PrOP-M moving on skis.gif
Moving rover
Mission typeMars rover
OperatorSoviet Space Program
COSPAR ID Edit this at Wikidata
Spacecraft properties
ManufacturerMobile Vehicle Engineering Institute
Start of mission
Launch date1971

PrOP-M (Russian: Прибор оценки проходимости — Марс (ПрОП-М), Passability Estimating Vehicle for Mars or Device Evaluation Terrain—Mars[1]) were two Soviet Mars rovers that were launched on the unsuccessful Mars 2 and Mars 3 missions in 1971. PrOP-M were the first rovers to be launched to Mars, 26 years before the first successful rover mission of NASA's Sojourner in 1997. Because the Mars 2 and Mars 3 missions failed, the existence of the rovers was kept secret for nearly 20 years.

The rovers were built by a team led by Alexander Kemurdzhian; they were small, rectangular devices that were tethered to the lander and used skis for movement.


PrOP-M on the manipulator arm of the lander
PrOP-M on the manipulator arm of the lander
Mars 3 Lander model at the Memorial Museum of Cosmonautics in Moscow. PrOP-M is seen on top.
Mars 3 Lander model at the Memorial Museum of Cosmonautics in Moscow. PrOP-M is seen on top.

The PrOP-M rover was designed and manufactured at the Mobile Vehicle Engineering Institute (VNIITransmash) by a team of approximately 150 engineers led by Alexander Kemurdzhian, who also developed the Lunokhod rover.[2]

The Mars 2 and Mars 3 landers each carried a PrOP-M rover, designed to move across the Martian surface on skis while connected to the lander with a 15-meter (49 ft)-long power cable. Two small metal rods were used for autonomous obstacle avoidance because radio signals from Earth would have taken too long to drive the rovers using remote control. Each rover carried a dynamic penetrometer (made by Transmash) and a gamma-ray[3] densitometer (made by the Institute of Geochemistry of the Soviet Academy of Sciences).[4][5] After landing, the rovers were planned to be placed on the Martian surface by a 6-joint manipulator arm and to move in the field of view of the lander's cameras. They would have stopped to make measurements every 1.5 m (4.9 ft), with maximum range of 15 m (49 ft)—the length of the tether. The rovers' tracks in the Martian soil would have been used to determine the soil's material properties.[3][1][2]

The rovers' main rover chassis was a 4.5-kilogram (9.9 lb) square box with a small protrusion at the center. Sources differ on the dimensions of the rover.[a] The frame was supported on two wide, flat skis, one extending from each side, elevating the frame slightly above the surface. At the front of the box were obstacle detection bars.[2] Rover's maximum speed was up to 1 meter per hour.[9]

Alex Ellery in Planetary Rovers. Robotic Exploration of the Solar System wrote:

All planetary rover missions to date have adopted wheeled chassis designs across a range of rover sizes for mechanical simplicity and high reliability. This trend looks set to continue for the foreseeable future. One exception was the Prop-M nanorover on the Russian Mars 3 lander (1971). The 4.5 kg Prop-M used a pair of skis mounted onto legs.[10]

The rover had a primitive artificial intelligence: if it met an obstacle it was programmed to reverse and "use the skids on alternate sides to walk around the obstacle".[6]

The first rover was destroyed in the November 27, 1971 crash landing of Mars 2, launched May 19, 1971.[11] The second one was launched on May 28, 1971 on Mars 3 and lost when the lander stopped communicating 110 seconds after landing on December 2, 1971.[12] The loss of communication may have been due to the extremely powerful Martian dust storm taking place at the time or a problem with the Mars 3 orbiter's ability to relay communications.[1] The second rover was never deployed. The rover missions were secret[6][13] and were not mentioned in official news reports about the landings; their existence was revealed almost 20 years later in 1990.[13] The PrOP-M rovers preceded NASA's 1997 Sojourner by 26 years.[14] Authors of the Planetary Landers and Entry Probes wrote that Mars 6 and Mars 7 also carried PrOP-M rovers.[15]

