence of a certain field (column) or, with a 0, the absence of that field in the remainder of the record. Fields indicated as being present will exist in the file in consecutive columns in the same order as shown in Tables 11 through 51, with no gaps or spaces for fields indicated as absent. As a result, the number of fields may vary from record to record and there will never be as many fields in the data record as columns specified in the governing table (unless all data product flag digits have been set to 1).

 

Some data types contain data quality flags, in which a 1 indicates that the corresponding description is true. The digits in the data quality flags are also read right to left.

 

For example, a KBR1A file might contain, in the data product flags, a 1 at digit 13 (fourteenth digit from the right), and the rest zeros. This would indicate that after the data quality flags in column seven, the eighth column would contain Ka-Band carrier phase data. There would be no additional columns for fields represented by zeros in the data product flag.

 

Some SBR1A files have records with data product flags 0000001000001000, meaning that received S-Band carrier phase and S-Band receiver channel follow the data quality flags.  Other records in the same file have data product flags 0000001001001001, meaning that S-Band pseudo-range, received S-Band carrier phase, S-Band SNR, and S-Band receiver channel follow the data quality flags in that order.  Thus, records with 9 fields are interleaved with records having 11 fields; no SBR1A record has all 23 columns defined.

 

5.2.2.1        Level 1A

 

Table 12.            CLK1A Record Format

Column #

CLK1A

Level 1A TDB to LGRS + Bias time correlation

1.

TDB time , in integer seconds

2.

TDB time , microseconds part

3.

Input Time scale where ‘T’ = TDB

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

Not applicable

6.

eps_time (seconds), where LGRS + bias Time = TDB  time + eps_time

7.

Formal error on eps_time (s) (not used by GRAIL, set to 0)

8.

clock drift (s/s); if not calculated, then set to 0

9.

Formal error on clock drift (s/s); if not calculated, then set to 0

10.

bitrate of SFDU packet; if not calculated, then set to 0

11.

delay by bitrate of SFDU packet; if not calculated, then set to 0

12.

data quality flags (digit 0 is on the right, digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = 1 -> linear extrapolation not valid AFTER input time

digit  1 = 1 -> linear extrapolation not valid BEFORE input time

digit  2 = 1 -> filled data using KBR1C

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 13.            DEL1A Record Format

Column #

DEL1A

Inter-satellite LGRS clock offset between spacecraft

1.

TDB time, in integer seconds

2.

TDB time, microseconds part

3.

Input Time scale where ‘T’ = TDB

4.

GRAIL satellite ID ‘X’ to indicate a single product for two spacecraft

5.

Not applicable

6.

eps_time (in LGRS seconds), where   eps_time = LGRS-A clock – LGRS-B clock

7.

Formal error on eps_time (s); if not calculated, then set to 0

8.

Clock offset corrected for LGRS resets. Identical to column 6 if no reset.

9.

Formal error on clock drift (s/s); if not calculated, then set to 0

10.

bitrate of SFDU packet; if not calculated, then set to 0

11.

delay by bitrate of SFDU packet; if not calculated, then set to 0

12.

data quality flags (digit 0 is on the right, digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = 1 -> linear extrapolation not valid AFTER input time

digit  1 = 1 -> linear extrapolation not valid BEFORE input time

digit  2 = 1 -> filled data using KBR1C

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 14.            EHK1A Record Format

Column #

EHK1A

Level 1A Spacecraft temperature sensor data from Engineering Housekeeping data for KBR data correction

1.

UTC SCET, integer seconds past 12:00:00 noon 01-Jan-2000

2.

UTC SCET, microseconds part

3.

Time reference where 'U' = UTC SCET

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

Microwave Assembly T1 temperature in C

6.

Microwave Assembly T2 temperature in C

7.

Waveguide transmit Ka-Band Assembly temperature in C

8.

Waveguide transmit Microwave Assembly temperature in C

9.

Waveguide Rx Mid temperature in C

10.

Waveguide Tx Mid temperature in C

11.

Aperture temperature in C

12.

Radome temperature in C

13.

HornBase temperature in C

14.

Midway on Horn temperature in C

15.

Orthomode Transducer (where transmit and receive modules are split off at base of horn) temperature in C

16.

data quality flags  (digit 0 is on the right, digit 7 is on the left)

LSB    = digit 0

digit  0 = Not Defined

digit  1 = Not Defined

digit  2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 15.            IHK1A Record Format

Column #

IHK1A

Level 1A LGRS Housekeeping Data

1.

