Mars Reconnaissance Orbiter

Conceptual image depicting the Mars ReconnaissanceOrbiter in an elliptical low­planet orbit around Mars

Mission type Mars orbiter

Operator NASA / JPL

COSPAR ID 2005­029A

SATCAT 28788

Website marsprogram.jpl.nasa.gov/mro/ (http://marsprogram.jpl.nasa.gov/mro/)www.nasa.gov/mission_pages/MRO/main/index.html (http://www.nasa.gov/mission_pages/MRO/main/index.html)

Missionduration

Primary mission: two years

Elapsed:11 years, 2 months and 26 days fromlaunch

10 years, 7 months and 28 days (3791 sols) at Mars

Spacecraft properties

Manufacturer Lockheed Martin / University of Arizona /APL / ASI / Malin Space Science Systems

Launch mass 2,180 kg (4,810 lb)

Dry mass 1,031 kg (2,273 lb)

Payload mass 139 kg (306 lb)

Power 2,000.0 watts

Start of mission

Launch date 12 August 2005, 11:43:00 UTC

Mars Reconnaissance OrbiterFrom Wikipedia, the free encyclopedia

Mars Reconnaissance Orbiter (MRO) is a multipurposespacecraft designed to conduct reconnaissance andexploration of Mars from orbit. The US$720 millionspacecraft was built by Lockheed Martin under thesupervision of the Jet Propulsion Laboratory (JPL). Themission is managed by the California Institute ofTechnology, at the JPL, in La Cañada Flintridge,California, for the NASA Science Mission Directorate,Washington, D.C. It was launched August 12, 2005, andattained Martian orbit on March 10, 2006. In November2006, after five months of aerobraking, it entered its finalscience orbit and began its primary science phase. AsMRO entered orbit, it joined five other active spacecraftthat were either in orbit or on the planet's surface: MarsGlobal Surveyor, Mars Express, 2001 Mars Odyssey, andthe two Mars Exploration Rovers (Spirit andOpportunity); at the time, this set a record for the mostoperational spacecraft in the immediate vicinity of Mars.Mars Global Surveyor and the Spirit rover have sinceceased to function; the remainder remain operational as ofSeptember 2016.

MRO contains a host of scientific instruments such ascameras, spectrometers, and radar, which are used toanalyze the landforms, stratigraphy, minerals, and ice ofMars. It paves the way for future spacecraft bymonitoring Mars' daily weather and surface conditions,studying potential landing sites, and hosting a newtelecommunications system. MRO's telecommunicationssystem will transfer more data back to Earth than allprevious interplanetary missions combined, and MROwill serve as a highly capable relay satellite for futuremissions.[2]

Contents

1 Pre­launch2 Mission objectives3 Launch and orbital insertion4 Timeline5 Instruments

5.1 HiRISE (camera)5.2 CTX (camera)5.3 MARCI (camera)

5.4 CRISM (spectrometer)

Rocket Atlas V 401

Launch site Cape Canaveral SLC­41

Contractor ILS

Orbital parameters

Referencesystem

Areocentric

Regime Sun­synchronous[1]

Inclination 93 degrees[1]

Mars orbiter

Orbitalinsertion

10 March 2006, 21:24:00 UTCMSD 46990 12:48 AMT

20 Dhanus 211 Darian

Diagram of instrumentation aboardMRO

5.4 CRISM (spectrometer)5.5 Mars Climate Sounder5.6 SHARAD (radar)5.7 Engineering instruments

6 Engineering data6.1 Structure6.2 Power systems6.3 Electronic systems6.4 Telecommunications system6.5 Propulsion and attitude

control7 Discoveries and photographs

7.1 Water ice in ice cap measured7.2 Ice exposed in new craters7.3 Ice in lobate debris aprons7.4 Chloride deposits7.5 Other aqueous minerals7.6 Avalanches7.7 Other spacecraft7.8 Flowing salty water

8 See also9 References10 Further reading11 External links

Pre­launch

One of two missions considered for the 2003 Mars launchwindow, the MRO proposal lost against what becameknown as the Mars Exploration Rovers. The orbiter mission wasrescheduled for launch in 2005,[3] and NASA announced its final name,Mars Reconnaissance Orbiter, on October 26, 2000.[4]

MRO is modeled after NASA's highly successful Mars Global Surveyor toconduct surveillance of Mars from orbit. Early specifications of the satelliteincluded a large camera to take high resolution pictures of Mars. In thisregard, James B. Garvin, the Mars exploration program scientist for NASA,proclaimed that MRO would be a "microscope in orbit".[5] The satellite wasalso to include a visible­near­infrared spectrograph.

On October 3, 2001, NASA chose Lockheed Martin as the primarycontractor for the spacecraft's fabrication.[6] By the end of 2001 all of the mission's instruments were selected.There were no major setbacks during MRO's construction, and the spacecraft was moved to John F. KennedySpace Center on May 1, 2005 to prepare it for launch.[7]

Mission objectives

MRO science operations were initially scheduled to last two Earth years, from November 2006 to November 2008.One of the mission's main goals is to map the Martian landscape with its high­resolution cameras in order tochoose landing sites for future surface missions. The MRO played an important role in choosing the landing site of

Launch of AtlasV carrying theMarsReconnaissanceOrbiter,11:43:00 UTCAugust 12, 2005

Transfer orbit from Earth to Mars.TCM­1 to TCM­4 denote the plannedtrajectory correction maneuvers.

the Phoenix Lander, which explored the Martian Arctic in Green Valley.[8] The initial site chosen by scientists wasimaged with the HiRISE camera and found to be littered with boulders. After analysis with HiRISE and the MarsOdyssey's THEMIS instrument a new site was chosen. Mars Science Laboratory, a highly maneuverable rover,also had its landing site inspected. The MRO provided critical navigation data during their landings and acts as atelecommunications relay.

