The following table is a list of Mars orbiters, consisting of space probes which were launched from Earth and are currently orbiting Mars. As of August 2023, there have been 18 spacecraft missions operating in Mars' orbit, 7 of which are currently active.
The Soviets' Mars program and the United States's Mariner program became the two first successful space programs that intended to explore Mars through orbiters. Mars 2, Mars 3 and Mariner 9 were all launched into space in May 1971, and all entered Mars’ orbit that same year. NASA's Mariner 9 reached the planet's orbit first on November 14, narrowly beating the Soviet's spacecraft amid the space race, and subsequently became the first spacecraft to orbit another planet. [1]
Contact with all eight Mars orbiters launched during the 20th century has been lost. NASA's four spacecraft are conjectured to remain in Mars' orbit. Mariner 9, Viking 1 and Viking 2 are expected to lower down into the Martian atmosphere by 2022 and either burn up or crash into the planet's surface. [2] Mars Global Surveyor is expected to crash onto the surface of the planet by 2047. The fate of the Soviet's three Mars program orbiters and Phobos 2 remains unclear, but they are still presumed to be in orbit. [3]
In 1999 the Mars Climate Orbiter impacted the Martian atmosphere.
2001 Mars Odyssey was launched April 7, 2001 on a Delta II rocket and currently holds the record for the longest-surviving continually active spacecraft in orbit around a planet other than Earth at 22 years, 1 month and 21 days. [4]
In 2003, the European Space Agency (ESA) launched their first planetary mission with Mars Express to conduct reconnaissance and exploration of Mars from orbit. [5] On 12 August 2005, NASA launched Mars Reconnaissance Orbiter (MRO). As MRO entered orbit in 2006, it joined three other active spacecraft which were in Mars' orbit: Mars Global Surveyor (MGS), Mars Express, and 2001 Mars Odyssey; at the time, this set a record for the most operational spacecraft in the immediate vicinity of Mars. MGS has since ceased to function.
On November 5, 2013, the Mars Orbiter Mission (Mangalyaan-1) was launched by the Indian Space Research Organisation (ISRO) as a "technology demonstrator" project. Its secondary goal is to analyze the Martian atmosphere and topography. The orbiter reached Mars orbit on September 24, 2014. Through this mission, ISRO became the first space agency to succeed in its first attempt at a Mars orbiter. The mission is the first successful Asian interplanetary mission. [6] Ten days after ISRO's launch, NASA launched their seventh Mars orbiter MAVEN to study the Martian atmosphere. Its goals include determining how the planet's atmosphere and water, presumed to have once been substantial, were lost over time. [7]
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After achieving orbit, functional or not, Mars orbiters have been predicted to remain in orbit for a certain amount of time. [8]
Besides decaying to Mars, a collision with a moon or other spacecraft is also a possibility. [12] In March 2017, MAVEN had to change its orbit to avoid colliding with Phobos, and with an increasing number of spacecraft at Mars this risk increases. [13] The Mars Global Surveyor is still being tracked, although it is no longer functioning. [14]
| Color legend | |
|---|---|
| Destroyed | |
| Loss of contact | |
| Operational | |
Note that days active category does not necessarily equate to time in orbit, for example Mars Global Surveyor is expected remain in Mars orbit for 50 years after its arrival. [15] The detection of derelict spacecraft in Mars orbit has some interest due to the minute risk of collision with such a spacecraft. One example of this is a proposal to use the Optical Navigation Camera on the Mars Reconnaissance Orbiter to search for small moons, dust rings, and old orbiters. [16]
| Artificial object | Agency | Launch date | Entered orbit | Days active | Image |
|---|---|---|---|---|---|
| Mars 2 |  Lavochkin | 19 May 1971 | 27 November 1971 | 269 days |  |
| Mars 3 | Lavochkin | 28 May 1971 | 2 December 1971 | 264 days | |
