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Meanwhile, the two rovers on the surface of Mars have been very busy. On Wednesday, Spirit broke its own record set earlier in the week for the longest one-day drive on Mars. The rover added 24.4 meters (80 feet) to its odometer, bringing the total to 57.4 meters (188 feet) and ending its day near a cluster of rocks dubbed "Stone Council." In coming weeks, scientists and engineers plan for Spirit to drive up to the rim of a crater dubbed "Bonneville," still more than two football-field lengths away, in hopes of peering inside and seeing rock layers that could tell the geologic history and the potential role of water at the Gusev site. Opportunity drove Friday morning to the fourth counterclockwise position in its survey of a rock outcrop along the inner slope of the crater in which it landed. Based on the survey, scientists will choose a small number of locations on the outcrop to come back to for more thorough examination later. The flight team has learned to compensate for wheel slippage in the soil on the slope. "When we attempt to drive up the slope we intentionally overdrive, and when we drive down a slope we intentionally underdrive," Art Thompson of the rover flight team said. Both rovers have used an infrared sensing instrument called the miniature thermal emission spectrometer to study the sky, as well as the ground. These atmospheric observations are revealing rapid temperature changes in the lower atmosphere. In mid-morning, the air temperature at about the height of an eight-story building swings up and down by several degrees within a minute. "Warmer and colder blobs of air are intermittently passing over the rover," Dr. Don Banfield, a rover science team collaborator from Cornell University, said. "We're watching the overturning of the atmosphere as it's warming up in the morning." Rising warmer air carries heat to upper layers of the atmosphere. Observing the details of these changes helps scientists improve their models for understanding Mars' winds. Better understanding of Mars' winds is important not only for the design of future landings on the planet, but also for interpreting some features on the surface. "We've been talking a lot about water on Mars in the past, but wind is currently the important agent of change on Mars," Banfield said. Microscopic images indicate that windblown
sand is eroding the outcrop that Opportunity is studying. Dr.
Mark Lemmon, science team member from Texas A&M University,
College Station, said that taking a series of images with that
instrument at slightly different distances from the target allows
creation of a three-dimensional view. "We're gathering as
much information about the things we're looking at as we possibly
can," he said. Previous article: Opportunity's Landing Analyzed |
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