MRO is using its onboard scientific equipment to study the Martian climate, weather, atmosphere, and geology,and to search for signs of liquid water in the polar caps and underground. In addition, MRO was tasked withlooking for the remains of the previously lost Mars Polar Lander and Beagle 2 spacecraft.[9] Beagle 2 was found bythe orbiter at the beginning of 2015.[10] After its main science operations are completed, the probe's extendedmission is to be the communication and navigation system for landers and rover probes.[11]

Launch and orbital insertion

On August 12, 2005, MRO was launched aboard anAtlas V­401 rocket from Space Launch Complex 41 atCape Canaveral Air Force Station.[12] The Centaurupper stage of the rocket completed its burns over afifty­six­minute period and placed MRO into aninterplanetary transfer orbit towards Mars.[13]

MRO cruised through interplanetary space for sevenand a half months before reaching Mars. While enroute most of the scientific instruments andexperiments were tested and calibrated. To ensureproper orbital insertion upon reaching Mars, fourtrajectory correction maneuvers were planned and afifth emergency maneuver was discussed.[14] However,only three trajectory correction maneuvers werenecessary, which saved 60 pounds (27 kg) fuel thatwould be usable during MRO's extended mission.[15]

MRO began orbital insertion by approaching Mars on March 10, 2006, and passing above its southern hemisphereat an altitude of 370–400 kilometers (230–250 mi). All six of MRO's main engines burned for 27 minutes to slowthe probe from 2,900 to 1,900 meters per second (9,500 to 6,200 ft/s). The helium pressurization tank was colderthan expected, which reduced the pressure in the fuel tank by about 21 kilopascals (3.0 psi). The reduced pressurecaused the engine thrust to be diminished by 2%, but MRO automatically compensated by extending the burn timeby 33 seconds.[16]

Completion of the orbital insertion placed the orbiter in a highly elliptical polar orbit with a period ofapproximately 35.5 hours.[17] Shortly after insertion, the periapsis – the point in the orbit closest to Mars – was426 km (265 mi) from the surface[17] (3,806 km (2,365 mi) from the planet's center). The apoapsis – the point inthe orbit farthest from Mars – was 44,500 km (27,700 mi) from the surface (47,972 km (29,808 mi) from theplanet's center).

On March 30, 2006, MRO began the process of aerobraking, a three­step procedure that cuts in half the fuelneeded to achieve a lower, more circular orbit with a shorter period. First, during its first five orbits of the planet(one Earth week), MRO used its thrusters to drop the periapsis of its orbit into aerobraking altitude. This altitudedepends on the thickness of the atmosphere because Martian atmospheric density changes with its seasons. Second,

Artwork of MRO aerobraking

Tectonic fractures within the CandorChasma region of Valles Marineris,Mars, retain ridge­like shapes as thesurrounding bedrock erodes away.This points to past episodes of fluidalteration along the fractures andreveals clues into past fluid flow andgeochemical conditions below thesurface.

while using its thrusters to make minor corrections to its periapsis altitude,MRO maintained aerobraking altitude for 445 planetary orbits (about fiveEarth months) to reduce the apoapsis of the orbit to 450 kilometres(280 mi). This was done in such a way so as to not heat the spacecraft toomuch, but also dip enough into the atmosphere to slow the spacecraft down.After the process was complete, MRO used its thrusters to move itsperiapsis out of the edge of the Martian atmosphere on August 30,2006.[18][19]

In September 2006 MRO fired its thrusters twice more to fine­tune its final,nearly circular orbit to approximately 250 to 316 km (155 to 196 mi) abovethe Martian surface, with a period of about 112 minutes.[20][21] TheSHARAD radar antennas were deployed on September 16. All of the scientific instruments were tested and mostwere turned off prior to the solar conjunction that occurred from October 7 to November 6, 2006. After theconjunction ended the "primary science phase" began.

On November 17, 2006 NASA announced the successful test of the MRO as an orbital communications relay.Using the NASA rover "Spirit" as the point of origin for the transmission, the MRO acted as a relay fortransmitting data back to Earth.

Timeline

On September 29, 2006 (sol 402), MRO took its first high resolution imagefrom its science orbit. This image is said to resolve items as small as 90 cm(3 feet) in diameter. On October 6, NASA released detailed pictures fromthe MRO of Victoria crater along with the Opportunity rover on the rimabove it.[22] In November, problems began to surface in the operation oftwo MRO spacecraft instruments. A stepping mechanism in the MarsClimate Sounder (MCS) skipped on multiple occasions resulting in a fieldof view that is slightly out of position. By December normal operations ofthe instrument was suspended, although a mitigation strategy allows theinstrument to continue making most of its intended observations.[23] Also,an increase in noise and resulting bad pixels has been observed in severalCCDs of the High Resolution Imaging Science Experiment (HiRISE).Operation of this camera with a longer warm­up time has alleviated theissue. However, the cause is still unknown and may return.[24]

HiRISE continues to return images that have enabled discoveries regardingthe geology of Mars. Foremost among these is the announcement of bandedterrain observations indicating the presence and action of liquid carbondioxide (CO2) or water on the surface of Mars in its recent geological past.HiRISE was able to photograph the Phoenix lander during its parachuted descent to Vastitas Borealis on May 25,2008 (sol 990).

The orbiter continued to experience recurring problems in 2009, including four spontaneous resets, culminating ina four­month shut­down of the spacecraft from August to December.[25] While engineers have not determined thecause of the recurrent resets, they have created new software to help troubleshoot the problem should it recur.

HiRISE camera structure

HiRISE image of the 'face' at CydoniaMesa

On March 3, 2010, the Mars Reconnaissance Orbiter passed another significant milestone, having transmitted over100 terabits of data back to Earth, which was more than all other interplanetary probes sent from Earthcombined.[26]

On August 6, 2012 (sol 2483, the orbiter passed over Gale crater, the landing site of the Mars Science Laboratorymission, during its EDL phase. It captured an image via the HiRISE camera of the Curiosity rover descending withits backshell and supersonic parachute.