One rover can be seen now in the Memorial Museum of Cosmonautics in Moscow, another is in the Museum of Space and Missile Technology in Saint Petersburg.[1][16]

In culture

PrOP-M rover and Mars 3 lander were featured in the 2013 videogame about Mars exploration Take On Mars.[17]


  1. ^ Sources give the following numbers:
    25 cm × 22 cm × 4 cm (9.8 in × 8.7 in × 1.6 in),[2][6]
    25 cm × 25 cm × 4 cm (9.8 in × 9.8 in × 1.6 in),[3]
    21.5 cm × 16 cm × 6 cm (8.5 in × 6.3 in × 2.4 in),[4][7]
    25 cm × 20 cm × 4 cm (9.8 in × 7.9 in × 1.6 in)[8]


  1. ^ a b c d Ackerman, Evan. "Meet the Very First Rover to Land on Mars". Retrieved 28 October 2021.
  2. ^ a b c d "Марс-3". Retrieved 28 October 2021.
  3. ^ a b c Huntress, Wesley T. (2011). Soviet robots in the solar system : mission technologies and discoveries. New York: Springer. p. 256. ISBN 978-1441978974.
  4. ^ a b Ulivi, Paolo (2007). Robotic exploration of the solar system. Berlin: Springer. p. 105. ISBN 978-0387493268.
  5. ^ Perminov, V.G. (July 1999). The Difficult Road to Mars - A Brief History of Mars Exploration in the Soviet Union. NASA Headquarters History Division. pp. 34–60. ISBN 0-16-058859-6.
  6. ^ a b c Harvey, Brian (2007). Russian Planetary Exploration: History, Development, Legacy and Prospects. Springer Science & Business Media. p. 134. ISBN 9780387496641.
  7. ^ Gao, Yang (13 September 2016). Contemporary Planetary Robotics: An Approach Toward Autonomous Systems. Weinheim, Germany: John Wiley & Sons. p. 33. ISBN 978-3-527-41325-6. Retrieved 17 January 2022.
  8. ^ Harvey, Brian (2011). Russian space probes : scientific discoveries and future missions. New York: Springer. p. 270. ISBN 9781441981509. Retrieved 18 January 2022.
  9. ^ Truszkowski, Walt; Rouff, Christopher; Akhavannik, Mohammad; Tunstel, Edward (30 January 2020). Robot Memetics: A Space Exploration Perspective. Springer Nature. p. 7. ISBN 978-3-030-37952-0. Retrieved 17 January 2022.
  10. ^ Ellery, Alex (2016). Planetary rovers : robotic exploration of the solar system. Berlin. p. 59. ISBN 9783642032592.
  11. ^ "Mars 2 Lander". NASA Space Science Data Coordinated Archive. NASA. NSSDCA/COSPAR ID: 1971-045D. Retrieved 7 November 2021.
  12. ^ "Mars 3 Lander". NASA Space Science Data Coordinated Archive. NASA. NSSDCA/COSPAR ID: 1971-049F. Retrieved 7 November 2021.
  13. ^ a b Anderson, Charlene. "The First Rover on Mars - The Soviets Did It in 1971". Planetary Society. Retrieved 28 October 2021.
  14. ^ Bard, Jonathan (2020). Destination Mars. Gareth Stevens Pub. p. 15. ISBN 9781538258736.
  15. ^ Ball, Andrew; Garry, James; Lorenz, Ralph; Kerzhanovich, Viktor (10 May 2007). Planetary Landers and Entry Probes. Cambridge University Press. p. 127. ISBN 978-1-139-46161-0. Retrieved 17 January 2022.
  16. ^ "Первая колея на Луне. Выставка приурочена к юбилею конструктора планетоходов Александра Кемурджяна" [The first track on the moon. The exhibition is timed to the anniversary of the designer of planetary rovers Alexander Kemurdzhian]. Retrieved 24 November 2021.
  17. ^ "Tech-Enhanced update for Take On Mars | Blog". Bohemia Interactive. Retrieved 22 January 2022.