| Mariner 9 |  NASA | 30 May 1971 | 14 November 1971 | 348 days |  |
| Mars 5 | Lavochkin | 25 July 1973 | 12 February 1974 | 16 days | |
| Viking 1 | NASA | 20 August 1975 | 19 June 1976 | 1,520 days |  |
| Viking 2 | NASA | 9 September 1975 | 7 August 1976 | 717 days | |
| Phobos 2 | Lavochkin | 12 July 1988 | 29 January 1989 | 57 days |  |
| Mars Global Surveyor | NASA | 7 November 1996 | 12 September 1997 | 3,338 days |  |
| 2001 Mars Odyssey | NASA | 7 April 2001 | 24 October 2001 | 8,087 days |  |
| Mars Express |  ESA | 2 June 2003 | 25 December 2003 | 7,295 days |  |
| Mars Reconnaissance Orbiter | NASA | 12 August 2005 | 10 March 2006 | 6,489 days |  |
| Mars Orbiter Mission (Mangalyaan) |  ISRO | 5 November 2013 | 24 September 2014 | 3,369 days |  |
| MAVEN | NASA | 18 November 2013 | 22 September 2014 | 3,371 days |  |
| ExoMars Trace Gas Orbiter | ESA  Roscosmos | 14 March 2016 | 19 October 2016 | 2,613 days |  |
| Emirates Mars Mission (Hope) |  UAESA | 19 July 2020 | 9 February 2021 | 1,039 days | |
| Tianwen 1 orbiter |  CNSA | 23 July 2020 | 10 February 2021 | 1,038 days | |
| Tianwen 1 Deployable Camera 2 | CNSA | 23 July 2020 | 10 February 2021 (released on 31 December 2021) | <1 day |
2001 Mars Odyssey is a robotic spacecraft orbiting the planet Mars. The project was developed by NASA, and contracted out to Lockheed Martin, with an expected cost for the entire mission of US$297 million. Its mission is to use spectrometers and a thermal imager to detect evidence of past or present water and ice, as well as study the planet's geology and radiation environment. It is hoped that the data Odyssey obtains will help answer the question of whether life existed on Mars and create a risk-assessment of the radiation that future astronauts on Mars might experience. It also acts as a relay for communications between the Curiosity rover, and previously the Mars Exploration Rovers and Phoenix lander, to Earth. The mission was named as a tribute to Arthur C. Clarke, evoking the name of his and Stanley Kubrick's 1968 film 2001: A Space Odyssey.
The Mariner program was conducted by the American space agency NASA to explore other planets. Between 1962 and late 1973, NASA's Jet Propulsion Laboratory (JPL) designed and built 10 robotic interplanetary probes named Mariner to explore the inner Solar System - visiting the planets Venus, Mars and Mercury for the first time, and returning to Venus and Mars for additional close observations.
Mariner 9 was a robotic spacecraft that contributed greatly to the exploration of Mars and was part of the NASA Mariner program. Mariner 9 was launched toward Mars on May 30, 1971, from LC-36B at Cape Canaveral Air Force Station, Florida, and reached the planet on November 14 of the same year, becoming the first spacecraft to orbit another planet – only narrowly beating the Soviet probes Mars 2 and Mars 3, which both arrived at Mars only weeks later.
The Mars 2 was an uncrewed space probe of the Mars program, a series of uncrewed Mars landers and orbiters launched by the Soviet Union beginning 19 May 1971. The Mars 2 and Mars 3 missions consisted of identical spacecraft, each with an orbiter and an attached lander. The orbiter is identical to the Venera 9 bus. The type of bus/orbiter is the 4MV. They were launched by a Proton-K heavy launch vehicle with a Blok D upper stage. The lander of Mars 2 became the first human-made object to reach the surface of Mars, although the landing system failed and the lander was lost.
Mars 3 was a robotic space probe of the Soviet Mars program, launched May 28, 1971, nine days after its twin spacecraft Mars 2. The probes were identical robotic spacecraft launched by Proton-K rockets with a Blok D upper stage, each consisting of an orbiter and an attached lander. After the Mars 2 lander crashed on the Martian surface, the Mars 3 lander became the first spacecraft to attain a soft landing on Mars, on December 2, 1971. It failed 110 seconds after landing, having transmitted only a gray image with no details. The Mars 2 orbiter and Mars 3 orbiter continued to circle Mars and transmit images back to Earth for another eight months.