LGRS time +Bias, integer seconds past 12:00:00 noon 01-Jan-2000

2.

LGRS time +Bias, microseconds part

3.

Time reference where 'R' = LGRS time +Bias

4.

GRAIL satellite ID

5.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = No On-Board Data Handler->Receiver time mapping

digit 7 = No Clock correction available

6.

Observation type

V = Voltage in Volts

T = Temperature in Degrees C

I = Current in Amperes

? = Observation type not applicable

7.

Value of observation

8.

Sensor name

 

Table 16.            IHS1A Record Format

Column #

IHS1A

LGRS Health Status Data

1.

LGRS time +Bias, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

Clock offset reported in latest time transfer packet (seconds)

4.

Seconds expired since last reboot

5.

time reported in latest PPS Time packet (seconds) in LGRS time

6.

count of times since reboot that integrity monitor has restarted trackers

7.

SNR reported in latest Ka band quadratic fit packet (0.1 dB-Hz)

8.

SNR reported in latest S-band quadratic fit packet (V/V)

9.

Data quality flags (digit 0 is on the right and digit 7 is on the left)

LSB    = digit 0

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

 

Table 17.            ILG1A Record Format

Column #

ILG1A

LGRS Log Messages

1.

LGRS+Bias time, seconds past 12:00:00 noon 01-Jan-2000

2.

counts packets with that rcv_time (1,2,3,...)

3.

GRAIL satellite ID ‘A’ or ‘B’

4.

carriage-return terminated  log message string

 

Table 18.            KBR1A Record Format

Column #

KBR1A

Level 1A Ka-Band Ranging Data

1

LGRS time +Bias, integer seconds past 12:00:00 noon 01-Jan-2000 (s)

2.

LGRS time +Bias, microseconds part

3.

GRAIL satellite ID ‘A’ or ‘B’

4.

GRAIL transmission channel number

50 for Ka-Band for both spacecraft

5.

KBR antenna ID on GRAIL spacecraft

ant_id = 11 for KBR antenna

6.

data product flags. Set digits indicate quantities stored after column 7 as follows (digit 0 is on the right and digit 15 is on the left):

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

digit 8 = Not Defined

digit 9 = Not Defined

digit 10 = Not Defined

digit 11 = Not Defined

digit 12 = Correction of Ka phase

digit 13 = Received Ka-band carrier phase minus transmitted Ka-band carrier phase (cycles)

digit 14 = Not Defined

digit 15 = Ka-Band SNR  0.1 dB-Hz

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = phase break occurred in Ka-Band at LGRS time + Bias

digit 2 = Not Defined

digit 3 = cycle slip detected in Ka-Band

digit 4 = corrupted Ka-Band phase reconstruction polynomial detected

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Ka SNR < 450

8.

Not Defined

9. 

Not Defined

10.

Not Defined

11.

Not Defined

12.

Not Defined

13.

Not Defined

14.

Not Defined

15.

Not Defined

16.

Not Defined

17.

Not Defined

18.

Not Defined

19.

Not Defined

20.

Not Defined

21.

Ka-band carrier phase (cycles)

22.

Not Defined

23.

Ka-Band SNR (0.1 dB-Hz)

 

Table 19.            LTM1A Record Format

Column #

LTM1A

Position vector and light time in EME 2000 (Earth-centered) of transmitting spacecraft at time of signal reception at DSN station

1.

Receive time (TDB), seconds past 12:00:00 noon 01-Jan-2000

2.

Receiver ID

number = DSN ID

3.

Transmitter ID

'A' = GRAIL-A

'B' = GRAIL-B

4.

Light time between transmitter and receiver (sec) (transmit time = receive time + light time)

5.

Position of transmitting spacecraft at receive time, x value (Earth-centered) (km)

6.

Position of transmitting spacecraft at receive time, y value (Earth-centered) (km)

7.

Position, of transmitting spacecraft at receive time z value (Earth-centered) (km)

 

Table 20.            MAS1A Record Format

Column #

MAS1A

Level 1A Spacecraft Mass Data

1.

UTC SCET, integer seconds past 12:00:00 noon 01-Jan-2000

2.

UTC SCET, microseconds part

3.

