Mars Reconnaissance Orbiter

Mars Reconnaissance Orbiter

active Mission

MRO studies seasonal and annual climate changes, and searches for evidence whether Martian water ever lasted long enough to provide a habitat for life, in addition to surveying possible landing sites for future Mars missions.




Aug. 12, 2005




Evidence of Primeval Water

What is Mars Reconnaissance Orbiter?

NASA's Mars Reconnaissance Orbiter (MRO) is the second longest-lived spacecraft to orbit Mars, after 2001 Mars Odyssey. It has been studying the Red Planet since March 2006.

  • The spacecraft collects and relays daily science and weather data.
  • It also scouts for landing locations for Mars landers and serves as a critical relay station for science beamed back from the Red Planet.

United States of America (USA)
Mars Orbit
Spacecraft Mass
4,810 pounds (2,180 kilograms)
Mission Design and Management
Launch Vehicle
Atlas V 401 (AV-007)
Launch Date and Time
Aug. 12, 2005 / 11:43:00 UTC
Launch Site
Cape Canaveral, Fla. / SLC-41
Scientific Instruments
1. High-Resolution Imaging Science Experiment Camera (HiRISE)
2. Context Camera (CTX)
3. Mars Color Imager (MARCI)
4. Compact Reconnaissance Imaging Spectrometer (CRISM)
5. Mars Climate Sounder (MCS)
6. Shallow Subsurface Radar (SHARAD)
7. Optical Navigation Camera
8. Electra Communications Package
9. Gravity Field Investigation Package
10. Atmospheric Structure Investigation


  • First spacecraft to photograph another spacecraft landing on Mars (Phoenix in 2008)

Key Dates

Aug. 12, 2005: Launch

Sept. 11, 2006: Began orbiting Mars

In Depth: Mars Reconnaissance Orbiter

Mars Reconnaissance Orbiter (MRO) is a large orbiter, modeled in part on NASA’s highly successful Mars Global Surveyor spacecraft, designed to photograph Mars from orbit.

Its primary goals are to map the Martian surface with a high-resolution telescopic camera, at least partly to help select sites for future landing missions. The camera, called the high-resolution imaging science experiment camera, or HiRISE, is a 1.6-foot (0.5-meter) diameter reflecting telescope, the largest ever carried on a deep space mission.

Supplementary investigations have included studies of the Martian climate, weather, atmosphere and geology. Along with the basic six instruments, MRO also carries an optical navigation camera and Electra, a UHF telecommunications package to provide navigation and communications support to other landers and rovers on the surface of Mars.

After launch, at 11:43:00 UTC Aug. 12, 2005, MRO entered orbit around Earth. Soon after, the Centaur upper stage fired for a second time to dispatch its payload (and itself) to escape velocity on a trajectory to intercept with Mars.

After a seven-month trip and three course corrections, MRO approached Mars and, on March 10, 2006, fired its six engines (which displayed slightly reduced thrust), and successfully entered into a highly elliptical orbit around the Red Planet with parameters of about 265 x 27,650 miles (426 × 44,500 kilometers) with a period of 35.5 hours.

A subsequent combination of aerobraking in the upper atmosphere and engine burns between April 7 and Sept. 11, 2006, put MRO in its final operational orbit of approximately 155 x 195 miles (250 × 316 kilometers).

Two months later, it began its primary science mission, joining five other active spacecraft in orbit or on the surface of Mars: Mars Global Surveyor, 2001 Mars Odyssey, the two Mars Exploration Rovers, and the European Mars Express.

By December 2006, the operation of one of MRO’s instruments, the Mars climate sounder, was suspended due to anomalies in its field of view. All other instruments, however, returned vast amounts of uninterrupted and valuable data during the first two years of MRO’s operations, known as the Primary Science Phase, which ran from November 2006 to November 2008.

One of the early findings from imagery collected by HiRISE was the presence of liquid carbon dioxide or water on the surface of Mars in its recent past. During the Extended Science Phase, from November 2008 to December 2010, MRO faced a number of technical obstacles, primarily related to seemingly spontaneous rebooting of its computer four times in 2009. At one point, the spacecraft was essentially shut down beginning Aug. 26.

Finally, on Dec. 8, 2009, engineers commanded the orbiter out of safe mode and slowly began initiating science operations using its scientific instruments.

Back on the job, MRO passed an important symbolic milestone March 3, 2010: It had transmitted 100 terabits of data back to Earth, which NASA said was “more than three times the amount of data from all other deep-space missions combined.”

Color-enhanced view of Jezero crater on Mars.
Water carved channels and transported sediments form fans and deltas within lake basins in this image of Mars' Jezero crater.