A lander is a spacecraft that descends towards, then comes to rest on the surface of an astronomical body other than Earth. In contrast to an impact probe, which makes a hard landing that damages or destroys the probe upon reaching the surface, a lander makes a soft landing after which the probe remains functional.
Mars Global Surveyor (MGS) was an American robotic space probe developed by NASA's Jet Propulsion Laboratory and launched November 1996. MGS was a global mapping mission that examined the entire planet, from the ionosphere down through the atmosphere to the surface. As part of the larger Mars Exploration Program, Mars Global Surveyor performed atmospheric monitoring for sister orbiters during aerobraking, and helped Mars rovers and lander missions by identifying potential landing sites and relaying surface telemetry.
The Mars Polar Lander, also known as the Mars Surveyor '98 Lander, was a 290-kilogram robotic spacecraft lander launched by NASA on January 3, 1999, to study the soil and climate of Planum Australe, a region near the south pole on Mars. It formed part of the Mars Surveyor '98 mission. On December 3, 1999, however, after the descent phase was expected to be complete, the lander failed to reestablish communication with Earth. A post-mortem analysis determined the most likely cause of the mishap was premature termination of the engine firing prior to the lander touching the surface, causing it to strike the planet at a high velocity.
The planet Mars has been explored remotely by spacecraft. Probes sent from Earth, beginning in the late 20th century, have yielded a large increase in knowledge about the Martian system, focused primarily on understanding its geology and habitability potential. Engineering interplanetary journeys is complicated and the exploration of Mars has experienced a high failure rate, especially the early attempts. Roughly sixty percent of all spacecraft destined for Mars failed before completing their missions and some failed before their observations could begin. Some missions have been met with unexpected success, such as the twin Mars Exploration Rovers, Spirit and Opportunity, which operated for years beyond their specification.
The Mars Reconnaissance Orbiter (MRO) is a spacecraft designed to search for the existence of water on Mars and provide support for missions to Mars, as part of NASA's Mars Exploration Program. It was launched from Cape Canaveral on August 12, 2005, at 11:43 UTC and reached Mars on March 10, 2006, at 21:24 UTC. In November 2006, after six months of aerobraking, it entered its final science orbit and began its primary science phase.
The Lunar Precursor Robotic Program (LPRP) is a NASA program that uses robotic spacecraft to prepare for future crewed missions to the Moon. The program gathers data such as lunar radiation, surface imaging, areas of scientific interest, temperature and lighting conditions, and potential resource identification.
A Moon landing or lunar landing is the arrival of a spacecraft on the surface of the Moon. This includes both crewed and robotic missions. The first human-made object to touch the Moon was the Soviet Union's Luna 2, on 13 September 1959.
Timeline for the Mars Reconnaissance Orbiter (MRO) lists the significant events of the launch, aerobraking, and transition phases as well as subsequent significant operational mission events; by date and brief description.
A Mars landing is a landing of a spacecraft on the surface of Mars. Of multiple attempted Mars landings by robotic, uncrewed spacecraft, ten have had successful soft landings. There have also been studies for a possible human mission to Mars, including a landing, but none have been attempted. Soviet Union’s Mars 3, which landed in 1971, was the first successful Mars landing. As of 2023, the Soviet Union, United States and China have conducted Mars landings successfully.
The following outline is provided as an overview of and topical guide to Mars:
It was the first spacecraft to enter orbit around another world. ... [It] continues to orbit Mars to this day, sailing around the planet deaf and dumb in the cold darkness.
It's expected to orbit Mars for at least 50 years before crashing onto the surface of the planet.
It's expected to orbit Mars for at least 50 years before crashing onto the surface of the planet.
It's expected to orbit Mars for at least 50 years before crashing onto the surface of the planet.
It's expected to orbit Mars for at least 50 years before crashing onto the surface of the planet.
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| Past |
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| Future |
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| Exploration |
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Missions are ordered by launch date. Sign † indicates failure en route or before intended mission data returned. | |||||||||
