PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "2006-06-07, R. Sharrow, initial; 2006-12-20, S. Slavney, revised; 2021-04-13, S. Slavney, revised; 2025-07-11, N. Putzig, revised" RECORD_TYPE = STREAM OBJECT = INSTRUMENT_HOST INSTRUMENT_HOST_ID = "MRO" OBJECT = INSTRUMENT_HOST_INFORMATION INSTRUMENT_HOST_NAME = "MARS RECONNAISSANCE ORBITER" INSTRUMENT_HOST_TYPE = "SPACECRAFT" INSTRUMENT_HOST_DESC = " Instrument Host Overview ======================== Mars Reconnaissance Orbiter Spacecraft -------------------------------------- Mars Reconnaissance Orbiter uses a spacecraft design provided by Lockheed Martin Space Systems that is smarter, more reliable, more agile, and more productive than any previous Mars orbiter. It is the first spacecraft designed from the ground up for aerobraking, a rigorous phase of the mission where the orbiter uses the friction of the Martian atmosphere to slow down in order to settle into its final orbit around Mars. When fully assembled and fueled, the spacecraft had to weigh less than 2,180 kilograms (4,806 pounds) so that the Atlas V launch vehicle could lift it into the proper orbit. All subsystems and instruments on board (the so-called 'dry mass') weigh less than 1,031 kilograms (2,273 pounds) to allow room for 1,149 kilograms (2,533 pounds) of propellant for trajectory correction maneuvers that kept the spacecraft on target during the cruise to Mars, for burns that helped capture the spacecraft into orbit around Mars, and to keep the spacecraft in its fixed-local-time orbit. Spacecraft Configurations ------------------------- Through its initial five-year mission, the spacecraft operated in four distinct mission phases. Launch: During launch, the spacecraft had to fit within the nose cone, or payload fairing, of the launch vehicle, so the large parts like the high-gain antenna and the solar arrays were designed to be folded up. As soon as the launch vehicle placed the spacecraft on a course to leave Earth orbit for its journey to Mars, it disconnected itself from the spacecraft. Cruise: As soon as the spacecraft was clear of the launch vehicle, the orbiter deployed its solar arrays to begin producing power. The high-gain antenna was also deployed at this point. The high-gain antenna moved to track the Earth, while the solar panels remained fixed. Mars Orbit Insertion and Aerobraking: The Mars orbit insertion and aerobraking configuration looked very much like the cruise configuration, except that the high-gain antenna was moved to a position that balanced the solar arrays as it flew through the upper atmosphere of Mars. The heaviest part of the spacecraft (the propellant tank) also made the spacecraft very stable. Due to the large area (37.7 square meters or 405.8 square feet) of the spacecraft in this configuration, each pass through the Martian atmosphere during aerobraking caused significant slowing, thus reducing the size of the orbit. Friction from the atmosphere had the additional effect of heating up the spacecraft, so components were designed to withstand this heating. The flight team could further control the heating by changing how deeply the spacecraft dipped into the atmosphere on each orbit. Science Operations: During the primary science phase, the orbiter's job was to point its science instruments at Mars to collect images and other data from targets on the surface of Mars, while ensuring that the high-gain antenna and solar arrays were continuously tracking the Earth and the Sun, respectively. The same has applied for all subsequent phases. The orbiter typically keeps its science instruments pointed to nadir (looking straight down at the surface). A few times per day, and for about fifteen minutes each time, the orbiter points side- to-side in order to capture high-priority science targets that do not fall directly beneath the spacecraft. The spacecraft rolls to point off-nadir up to 30 degrees during normal operations. Larger rolls have been executed for special observing cases, mostly to image other bodies (Earth, the Moon, Phobos, Deimos) and landed spacecraft on their descent through the Martian atmosphere. Beginning in 2023, MRO began carrying out rolls of 120 degrees to improve the radar sounding capabilities for special observations. Major Spacecraft Components --------------------------- Science Payload Instruments: To fulfill the mission science objectives, seven scientific investigations teams were selected by NASA. Four teams (MARCI, MCS, HiRISE, and CRISM) are led by Principal Investigators (PI). Each PI-lead team is responsible for the provision and operation of a scientific instrument and the analysis of its data. The PI-lead investigations are: Mars Color Imager (MARCI); Mars Climate Sounder, (MCS); High Resolution Imaging Science Experiment, (HiRISE); and Compact Reconnaissance Imaging Spectrometer for Mars, (CRISM). In addition to the PI-lead teams, there are two investigation teams that make use of facility instruments. The facility instruments are Context Imager (CTX) and the Shallow Radar (SHARAD) sounder. The MARCI PI and Science Team also act as Team Leader (TL) and Team Members for the CTX facility instrument. The Italian Space Agency (ASI) provided the second facility instrument, SHARAD, for flight on MRO. ASI and NASA both selected members of the SHARAD investigation team with ASI appointing the Team Leader and NASA appointing the Deputy Team Leader. In addition to the instrument investigations, Gravity Science and Atmospheric Structure Facility Investigation Teams used data from the spacecraft telecommunications and accelerometers, respectively, to conduct scientific investigations. The science instruments are summarized below. Instrument: CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) Type: High-Resolution Imaging Spectrometer Measurements: Hyper-spectral Image Cubes, 514 spectral bands, 0.4-4 microns, 7 nm resolution, from 300km; 20 m/pixel, 11 km swath. Science Goals: Regional & local surface composition and morphology. Key Attributes: Moderately high spectral & spatial resolution, targeted and regional survey, very high data rate. Principal Investigator: Scott Murchie, Johns Hopkins University Applied Physics Lab. This instrument was turned off in 2022 due to budget constraints. Instrument: CTX (Context Imager) Type: Mono-chromatic Context Camera Measurements: Panchromatic (minus blue)Images from 300km altitude; 30km swath & 6m/pixel context imaging for HiRISE/CRISM & MRO science. Science Goals: Regional stratigraphy and morphology. Key Attributes: Moderately high resolution with coverage, targeted & regional survey; high data rate. Team Leader: Michael Malin, Malin Space Science Systems (MSSS). Instrument: HiRISE (High Resolution Imaging Science Experiment) Type: High-Resolution Camera (0.5 m aperture) Measurements: Color images, stereo by site revisit, from 300km; < 1m/pixel (ground sampling @ 0.3 m/pixel), 6 km swath in red (broadband), 1.2km swath in blue-green & NIR. Science Goals: Stratigraphy, geologic processes and morphology. Key Attributes: Very high resolution targeted imaging, very high data rate. Principal Investigator: To 2025: Alfred McEwen, University of Arizona. From 2025: Shane Byrne, University of Arizona. Instrument: MARCI (Mars Color Imager) Type: Wide-Angle Color Imager Measurements: Coverage of atmospheric clouds, hazes and ozone, and surface albedo in 7 color bands (0.28-0.8 micrometers) (2 UV, 5 Visible). Science Goals: Global weather and surface change. Key Attributes: Daily global coverage daily global mapping, continuous operations dayside; moderate data rate. Principal Investigator: Michael Malin, Malin Space Science Systems (MSSS). Instrument: MCS Type: Atmospheric Sounder Measurements: Atmospheric profiles of water, dust, co2 & temperature, polar radiation balance, 0-80km vertical coverage, vertical resolution ~5km. Science Goals: Atmospheric structure, transport and polar processes. Key Attributes: Global limb sounding; daily, global limb & on-planet mapping; continuous operations day and night; low data rate. Principal Investigator: Originally Daniel J. McCleese, Jet Propulsion Lab (JPL); later David Kass, JPL; from 2025 Armin Kleinboehl, JPL. Instrument: SHARAD Type: Shallow Radar Sounder Measurements: Ground penetrating radar; 10-MHz band centered at 20 MHz; 15 m free space vertical resolution; 3-6 km horizontal resolution, improved to 0.3-1 km along-track with SAR processing. Science Goals: Regional near-surface ground structure. Key Attributes: Subsurface sounding for regional profiling of icy and non-icy terrains; surface roughness and material properties: ionospheric total electron content; high data rate. Team Leader: To 2024: Roberto Seu, University of Rome, Italy. From 2025: Pierfrancesco Lombardo, University of Rome, Italy. Deputy Team Leader: To 2015: Roger Phillips, Washington University, St. Louis and Southwest Research Institute, Boulder Colorado; From 2015: Nathaniel Putzig, Planetary Science Institute, Lakewood Colorado. Engineering Instruments: Mars Reconnaissance Orbiter carries three instruments that assist in spacecraft navigation and communications. 1. Electra UHF Communications and Navigation Package: Electra allows the spacecraft to act as a communications relay between the Earth and landed spacecraft on Mars that may not have sufficient radio power to communicate directly with Earth by themselves. 