A Mars rover is a motor vehicle that travels across the surface of the planet Mars upon arrival. Rovers have several advantages over stationary landers: they examine more territory, they can be directed to interesting features, they can place themselves in sunny positions to weather winter months, and they can advance the knowledge of how to perform very remote robotic vehicle control. There have been four successful robotically operated Mars rovers, all managed by the Jet Propulsion Laboratory: Sojourner, Opportunity, Spirit and Curiosity. On January 24, 2016, NASA reported that current studies on Mars by Curiosity and Opportunity would be searching for evidence of ancient life, including a biosphere based on autotrophic, chemotrophic or chemolithoautotrophic microorganisms, as well as ancient water, including fluvio-lacustrine environments that may have been habitable. The search for evidence of habitability, taphonomy, and organic carbon on Mars is now a primary NASA objective. In June 2018, Opportunity went out of contact after going into hibernation mode in a dust storm. NASA declared the end of the Opportunity mission on February 13, 2019, after numerous failures to wake up the rover. Mars 2, Mars 3 were physically tethered probes; Sojourner was dependent on the Mars Pathfinderbase station for communication with Earth; MER-A & B and Curiosity were on their own. As of , Curiosity is still active, while Spirit, Opportunity, and Sojourner completed their missions before losing contact.
Missions
Six rovers have been dispatched to Mars:
Mars 2, Prop-M rover, 1971, Mars 2 landing failed taking Prop-M with it. The Mars 2 and 3 spacecraft from the Soviet Union had identical 4.5 kg Prop-M rovers. They were to move on skis while connected to the landers with cables.
Mars 3, Prop-M rover, 1971, lost when Mars 3 lander stopped communicating about 20 seconds after landing.
Sojourner rover, Mars Pathfinder, landed successfully on July 4, 1997. Communications were lost on September 27, 1997.
Spirit, Mars Exploration Rover, launched on June 10, 2003, and landed on January 4, 2004. Nearly 6 years after the original mission limit, Spirit had covered a total distance of but its wheels became trapped in sand. The last communication received from the rover was on March 22, 2010, and NASA ceased attempts to re-establish communication on May 25, 2011.
Opportunity, Mars Exploration Rover, launched on July 7, 2003 and landed on January 25, 2004. Opportunity surpassed the previous records for longevity at 5,352 sols and coverance of. The rover sent its last status on 10 June 2018 when a global 2018 Mars dust storm blocked the sunlight needed to recharge its batteries. After hundreds of attempts to reactivate the rover, NASA declared the mission complete on February 13, 2019.
, a Chinese project, launched on Thursday 23rd July 2020 and is currently en-route to Mars following a successful launch. Perseverance, a NASA rover, based on the successful Curiosity design launched on Thursday 30th July 2020 and is currently en-route to Mars following a successful launch.
Planned
The European-Russian ExoMars rover Rosalind Franklin is planned to launch in 2022.
Undeveloped
Astrobiology Field Laboratory, proposed in the 2000-2010 period as a follow on to MSL.
Mars Astrobiology Explorer-Cacher, cancelled 2011
Mars Surveyor 2001 rover,
Zephyr rover, would use a rigid sail for wind propulsion.
Mars Tumbleweed Rover, a spherical wind-propelled rover.
In 2018, a kind of cushion-air rover was proposed, which in contrast with traditional hovercrafts does not use blowers to pressurize the gas in the chamber but rather uses stored pressurized CO2 obtained from a freezing process which does not require mechanical compression.
Examples of instruments
Examples of instruments onboard landed rovers include:
Alpha particle X-ray spectrometer
CheMin
Chemistry and Camera complex
Dynamic Albedo of Neutrons
Hazcam
MarsDial
Materials Adherence Experiment
MIMOS II
Mini-TES
Mars Hand Lens Imager
Navcam
Pancam
Rock Abrasion Tool
Radiation assessment detector
Rover Environmental Monitoring Station
Sample Analysis at Mars
Locations of Mars rovers, in context
NASA Mars rover goals (circa 2010s)
NASA distinguishes between "mission" objectives and "science" objectives. Mission objectives are related to progress in space technology and development processes. Science objectives are met by the instruments during their mission in space. The science instruments are chosen and designed based on the science objectives and goals. The primary goal of the Spirit and Opportunity rovers was to investigate "the history of water on Mars". The four science goals of NASA's long-term Mars Exploration Program are:
