Spirit Healthy But Computer Reboots Raise Concerns

MARSDAILY

Four Drives Add to Progress - sols 1865-1871
Spirit has been busy making good progress around the western edge of "Home Plate." The rover drove four out of the past seven sols, making more than 40 meters (131 feet) of total distance. First, Spirit completed a science campaign on light-toned material unearthed the preceding week, then the rover resumed driving on Sol 1866 (April 3, 2009; no sol number for Spirit corresponded to April 2, 2009, using the criterion of the date in Los Angeles at local solar noon on Mars). The Sol 1866 drive achieved only about 3 meters (10 feet) of progress due to excessive slip. On the next drive sol, Sol 1868 (April 5, 2009), Spirit avoided the troubled terrain and completed about 17.5 meters (57 feet). A pair of drives on Sols 1870 and 1871 (April 7 and 8, 2009) added another 20 meters (66 feet) of progress. As of Sol 1871 (April 8, 2009), Spirit's solar array energy production is 240 watt-hours, equivalent to what it takes to light a 100-watt bulb for 2.4 hours. Atmospheric opacity (tau) has improved slightly to 0.99. The dust factor is 0.304, meaning that 30.4 percent of sunlight hitting the solar array penetrates the layer of accumulated dust on the array. The rover is in good health as it makes progress around Home Plate. Spirit's total odometry is 7,726.78 meters (4.80 miles).

More Bright Soil Exposed by Driving - sols 1859-1864
Spirit is running under new flight software, version R9.3, and all is working well. The rover continued driving around the west of "Home Plate." A drive on Sol 1861 (March 28, 2009) achieved almost 23 meters (75 feet) and something extra. Light-toned soil was unearthed by the right-front wheel as the rover drove along this western portion of Home Plate. The science team, suspecting that this may be more silica, developed a contact science campaign for this revealed material. On Sol 1863 (March 30, 2009), the robotic arm (IDD) was deployed and extended to the light-toned soil. A microscopic imager (MI) stack of images was collected and then the alpha particle X-ray spectrometer (APXS) was placed right on the target soil. Integration with the APXS continued through Sol 1864 (March 31, 2009). Observations of this light-toned material were also made with the miniature thermal emission spectrometer (Mini-TES). As of Sol 1864 (March 31, 2009), Spirit's solar array energy production is 223 watt-hours. Atmospheric opacity (tau) remains elevated at 1.19. The dust factor on the solar array has worsened slightly to 0.297, meaning that 29.7 percent of sunlight hitting the solar array penetrates the layer of accumulated dust on the array. The rover is in good health despite dusty skies. Spirit's total odometry is 7,686.61 meters (4.78 miles).

by Staff Writers
Pasadena CA (SPX) Apr 14, 2009
The team operating NASA's Mars Exploration Rover Spirit is examining data received from Spirit in recent days to diagnose why the rover apparently rebooted its computer at least twice over the April 11-12 weekend.

"While we don't have an explanation yet, we do know that Spirit's batteries are charged, the solar arrays are producing energy and temperatures are well within allowable ranges. We have time to respond carefully and investigate this thoroughly," said John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif., project manager for Spirit and twin-rover Opportunity.

"The rover is in a stable operations state called automode and taking care of itself. It could stay in this stable mode for some time if necessary while we diagnose the problem."

Spirit communicated with controllers Friday, Saturday and Sunday, but some of the communication sessions were irregular. One of the computer resets apparently coincided in timing with operation of the rover's high-gain dish antenna.

The rover team has the advantage of multiple communication options. Spirit can communicate directly with Earth via either the pointable high-gain antenna or, at a slower data rate, through a low-gain antenna that does not move.

Additionally, communications can be relayed by Mars orbiters, using the UHF (ultra-high frequency) transceiver, a separate radio system on the rover.

"To avoid potential problems using the pointable antenna, we might consider for the time being just communicating by UHF relay or using the low-gain antenna," Callas said.

Spirit finished its three-month prime mission on Mars five years ago and has kept operating through multiple mission extensions.

The rover's onboard software has been updated several times to add new capabilities for the mission, most recently last month. The team is investigating whether the unexpected behavior in recent days could be related to the new software, but the same software is operating on Opportunity without incident.

"We are aware of the reality that we have an aging rover, and there may be age-related effects here," Callas said.

In the past five weeks, Spirit has made 119 meters (390 feet) of progress going counterclockwise around a low plateau called "Home Plate" to get from the place where it spent the past Martian winter on the northern edge of Home Plate toward destinations of scientific interest south of the plateau.

On March 10, after several attempts to get past obstacles at the northeastern corner of Home Plate, the rover team decided to switch from a clockwise route to the counterclockwise one.

Subsequent events have included Spirit's longest one-day drive since the rover lost use of one of its wheels three years ago, plus detailed inspection of light-toned soil exposed by the dragging of the inoperable wheel.

Halfway around Mars, meanwhile, Opportunity has continued progress on a long-term trek toward Endeavour Crater, a bowl 22 kilometers (14 miles) in diameter and still about 12 kilometers (12 miles) away. Last week, a beneficial wind removed some dust from Opportunity's solar array, resulting in an increase by about 40 percent in the amount of electrical output from the rover's solar panels.

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Cleaning Event Boosts Energy For Mars Rover Opportunity

Pasadena CA (JPL) Apr 14, 2009
On Sol 1845 (April 2, 2009), the rover's robotic arm (IDD) placed the Mossbauer (MB) spectrometer on the outcrop target "Penrhyn" for a multi-sol integration. On Sol 1850 (April 7, 2009), a temporary stand-down on driving was provisionally lifted and Opportunity resumed driving. The MB was retracted and the arm moved into the driving stow position.

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