Try, Try Again: NASA Targets Two Rovers for Mars
(From the November/December 2000 issue of StarDate magazine)
Just months after scrapping its two-at-a-time plan for future missions to Mars, NASA reversed course in August and said it will send a pair of rovers to the planet in 2003. The agency says it has confidence in the plan because the rovers will be identical, so they will require only one development program.
Both rovers will search for evidence that liquid water once flowed across the Martian surface. Although Mars is arid today, with only small amounts of water in its atmosphere, polar ice caps, and layers of permafrost, orbiting spacecraft have discovered many dry riverbeds crisscrossing the planet's surface. Mars Global Surveyor, which has been orbiting Mars since 1997, has found evidence that a large ocean once covered much of the surface.
Scientists hope the rovers will help explain how much water once flowed across Mars in the past, and how and why the water disappeared. Global Surveyor has photographed sites where liquid water may have gushed to the surface from underground reservoirs in the recent past, and one or both of the rovers may examine these sites.
The 330-pound (150-kg) rovers will be based on the successful Sojourner rover, part of the Mars Pathfinder mission that landed in 1997. While Mars Pathfinder consisted of both a rover and a stationary set of instruments, though, the 2003 missions will rely solely on the rovers. They will land on Mars encased in airbag cocoons, as Pathfinder did, then roam up to 110 yards (100 meters) every Martian day (a Martian day is 40 minutes longer than a day on Earth).
Instruments aboard the rovers will photograph their surroundings and analyze the chemical and mineral composition of selected rocks.
The rovers will be launched in May and June of 2003 and arrive at Mars in January 2004, and will be designed to survive the intense Martian cold for at least 90 days. Scientists will select landing sites in two or three years, after analyzing images from Global Surveyor and another orbiter scheduled for launch next year.
Last year's loss of both Mars Climate Orbiter and Mars Polar Lander during their final approach to Mars forced NASA to scrap plans for a 2001 lander. Review panels attributed the loss of both spacecraft to inadequate oversight, poor internal communications, and other problems. Some questioned the wisdom of the "faster, better, cheaper" philosophy underlying NASA's entire Mars exploration program and other scientific missions. The 2003 rovers will keep with the philosophy, but NASA has added additional money for testing and oversight. -- — Damond Benningfield
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