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Mars Exploration Rover A, B (MER A, B / Spirit / Opportunity)

MER A (Cruise configuration) [NASA]

MER A (Lander) [NASA]

The MER (Mars Exploration Rover) mission consists of two identical rovers, which are large (~130 kg) vehicles based on the Athena Rover design that was originally considered for the Mars 2001 Lander mission. The Cruise configuration is based on the Mars Pathfinder spacecraft. The rovers were landed using an airbag system similar to that used on Mars Pathfinder but without the stationary lander. The first landing took place on 4 January 2004 and the second 18 days later on 25 January. The two landing sites were chosen: Gusev Crater and Meridani Planum. The mission was to last for at least 90 days each, until late April. The rovers are designed to cover roughly 100 meters each Martian day, or sol (approximately 24 hours, 37 minutes). They carry a scientific packages which includes:

  • a panoramic camera (Pancam),
  • a rock abrasion tool (RAT) to expose fresh surfaces of rock,
  • a miniature thermal infrared spectrometer (MiniTES),
  • a microscopic camera,
  • a Mössbauer spectrometer, and
  • an alpha-proton-X-ray spectrometer (APXS).

The MER-A probe features the MER-2 rover, while MER-B flies with the MER-1 rover. MER A and B have been named Spirit and Opportunity respectively. The names were selected from a naming contest.

MER-A landed on 4 January 2004 in Gusev Crater. A few days later, the rover Spirit left the landing unit. On January 21st the Spirit rover entered save mode and stopped sending data. NASA resolved the software problem and Spirit resumed work.

MER B with the rover Opportunity landed on Mars in Meridani Planum on 25 January 2004.

Both rovers far surpaced the originally planned lifetime of 90 days. MER A (Spirit) lost contact on 22 Mrch 2010, after being stuck in sand since spring 2009. MER B (Opportunity) is still active by early 2016.

Nation: USA
Type / Application: Mars Lander / Rover
Operator: Jet Propulsion Laboratory for NASA
Contractors: Jet Propulsion Laboratory
Equipment: see above
Configuration: Spin stabilized cruise stage, airbag-cushioned lander, rover
Propulsion: ?
Power: Solar cells, batteries (cruise stage); fixed solar arrays, batteries (rover)
Lifetime: 3 month (design), still operational (#2)
Mass: 1063 kg
Orbit: 1.042 AU × 1.550 AU, 0.26° heliocentric (#A)
Satellite COSPAR Date LS Launch Vehicle Remarks
Mars Exploration Rover A (MER A, MER 2, Spirit) 2003-027A 10.06.2003 CC SLC-17A Delta-7925 Lander contained rover
Mars Exploration Rover B (MER B, MER 1, Opportunity) 2003-032A 08.07.2003 CC SLC-17B Delta-7925H Lander contained rover


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