With its front legs just on the lip of the small crater, Opportunity was able to extend its robotic arm to characterize some of the mineralogy found here.

Sol-by-sol summaries:

The last previous drive left Opportunity in a position where it could make its final approach to the lip of one of the craters in a cluster of three small craters.

On sol 389 (Feb. 26, 2005) the rover took images of the site with its panoramic camera and its miniature thermal emission spectrometer. On sol 390, Opportunity took a panoramic camera mosaic of the crater, then bumped forward to the edge of the crater. Sol 391 was another day of remote-sensing science and rest.

For sol 392, the team decided to take an in situ look at a rock target called "Normandy." The Moessbauer spectrometer was placed on the rock and it conducted a three-hour long integration. Then the rover switched to the alpha particle X-ray spectrometer and performed a very short (10-minute) measurement.

The science team needed a sample reading, and by using this technique, the engineering team was able to give the scientists some idea of what they had in time for a communication window with Mars Odyssey.

The science team used this data to determine if sol 393 would be a grinding day (with the rock abrasion tool).

After getting the alpha particle X-ray spectrometer reading, the rover went to sleep, woke up at about 4:00 a.m. local solar time and started collecting data again with the alpha particle X-ray spectrometer. The instrument ran for about 6 hours.

On sol 393, the rover switched back to the Moessbauer spectrometer and started a very long (about 12-hour) integration. The rover was able to use the mini-deep-sleep mode after the integration.

Plans for sols 394 and 395, uplinked on March 3, call for the rover to stow its robotic arm and back away from the crater on sol 394. At this point the rover will take some remote-sensing images. After confirmation that these important images have been acquired, Opportunity will turn and drive toward Vostok.

Spirit Captures Two Dust Devils On the Move

Twin Dust Devils captured over two days. Desktop available.

At the Gusev site recently, skies have been very dusty, and on its 421st sol (March 10, 2005) NASA's Mars Exploration Rover Spirit spied two dust devils in action. This is an image from the rover's navigation camera.

Views of the Gusev landing region from orbit show many dark streaks across the landscape - tracks where dust devils have removed surface dust to show relatively darker soil below - but this is the first time Spirit has photographed an active dust devil.

Scientists are considering several causes of these small phenomena. Dust devils often occur when the Sun heats the surface of Mars. Warmed soil and rocks heat the layer of atmosphere closest to the surface, and the warm air rises in a whirling motion, stirring dust up from the surface like a miniature tornado.

Another possibility is that a flow structure might develop over craters as wind speeds increase. As winds pick up, turbulence eddies and rotating columns of air form.

As these columns grow in diameter they become taller and gain rotational speed. Eventually they become self-sustaining and the wind blows them down range.

One sol before this image was taken, power output from Spirit's solar panels went up by about 50 percent when the amount of dust on the panels decreased. Was this a coincidence, or did a helpful dust devil pass over Spirit and lift off some of the dust?

By comparing the separate images from the rover's different cameras, team members estimate that the dust devils moved about 500 meters (1,640 feet) in the 155 seconds between the navigation camera and hazard-avoidance camera frames; that equates to about 3 meters per second (7 miles per hour). The dust devils appear to be about 1,100 meters (almost three-quarters of a mile) from the rover.

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