8 Nov 2004
(Source: Jet Propulsion Laboratory)
OPPORTUNITY UPDATE: Journey toward 'Burns Cliff' Continues - sol 265-271, November 08, 2004
Opportunity's trek towards "Burns Cliff" continues. The journey has been much more difficult than anticipated. The rover has experienced drive slippage of up to 100 percent. The plan is to attempt a couple of sols of up-slope, switchback driving and then review options to get to Burns Cliff.
The rover team celebrated Opportunity's 300-percent mission success anniversary on sol 270. The rover is showing no signs of slowing down despite its advanced age. Spacecraft health is excellent, and solar power is plentiful.
On sol 265 Opportunity began its drive away from a boulder called 'Wopmay.' The rover performed 45 minutes of remote observations and then attempted a 21-meter (69-foot) drive away from Wopmay. The drive stopped after 3.5 meters (11.5 feet). Opportunity experienced a drive and mobility goal error due to high current draw in the steering motors.
Sols 266, 267, and 268 were planned as a single 3-sol weekend plan. Due to the rover's heading at the end of sol 265, the morning uplink session on sol 266 was occluded by the panoramic camera, raising concern that we might fail to get the 3-sol command load to the spacecraft. To avoid this problem, the team instead chose to implement a high-priority communication window at 11:30 local solar time and to uplink all sequences at that time, activating the sol 266 master sequence by real-time command. This plan worked as designed, and all sequences got onboard.
The original plan for sols 266 and 267 was to place the alpha particle X-ray spectrometer on the filter magnet for extended integrations. However, Opportunity's position against a buried rock (informally named "Son of Bane") and the churning up of sandy terrain meant that we could not rule out the possibility of an unseen rock in the robotic arm's work volume. As a consequence, the arm deployment was cancelled, and the activities for sols 266-267 were limited to remote-sensing observations.
On sol 268, Opportunity drove away from Son of Bane. The rover turned and drove forward a short distance to get out of the hole it had dug for itself. It drove about 4.5 meters (about 15 feet) cross slope, and then began an up-slope drive designed to cover 9 meters (29.5 feet). Only about 0.4 meter (1.3 feet) of this last leg was achieved before the rover again encountered 100 percent slip.
Due to the large slippage and unsuccessful drive on sol 269, the day was used to take detailed images of the rover's position and to allow the rover mobility team to plan drive strategies for subsequent sols. Opportunity performed more than two hours of remote observations. The rover began a routine of forfeiting deep sleep for as many sols as the battery state of charge would allow. Solar exposure has been favorable enough to reduce the need for deep sleep. In an effort to reduce the backlog of onboard science telemetry that has not been downlinked, Opportunity will support early morning Mars Odyssey communication sessions as long as the battery state of charge is not impaired.
Sol 270 was the first sol dedicated to a potpourri of mobility maneuvers to gain a better understanding of the terrain on which Opportunity is driving. The rover completed the drive with no errors and achieved a positive elevation change of more than a meter (3.3 feet). Driving at a 45-degree angle to the slope appears to be the most productive operation.
With enthusiasm running high, the uplink team employed strategies of the drive from sol 270 to plan sols 271's drive. Opportunity was to drive up-slope at an angle heading east, towards Burns Cliff, as part of a longer switchback drive operation. But as has often been the case recently, the drive was not successful. Opportunity moved 0.78 meters in a beeline (about 2.6 feet) but experienced 100 percent slippage for most of the drive and ended up approximately 0.35 meters (1.1 feet) lower. Sol 271 ended on Oct. 28, PDT.
The result of this drive calls into question Opportunity's ability to reach Burns Cliff with the current approach. The team is assessing other possibilities.
Total odometry after sol 271 is 1664.43 meters (1.03 miles).