Contents

List of Mars orbiters

List of spacecraft orbiting the planet Mars

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.

History[edit]

20th century[edit]

The Soviets' Mars program and the United States' 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.

21st century[edit]

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, 7 months 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]

Fate[edit]

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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]

• Viking 1 orbiter, likely to be in orbit as of 2019.^[9]
• Mariner 9 was expected to remain in orbit until approximately 2022, when the spacecraft was projected to enter the Martian atmosphere and either burn up or crash into the planet's surface.^[10]
• Mars Global Surveyor is predicted to orbit until 2046 (50 years after insertion).^[11]

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]

Table of objects[edit]

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	8,269 days
Mars Express	ESA	2 June 2003	25 December 2003	7,477 days
Mars Reconnaissance Orbiter	NASA	12 August 2005	10 March 2006	6,671 days
Mars Orbiter Mission (Mangalyaan)	ISRO	5 November 2013	24 September 2014	3,551 days
MAVEN	NASA	18 November 2013	22 September 2014	3,553 days
ExoMars Trace Gas Orbiter	ESA Roscosmos	14 March 2016	19 October 2016	2,795 days
Emirates Mars Mission (Hope)	UAESA	19 July 2020	9 February 2021	1,221 days
Tianwen 1 orbiter	CNSA	23 July 2020	10 February 2021	1,220 days
Tianwen 1 Deployable Camera 2	CNSA	23 July 2020	10 February 2021 (released on 31 December 2021)	<1 day

See also[edit]

• Lists of spacecraft
• Exploration of Mars
• List of missions to Mars
• Robotic spacecraft
• Timeline of artificial satellites and space probes
• Timeline of planetary exploration

References[edit]