Time reference where 'U' = UTC SCET

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined                                                                           

6.

data product flags. Set digits indicate quantities stored in following columns as follows (digit 0 is on the right and digit 7 is on the left):

Set digits (value = 1) have the following meanings:

digit 0 = spacecraft mass based on propellant consumption

digit 1 = undefined

digit 2 = undefined

digit 3 = undefined

digit 4 = undefined

digit 5 = undefined

digit 6 = undefined

digit 7 = undefined

7

Spacecraft Mass based on propellant consumption  in kg..

 

Table 21.            PCI1A Record Format

Column #

PCI1A

Phase Center to Center of Mass Correction

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

Antenna phase center range correction (m)

4.

Antenna phase center range rate correction (m/sec)

5.

Antenna phase center range acceleration correction (m/sec^2)

6.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = bit  1 = From raw data for ka boresight calibration period or prediction change period

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

 

Table 22.            PLT1A Record Format

Column #

PLT1A

Position vector and light time in EME 2000 (moon centered) of transmitting spacecraft at time of signal reception at receiving spacecraft

1.

Receive time (TDB), seconds past 12:00:00 noon 01-Jan-2000

2.

Receiver ID

'A' = GRAIL-A

'B' = GRAIL-B

3.

Transmitter ID

'A' = GRAIL-A

'B' = GRAIL-B

4.

Light time between transmitter and receiver (sec) (transmit time = receive time + light time)

5.

Position of transmitting spacecraft at receive time, x value (moon centered) (km)

6.

Position of transmitting spacecraft at receive time, y value (moon centered) (km)

7.

Position of transmitting spacecraft at receive time z value (moon centered) (km)

 

Table 23.            PPS1A Record Format

Column #

PPS1A

LGRS Pulse Per Second (PPS) Time Record

1.

LGRS time +Bias, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

LGRS time

 

Table 24.            REL1A Record Format

Column #

REL1A

Relativistic time correction (TDB to onboard satellite proper time)

1.

TDB, in integer seconds

2.

TDB, microseconds part

3.

Time scale where  ‘T’ = TDB

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

Not applicable

6.

eps_time (seconds), where onboard satellite proper time = TDB + eps_time

Correction to TDB to calculate proper spacecraft time

7.

Formal error on eps_time (s) (not used by GRAIL, set to 0)

8.

clock drift (s/s); if not calculated, then set to 0

9.

Formal error on clock drift (s/s); if not calculated, then set to 0

10.

bitrate of SFDU packet; if not calculated, then set to 0

11.

delay by bitrate of SFDU packet; if not calculated, then set to 0

12.

data quality flags (digit 0 is on the right, digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = 1 -> linear extrapolation not valid AFTER input time

digit  1 = 1 -> linear extrapolation not valid BEFORE input time

digit  2 = 1 -> filled data using KBR1C

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

Table 25.            SAE1A Record Format

Column #

SAE1A

Level 1A Solar array eclipse data

1.

UTC SCET, integer seconds past 12:00:00 noon 01-Jan-2000

2.

UTC SCET, microseconds part

3.

Time reference frame where 'U' = UTC SCET  

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

Solar array short circuit current (Amperes / 2.442000E-04), as reported by the Solar Array Battery Control

6.

Solar array open circuit voltage (Volts / 9.760000E-04), as reported by the Solar Array Battery Control

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

LSB    = digit 0

digit  0 = Not Defined

digit  1 = Not Defined

digit  2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 26.            SBR1A Record Format

Column #

SBR1A

Level 1A S-Band Ranging Data

1

LGRS time +Bias, integer seconds past 12:00:00 noon 01-Jan-2000 (s)

2.

LGRS time +Bias, microseconds part

3.

GRAIL satellite ID ‘A’ or ‘B’

4.

GRAIL transmission channel number

2 for GRAIL-A

1 for GRAIL-B

5.

SBR antenna ID on GRAIL spacecraft

Antenna ID = 3 for SBR antenna

6.

data product flags. Set digits indicate quantities stored after column 7 as follows (digit 0 is on the right and digit 15 is on the left):

Set digits (value = 1) have the following meanings:

digit 0 = S-band pseudo range (m) (includes transmitter and receiver clock errors)

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Received S-band carrier phase minus spacecraft-specific reference S-band carrier phase (cycles)

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = S-Band SNR  (V/V)

digit 7 = Not Defined

digit 8 = Not Defined

digit 9 = S-band receiver channel

digit 10 = Not Defined

digit 11 = Not Defined

digit 12 = Not Defined

digit 13 = Not Defined

digit 14 = Not Defined

digit 15 = Not Defined

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

8.

S-band pseudo Range (m)

Pseudo range contains actual range + clock offset effect

9. 