NASA reported that the Mars Reconnaissance Orbiter,[27] as well as the Mars Odyssey Orbiter[28] and MAVENorbiter[29] had a chance to study the Comet Siding Spring flyby on October 19, 2014.[30][31]

On July 29, 2015, the Mars Reconnaissance Orbiter was placed into a new orbit to provide communicationssupport during the arrival of the InSight Mars lander mission on September 28, 2016.[32] The maneuver's engineburn lasted for 75 seconds.[33]

Instruments

Three cameras, two spectrometers and a radar are included on the orbiter along with two "science­facilityinstruments", which use data from engineering subsystems to collect science data. Three technology experimentswill test and demonstrate new equipment for future missions.[34] It is expected MRO will obtain about 5,000images per year.[35]

HiRISE (camera)

The High Resolution Imaging Science Experiment camera is a 0.5 m (1 ft8 in) reflecting telescope, the largest ever carried on a deep space mission,and has a resolution of 1 microradian (μrad), or 0.3 m (1 ft 0 in) from analtitude of 300 km (190 mi). In comparison, satellite images of Earth aregenerally available with a resolution of 0.5 m (1 ft 8 in), and satelliteimages on Google Maps are available to 1 m (3 ft 3 in).[36] HiRISE collectsimages in three color bands, 400 to 600 nm (blue­green or B­G), 550 to850 nm (red) and 800 to 1,000 nm (near infrared or NIR).[37]

Red color images are 20,264pixels across (6 km (3.7 mi)

wide), and B­G and NIR are 4,048 pixels across (1.2 km (0.75 mi)wide). HiRISE's onboard computer reads these lines in time with theorbiter's ground speed, and images are potentially unlimited in length.Practically however, their length is limited by the computer's 28Gigabit (Gb) memory capacity, and the nominal maximum size is20,000 × 40,000 pixels (800 megapixels) and 4,000 × 40,000 pixels(160 megapixels) for B­G and NIR images. Each 16.4 Gb image iscompressed to 5 Gb before transmission and release to the generalpublic on the HiRISE website (http://hirise.lpl.arizona.edu/) in JPEG2000 format.[21][38] To facilitate the mapping of potential landing sites,HiRISE can produce stereo pairs of images from which topographycan be calculated to an accuracy of 0.25 m (9.8 in).[39] HiRISE wasbuilt by Ball Aerospace & Technologies Corp.

Mars Color Imager on the right side

Resolution and field ofview compared forHiRISE and MarsOrbiter Camera onMars Global Surveyor.

CTX (camera)

The Context Camera (CTX) provides grayscale images (500 to 800 nm) with a pixel resolution up to about 6 m(20 ft). CTX is designed to provide context maps for the targeted observations of HiRISE and CRISM, and is alsoused to mosaic large areas of Mars, monitor a number of locations for changes over time, and to acquire stereo(3D) coverage of key regions and potential future landing sites.[40][41] The optics of CTX consist of a 350 mm(14 in) focal length Maksutov Cassegrain telescope with a 5,064 pixel wide line array CCD. The instrument takespictures 30 km (19 mi) wide and has enough internal memory to store an image 160 km (99 mi) long beforeloading it into the main computer.[42] The camera was built, and is operated by Malin Space Science Systems.CTX mapped 50% of Mars by February 2010.[43] In 2012 it found the impacts of six 55­pound (25­kilogram) entryballast masses from Mars Science Laboratory's landing of Curiosity rover.[44]

MARCI (camera)

The Mars Color Imager (MARCI) is a wide­angle, relatively low­resolutioncamera that views the surface of Mars in five visible and two ultravioletbands. Each day, MARCI collects about 84 images and produces a globalmap with pixel resolutions of 1 to 10 km (0.62 to 6.21 mi). This mapprovides a daily weather report for Mars (http://www.msss.com/msss_images/latest_weather.html), helps to characterize its seasonal and annualvariations, and maps the presence of water vapor and ozone in itsatmosphere.[45] The camera was built and is operated by Malin SpaceScience Systems. It has a 180­degree fisheye lens with the seven colorfilters bonded directly a single CCD sensor.[46]

CRISM (spectrometer)

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument is a visible and near infrared(VNIR) spectrometer that is used to produce detailed maps of the surface mineralogy of Mars. It operates from 370to 3920 nm, measures the spectrum in 544 channels (each 6.55 nm wide), and has a resolution of 18 m (59 ft) at analtitude of 300 km (190 mi). CRISM is being used to identify minerals and chemicals indicative of the past orpresent existence of water on the surface of Mars. These materials include iron, oxides, phyllosilicates, andcarbonates, which have characteristic patterns in their visible­infrared energy.[47]

CRISM Instrument

An artist's concept of MRO usingSHARAD to "look" under the surfaceof Mars

Mars Climate Sounder

The Mars Climate Sounder (MCS) looks both down and horizontallythrough the atmosphere in order to quantify the global atmosphere’svertical variations. It is a spectrometer with one visible/near infraredchannel (0.3 to 3.0 μm) and eight far infrared (12 to 50 μm) channelsselected for the purpose. MCS observes the atmosphere on the horizon ofMars (as viewed from MRO) by breaking it up into vertical slices andtaking measurements within each slice in 5 km (3.1 mi) increments. Thesemeasurements are assembled into daily global weather maps to show thebasic variables of Martian weather: temperature, pressure, humidity, anddust density.[48]

This instrument, supplied by NASA’s Jet Propulsion Laboratory, Pasadena, California, utilizes technologicaladvances to achieve the measurement objectives of a heavier, larger instrument originally developed at JPL for the1992 Mars Observer and 1998 Mars Climate Orbiter missions.

