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') weighed 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 and    for burns that helped capture the spacecraft into orbit around    Mars.    Spacecraft Configurations    -------------------------    During its five-year mission, the spacecraft needed to operate 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 be 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 orbiter typically kept 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 pointed side-    to-side in order to capture high-priority science targets that did    not fall directly beneath the spacecraft. The spacecraft could    point off-nadir up to 30 degrees.    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) were led by    Principal Investigators (PI).  Each PI lead team was responsible    for the provision and operation of a scientific instrument and the    analysis of its data. The PI lead investigations were: 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 were two investigation    teams that made use of facility instruments. The facility    instruments were Context Imager (CTX) and Shallow (Subsurface)    Radar (SHARAD).    The MARCI PI and Science Team also acted as Team Leader (TL) and    Team     Members for the CTX facility instrument.  The Italian    Space Agency (ASI) provided a 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.    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: Alfred McEwen, 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 micro-m) (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: Daniel J. McCleese, Jet Propulsion Lab (JPL).    Instrument: SHARAD    Type: Shallow Subsurface Radar    Measurements: Ground penetrating radar; transmit split band at      20mhz <1km; 10-20 m vertical resolution 1km x 5km.    Science Goals: Regional near-surface ground structure.    Key Attributes:  Shallow sounding; regional profiling; high data      rate.    Team Leader: Roberto Seu, University of Rome, Italy.    Deputy Team Leader: Roger Phillips, Washington University, St.      Louis.    Engineering Instruments: Mars Reconnaissance Orbiter carried three    instruments that will assist in spacecraft navigation and    communications.    1. Electra UHF Communications and Navigation Package: Electra    allowed the spacecraft to act as a communications relay between    the Earth and landed crafts on Mars that may not have sufficient    radio power to communicate directly with Earth by themselves.    2. Optical Navigation Camera: This camera was being tested for    improved navigation capability for future missions. Similar    cameras placed on orbiters of the future would be 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 tested the use of a radio frequency    called 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 supported and protected 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 on board Mars    Reconnaissance Orbiter:    * one that allowed the high-gain antenna to move in order to point      at earth    * two that allowed 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 traveled around Mars each orbit, these gimbals    allowed both solar arrays to be always pointed toward the sun,    while the high-gain antenna could simultaneously always be pointed    at earth.    Telecommunications System:  The telecommunications subsystem was a    two-way radio system used for receiving and transmitting commands    and data between the Mars Reconnaissance Orbiter and the Deep    Space Network antenna on earth. With its large-dish antenna,    powerful amplifier, and fast computer, Mars Reconnaissance Orbiter    could 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 operated in the X-band of the radio spectrum, at a    frequency of around 8 Gigahertz.    Major components of the telecom subsystem included:    * 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 on board was Electra, a UHF telecommunications package that    was one of the engineering instruments providing navigation and    communications support to landers and rovers on the surface of    Mars. Electra allowed 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    remained deployed for the remainder of the mission. It served as    the primary means of communication to and from the orbiter. The    high-gain antenna had to be pointed accurately and was therefore    steered using the gimbal mechanism.    Low-gain Antennas: Two smaller antennas were present for lower-    rate communication during emergencies and special events, such as    launch and Mars Orbit Insertion. The data rate of these antennas    was lower because they focused the radio beam much more broadly    than the high gain antenna, so less of the signal reached earth.    But the Deep Space Network station on the earth could detect the    signal even when the spacecraft was not pointed at earth, and    therefore these antennas were useful for emergencies. The low-gain    antennas had the capability to transmit and receive. The two low-    gain antennas were mounted on the high-gain antenna dish--one on    the front side and one on the back--and were moved with it. Two    were needed in that placement so that communication was 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 was    the     enclosure for the Traveling Wave Tube Amplifiers, which    boosted the power of radio signals so that they were strong enough    to be received at the Deep Space Network antennas. There were    three amplifiers on board:    * two for the X-band radio frequency that transmitted radio    signals at a power of 100 watts (the second one was for back up    to ensure communications in case the first amplifier failed)    * one for Ka-band radio frequency that was capable of transmitting    at 35 watts.    Transponders: Mars Reconnaissance Orbiter carried two    transponders, which are special types of radio    receiver/transmitters, specially designed for long-range space    communications. The second transponder was a backup. The    transponders had several functions:    * transmit/receive function: translated digital electrical signals    into radio signals for sending data to earth, and translated radio    signals to digital electrical signals for receiving commands from    earth    * transponding function: listened for and detected a signal coming    in from earth, to which it automatically responded    * navigation function: transmitted several types of signals that    provided     critical navigation clues, enabling navigators on the    ground to make precise calculations of the spacecraft speed and    distance from earth    Propulsion: The propulsion subsystem performed major maneuvers    such as trajectory correction maneuvers and Mars orbit insertion.    The propulsion subsystem was also used to control the spacecraft's    position, as a backup to the reaction wheels.    Mars Reconnaissance Orbiter used a monopropellant propulsion    system: it carried fuel (hydrazine), but no oxidizer. Thrust was    produced by passing the fuel over beds of catalyst material just    before it entered the thruster, which caused the hydrazine to    combust.    The propulsion system included:    Propellant Tank    The monopropellant hydrazine tank held 1187 kilograms (2617    pounds) of usable propellant. Over 70% of the total propellant was    used during Mars orbit insertion.    Pressurant Tank    Mars Reconnaissance Orbiter fed pressurized helium gas from a    separate high- pressure tank, through a regulator, into the    propellant tank where it put the hydrazine propellant under    pressure.    Lines, Valves, and Regulators    The pressurized hydrazine flowed through a system of metal tubing    to each of the thrusters. Each thruster had a valve so that it    could be fired independently. Additional valves in the propellant    lines turned on and off the flow to groups of thrusters.    Thrusters    A total of 20 rocket engine thrusters were 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 controlled all spacecraft functions. This system:    * managed all forms of data on the spacecraft;    * carried out commands sent from earth;    * prepared data for transmission to the earth;    * managed collection of solar power and charging of the batteries;    * collected and processed information about all subsystems and      payloads;    * kept and distributed the spacecraft time;    * calculated its position in orbit around Mars;    * carried out commanded maneuvers; and    * autonomously monitored and responded to any onboard      problems that occurred.    The key parts of this system were:    * 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 was 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 was 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.    Once in orbit around Mars, this subsystem also maintained constant    knowledge of where the spacecraft was in its orbit, and was able to    point the science cameras to an accuracy of about 1/20th of one    degree.    Electrical Power:  The electrical power subsystem was responsible    for generating, storing, and distributing power to the orbiter    systems and included two solar panels and two nickel-hydrogen    batteries.    Solar panels: The one and only source of power for Mars    Reconnaissance Orbiter was 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 had an area of    approximately 10 square meters (107.6 square feet), and contained    3,744 individual solar cells. The solar cells were able to convert    more than 26% of the sun's energy directly into electricity. The    solar panels were deployed soon after launch and 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 used 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 was intended to be    used. The batteries charged during the day side of each two-hour    orbit around Mars, using electricity produced by the solar cells,    and provided power during the night side of each orbit.    Thermal Systems: The thermal subsystem maintained the right    temperatures in all parts of the spacecraft. It employed several    conduction- and radiation-based techniques for thermal control:    * Radiators    * Surface coatings    * Thermal blankets    * Heaters.