Not Defined

10.

Not Defined

11.

S-band carrier Phase (cycles)

12.

Not Defined

13.

Not Defined

14.

S-band SNR (V/V)

15.

Not Defined

16.

Not Defined

17.

S-band receiver channel number

18.

Not Defined

19.

Not Defined

20.

Not Defined

21.

Not Defined

22.

Not Defined

23.

Not Defined

Table 27.            SCA1A Record Format

Column #

SCA1A

Level 1A Star Tracker Data

1.

BTC time, in seconds

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

Application Packet Identification

4.

cos mu/2 element of quaternion

5.

I element of quaternion rotation axis

6.

J element of quaternion rotation axis

7.

K element of quaternion rotation axis

8.

rss of formal error of quaternions; if not calculated, then set to 0

9.

data quality flags (digit 0 is at the right and digit 7 is at the left).

LSB    = digit 0

digit  0 = Not Defined

digit  1 = Ka boresight calibration period or prediction change period

digit  2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 28.            SNV1A Record Format

Column #

SNV1A

S-Band Navigation Product

1.

LGRS time + Bias, seconds past 12:00:00 noon 01-Jan-2000

2

LGRS time + Bias, microseconds part

3.

GRAIL satellite ID ‘A’ or ‘B’

4.

Measured  range =(local measured pseudorange range + remote measured pseudorange)/2 (seconds). Pseudorange contains actual range + clock offset effect.

5.

Measured clock offset =(local measuredpseudorange– remote measured pseudorange)/2 (seconds). Pseudorange contains actual range + clock offset effect.

6.

Local spacecraft S-Band SNR (V/V)

7.

Remote spacecraft S-Band SNR (V/V); if not calculated, then set to 0

8.

Local spacecraft Ka-Band SNR (0.1 dB-Hz)

9.

Remote spacecraft Ka-Band SNR  (0.1 dB-Hz); if not calculated, then set to 0

10.

data quality flags (digit 0 is on the right and digit 7 is on the left

LSB    = digit 0

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

 

Table 29.            TC11A Record Format

Column #

TC11A

LGRS to BTC time correlation

1.

Input time, in integer seconds

2.

Input time, microseconds part

3.

Time scale where ‘L’ = LGRS time + Bias  

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

Not applicable

6.

eps_time (seconds), where Output time scale = Input time scale + eps_time

7.

Formal error on eps_time (s); if not calculated then set to 0

8.

Blackjack packet arrival time in RTC time

9.

Formal error on clock drift (s/s); if not calculated then set to 0

10.

bitrate of SFDU packet; if not calculated, then set to 0

11.

delay by bitrate of SFDU packet; if not calculated, then set to 0

12.

data quality flags (digit 0 is on the right, digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = 1 -> linear extrapolation not valid AFTER input time

digit  1 = 1 -> linear extrapolation not valid BEFORE input time

digit  2 = 1 -> filled data using KBR1C

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 30.            TC21A Record Format

Column #

TC21A

LGRS to BTC time correlation from BTC clock cycle counts

1.

LGRS time + Bias, in integer seconds

2.

LGRS time + Bias, microseconds part

3.

Time scale where ‘L’ = LGRS time + Bias

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

Not applicable

6.

eps_time (seconds), where   BTC time = LGRS time + Bias + eps_time

7.

Formal error on eps_time (s); if not calculated, then set to 0

8.

Not applicable and set to 0

9.

Formal error on clock drift (s/s); if not calculated, then set to 0

10.

bitrate of SFDU packet; if not calculated, then set to 0

11.

delay by bitrate of SFDU packet; if not calculated, then set to 0

12.

data quality flags (digit 0 is on the right, digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = 1 -> linear extrapolation not valid AFTER input time

digit  1 = 1 -> linear extrapolation not valid BEFORE input time

digit  2 = 1 -> filled data using KBR1C

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 31.            TC31A Record Format

Column #

TC31A

BTC to RTC time correlation

1.

BTC, in integer seconds

2.

BTC, microseconds part

3.

Time scale where  ‘B’ = BTC time

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

Not applicable

6.

eps_time (seconds), where    RTC = BTC + eps_time

7.

Formal error on eps_time (s); if not calculated, then set to 0

8.

Not applicable and set to 0

9.