SHARAD (radar)

MRO's Shallow Subsurface Radar (SHARAD) experiment is designed toprobe the internal structure of the Martian polar ice caps. It also gathersplanet­wide information about underground layers of ice, rock and possiblyliquid water that might be accessible from the surface. SHARAD uses HFradio waves between 15 and 25 MHz, a range that allows it to resolvelayers as thin as 7 m (23 ft) to a maximum depth of 1 km (0.6 mi). It has ahorizontal resolution of 0.3 to 3 km (0.2 to 1.9 mi).[49] SHARAD isdesigned to operate in conjunction with the Mars Express MARSIS, whichhas lower resolution but penetrates to a much greater depth. BothSHARAD and MARSIS were made by the Italian Space Agency.[50]

Engineering instruments

In addition to its imaging equipment, MRO carries a variety of engineeringinstruments. The Gravity Field Investigation Package measures variations in the Martian gravitational fieldthrough variations in the spacecraft's velocity. Velocity changes are detected by measuring doppler shifts in MRO'sradio signals received on Earth. The package also includes sensitive onboard accelerometers used to deduce the insitu atmospheric density of Mars during aerobraking.[51]

The Electra communications package is a UHF software­defined radio (SDR) that provides a flexible platform forevolving relay capabilities.[52] It is designed to communicate with other spacecraft as they approach, land, andoperate on Mars. In addition to protocol controlled inter­spacecraft data links of 1 kbit/s to 2 Mbit/s, Electra alsoprovides Doppler data collection, open loop recording and a highly accurate timing service based on a 5e−13 USO.Doppler information for approaching vehicles can be used for final descent targeting or descent and landingtrajectory recreation. Doppler information on landed vehicles will also enable scientists to accurately determine thesurface location of Mars landers and rovers. The two MER spacecraft currently on Mars utilize an earliergeneration UHF relay radio providing similar functions through the Mars Odyssey orbiter. The Electra radio hasproven its functionality by relaying information to and from the MER spacecraft, Phoenix Mars lander andCuriosity rover.

Size comparison of MRO withpredecessors

The Mars Reconnaissance Orbitersolar panel

The Optical Navigation Camera images the Martian moons, Phobos and Deimos, against background stars toprecisely determine MRO's orbit. Although moon imaging is not mission critical, it was included as a technologytest for future orbiting and landing of spacecraft.[53] The Optical Navigation Camera was tested successfully inFebruary and March 2006.[54] There is a proposal to search for small moons, dust rings, and old orbiters with it.[55]

Engineering data

Structure

Workers at Lockheed Martin Space Systems in Denver assembled thespacecraft structure and attached the instruments. Instruments wereconstructed at the Jet Propulsion Laboratory, the University of ArizonaLunar and Planetary Laboratory in Tucson, Arizona, Johns HopkinsUniversity Applied Physics Laboratory in Laurel, Maryland, the ItalianSpace Agency in Rome, and Malin Space Science Systems in SanDiego.[56] The total cost of the spacecraft was $720 million USD.[57]

The structure is made of mostly carbon composites and aluminum­honeycombed plates. The titanium fuel tanktakes up most of the volume and mass of the spacecraft and provides most of its structural integrity. Thespacecraft's total mass is less than 2,180 kg (4,810 lb) with an unfueled dry mass less than 1,031 kg (2,273 lb).[58]

Power systems

MRO gets all of its electrical power from two solar panels, each of whichcan move independently around two axes (up­down, or left­right rotation).Each solar panel measures 5.35 m × 2.53 m (17.6 ft × 8.3 ft) and has 9.5 m2

(102 sq ft) covered with 3,744 individual photovoltaic cells. Its high­efficiency triple junction solar cells are able to convert more than 26% ofthe Sun's energy directly into electricity and are connected together toproduce a total output of 32 volts. At Mars, each of the panels producesmore than 1,000 watts of power;[59] in contrast, the panels would generate3,000 watts in a comparable Earth orbit by being closer to the Sun.[60]

MRO has two rechargeable nickel­hydrogen batteries used to power thespacecraft when it is not facing the Sun. Each battery has an energy storagecapacity of 50 ampere­hours (180 kC). The full range of the batteriescannot be used due to voltage constraints on the spacecraft, but allows theoperators to extend the battery life—a valuable capability, given that battery drain is one of the most commoncauses of long­term satellite failure. Planners anticipate that only 40% of the batteries' capacities will be requiredduring the lifetime of the spacecraft.[60]

Electronic systems

MRO's main computer is a 133 MHz, 10.4 million transistor, 32­bit, RAD750 processor. This processor is aradiation­hardened version of a PowerPC 750 or G3 processor with a specially built motherboard. The RAD750 isa successor to the RAD6000. This processor may seem underpowered in comparison to a modern PC processor,but it is extremely reliable, resilient, and can function in solar flare­ravaged deep space.[61] The operating systemsoftware is VxWorks and has extensive fault protection protocols and monitoring.[62]

MRO High Gain Antenna installation

Data is stored in a 160 Gb (20 GB) flash memory module consisting of over 700 memory chips, each with a256 Mbit capacity. This memory capacity is not actually that large considering the amount of data to be acquired;for example, a single image from the HiRISE camera can be as large as 28 Gb.[62]

Telecommunications system

The Telecom Subsystem on MRO is the best digital communication systemsent into deep space so far and for the first time using capacity approachingturbo­codes. The Electra communications package is a UHF software­defined radio (SDR) that provides a flexible platform for evolving relaycapabilities.[52] It is designed to communicate with other spacecraft as theyapproach, land, and operate on Mars. The system consists of a very large (3metres (9.8 ft)) antenna, which is used to transmit data through the DeepSpace Network via X­band frequencies at 8 GHz, and it demonstrates theuse of the Ka band at 32 GHz for higher data rates. Maximum transmissionspeed from Mars is projected to be as high as 6 Mbit/s, a rate ten timeshigher than previous Mars orbiters. The spacecraft carries two 100­watt X­band amplifiers (one of which is a backup), one 35­watt Ka­band amplifier,

and two Small Deep Space Transponders (SDSTs).[2]

Two smaller low­gain antennas are also present for lower­ratecommunication during emergencies and special events, such as launch andMars Orbit Insertion. These antennas do not have focusing dishes and cantransmit and receive from any direction. They are an important backupsystem to ensure that MRO can always be reached, even if its main antennais pointed away from the Earth.[2]

