http://www.nytimes.com/2009/01/30/science/space/30rover.html?ref=science
January 30, 2009
Mars Rover Doing Well After Memory Glitch
By
<http://topics.nytimes.com/top/reference/timestopics/people/c/kenneth_chang/index.html?inline=nyt-per>KENNETH
CHANG
NASA’s Mars Spirit rover may be rolling again as
soon as this weekend, although engineers remain
perplexed as to what caused it to lose memory and
abort an attempted drive last Sunday.
“Spirit is doing pretty good, as a matter of
fact,” said R. William Nelson, the chief of the
engineering team for the two Mars rovers, Spirit and Opportunity.
On Sunday, Spirit did not move as instructed and,
oddly, did not keep the data recording what it
had done. The data files are usually written to a
part of the rover’s memory known as “flash
memory,” which retains information even after power is turned off.
The best guess for what happened is that Spirit
somehow slipped into what NASA engineers call the
“cripple mode,” in which the rover avoids using
flash memory and instead writes to so-called
random access memory. The data may have
disappeared when the rover went back to sleep
after trying to execute the instructions.
This cripple mode proved invaluable during
Spirit’s early days on Mars, when a software
glitch caused the flash memory to overflow and
Spirit was caught in a cycle of continually
rebooting itself. By avoiding flash memory,
engineers were able to troubleshoot the problem
and send a software fix to the rover.
The hypothesis would explain Spirit’s amnesia,
but it is not at all clear how the rover could
have instructed itself to go into the cripple
mode. “It’s all very mysterious at this point,
and we may never find out what happened,” Mr. Nelson said.
The engineers are also investigating a second,
apparently unrelated glitch: the rover thinks the
Sun’s position in the sky is four degrees off the
actual position. Analysis on Thursday ruled out a
problem with the camera, and the prime suspect
for the error is a problem with the rover’s gyroscopes.
Mr. Nelson said that the team could work around
any problems with the gyroscopes and that the
rover otherwise appears to be in good health.
<http://www.nytimes.com/ref/membercenter/help/copyright.html>Copyright
2009 <http://www.nytco.com/>The New York Times Company
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2009/01/29/MNN915JL6B.DTL
Mars rover may be feeling its age - finally
<mailto:[log in to unmask]>David Perlman, Chronicle Science Editor
Friday, January 30, 2009
Spirit, the aged and somewhat creaky Mars rover,
is stalled on the Red Planet with a touch of
bewilderment, but earthbound engineers are
confident they'll get the mobile explorer up and running smoothly soon.
The Spirit and its sister rover, Opportunity,
landed on Mars five years ago for what was
designed as a 90-day mission, but have far
exceeded all expectations, exploring successfully
on opposite sides of the planet ever since. The
only signs of age have been a little wear on the
wheels and problems with some of their onboard instruments.
Lately, though, the Spirit apparently is
disoriented. The robot vehicle has failed to obey
radio commands from Earth to start driving, and
has been unable to find the sun, NASA scientists say.
"We may never know what went wrong up there, or
what caused the problem," Bill Nelson, a leading
engineer at the Jet Propulsion Laboratory in
Pasadena where Spirit and Opportunity are
controlled, said Thursday. "But we're quite
optimistic that it won't stop the vehicle."
Scientists and mission control engineers
calculate that a Mars day, or "sol," is 39
minutes and 35 seconds longer than a day on
Earth. It was during Spirit's 1,800th sol on the
planet Sunday that it failed to start driving.
Two sols later, it was told to find the sun with
its camera, but the rover was disoriented and
reported the sun's location in the wrong place.
Communication between Earth and the rovers is
relayed by the Mars Odyssey spacecraft, which has
been orbiting Mars for almost nine years, and on
Thursday Nelson and mission controllers were
awaiting a new downlink carrying a fresh report
from Spirit via Odyssey to help efforts at diagnosing the problems.
One possible cause of the communication problem,
Nelson said, might be an errant cosmic ray from
distant space that somehow sparked a glitch in
Spirit's computer and prevented it from storing
the proper commands from Earth and responding correctly to them.