Formal error on clock drift (s/s); if not calculated, then set to 0

10.

bitrate of SFDU packet; if not calculated, then set to 0

11.

delay by bitrate of SFDU packet; if not calculated, then set to 0

12.

data quality flags (digit 0 is on the right, digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = 1 -> linear extrapolation not valid AFTER input time

digit  1 = 1 -> linear extrapolation not valid BEFORE input time

digit  2 = 1 -> filled data using KBR1C

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 32.            TC41A Record Format

Column #

TC41A

LGRS to RTC time correlation

1.

LGRS time + Bias, in integer seconds

2.

LGRS time + Bias, microseconds part

3.

Time scale where ‘L’ = LGRS time + Bias

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

Not applicable

6.

eps_time (seconds), where RTC = LGRS time + Bias + eps_time

7.

Formal error on eps_time (s); if not calculated, then set to 0

8.

Not applicable and set to 0

9.

Formal error on clock drift (s/s); if not calculated, then set to 0

10.

bitrate of SFDU packet; if not calculated, then set to 0

11.

delay by bitrate of SFDU packet; if not calculated, then set to 0

12.

data quality flags (digit 0 is on the right, digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = 1 -> linear extrapolation not valid AFTER input time

digit  1 = 1 -> linear extrapolation not valid BEFORE input time

digit  2 = 1 -> filled data using KBR1C

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 33.            TC51A Record Format

Column #

TC51A

RTC to UTC time correlation

1.

RTC, in integer seconds

2.

RTC, microseconds part

3.

Time scale where  ‘R’ = RTC time

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

DSN station ID

6.

eps_time (seconds), where UTC at DSN station  = RTC + eps_time   and UTC is in seconds since 12:00:00 noon on 1 January 2000

7.

Formal error on eps_time (s); if not calculated, then set to 0

8.

Not applicable and set to 0

9.

Formal error on clock drift (s/s); if not calculated, then set to 0

10.

bitrate of SFDU packet

11.

delay by bitrate of SFDU packet; if not calculated, then set to 0

12.

data quality flags (digit 0 is on the right, digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = 1 -> linear extrapolation not valid AFTER input time

digit  1 = 1 -> linear extrapolation not valid BEFORE input time

digit  2 = 1 -> filled data using KBR1C

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 34.            TC61A Record Format

Column #

TC61A

UTC to TDB time correlation

1.

UTC, in integer seconds

2.

UTC, microseconds part

3.

Time scale where  ‘U’ = UTC

4.

GRAIL satellite ID ‘X’ to indicate a single product for two spacecraft

5.

Not applicable

6.

eps_time (seconds), where TDB = UTC + eps_time

7.

Formal error on eps_time (s); if not calculated, then set to 0

8.

Clock drift (s/s) deps_time/dt

9.

Formal error on clock drift (s/s); if not calculated, then set to 0

10.

bitrate of SFDU packet ; if not calculated, then set to 0

11.

delay by bitrate of SFDU packet; if not calculated, then set to 0

12.

data quality flags (digit 0 is on the right, digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = 1 -> linear extrapolation not valid AFTER input time

digit  1 = 1 -> linear extrapolation not valid BEFORE input time

digit  2 = 1 -> filled data using KBR1C

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 35.            THR1A Record Format

Column #

THR1A

Level 1A Thruster Activation Data

1.

UTC SCET, integer seconds past 12:00:00 noon 01-Jan-2000

2.

UTC SCET, microseconds part

3.

Time reference frame where 'U' = UTC SCET  

4.

GRAIL satellite ID ‘A’ or ‘B’

5-12.

Count of number of work cycles that each thruster has been activated

Set to 0 for GRAIL.

13-20.

Thruster on-time for this activation time (milliseconds)

21-28.

Accumulated thruster firing duration time (milliseconds)

integer will wrap after 4294967295

29.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = 1 On time not calculated

digit 1 = 1 Multiple unaccounted thrusts prior to current record

digit 2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 36.            USO1A Record Format

Column #

USO1A

Level 1A Ultra Stable Oscillator Stability Data

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

USO identification number set to 0

4.

Not applicable, set to 0

5.

X-Band RSB frequency (Hz)

6.

Not applicable, set to 0

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = Not Defined

digit  1 = Not Defined

digit  2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 37.            VCM1A Record Format

Column #

VCM1A

Level 1A Center of mass displacement from spacecraft mechanical frame origin

1.

UTC SCET, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

Magnitude of center of mass vector in mechanical frame (m)

4.

Direction cosine of vector with Mechanical Reference Frame x-axis

5.

Direction cosine of vector with Mechanical Reference Frame y-axis

6.

