NASA Concludes Attempts to Contact Mars Rover Spirit

[dlavery]

Spirit's successes went way beyond those that were established as the original science objectives of the mission. Measured against the original mission success criteria, Spirit's accomplishments included:

- Located and characterized a variety of rocks and soils that held clues to past water activity. In particular, samples found included minerals deposited by water-related processes such as precipitation, evaporation, sedimentary cementation, or hydrothermal activity.

- Determined the distribution and composition of minerals, rocks, and soils surrounding the landing sites.

- Determined what geologic processes shaped the local terrain and influenced the chemistry. Such processes included water / wind erosion, sedimentation, volcanism, and cratering.

- Performed "ground truth" -- calibration and validation -- of surface observations made by Mars orbiter instruments. This helped determine the accuracy and effectiveness of various instruments that survey Martian geology from orbit.

- Searched for iron-containing minerals, and identified and quantified relative amounts of specific mineral types that contained water or were formed in water, such as iron-bearing carbonates.

- Characterized the mineralogy and textures of rocks and soils and determine the processes that created them.

- Searched for geological clues to the environmental conditions that existed when liquid water was present. Assessed whether those environments were conducive to life.

Beyond the mission success criteria, Spirit drove 7.73 kilometers, more than 12 times the 600-meter goal set for the mission. The drives crossed a plain to reach a distant range of hills that appeared as mere bumps on the horizon from the landing site; climbed slopes up to 30 degrees as Spirit became the first robot to summit a hill on another planet; and covered more than a kilometer after Spirit's right-front wheel became immobile in 2006. The rover returned more than 124,000 images. It ground the surfaces off 15 rock targets and scoured 92 targets with a brush to prepare the targets for inspection with spectrometers and a microscopic imager. The drill aboard the rover was so well used that the drill bit became completely worn out by mid-way through the mission.

One major finding came, ironically, from dragging the inoperable right-front wheel as the rover was driving backwards in 2007. That wheel plowed up bright white soil. Spirit's Alpha Particle X-ray Spectrometer and Miniature Thermal Emission Spectrometer revealed that the bright material was nearly pure silica. This was one of the most important discoveries by either rover for the entire mission (so far). It showed that there were once hot springs or geothermal activity in the region, which could have been an environment conducive to the formation of microbial life.

Likewise, the data from Spirit's Miniature Thermal Emission Spectrometer (Mini-TES) and Moessbauer Spectrometer showed a high concentration of carbonates. This is further evidence of a wet, non-acidic ancient environment that was very unlike the cold, dry Mars that we know today.

-dave