The inability of Spirit's camera to locate the
sun, he said, could have been a case of mistaken
identity when it instead picked up a bright glint
caused by the sun's reflection on one of the rover's metal body parts.
Spirit was supposed to start trundling 20 to 25
feet this week from its present location in a
spot on the Martian surface known as Home Plate.
And that would precede a journey of about 900
feet to a new location called Goddard-von Braun,
named for rocket pioneers Robert Goddard and Wernher von Braun.
Both Spirit and Opportunity are powered by solar
arrays, and dust storms now and then have left
dusty films on their solar panels, Nelson said.
This has cut power for both rovers, he said, but
hasn't immobilized them, and once Spirit's health
is restored, its stalled drive will start again.
Since January 2004, when they landed, Spirit has
roamed across the Martian surface for a total of
about 4.7 miles, and Opportunity has journeyed
8.5 miles - not much for a human hiker, but a lot for a Mars rover.
E-mail David Perlman at
<mailto:[log in to unmask]>[log in to unmask]
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This article appeared on page A - 8 of the San Francisco Chronicle
San Francisco Chronicle Sections
<http://www.sfgate.com/chronicle/info/copyright/>©
2009 Hearst Communications Inc.
http://www.foxnews.com/story/0,2933,485345,00.html
Mars Rover's Bizarre Behavior Puzzles NASA
Thursday , January 29, 2009
By Tariq Malik
NASA engineers are scratching their heads over
some unexpected behavior from the long-lived
Spirit rover, which began its sixth year exploring Mars this month.
Spirit failed to report in to engineers at NASA's
Jet Propulsion Laboratory (JPL) in Pasadena,
Calif., last weekend, prompting a series of
diagnostic tests this week to hunt the glitch's source.
The
<http://www.space.com/common/media/video/player.php?videoRef=SP_090128_spirit&mode=>aging
Mars rover did not beam home a record of its
weekend activities and, more puzzlingly,
apparently failed to even record any of its
actions on Sunday, mission managers said.
"We don't have a good explanation yet for the way
Spirit has been acting for the past few days,"
said NASA's Sharon Laubach, who leads the JPL
team that that writes and checks commands for the
rover and its robotic twin Opportunity. "Our next
steps will be diagnostic activities."
Sunday marked Spirit's 1,800th Martian day, or
sol, exploring a region known as "Home Plate" in
the planet's expansive Gusev Crater.
Spirit and its twin Opportunity were initially
expected to spend just 90 days exploring the
Martian surface when they landed in succession
<http://www.space.com/missionlaunches/090103-mars-rovers-fifth-anniversary.html>more
than five years ago this month. Opportunity is
currently headed for the
<http://www.space.com/missionlaunches/080923-mars-rover-crater.html>monster
crater Endeavour on the other side of Mars.
On Sunday, Spirit apparently received commands to
drive to its next waypoint, but failed to move an inch, mission managers said.
While that glitch can have any number of causes,
such as Spirit not properly perceiving it was
ready to drive, the rover's failure to record its
daily work in its non-volatile computer memory is perplexing, they added.
By Monday, Spirit's mission controllers decided
to tell the rover to find the sun with its camera
on Tuesday to determine its location on Mars.
Early Tuesday, the rover beamed back that it had
tried to follow the instructions of its human
handlers, but couldn't find the sun.
NASA engineers believe Spirit's woes may be due
to a transitory cause, such as a high-energy
cosmic ray hitting the rover's electronics. On
Tuesday, the rover's non-volatile memory appeared
to be working fine, mission managers said.
The rovers Spirit and Opportunity have lasted
more than 20 times their initial three-month
mission plan, with each suffering from aches and
pains associated with their longevity.
Spirit initially bounced back from a worrying
computer glitch early in its mission and has
since
<http://www.space.com/news/081112-mars-rover-spirit.html>survived
frigid winters on Mars and scaled a nearby hill.
Both rovers have expanded scientists' knowledge
of the history of liquid water on Mars during their respective missions.
While puzzling, Spirit's new glitches don't
appear to be a serious concern at present,
according to NASA's rover mission chief John Callas.
"Right now, Spirit is under normal sequence
control, reporting good health and responsive to
commands from the ground," he added.
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