2003 Mars Exploration Rover Mission

Launch Date: June-July 2003
Arrival Date: January 2004
Mass: 180 kilograms (about 400 pounds)
Science instruments on board: Miniature Thermal Emission Spectrometer, Alpha Particle X-ray Spectrometer, Mössbauer Spectrometer, Panoramic Camera and Microscopic Imager

Eight years ago, in 1996, a rover called the Mars Pathfinder, was launched by NASA to investigate the Martian surface. Arriving in 1997, it however lost contact after barely three months of transmission. In 2001, NASA launched the Mars Exploration Rover mission in the hope of sending two of the most sophisticated and largest rovers ever built to explore Mars, Opportunity and Spirit. After 3 years of planning, Spirit and Opportunity were sent on their six month long voyage to Mars on 10 June, 2003, and 7 July, 2003 respectively; their Delta II launchers taking them on their journey from Cape Canaveral Air Force Station, Florida.

Rovers Opportunity and Spirit

Compared to the Sojourner rover in the 1996 Mars Pathfinder mission, the rovers Opportunity and Spirit were larger, reaching nearly 180 kilograms in mass. This extra mass meant that the rovers are able to carry all their scientific instruments with them, unlike the Sojourner rover where its instruments were left with the lander. Other than its greater mass, the new rovers also possessed greater mobility, being able to cover 40 metres per Martian day, or per sol. In comparison, the rovers are able to travel in one Martian day as much distance as the Sojourner rover did in its entire lifetime. Altogether, the mission cost 820 million dollars.

After six months travel, the two rovers reached Mars. Spirit, setting off early, reached Mars on 3 January. Both rovers used the same descent method used by the Pathfinder in order to stop the 827 kilogram spacecraft from crashing into Mars at 1600 kilometres per hour. The craft first opens its parachute and slowly decelerate as it reaches the Martian surface. There it fires its retro-rockets to slow its landing speed before bouncing at least a dozen times before coming to a halt. After stopping, the air bags deflate and the petals on the lander open, allowing the rover to have its first peep of Mars; a 360 degrees reconnaissance of its surrounding landscape. The rover Spirit successfully landed in Gusev Crater. However, unexpectedly communications with Spirit were disrupted. As NASA and the world waited in silence, Opportunity in the meantime arrived on 24 January in Meridiani Planum Crater. As people cheered Opportunity's landing, the problems causing communication disruption with Spirit was found. The craft's computer had been overloaded with unnecessary data. After some work, NASA managed to reestablish communications with Spirit, allowing the world to cheer the double joy of both rovers making a safe landing on Mars. NASA now has two twin rovers operating on different areas of Mars.

The main mission for both the rovers is to answer an age-old question about Mars: Is or was there water? The two sites have been chosen after surveys by the orbiting Mars Global Surveyor and data from the Mars Pathfinder mission pointing to the possibility of the areas once having water. Gusev Crater, for example, may have once been a lake, and the Meridiani Planum Crater contains gray hematite, which usually forms in the presence of water.