Spirit rover will leave a 'long legacy for exploration'
When NASA's robotic exploration rover Spirit touched down on the surface of Mars in January 2004, the agency never dreamed it would operate for over six years, travel more than four miles or return more than 124,000 images of the surface. In April, NASA sent the last recovery command to Spirit but will continue operating a second rover, Opportunity, which touched down on Mars, just three weeks after Spirit.
The success even astounded veteran scientist Raymond Arvidson (right), James S. McDonell distinguished university professor at Washington University in St. Louis, who played a major role in planning the exploration and analyzing the data. He is the deputy principal investigator for the Mars Exploration Rover Mission.
"We succeeded beyond my wildest dreams, clearly both Spirit and Opportunity succeeded in their missions and have left a big impact for future study," Arvidson said.
Arvidson is assisting with the Opportunity rover's mission but is eager to continue to analyze the volumes of data that Spirit sent back.
"We will be analyzing data from the Spirit rover for years to come; we have a lot of information so we have a lot more to learn from its mission," Arvidson said. "These rovers set the bar really high in terms of robotic exploration. They were well tested and well designed."
Equipped with geological analysis equipment, the rover's scientific objective was to search for and characterize rocks and soils that led to evidence of past water and organic life on Mars. One of the major discoveries from this mission was the uncovering of a bright white soil near a low plateau called Home Plate. Spirit analyzed this soil with its alpha particle X-ray spectrometer and miniature thermal emission spectrometer revealing the bright material was nearly pure silica. Many experts including Steve Squyres, of Cornell University and principal investigator for the rover missions, believe the material provides evidence for ancient hot springs or stream vents on the surface similar to the hot springs at Yellowstone National Park.
"The data from Spirit show us that Mars was a very different place in the past from what we see today. This surface area that Spirit explored had a lot of explosions as it was a hot, wet, watery place," Squyres said.
This is only one scientific discovery that the rovers have revealed and these revelations could keep coming as scientists continue to analyze the data from Spirit.
"The engineering really allowed us to do more than was expected. A lot of care was taken into building and designing these rovers, and it really showed with the data that we have been able to collect," said Bruce Banerdt, NASA project scientist for the Mars Rovers.
Spirit Met And Overcame Obstacles
The Spirit and Opportunity rovers were designed as three-month missions and because of their durability, they were able to serve for additional years. That design and durability of the Spirit rover was tested in a major way two years into the mission when the right front-wheel motor became inoperable.
"Spirit faced a lot of challenges on Mars," Banerdt said. "When the wheel went out, we had to relearn how to drive the rover. It is truly remarkable what we were able to achieve with this rover with only five wheels."
This inoperable wheel was a gift and a curse for Spirit. The bum wheel assisted in the discovery of the silica-rich soil as it dragged across the surface while the rover was backing up. Still, the broken wheel made it difficult for the rover to continue in the harsh Martian environment as dust accumulated and limited its mobility.
With winter looming, the science team made a push to move toward the south, going around Home Plate to the west. The rover was unable to climb any soil-covered slopes and it was forced to travel around Home Plate. As the rover moved along this path, it broke through an unseen hazard as it became trapped in a patch of soil crust.
While the rover was stuck, Arvidson and the Department of Earth and Planetary Sciences at Washington University were able to analyze the soil around it.
"The place where Spirit is trapped in turned out to be a geological treasure trove," Arvidson said. "We have learned a lot about Mars from these missions and we will continue to make discoveries as we analyze more data."
Opportunity continues to explore Mars as it reaches the rim of a large crater called Endeavour. This crater offers many areas for scientific exploration as orbital observations indicate the ridges along the craters southern tip has exposed rock outcrops, which are older than any that has been analyzed before.
Future Rover Missions
The next chapter for the Mars Exploration Rover Mission will be investigating Mars' past or present ability to sustain microbial life. NASA is currently testing its Curiosity rover in preparation for launch this fall. The rover is said to be the most sophisticated vehicle sent to Mars. The size of a Mini Cooper, Curiosity is equipped with a drill that will be able to collect sample material from inside of rocks and a scoop allowing the rover to pick up samples for further analysis with instruments inside the rover.
Curiosity's mission has been slow to get started as the project is currently over budget and behind schedule. The mission cost has risen from $2.5 billion from its original $1.6 billion budget and the launch had to be pushed back two years because of problems during construction.
Once it lands on the surface of Mars however, Squyres and other scientists are excited to see the results it will bring.
"The Spirit and Opportunity rovers have left a long legacy for exploration and the Curiosity rover will have a lot to live up to," Squyres said. "If these rovers can be used as an inspiration to people to explore then that will leave a greater legacy than what is in the science."
Jonathan Ernst, a student at St. Louis University, is a summer intern at the Beacon. To reach him, contact Beacon health and science editor Sally J. Altman.