MRO continued to return high-quality data, despite another reboot event in September 2010. Many of its activities were coordinated with other Mars spacecraft. For example, in December 2010, researchers used data from the compact reconnaissance imaging spectrometer (CRISM) to help the Opportunity rover study the distribution of minerals in Endeavour Crater.

A new phase of MRO’s mission began in December 2010, the Extended Mission. The goals were to explore seasonal processes on Mars, search for surface changes, and also to provide support for other Martian spacecraft including the Mars Science Laboratory (MSL). It was during this period, in March 2011, that MRO passed its five-year anniversary orbiting Mars.

Later in August 2011, NASA announced that MRO data indicated that water might actually be flowing on Mars during the warmest months of the year. MRO images had shown dark fingerlike features, known as recurring slope linea (RSLs) that appear and disappear on some slopes during late spring through summer, but disappear during winter.

On March 14, 2012, MRO captured a 12-mile-high (20-kilometer-high) dust devil whirling its way across the Amazonis Planitia region of northern Mars.

In October 2012, NASA initiated MRO’s second Extended Mission, which lasted until October 2014. During this second Extended Mission, MRO passed the point of transmitting 200 terabits of science data back to Earth.

In 2013, MRO turned its gaze outward to Comet ISON, a comet racing in from the Oort Cloud, which passed by Mars on Sept. 29.

There was another computer anomaly on March 9, 2014. MRO put itself in safe mode after an unscheduled swap from one main computer to another. Four days later, the vehicle resumed normal science operations along with its activities relaying data back to Earth from the Curiosity rover.

Because of the impending flyby of Comet C/2013A1 (or Comet Siding Spring) on Oct. 19, 2014, NASA began to shift the orbit of MRO (as well as its other operational orbiter, 2001 Mars Odyssey) to minimize the risk of damage from material shed by the comet. Orbit adjustments were made by MRO on July 2 and then again Aug. 27. During the flyby, MRO captured the best ever views of a comet from the Oort Cloud when Siding Spring flew by Mars. The spacecraft wasn’t damaged by the comet.

For the seventh time during its time in orbit, MRO put itself in a precautionary standby mode April 11, 2015, when there was an unplanned switch from one main computer to another. Within a week the spacecraft once again returned to full operational capability.

In August 2015, MRO celebrated a decade since its launch, by which time it had orbited Mars 40,000 times and returned 250 terabits of data. NASA announced that every week, the spacecraft was still returning more information on Mars than the weekly total of all other active Mars missions.

In September 2015, scientists published evidence in the journal Nature Geoscience that data from MRO’s imaging spectrometer provided the strongest evidence yet that liquid water still flows intermittently on present-day Mars. Scientists later concluded that water ice makes up half or more of an underground layer in the Utopia Planitia region.

In January 2016, controllers completed a planned flash-memory rewrite in one of the spacecraft’s redundant computers in order to load new data in the form of tables on the positions of Earth and the Sun.

In July 2016, research results were published indicating that gullies on modern-day Mars – channels with an alcove at the top and deposited material at the bottom – were probably not formed by flowing liquid water, and instead perhaps by the freeze and thaw of carbon dioxide frost.

The data from MRO also provided the basis for a large crowd-sourced experiment in 2016. Using the Planet Four: Terrains website, 10,000 volunteers used images taken by the context camera (CTX) of the Martian south polar regions to identify targets for closer inspection by the HiRISE camera. This generated new insights on seasonal slabs of carbon dioxide and erosional features on Mars known as “spiders.”

In late 2018, MRO helped pinpoint the exact location of NASA's InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) spacecraft, which landed Nov. 26, 2018. The InSight lander, its heat shield and parachute were spotted by MRO’s HiRISE on Dec. 6 and again Dec. 11, 2018. The lander, heat shield and parachute are within 1,000 feet (several hundred meters) of one another on Elysium Planitia, the flat lava plain selected as InSight's landing location.

At several other points during its mission, MRO photographed spacecraft on the Martian surface.

In January 2015, NASA announced that high-resolution images taken by MRO had identified the wreckage of Britain’s Beagle 2 (launched June 2, 2003) on the Martian surface. In December 2014 and April 2015 images taken by the HiRISE instrument showed NASA’s Curiosity rover inside Gale Crater. In October 2016 images taken by both the CTX and the HiRISE cameras showed ESA’s Schiaparelli test lander that stopped transmitting before final impact in October 2016.

Mars Reconnaissance Orbiter completed 60,000 orbits at Mars at 5:39 p.m. UTC on May 15, 2019.

MRO remains operational and is the second longest-lived spacecraft to orbit Mars, after 2001 Mars Odyssey.

Key Source

Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.

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