The Ka­band subsystem was used for demonstration purposes. Due to lack of spectrum at 8.41 GHz X­band, futurehigh­rate deep space missions will use 32 GHz Ka­band. NASA Deep Space Network (DSN) implemented Ka­band receiving capabilities at all three of its complexes (Goldstone, Canberra and Madrid) over its 34­m beam­waveguide (BWG) antenna subnet. During the cruise phase, spacecraft Ka­band telemetry was tracked 36 times bythese antennas proving functionality at all antennas. Ka­band tests were also planned during the science phase, but

during aerobraking a switch failed, limiting the X­band high gain antenna to a single amplifier.[63] If this amplifierfails all high­speed X­band communications will be lost. The Ka downlink is the only remaining backup for this

functionality, and since the Ka­band capability of one of the SDST transponders has already failed,[64] (and theother might have the same problem) JPL decided to halt all Ka­band demonstrations and hold the remaining

capability in reserve.[65]

By November 2013, the MRO had passed 200 terabits in the amount of science data returned. The data returned bythe mission alone is more than three times the total data returned via NASA's Deep Space Network for all the othermissions managed by NASA's Jet Propulsion Laboratory over the past 10 years.[66]

Propulsion and attitude control

Data comparison chart

The spacecraft uses a 1,175 l (258 imp gal; 310 US gal) fuel tank filledwith 1,187 kg (2,617 lb) of hydrazine monopropellant. Fuel pressure isregulated by adding pressurized helium gas from an external tank. Seventypercent of the propellant was used for orbital insertion,[67] and it hasenough propellant to keep functioning into the 2030s.[68]

MRO has twenty rocket engine thrusters on board. Six large thrusters eachproduce 170 N (38 lbf) of thrust for a total of 1,020 N (230 lbf) meantmainly for orbital insertion. These thrusters were originally designed for theMars Surveyor 2001 Lander. Six medium thrusters each produce 22 N

(4.9 lbf) of thrust for trajectory correction maneuvers and attitude control during orbit insertion. Finally, eight small

thrusters each produce 0.9 N (0.20 lbf) of thrust for attitude control during normal operations.[67]

Four reaction wheels are also used for precise attitude control during activities requiring a highly stable platform,such as high­resolution imaging, in which even small motions can cause blurring of the image. Each wheel is usedfor one axis of motion. The fourth (skewed) wheel is a backup in case one of the other three wheels fails. Eachwheel weighs 10 kg (22 lb) and can be spun as fast as 100 Hz or 6,000 rpm.[67]

In order to determine the spacecraft's orbit and facilitate maneuvers, sixteen Sun sensors – eight primaries andeight backups – are placed around the spacecraft to calibrate solar direction relative to the orbiter's frame. Two startrackers, digital cameras used to map the position of catalogued stars, provide NASA with full, three­axisknowledge of the spacecraft orientation and attitude. A primary and backup Miniature Inertial Measurement Unit(MIMU), provided by Honeywell, measures changes to the spacecraft attitude as well as any non­gravitationallyinduced changes to its linear velocity. Each MIMU is a combination of three accelerometers and three ring­lasergyroscopes. These systems are all critically important to MRO, as it must be able to point its camera to a very highprecision in order to take the high­quality pictures that the mission requires. It has also been specifically designedto minimize any vibrations on the spacecraft, so as to allow its instruments to take images without any distortionscaused by vibrations.[69]

Discoveries and photographs

Water ice in ice cap measured

Results published in 2009 of radar measurements of the north polar ice cap determined that the volume of water icein the cap is 821,000 cubic kilometres (197,000 cu mi), equal to 30% of the Earth's Greenland ice sheet.[70]

Ice exposed in new craters

An article in the journal Science in September 2009,[71] reported that some new craters on Mars have excavatedrelatively pure water ice. After being exposed, the ice gradually fades as it sublimates away. These new craterswere found and dated by the CTX camera, and the identification of the ice was confirmed with the CompactImaging Spectrometer (CRISM) on board the Mars Reconnaissance Orbiter (MRO). The ice was found in a total offive locations. Three of the locations are in the Cebrenia quadrangle. These locations are ;

; and . Two others are in the Diacria quadrangle: and.[72][73]

Ice in lobate debris aprons

55.57°N 150.62°E43.28°N 176.9°E 45°N 164.5°E 46.7°N 176.8°E46.33°N 176.9°E

Water ice excavated by an impactcrater that formed between Januaryand September 2008. The ice wasidentified spectroscopically usingCRISM.

Lobate debris apron in PhlegraMontes, Cebrenia quadrangle. Thedebris apron is probably mostly icewith a thin covering of rock debris,so it could be a source of water forfuture Martian colonists. Scale bar is500 m (1,600 ft).

Chloride deposits in Terra Sirenum

Radar results from SHARAD suggested that features termed lobate debrisaprons (LDAs) contain large amounts of water ice. Of interest from thedays of the Viking Orbiters, these LDA are aprons of material surroundingcliffs. They have a convex topography and a gentle slope; this suggestsflow away from the steep source cliff. In addition, lobate debris aprons canshow surface lineations just as rock glaciers on the Earth.[74] SHARAD hasprovided strong evidence that the LDAs in Hellas Planitia are glaciers thatare covered with a thin layer of debris (i.e. rocks and dust); a strongreflection from the top and base of LDAs was observed, suggesting thatpure water ice makes up the bulk of the formation (between the tworeflections).[75] Based on the experiments of the Phoenix lander and thestudies of the Mars Odyssey from orbit, water ice is known to exist justunder the surface of Mars in the far north and south (high latitudes).

