Press Release

Computer Reboots Raise Concerns About Mars Rover Spirit

By SpaceRef Editor
April 13, 2009
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Computer Reboots Raise Concerns About Mars Rover Spirit
Mars Rover Spirit

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.

JPL, a division of the California Institute of Technology in Pasadena,
manages the Mars Exploration Rover project for NASA’s Science Mission
Directorate, Washington.

SpaceRef staff editor.