SPIRIT UPDATE: Spirit at 'Peace' - sol 367-373, January 24, 2005
Spirit is healthy, but reduced sunlight has been reaching the rover through the atmosphere due to a possible dust storm identified from orbital data. Despite limited energy during the period from sol 367 through sol 373, Spirit made good progress by driving about 20 meters (66 feet) closer to top of "Cumberland Ridge." Spirit is investigating a rock called "Peace."
During a two-sol plan on sols 367 and 368, Spirit traversed about 14 meters (46 feet) up the steep hillside toward the ridge and a target named "Larry's Lookout." The average slippage during the drive is estimated at 14 percent, indicating much firmer footing than previous drives. Sol 368 was a remote sensing sol. Spirit made observations with its panoramic camera and its miniature thermal emission spectrometer and performed a successful test of the right eye of the panoramic camera to find the Sun. The rover team usually uses the left panoramic camera to locate the Sun.
"Sun finding" is sometimes called "get fine attitude" or "attitude update," and is something engineers do every couple of weeks to correct error in the rover's knowledge of attitude -- mostly which way is north. This takes the same kind of images of the Sun that the atmospheric science team does, but the engineers use the data to determine attitude. Between the updates, the rover uses the onboard computer to keep track of attitude changes, but error builds up in this measurement over time. In general, most of the panoramic camera images of the Sun are acquired for atmospheric science. Many images are used to determine how much dust is in the atmosphere (atmospheric opacity or Tau). Usually engineers take these images three or four times during the day. With the current dust storms, the team is taking even more images of the Sun.
Sols 369, 370, and 371 were part of a three-sol plan. On sols 369 and 370, Spirit looked for more science targets en route to Larry's Lookout. On sol 371, Spirit completed a 6-meter (20-foot) drive to arrive at the rock target "Peace." Due to the slope and small rocks in area, Spirit sat at an overall tilt of 19 degrees to the north-northeast, which was very good for maximizing solar energy.
On sol 372, Spirit deployed the rover arm and acquired a set of images of Peace taken by the microscopic imager. A sequencing error prevented the alpha particle X-ray spectrometer from being placed on the rock, delaying the planned integration. The opacity of the sky, or Tau, which is the amount of light that cannot penetrate through the atmosphere, rose sharply from 0.8 to 1.1.
On sol 373, Spirit acquired more images with the microscopic imager and brushed Peace with the rock abrasion tool. The rover then placed the alpha particle X-ray spectrometer on Peace successfully for a nighttime integration. Tau continued upwards to 1.3, further reducing solar energy for Spirit.
Solar energy continues to be a precious resource because of the high Tau on sol 373. Although dust storms are more likely at this time of martian year, the start of the true dust storm season is still months away. Sol 373 ended on Jan. 20, 2005.
OPPORTUNITY UPDATE: Opportunity Continues on the Plains After Marking One Year on Mars - sol 353-359, January 28, 2005
After spending 25 sols at the heat shield and nearby meteorite, Opportunity has completed its investigation of both and has started a long migration south. The rover is currently heading for a small crater called "Argo." Dust storms in the vicinity of Meridiani Planum appear to be settling down, and solar power has stabilized. On Jan. 24, 2005, the rover team celebrated Opportunity's first anniversary (one Earth year) on Mars. The rover continues to be in excellent health for its long drives out on the plains of Meridiani.
Sol 353 was a restricted sol. (Results of 352 drive were not known by the planning team in time to calculate the final heat shield approach). Opportunity performed over two hours of observations using the panoramic camera and miniature thermal emission spectrometer.
On sol 354, Opportunity performed 10 minutes of pre-drive remote-sensing observations, then moved forward to get in final position for extending its instrument deployment device (robotic arm) to the heat shield. A drive of 0.7 meter (2.3 feet) was successful, placing the heat shield in reach of the arm. Opportunity performed more than an hour of post-drive imaging.
Sol 355 was a restricted sol. Opportunity performed over two hours of remote sensing.
Sols 356 and 357 were planned in a single planning cycle. On sol 356, Opportunity used the microscopic imager to examine the heat shield. Using the arm to position the microscopic imager, Opportunity spent 90 minutes collecting high-resolution images of the heat shield. On sol 357, the rover performed thermal inertia measurements throughout the sol. Using the miniature thermal emission spectrometer to image the same target at different times, Opportunity took measurements as late as 23:00 Mars local solar time.
On sol 358, Opportunity retook some microscopic images of the heat shield with the dust cover open. The rover then stowed its arm and began its drive south, away from the heat shield. Opportunity is now headed for a small crater called Argo, which is approximately 300 meters (about 984 feet) away. Opportunity successfully covered 86.3 meters (283 feet) on this sol.
Sol 359, which ended on Jan. 27, was another restricted sol. The rover was sent commands for over 2.5 hours of remote sensing.
Total odometry as of sol 358 is 2,200.6 meters (1.37 miles).