Chloride deposits

Using data from Mars Global Surveyor, Mars Odyssey and the MarsReconnaissance Orbiter, scientists have found widespread deposits ofchloride minerals. Evidence suggests that the deposits were formed fromthe evaporation of mineral enriched waters. The research suggests thatlakes may have been scattered over large areas of the Martian surface.Usually chlorides are the last minerals to come out of solution. Carbonates,sulfates, and silica should precipitate out ahead of them. Sulfates and silicahave been found by the Mars Rovers on the surface. Places with chlorideminerals may have once held various life forms. Furthermore, such areascould preserve traces of ancient life.[76]

Other aqueous minerals

In 2009, a group of scientists from the CRISM team reported on 9 to 10different classes of minerals formed in the presence of water. Differenttypes of clays (also called phyllosilicates) were found in many locations.The physilicates identified included aluminum smectite, iron/magnesiumsmectite, kaolinite, prehnite, and chlorite. Rocks containing carbonate werefound around the Isidis basin. Carbonates belong to one class in which lifecould have developed. Areas around Valles Marineris were found to containhydrated silica and hydrated sulfates. The researchers identified hydratedsulfates and ferric minerals in Terra Meridiani and in Valles Marineris.Other minerals found on Mars were jarosite, alunite, hematite, opal, andgypsum. Two to five of the mineral classes were formed with the right pHand sufficient water to permit life to grow.[77]

Avalanches

The Mars Reconnaissance Orbiter CTX and HiRISE cameras havephotographed a number of avalanches off the scarps of the northern polarcap as they were occurring.[78]

Martian avalanche anddebris falls (HiRISE2008)

A photo with scaledemonstrates the sizeof the avalanche.

Other spacecraft

Image of Phoenixlanding on Mars, asseen by HiRISE.Although in the imageit appears to bedescending into thecrater, Phoenix actuallylanded 20 km (12 mi)away from it.

The Phoenix landerand its heatshield asseen by HiRISE

Tracks of the roverOpportunity, as seenby HiRISE. The whitedots are places wherethe rover stopped toperform scientificobservations or turned.

Opportunity as seen byHiRISE on January 29,2009. Opportunity ison its way toEndeavour Crater,17 km (11 mi) away atthis point.

The Curiosity roverduring atmosphericentry as seen byHiRISE on August 6,2012. Supersonicparachute andbackshell visible.

Flowing salty water

On August 4, 2011 (sol 2125), NASA announced that MRO had detected what appeared to be flowing salty wateron the surface or subsurface of Mars.[79] On September 28, 2015, this finding was confirmed at a special NASAnews conference.[80][81]

See also

References

ExoMars Trace Gas OrbiterExploration of MarsGeography of MarsList of Mars orbitersList of missions to MarsMars ExpressMars Global SurveyorMars Orbiter MissionMAVEN

1. Lyons, Daniel T. (August 5–8, 2002). "MARS RECONNAISSANCE ORBITER: AEROBRAKING REFERENCETRAJECTORY" (PDF). AIAA/AAS Astrodynamics Specialist Conference and Exhibit. Retrieved March 9, 2012.

2. "Spacecraft Parts: Telecommunications". NASA's MRO website. Archived from the original on March 17, 2006.Retrieved May 28, 2006.

3. "NASA GOES BACK TO THE FUTURE WITH PLANS FOR A MARS ROVER IN 2003". NASA. Retrieved July 7,2006.

4. "NASA Unveils Plans for 21st Century Mars Campaign". Space.com. Archived from the original on December 10, 2004.Retrieved July 4, 2006.

5. "NASA outlines Mars Missions". Space.com. Archived from the original on February 28, 2006. Retrieved July 4, 2006.6. "NASA Picks Lockheed Martin to Build 2005 Mars Craft". Space.com. Archived from the original on February 12, 2006.Retrieved July 4, 2006.

7. "Moving Day For Mars Reconnaissance Orbiter". Space.com. Retrieved July 4, 2006.8. Spaceflight Now | Delta Launch Report | Lander targets Mars' water (http://spaceflightnow.com/mars/phoenix/070805mars.html)

9. "Mars Reconnaissance Orbiter Overview". Mars Reconnaissance Orbiter Website. Retrieved February 11, 2005.10. Knapton, Sarah (16 Jan 2015). "Beagle 2 found on surface of Mars after vanishing for 12 years". The Telegraph.

Retrieved 3 March 2015.11. "Mission Timeline: Communications Relay". Mars Reconnaissance Orbiter Website. Archived from the original on

March 6, 2006. Retrieved May 28, 2006.12. "ILS To Launch Mars Reconnaissance Orbiter For NASA On Atlas V". International Launch Services. Archived from

the original on March 11, 2006. Retrieved June 30, 2006.13. "NASA's Multipurpose Mars Mission Successfully Launched". NASA Press Release from August 12, 2005. Retrieved

May 30, 2006.14. "Mars Reconnaissance Orbiter: Multimedia". Archived from the original on April 10, 2006. Retrieved May 28, 2006.15. Leary, Warren E. (March 11, 2006). "U.S. Spacecraft Enters Orbit Around Mars". New York Times. Retrieved March 31,

2012.16. " "Spaceflight Now" MRO Mission Status Center". Retrieved March 12, 2006.17. "New Mars Orbiter Ready for Action". Space.com. Retrieved May 28, 2006.18. "Mission Timeline: Aerobraking". Mars Reconnaissance Orbiter: The Mission. Archived from the original on March 6,

2006. Retrieved May 28, 2006.19. "Mars Orbiter Successfully Makes Big Burn". Retrieved August 30, 2006.

20. "Mars Reconnaissance Orbiter Reaches Planned Flight Path". JPL. Retrieved September 13, 2006.21. "Fact Sheet: HiRISE" (PDF). National Air and Space Museum. Retrieved February 18, 2006. (PDF)22. Mars orbiter looks down on rover (http://news.bbc.co.uk/1/hi/sci/tech/5413754.stm)23. Mars Climate Sounder Team Website – What We Do | The Planetary Society (http://www.planetary.org/programs/project

s/mars_climate_sounder/)24. Deterioration of the sharpest eyes on Mars has stopped – mars­rovers – March 24, 2007 – New Scientist Space (http://spa

ce.newscientist.com/channel/space­tech/mars­rovers/mg19325963.800­deterioration­of­the­sharpest­eyes­on­mars­has­stopped.html)

25. Morris, Jefferson (January 4, 2010). "Power Cycle". Aviation Week. McGraw­Hill: 17.26. "Scientists Wowed by Data From Mars Probe". Retrieved April 21, 2013.27. Webster, Guy; Brown, Dwayne (October 19, 2014). "NASA's Mars Reconnaissance Orbiter Studies Comet Flyby".

