The Mars Reconnaissance Orbiter (MRO) is a $720 million USD spacecraft built by Lockheed Martin under the supervision of the Jet Propulsion Laboratory (JPL) to orbit Mars, map its surface in great detail, and study the Martian climate, weather, atmosphere, and geology. The craft was launched on an Atlas V booster on August 12, 2005, and took about seven months to reach Mars, entering a low orbit on March 10, 2006. It began making primary observations in November 2006. It will continue to observe until November 2008, when it may be granted a mission extension based on good performance.
The Reconnaissance Orbiter is one of five spacecraft that have landed on or are orbiting Mars. The Mars Global Surveyor, Mars Express, Mars Odyssey, and two Mars Exploration Rovers are among the others. Except for the Mars Express, which was sent by the European Space Agency, all of these are NASA’s property. The Reconnaissance Orbiter’s mission includes identifying potential landing zones for future Rovers like the Phoenix lander in 2008 and the Mars Science Laboratory in 2010. NASA has announced that a manned mission to Mars is in the works for 2025.
The orbiter entered a long, elliptical orbit after arriving at the planet, and used the technique of aerobraking — deliberately dipping low into the atmosphere — to slow down and achieve a more suitable orbit for observations. Its current orbit takes it between 155 and 196 miles (250 and 316 kilometers) above the Earth’s surface, a little lower than the International Space Station orbits the planet. Because of the planet’s lower gravity, Low Mars Orbit is slightly lower than Low Earth Orbit.
A few signs of past liquid water presence and the discovery of large, dark holes thought to be cave entrances are two of the Reconnaissance Orbiter’s most interesting discoveries. The orbiter’s signature instrument, the HiRISE camera, can take photos of the Martian surface with a resolution of 0.3 m per pixel, compared to 0.1 m per pixel for the best Earth-orbiting satellites and 1 m per pixel for Google Maps. The data from HiRISE has enabled the creation of a Google Mars. SHARAD, or Shallow Subsurface Radar, is another instrument that uses radar waves to look beneath the planet’s surface. It has a resolution of 7 meters and can resolve underground features up to 1 km deep.