urn:nasa:pds:mess_mla_calibrated:data_rdr_radr:mlascirdr1206010703.tab 1.0 1.10.1.0 Product_Observational 2018-06-08 1.0 PDS4 migrated product. 2012-06-01T07:03:47Z 2012-06-01T07:34:52Z MESSENGER Mission urn:nasa:pds:context:investigation:mission.messenger data_to_investigation MESSENGER Spacecraft urn:nasa:pds:context:instrument_host:spacecraft.mess is_instrument_host Mercury Laser Altimeter Instrument urn:nasa:pds:context:instrument:mla.mess is_instrument Mercury Planet urn:nasa:pds:context:target:planet.mercury data_to_target Mercury Orbit Year 2 935 1/247021693 1/247023557 mla_data mla_rdr 2.8 MESS-E/V/H-MLA-3/4-CDR/RDR-DATA-V1.0:MLASCICDR1206010703_TAB data_to_calibrated_source_product PDS Geosciences Node mlascirdr1206010703.tab 2015-12-03T20:27:42Z

0 230 7-Bit ASCII Text Column headings

230 47394 This product contains time-ordered, calibrated, geolocated altimetry data reduced by the Mercury Laser Altimeter (MLA) Science Team at the NASA Goddard Space Flight Center and the JHU Applied Physics Laboratory. Carriage-Return Line-Feed 24 0 230 longitude 1 1 ASCII_Real 9 The planetocentric longitude of the laser bounce point producing a trigger on a given channel. Longitudes increase to the East. latitude 2 11 ASCII_Real 10 The planetocentric latitude of the laser bounce point producing a trigger on a given channel. radius 3 22 ASCII_Real 9 km The planetary radius at the laser bounce point. Altitude was previously measured with respect to a reference sphere about the center of mass, but is now the total planetary radius. et_fire 4 32 ASCII_Real 17 second The independent variable of the equations of motion in the Solar System Barycentric frame at the laser fire time, in ET seconds from the J2000 epoch, also known as Ephemeris Time or Coordinate Time. Its practical realization is the project-supplied clock kernel, applied to the Spacecraft Clock Mission Elapsed Time (MET_SECONDS) that is transmitted to MESSENGER subsystems by the Integrated Electronics Module at the time of the 1 PPS signal. The NAIF SPICE spacecraft clock (SCLK) kernel determines a corresponding Terrestrial Dynamic Time. These times are synchronous with respect to an observer at the Solar System barycenter. The SPICE library routine SCS2E performs the conversion to Ephemeris Time as used by the JPL Planetary Ephemeris. met_seconds 5 50 ASCII_Integer 10 Spacecraft mission elapsed time. shot_number 6 61 ASCII_Integer 2 Number of 8 Hz shot or minor frame, 0-7 chanid 7 64 ASCII_String 2 Receiver channel of ground or noise trigger - =0 channel 1 high threshold. =1 channel 1 low =2 channel 2 low =3 ambiguous, assigned to channel 1 low =4 channel 3 low. =5 channel 1 high noise trigger =6 channel 1 low noise trigger =7 channel 2 low noise trigger =8 unassigned noise trigger =9 channel 3 low noise trigger. =A channel 1 high trigger with invalid STARTPLS_WIDTH. =B channel 1 low ground trigger with invalid STARTPLS_WIDTH. =C channel 2 low ground trigger with invalid STARTPLS_WIDTH. pulse_width 8 67 ASCII_Real 6 Received pulse width, nanoseconds. threshold 9 74 ASCII_Real 7 volt Discriminator threshold on receiver channel CHANID. vga_gain 10 82 ASCII_Real 6 Variable gain amplifier gain factor. range 11 89 ASCII_Real 10 km Range from spacecraft center of mass to bounce point, km. The time of flight from the laser transmit start pulse to the bounce point on Mercury, as seen by an observer at the Solar System barycenter, is calculated iteratively from the two-way time of flight using the spacecraft and planetary ephemerides in an inertial frame, and multiplied by the speed of light constant, 299,792.458 km/s. The range has been corrected for the offset of the laser zero-range point to the S/C COM in the boresight direction. emission_angle 12 100 ASCII_Real 6 Angle at a surface bounce point between a vector to MLA, and a radial vector from the center of mass. tx_energy 13 107 ASCII_Real 5 millijoule The measured transmitted pulse energy for the current SHOT_NUMBER. utc 14 113 ASCII_String 25 Laser shot time origin T0, converted to Coordinated Universal Time (UTC). The project-supplied clock kernel and NAIF routines convert MET into Terrestrial Dynamical Time (TDT) seconds past the J2000 epoch, and by accounting for leap seconds and the 32.184 s offset between TDT and UTC, to a standard calendar representation of UTC. The laser fire occurs about 0.97 to 1 ms after T0. time_of_flight 15 139 ASCII_Real 11 nanosecond Two-way time of flight, corrected for zero-range delay to spacecraft center of mass, in ET nanoseconds. sat_longitude 16 151 ASCII_Real 10 The planetocentric longitude of MESSENGER at the time of fire. sat_latitude 17 162 ASCII_Real 10 The planetocentric latitude of MESSENGER at the time of fire. sat_altitude 18 173 ASCII_Real 10 km The altitude of MESSENGER with respect to a reference surface about the center of mass, currently a sphere of 2440 km radius. offnadir_angle 19 184 ASCII_Real 8 Angle between a vector from MLA to the bounce point, and a vector from MLA to the center of mass. phase_angle 20 193 ASCII_Real 8 Solar phase angle at the bounce point. solar_incidence_angle 21 202 ASCII_Real 7 Angle at a surface bounce point between a vector to Sun and a radial vector from the center of mass. sc_range 22 210 ASCII_Integer 6 The spacecraft range value used by the science task for algorithm calculations, in units of approximately 30 meters per count. This value is calculated in real time by the spacecraft using its attitude and position knowledge relative to the planet. The range is provided to the instrument asynchronously at one second intervals. As soon as the science task receives a range message, it begins using the new range in its calculations. This value is an estimate only. The spacecraft range reported in telemetry may NOT be the one used throughout the entire second of algorithm calculations. sequence_id 23 217 ASCII_Integer 6 Unique sequential identifier for triggers recorded by the range measurement unit in the Calibrated Data Record. Many triggers lie well outside the normal slant range window and are discarded. The SEQUENCE_ID allows ground/noise editing to be transferred from previous processing versions. startpls_width 24 225 ASCII_Real 4 nanosecond Width of transmit laser pulse in nanoseconds, used to determine centroid time of outgoing pulse. A value of 99.9 denotes a measurement whose pulse width is invalid. In addition, this value is set to indicate an uncertain start time, leading to highly degraded range accuracy. 99.9 mlascirdr1206010703.lbl 0 PDS3 Original PDS3 label Carriage-Return Line-Feed