NASA. Retrieved October 20, 2014.28. Webster, Guy; Brown, Dwayne (October 19, 2014). "NASA's Mars Odyssey Orbiter Watches Comet Fly Near". NASA.

Retrieved October 20, 2014.29. Jones, Nancy; Steigerwald, Bill; Webster, Guy; Brown, Dwayne (October 19, 2014). "NASA's MAVEN Studies Passing

Comet and Its Effects". NASA. Retrieved October 20, 2014.30. Webster, Guy; Brown, Dwayne; Jones, Nancy; Steigerwald, Bill (October 19, 2014). "All Three NASA Mars Orbiters

Healthy After Comet Flyby". NASA. Retrieved October 20, 2014.31. France­Presse, Agence (October 19, 2014). "A Comet's Brush With Mars". New York Times. Retrieved October 20,

2014.32. Mars orbiter prepares for next year's InSight lander arrival (http://www.gizmag.com/mars­orbiter­prepares­for­new­arriva

l/38665/). July 29, 2015.33. NASA Mars Orbiter Preparing for Mars Lander's 2016 Arrival (http://www.nasa.gov/jpl/mro/nasa­mars­orbiter­preparing

­for­mars­landers­2016­arrival)34. "Spacecraft Parts: Instruments". Mars Reconnaissance Orbiter Website. Retrieved February 2005. Check date values in:

|access‐date= (help)35. "Stunning snaps from best camera ever sent to Mars". Newscientist. Retrieved December 2, 2006.36. "Google Earth FAQ (http://earth.google.com/faq.html#4)" Google Earth Website.37. "MRO HiRISE Camera Specifications". HiRISE website. Retrieved January 2, 2006.38. "HiRISE: Instrument Development" (PDF). NASA Ames Research Center website. Retrieved February 7, 2006. (PDF)39. "HiRISE". HiRISE website. Retrieved May 28, 2006.40. Malin, M. C.; et al. (2007). "Context Camera Investigation on board the Mars Reconnaissance Orbiter". Journal of

Geophysical Research. 112 (E05S04): 1–25. doi:10.1029/2006je002808.41. Harrison, Tanya N.; Malin, Michael C.; Edgett, Kenneth S. (2009). "Present­day activity, monitoring, and documentation

of gullies with the Mars Reconnaissance Orbiter (MRO) Context Camera (CTX)". Geological Society of AmericaAbstracts with Programs. 41 (7): 267. Bibcode:2009GSAA...41..267H.

42. "MRO Context Imager (CTX) Instrument Description". Malin Space Science Systems website. Retrieved June 6, 2006.43. MSSS – Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) (http://www.msss.com/all_projects/mro­ctx.php)44. NASA – First 360­Degree Panorama From NASA's Curiosity Mars Rover (http://www.nasa.gov/mission_pages/msl/new

s/msl20120808.html)45. "Spacecraft Parts: Instruments: MARCI". MARCI website. Retrieved June 2, 2006.46. Mars Color Imager: How MARCI Takes Color Images, MRO MARCI Release No. MARCI2­3, 13 April 2006 (http://w

ww.msss.com/mro/marci/images/2006/04/13/marci_detail/index.html)47. "CRISM Instrument Overview". CRISM Instrument Website. Archived from the original on March 7, 2005. Retrieved

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c_instru_sharad.html)50. KOMO­TV News Staff (August 12, 2005). NASA Launches Mars Orbiter (http://komonews.com/archive/nasa­launches­

mars­orbiter). KOMO­TV.51. "Spacecraft Parts: Gravity Field Investigation Package". Mars Reconnaissance Orbiter Website. Archived from the

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Thomas W. Fischer. "The Electra Proximity Link Payload for Mars Relay Telecommunications and Navigation" (PDF).53. "Spacecraft Parts: Optical Navigation Camera". Mars Reconnaissance Orbiter Website. Retrieved February 2005. Check

date values in: |access‐date= (help)

Further reading

Mishkin, Andrew (2004). Sojourner : An Insider's View of the Mars Pathfinder Mission. New York:Berkeley Books. ISBN 0­425­19199­0.Squyres, Steve (2005). Roving Mars: Spirit, Opportunity, and the Exploration of the Red Planet. New York:Hyperion. ISBN 1­4013­0149­5.

54. "Optical Navigation Demonstration Near Mars Multimedia Feature". NASA Mars Reconnaissance Orbiter Website.Retrieved March 2006. Check date values in: |access‐date= (help)

55. M. Adler, et al. – Use of MRO Optical Navigation Camera .. (2012) (http://www.lpi.usra.edu/meetings/marsconcepts2012/pdf/4337.pdf)

56. "Rad 750". BAE Aerospace Parts. Retrieved May 28, 2006.57. NASA Authorization Act of 2004, S.2541 (http://thomas.loc.gov/cgi­bin/query/F?c108:67:./temp/~mdbscqyyWC:e2344

0:). thomas.loc.gov. Retrieved May 27, 2006)58. "Spacecraft Summary". NASA's MRO website. Archived from the original on March 2, 2006. Retrieved May 29, 2006.59. Tariq Malik, NASA's Next Mars Probe Takes Aim at Red Planet (http://www.space.com/1351­nasa­mars­probe­takes­aim

­red­planet.html), Space.com, July 27, 2005 (Accessed May 2, 2012)60. "Spacecraft Parts: Electrical Power". NASA's MRO website. Archived from the original on March 31, 2006. Retrieved

May 28, 2006.61. "Rad 750" (PDF). BAE aerospace parts. Retrieved May 28, 2006.62. "Spacecraft Parts: Command and Data­Handling Systems". NASA's MRO website. Archived from the original on March

31, 2006. Retrieved May 28, 2006.63. "MRO Waveguide Transfer Switch Anomaly".64. "CSAM Augments X­Ray Inspection of Die Attach (MRO Ka­Band Anomaly)".65. Bayer, T.J. (2008). In­Flight Anomalies and Lessons Learned from the Mars Reconnaissance Orbiter Mission. 2008

IEEE Aerospace Conference. IEEE. pp. 1–13. doi:10.1109/AERO.2008.4526483.66. "Prolific NASA Mars Orbiter Passes Big Data Milestone". Jet Propulsion Laboratory ­ NASA. 8 November 2013.