Direction cosine of vector with Mechanical Reference Frame z-axis

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

 

Table 38.            WRS1A Record Format

Column #

WRS1A

Level 1A Wheel rotational speed data

1.

UTC SCET Activation time, integer seconds past 12:00:00 noon 01-01-2000

2.

Activation time, microseconds part

3.

Time reference frame where 'U' = UTC time

4.

GRAIL satellite id ‘A’ or ‘B’

5.

Reaction wheel 1 rotational speed as determined by digital tachometer (radians/sec)

6.

Reaction wheel 2 rotational speed as determined by digital tachometer (radians/sec)

7.

Reaction wheel 3 rotational speed as determined by digital tachometer (radians/sec)

8.

Reaction wheel 4 rotational speed as determined by digital tachometer (radians/sec)

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

 


5.2.2.2        Level 1B

 

Table 39.            CLK1B Record Format

Column #

CLK1B

Level 1B LGRS + bias to TDB Time correlation

1

LGRS time +Bias , seconds past 12:00:00 noon 01-Jan-2000 (s)

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

Clock ID (set to 1)

4.

eps_time (seconds), where TDB = LGRS time + Bias + eps_time

5.

Formal error on eps_time (s) (not used by GRAIL, set to 0)

6.

Clock drift (s/s) deps_time/dt

7.

Formal error on clock drift (s/s); if not calculated, then set to 0

8.

data quality flags (digit 0 is on the right, digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = 1 -> linear extrapolation not valid AFTER LGRS time + bias

digit  1 = 1 -> linear extrapolation not valid BEFORE LGRS time + bias

digit  2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined                                       

digit  7 = Not Defined

 

Table 40.            EHK1B Record Format

Column #

EHK1B

Level 1B Spacecraft temperature sensor data from Engineering Housekeeping data for KBR data correction

1.

TDB, integer seconds past 12:00:00 noon 01-Jan-2000

2.

TDB, microseconds part

3.

Time reference frame where 'T' = TDB

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

Microwave Assembly T1 temperature in C

6.

Microwave Assembly T2 temperature in C

7.

Waveguide transmit Ka-Band Assembly temperature in C

8.

Waveguide transmit Microwave Assembly temperature in C

9.

Waveguide Rx Mid temperature in C

10.

Waveguide Tx Mid temperature in C

11.

Aperture temperature in C

12.

Radome temperature in C

13.

HornBase temperature in C

14.

Midway on Horn temperature in C

15.

Orthomode Transducer (where transmit and receive modules are split off at base of horn) temperature in C

16.

data quality flags  (digit 0 is on the right, digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = Not Defined

digit  1 = Not Defined

digit  2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 41.            GNI1B Record Format

Column #

GNI1B

Navigation Level 1B satellite orbit solution in Moon-centered Inertial frame

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID, ‘1’ for GRAIL-A, ‘2’ for GRAIL-B

3.

Coordinate reference frame where

'I' = Inertial centered on Moon in EME 2000 Solar System Barycentric Frame

4.

Position, x value (m)

5.

Position, y value (m)

6.

Position, z value (m)

7.

Formal error on x position (m); if not calculated, then set to 0

8.

Formal error on y position (m); if not calculated, then set to 0

9.

Formal error on z position (m); if not calculated,  then set to 0

10.

Velocity along x-axis (m/s)

11.

Velocity along y-axis (m/s)

12.

Velocity along z-axis (m/s)

13.

Formal error in velocity along x-axis (m/s); if not calculated, then set to 0

14.

Formal error in velocity along y-axis (m/s); if not calculated, then set to 0

15.

Formal error in velocity along z-axis (m/s); if not calculated, then set to 0

16.

Data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = Not Defined

digit  1 = Not Defined

digit  2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 42.            GNV1B Record Format

Column #

GNV1B

Navigation Level 1B Satellite orbit solution in lunar body fixed frame

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID, ‘1’ for GRAIL-A, ‘2’ for GRAIL-B

3.

Coordinate reference frame where 'M' = Moon-centered-body-fixed

4.

Position, x value (m)

5.

Position, y value (m)

6.

Position, z value (m)

7.

Formal error on x position (m); if not calculated, then set to 0

8.

Formal error on y position (m); if not calculated, then set to 0

9.

Formal error on z position (m); if not calculated, then set to 0

10.

Velocity along x-axis (m/s)

11.

Velocity along y-axis (m/s)

12.

Velocity along z-axis (m/s)

13.

