The Mars Exploration Rover Mission

Twin rovers Spirit and Opportunity launched from Cape Canaveral in 2003 and landed on Mars in January 2004. Their mission was to determine if early Mars had an environment that could have supported life. Airbags were used to cushion the landings at two different locations along the equatorial region of the red planet. These landing sites may have contained liquid water in ancient times (billions of years ago!). Spirit landed at Gusev crater which was thought to be the site of a former lake, and Opportunity landed at Eagle crater where orbital data revealed the presence of the mineral hematite which usually forms in liquid water.

Each rover carried a suite of instruments to study the surface of Mars called the Athena Science Payload. It included a panoramic camera called Pancam to scan the martian terrain for rock and soil targets, a Miniature Thermal Emission Spectrometer called Mini-TES to identify minerals at target sites, an Alpha Particle X-Ray Spectrometer (APXS) to determine rock compositions, a Mössbauer Spectrometer (MB) to identify iron-bearing minerals, a Microscopic Imager (MI) for close up views, and a Rock Abrasion Tool (RAT) to grind into rocks to reveal fresh surfaces for study.

The Mars Exploration Rover mission was designed to last 90 days, but Spirit continued to work on the surface of Mars for 6 years and Opportunity for almost 15 years. In Spirit’s journey from Gusev Crater to Bonneville Crater and across the plains to Husband Hill and Home Plate in the Columbia Hills, the rover found soils and rocks with materials that usually form in either hot springs or volcanic vents. These types of locations on Earth can harbor microbes called extremophiles. Opportunity traveled from Eagle Crater to Endurance Crater, Victora Crater, and Endeavour Crater. During the rover’s traverse, it found evidence of ancient acidic water as well as evidence of ancient water with a more neutral pH showing that at some point in Mars’ history there was a period more conducive to a habitable environment and to life (note: the rovers did not find evidence of life itself).