2. Optical Navigation Camera: This camera was included for testing improved navigation capability for future missions. Similar cameras placed on orbiters of the future may able to serve as high-precision interplanetary 'eyes' to guide incoming spacecraft as they near Mars. 3. Ka-band Telecommunications Experiment Package: Mars Reconnaissance Orbiter has tested the use of a radio frequency Ka-band to demonstrate the potential for greater performance in communications using significantly less power. Structures: The structures subsystem is the skeleton around which the spacecraft was assembled. It supports and protects the other engineering subsystems and the science instruments. It was strong enough to survive launch, when the forces can exceed 5 g's. Extremely lightweight but strong materials were used to achieve this strength, including titanium, carbon composites, and aluminum honeycomb. Mechanisms: There were three main mechanisms onboard Mars Reconnaissance Orbiter: * one that allows the high-gain antenna to move in order to point at Earth * two that allows the solar arrays to move to point at the sun Each of these mechanisms, called gimbals, moved about two axes in much the same way that your wrist allows your hand to move in two axes: left/right and up/down. As the spacecraft travels around Mars on each orbit, these gimbals allow both solar arrays to be always pointed toward the sun, while the high-gain antenna can simultaneously always be pointed at Earth. Telecommunications System: The telecommunications subsystem is a two-way radio system used for receiving and transmitting commands and data between the Mars Reconnaissance Orbiter and the Deep Space Network antennas on Earth. With its large-dish antenna, powerful amplifier, and fast computer, Mars Reconnaissance Orbiter can transmit data to Earth at rates as high as 6 megabits per second, a rate ten times higher than previous Mars orbiters. The orbiter's radio operates in the X-band of the radio spectrum, at a frequency of around 8 Gigahertz. Major components of the telecom subsystem include: * Antennas for transmitting and receiving commands * Amplifiers for boosting the power of radio signals so that they are strong enough to be received at the Deep Space Network antennas * Transponders for translating navigation and other signals from the orbiter Also onboard is Electra, a UHF telecommunications package that is one of the engineering instruments providing navigation and communications support to landers and rovers on the surface of Mars. Electra allows the spacecraft to act as a relay between the Earth and landed crafts on Mars, which may not have sufficient radio power to communicate directly with Earth. High-gain Antenna: The high-gain antenna is a 3-meter diameter (10-foot) dish antenna for sending and receiving data at high rates. The high-gain antenna was deployed shortly after launch and has remained deployed throughout the mission. It serves as the primary means of communication to and from the orbiter. The high-gain antenna has to be pointed accurately and is therefore steered using the gimbal mechanism. Low-gain Antennas: Two smaller antennas are present for lower- rate communication during emergencies and special events, such as launch and Mars Orbit Insertion. The data rate of these antennas is lower because they focus the radio beam much more broadly than the high gain antenna, so less of the signal reaches Earth. But the Deep Space Network station on the Earth can detect the signal even when the spacecraft is not pointed at Earth, and therefore these antennas are useful for emergencies. The low-gain antennas has the capability to transmit and receive. The two low- gain antennas are mounted on the high-gain antenna dish--one on the front side and one on the back--and move with it. Two are needed in that placement so that communication is possible at all times, no matter what the position of the spacecraft might be at a given time. Amplifiers: Located on the backside of the high-gain antenna is the enclosure for the Traveling Wave Tube Amplifiers, which boost the power of radio signals so that they are strong enough to be received at the Deep Space Network antennas. There are three amplifiers on board: * two for the X-band radio frequency that transmitt radio signals at a power of 100 watts (the second one is for back up to ensure communications in case the first amplifier fails) * one for Ka-band radio frequency that is capable of transmitting at 35 watts. Transponders: Mars Reconnaissance Orbiter carries two transponders, which are special types of radio receiver/transmitters, specially designed for long-range space communications. The second transponder is a backup. The transponders have several functions: * transmit/receive function: translate digital electrical signals into radio signals for sending data to Earth, and translate radio signals to digital electrical signals for receiving commands from Earth * transponding function: listen for and detect a signal coming in from Earth, to which it responds automatically * navigation function: transmit several types of signals that provide critical navigation clues, enabling navigators on the ground to make precise calculations of the spacecraft speed and distance from Earth Propulsion: The propulsion subsystem performs major maneuvers such as trajectory correction maneuvers and Mars orbit insertion. The propulsion subsystem is also used to control the spacecraft's position, as a backup to the reaction wheels. Mars Reconnaissance Orbiter uses a monopropellant propulsion system: it carries fuel (hydrazine), but no