Formal error in velocity along x-axis (m/s); if not calculated, then set to 0

14.

Formal error in velocity along y-axis (m/s); if not calculated, then set to 0

15.

Formal error in velocity along z-axis (m/s); if not calculated, then set to 0

16.

Data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = Not Defined

digit  1 = Not Defined

digit  2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 43.            KBR1C Record Format

Column #

KBR1C

Level 1B Dual-One-Way Ka-Band Ranging Data

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000

2.

Biased dual one-way range between GRAIL-A and GRAIL-B (m)

3.

Range rate between GRAIL-A and GRAIL-B (m/s)

4.

Range acceleration between GRAIL-A and GRAIL-B (m/s**2)

5.

Biased ionospheric range correction between GRAIL-A and GRAIL-B for Ka-Band frequency (m). If not calculated, then set to 0

6.

Time of flight range correction between GRAIL-A and GRAIL-B (m). Includes relativistic effects.

7.

Time of flight range rate correction between GRAIL-A and GRAIL-B (m/sec). Includes relativistic effects.

8.

Time of flight range acceleration correction between GRAIL-A and GRAIL-B (m/sec^2). Includes relativistic effects.

9.

Ka-band antenna offset range correction (m)

10.

Ka-band antenna range rate correction (m/s)

11.

Ka-band antenna range acceleration correction (m/sec^2)

12.

Undefined (set to 0)

13.

SNR Ka band for GRAIL-A  0.1 db-Hz

14.

Undefined (set to 0)

15.

SNR Ka band for GRAIL-B  0.1 db-Hz

16.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = Not Defined

digit  1 = From raw data for Ka boresight calibration slew for antenna correction data

digit  2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

17.

Raw temperature range correction (m)

18.

Filtered temperature range correction (m)

19.

Filtered temperature range rate correction (m/s)

20.

Filtered temperature range acceleration correction (m/s/s)

 

Table 44.            MAS1B Record Format

Column #

MAS1B

Level 1B Spacecraft Mass Data

1.

TDB, integer seconds past 12:00:00 noon 01-Jan-2000

2.

TDB, microseconds part

3.

Time reference frame where 'T' = TDB

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined                                                                           

6.

data product flags. Set digits indicate quantities stored in following columns as follows (digit 0 is on the right and digit 7 is on the left):

Set digits (value = 1) have the following meanings:

digit 0 = spacecraft mass based on propellant consumption

digit 1 = undefined

digit 2 = undefined

digit 3 = undefined

digit 4 = undefined

digit 5 = undefined

digit 6 = undefined

digit 7 = undefined

7

Spacecraft Mass based on propellant consumption in kg..

Table 45.            SAE1B Record Format

Column #

SAE1B

Level 1B Solar array eclipse data

1.

TDB, integer seconds past 12:00:00 noon 01-Jan-2000

2.

TDB, microseconds part

3.

Time reference frame where  'T' = TDB

4.

GRAIL satellite ID ‘A’ or ‘B’

5.

Solar array short circuit current (Amperes / 2.442000E-04), as reported by the Solar Array Battery Control

6.

Solar array open circuit voltage (Volts / 9.760000E-04), as reported by the Solar Array Battery Control

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit  0 = Not Defined

digit  1 = Not Defined

digit  2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 46.            SBR1B Record Format

Column #

SBR1B

Level 1B Biased dual one-way S-Band Ranging data

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000

2.

Biased dual one-way range between GRAIL-A and B (m)

3.

Range rate between GRAIL-A and -B (m/s)

4.

Range acceleration between GRAIL-A & -B (m/s**2)

5.

Not Defined. Set to 0 for GRAIL

6.

Not defined. Set to 0 for GRAIL

7.

Not defined. Set to 0 for GRAIL

8.

Not defined. Set to 0 for GRAIL

9.

Not defined. Set to 0 for GRAIL

10.

Not defined. Set to 0 for GRAIL

11.

Not defined. Set to 0 for GRAIL

12.

Not defined. Set to 0 for GRAIL

13.

Not defined. Set to 0 for GRAIL

14.

Not defined. Set to 0 for GRAIL

15.

Not defined. Set to 0 for GRAIL

16.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = From raw data for Ka boresight calibration slew for antenna correction data

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

 

Table 47.            SCA1B Record Format

Column #

SCA1B

Level 1B Star Tracker Data

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

SCA identification number set to 1

4.

Cos mu/2 element of quaternion

5.