Retrieved 2013­11­09.67. "Spacecraft Parts: Propulsion". NASA's MRO website. Archived from the original on March 31, 2006. Retrieved May 28,

2006.68. Clark, Stephen (20 August 2015). "NASA to rely on Mars programme's silent workhorse for years to come". Astronomy

Now. Retrieved 2015­08­20.69. "Spacecraft Parts: Guidance, Navigation, and Control Systems". NASA's MRO website. Archived from the original on

March 31, 2006. Retrieved May 28, 2006.70. Radar Map of Buried Mars Layers Matches Climate Cycles. Keith Cowing, September 22, 2009. (http://onorbit.com/nod

e/1524)71. Byrne, S. et al. 2009. Distribution of Mid­Latitude Ground Ice on Mars from New Impact Craters: 329.1674–167672. Andrea Thompson (September 24, 2009). "Water Ice Exposed in Mars Craters". Space.com. Retrieved September 2,

2011.73. Susan Watanabe (September 23, 2009). "NASA to Hold Teleconference to Discuss New Findings About Mars". NASA.

Retrieved September 2, 2011.74. Hugh H. Kieffer (1992). Mars. University of Arizona Press. ISBN 978­0­8165­1257­7. Retrieved March 7, 2011.75. http://www.planetary.brown.edu/pdfs/3733.pdf76. Osterloo, M. et al. 2008. Chloride­Bearing Materials in the Southern Highlands of Mars. Science. 319:1651–165477. Murchie, S. et al. 2009. A synthesis of Martian aqueous mineralogy after 1 Mars year of observations from the Mars

Reconnaissance Orbiter. Journal of Geophysical Research: 114.78. Russell, P. et al. (2008). Seasonally active frost­dust avalanches on a north polar scarp of Mars captured by HiRISE.

Geophysical Research Letters 35, doi:10.1029/2008GL035790 (https://dx.doi.org/10.1029%2F2008GL035790).79. Omar M. "Salty water may be flowing on Mars". ScienceBlog.com. Retrieved 2012­08­07.80. Chang, Kenneth (28 September 2015). "NASA Says Signs of Liquid Water Flowing on Mars". The New York Times.

Retrieved 2015­09­28. "Christopher P. McKay, an astrobiologist at NASA’s Ames Research Center, does not think theR.S.L.s are a very promising place to look. For the water to be liquid, it must be so salty that nothing could live there, hesaid. “The short answer for habitability is it means nothing,” he said."

81. Ojha, Lujendra; Wilhelm, Mary Beth; Murchie, Scott L.; McEwen, Alfred S.; et al. (28 September 2015). "Spectralevidence for hydrated salts in recurring slope lineae on Mars". Nature Geoscience. doi:10.1038/ngeo2546. Retrieved2015­09­28.

Wikimedia Commons hasmedia related to MarsReconnaissance Orbiter.

Read, Peter L. & Lewis, Steven L. (2004). The Martian Climate Revisited: Atmosphere and Environment ofa Desert Planet. Berlin: Springer. ISBN 3­540­40743­X.Zubrin, Robert (1997). The Case for Mars. London: Pocket Books. ISBN 0­684­83550­9.

External links

A simulation of the arrival trajectory of the Mars ReconnaissanceOrbiter (http://www.orbitsimulator.com/gravity/articles/MROarrival.html)CRISM Real Time Observations Viewer Java Application at TheJohns Hopkins University Applied Physics Laboratory (http://crism.jhuapl.edu/science/CRISMview/)CTX Website (http://www.msss.com/mro/ctx/index.html)HiBlog, the HiRISE Blog. Contains information about MRO. (http://hirise.lpl.arizona.edu/HiBlog/)MARCI Website (http://www.msss.com/mro/marci/index.html)Mars Reconnaissance Orbiter Mission Profile (http://solarsystem.nasa.gov/missions/profile.cfm?MCode=MRO) by NASA's Solar System Exploration (http://solarsystem.nasa.gov)Mars Reconnaissance Orbiter Reception (http://www.uhf­satcom.com/mro/)HiRise Image Catalog. The Lunar and Planetary Laboratory at The University of Arizona (http://hirise.lpl.arizona.edu/katalogos.php)MARS TREK ­ Shows present over­head position of Mars Reconnaissance Orbiter (http://marstrek.jpl.nasa.gov/)Mars Reconnaissance Orbiter images at JPL (http://photojournal.jpl.nasa.gov/spacecraft/MRO)Mars Reconnaissance Orbiter Website at JPL (http://marsprogram.jpl.nasa.gov/mro/)Mars Reconnaissance Orbiter Website at NASA (http://www.nasa.gov/mission_pages/MRO/main/index.html)Patterns of Mars – 12 High Resolution Photos by HiRISE on www.time.com (http://feeds.feedburner.com/~r/time/topstories/~3/365740126/0,29307,1827176,00.html)SHARAD Website (http://www.sharad.org/)

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Categories: Mars Reconnaissance Orbiter Artificial satellites orbiting Mars Geography of MarsLockheed Martin satellites and probes Missions to Mars Space probes launched in 2005 Space probesSpacecraft launched by Atlas rockets

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