oxidizer. Thrust is produced by passing the fuel over beds of catalyst material just before it entered the thruster, which causes the hydrazine to combust. The propulsion system includes: Propellant Tank The monopropellant hydrazine tank held 1187 kilograms (2617 pounds) of usable propellant at launch. Over 70% of the total propellant was used during Mars orbit insertion. Pressurant Tank Mars Reconnaissance Orbiter feeds pressurized helium gas from a separate high- pressure tank, through a regulator, into the propellant tank where it puts the hydrazine propellant under pressure. Lines, Valves, and Regulators The pressurized hydrazine flows through a system of metal tubing to each of the thrusters. Each thruster has a valve so that it can be fired independently. Additional valves in the propellant lines turn on and off the flow to groups of thrusters. Thrusters A total of 20 rocket engine thrusters are onboard: * Six large thrusters, each producing 170 Newtons* (38 pounds force) of thrust for performing the Mars orbit insertion burn. Together, all six produce 1,020 Newtons (230 pounds force) of thrust. * Six medium thrusters, each producing 22 Newtons* (5 pounds force) of thrust for performing trajectory correction maneuvers, and for helping to keep the spacecraft pointing in the right direction during the Mars orbit insertion burn. * Eight small thrusters, each producing 0.9 Newtons* (0.2 pounds force) of thrust for controlling where the orbiter is pointed during normal operations as well as during Mars orbit insertion and trajectory correction maneuvers. Command and Data-Handling Systems: The Command and Data Handling subsystem controls all spacecraft functions. This system: * manages all forms of data on the spacecraft; * carries out commands sent from Earth; * prepares data for transmission to the Earth; * manages collection of solar power and charging of the batteries; * collects and processes information about all subsystems and payloads; * keeps and distributes the spacecraft time; * calculates its position in orbit around Mars; * carries out commanded maneuvers; and * autonomously monitors and responds to any onboard problems that occur. The key parts of this system are: * Space Flight Computer (a space-qualified processor based on the 133 MHz PowerPC processor) * Flight Software * Solid State Recorder (total capacity 160 Gigabits) Guidance, Navigation, and Control Systems: The guidance, navigation, and control subsystem is used to control the orientation of the orbiter as it travels through space and to maintain knowledge of where celestial bodies are located (for example, Earth and the sun). This knowledge is critical for the spacecraft to perform the correct maneuvers to get to Mars, to keep its solar arrays pointed toward the sun in order to produce power, and to keep its antenna pointed toward the Earth in order to maintain communications. In orbit around Mars, this subsystem also maintains constant knowledge of where the spacecraft is in its orbit, and is able to point the science cameras to an accuracy of about 1/20th of one degree. Electrical Power: The electrical power subsystem is responsible for generating, storing, and distributing power to the orbiter systems and includes two solar panels and two nickel-hydrogen batteries. Solar panels: The one and only source of power for Mars Reconnaissance Orbiter is sunlight. Mounted on opposite sides of the orbiter and capable of changing position to allow the orbiter to track the sun continuously, each solar panel has an area of approximately 10 square meters (107.6 square feet), and contains 3,744 individual solar cells. The solar cells are able to convert more than 26% of the sun's energy directly into electricity. The solar panels were deployed soon after launch and have remained deployed throughout the mission. During aerobraking the solar panels had a special role to play. As the spacecraft skimmed through the upper layers of the Martian atmosphere, the large, flat panels acted to slow the spacecraft down and reduce the size of its orbit. The solar arrays were designed to withstand temperatures of almost 200 Celsius. Nickel-hydrogen batteries: Mars Reconnaissance Orbiter uses two nickel-hydrogen rechargeable batteries, each with an energy storage capacity of 50 ampere-hours (at 32 volts, 1600 watts per hour). Only about 40% of the battery capacity is intended to be used. The batteries charges during the day side of each two-hour orbit around Mars, using electricity produced by the solar cells, and provides power during the night side of each orbit. Thermal Systems: The thermal subsystem maintains the right temperatures in all parts of the spacecraft. It employs several conduction- and radiation-based techniques for thermal control: * Radiators * Surface coatings * Thermal blankets * Heaters. " END_OBJECT = INSTRUMENT_HOST_INFORMATION OBJECT = INSTRUMENT_HOST_REFERENCE_INFO REFERENCE_KEY_ID = "UNK" END_OBJECT = INSTRUMENT_HOST_REFERENCE_INFO END_OBJECT = INSTRUMENT_HOST END