I element of quaternion rotation axis

6.

J element of quaternion rotation axis

7.

K element of quaternion rotation axis

8.

rss of formal error of quaternions; if not calculated, then set to 0

9.

data quality flags (digit 0 is at the right and digit 7 is at the left)

Set digits (value = 1) have the following meanings:

digit  0 = Data filled by interpolation

digit  1 = Ka boresight calibration periodor prediction change period

digit  2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 48.            THR1B Record Format

Column #

THR1B

Level 1B Thruster Activation Data

1.

TDB, integer seconds past 12:00:00 noon 01-Jan-2000

2.

TDB, microseconds part

3.

Time reference frame where  'T' = TDB

4.

GRAIL satellite ID ‘A’ or ‘B’

5-12.

Count of number of work cycles that each thruster has been activated

Set to 0 for GRAIL.

13-20.

Thruster on-time for this activation time (milliseconds)

21-28.

Accumulated thruster firing duration time (milliseconds)

integer will wrap after 4294967295

29.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = 1 On time not calculated

digit 1 = 1 Multiple unaccounted thrusts prior to current record

digit 2 = Not Defined

digit  3 = Not Defined

digit  4 = Not Defined

digit  5 = Not Defined

digit  6 = Not Defined

digit  7 = Not Defined

 

Table 49.            USO1B Record Format

Column #

USO1B

Level 1B Ultra Stable Oscillator Stability Data

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

USO identification number set to 0

4.

Frequency of USO (Hz)

5.

X-Band RSB frequency (Hz)

6.

Ka band frequency of KBR (Hz) for USO1B

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

 

Table 50.            VCM1B Record Format

Column #

VCM1B

Level 1B Center of mass displacement from spacecraft mechanical frame origin

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

Magnitude of center of mass vector in mechanical frame (m)

4.

Direction cosine of vector with Mechanical Reference Frame x-axis

5.

Direction cosine of vector with Mechanical Reference Frame y-axis

6.

Direction cosine of vector with Mechanical Reference Frame z-axis

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined            

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

 


Table 51.            VGS1B Record Format

Column #

VGS1B

S-Band antenna offset vector and switch time (TDB)

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

Magnitude of vector (m) for active antenna in mechanical reference frame

4.

Direction cosine of vector with Mechanical Reference Frame x-axis

5.

Direction cosine of vector with Mechanical Reference Frame y-axis

6.

Direction cosine of vector with Mechanical Reference Frame z-axis

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

 

Table 52.            VGX1B Record Format

Column #

VGX1B

X-Band antenna offset vector and switch time (TDB)

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000 in TDB

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

Magnitude of vector (m) for active antenna in mechanical reference frame

4.

Direction cosine of vector with Mechanical Reference Frame x-axis

5.

Direction cosine of vector with Mechanical Reference Frame y-axis

6.

Direction cosine of vector with Mechanical Reference Frame z-axis

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

 

Table 53.            VKB1B Record Format

Column #

VKB1B

Ka-Band Boresight Vector

1.

TDB, seconds past 12:00:00 noon 01-Jan-2000

2.

GRAIL satellite ID ‘A’ or ‘B’

3.

Magnitude of vector (m) for active antenna in science reference frame for VKB1B

4.

Direction cosine of vector with Science Reference Frame x-axis

5.

Direction cosine of vector with Science Reference Frame y-axis

6.

Direction cosine of vector with Science Reference Frame z-axis

7.

data quality flags (digit 0 is on the right and digit 7 is on the left)

Set digits (value = 1) have the following meanings:

digit 0 = Not Defined

digit 1 = Not Defined

digit 2 = Not Defined

digit 3 = Not Defined

digit 4 = Not Defined

digit 5 = Not Defined

digit 6 = Not Defined

digit 7 = Not Defined

 

Table 54.            WRS1B Record Format

Column #

WRS1B

Level 1B Wheel rotational speed data

1.

TDB Activation time, integer seconds past 12:00:00 noon 01-01-2000

2.

Activation time, microseconds part

3.

Time reference frame where 'T' = TDB time

4.

GRAIL satellite id ‘A’ or ‘B’

5.

Reaction wheel 1 rotational speed as determined by digital tachometer (radians/sec)

6.

Reaction wheel 2 rotational speed as determined by digital tachometer (radians/sec)

7.

Reaction wheel 3 rotational speed as determined by digital tachometer (radians/sec)

8.

Reaction wheel 4 rotational speed as determined by digital tachometer (radians/sec)