Flight controllers have established communications with Spirit, and the rover is transmitting engineering data. But the vehicle continues to behave erratically, and no science data has been received in more than two days. Flight controllers are uncertain if, or when, Spirit will return to normal operations.
Since the trouble began, Spirit’s computer has tried to reboot itself more than 60 times, but it has crashed during every attempt. The problem could be a software glitch, but it is more likely a symptom of a potentially more serious hardware failure. As a result, much of the data sent by Spirit over the past two days is gibberish, though some useful information about its power systems came through on the afternoon of January 23rd. Spirit is transmitting only on its low-gain antenna, which significantly reduces the data rate.
"We should expect that we will not be restoring functionality to Spirit for a significant period of time, many days, perhaps a couple of weeks, even in the best of circumstances," said project manager Pete Theisinger (Jet Propulsion Laboratory) at a January 23rd press conference.
The problem started on January 21st when the rover was operating a motor on its Mini-Thermal Emission Spectrometer. The motor sequence did not run to completion, and communications with Spirit have been irregular ever since. Ground controllers received several transmissions of engineering data on the 23rd, but the information has not enabled rover team members to diagnose the problem or develop a solution.
"We do not know to what extent we can restore functionality to the system because we don’t know what’s broke," said Theisinger, who suspects that a sequence of events ultimately caused the problem.
The flight team is also concerned that Spirit is not putting itself to sleep each night, causing extra drain on the batteries. Spirit’s solar-cell panels are able to generate power and recharge the batteries during the daytime, but the additional nighttime activity could limit the rover’s useful life if it can be restored to science operations. Spirit is already three weeks into a mission designed to last only three months.
On a positive note, there appears to be no life-threatening problems with the power system or temperature control, which buys time for the engineers. And the spacecraft is responding to commands sent from Earth. "We believe, based on everything we know now, that we can sustain the current state of the spacecraft from a health standpoint for a substantial and perhaps indefinite period of time," said Theisinger. A team formed to investigate the anomaly will begin meeting in the evening of January 23rd.
Theisinger remains guardedly optimistic: "I expect that we will get functionality back out of this rover. I think the chances that it will be perfect again are not good. The chances that it will not work at all, I think, are also low. I think we’re somewhere in that broad middle."
At the same press conference, NASA unveiled a new high-resolution image taken from orbit by Mars Global Surveyor showing Spirit’s lander, parachute, and aeroshell on the Martian surface. The image also shows a dark streak on the side of a crater left by the falling heat shield. "We even got the bounce marks," said Michael Malin (Malin Space Science Systems), principal investigator for Surveyor’s Mars Orbital Camera (MOC), which took the image. Malin added that MOC might try to image Beagle 2, the British lander that was scheduled to touch down on December 25, 2003, but has failed to signal Earth.
The problems with Spirit come at a time when many of the scientists and engineers are preparing for its twin, Opportunity, to land at 12:05 a.m. Eastern Standard Time on January 25th. "The successful landing of Spirit has given us very good confidence that the odds are with us for Opportunity," said Wayne Lee (JPL), lead engineer for the entry, descent, and landing team. "However, we are very respectful that landing on Mars is a risky endeavor and that there are no guarantees of success."
From its outward appearance, Spirit’s landing site in Gusev Crater closely matches what scientists anticipated prior to the mission. But nobody knows quite what to expect from Opportunity’s site in Meridiani Planum. "We expect this surface to look unlike the Pathfinder surface, the two Viking surfaces, or the Gusev surface," said deputy principal investigator Ray Arvidson (Washington University in St. Louis). Scientists chose Meridiani Planum because orbital data indicates it contains substantial outcrops of hematite, a gray iron-bearing mineral that often forms in liquid water on Earth.
Meanwhile, the European Space Agency (ESA) has released the first significant science results from its Mars Express orbiter. The spacecraft’s OMEGA instrument, a combined camera and infrared spectrometer, successfully detected surface water ice and carbon dioxide at the South Pole, something astronomers have known about since the 1970s.
Measurements from the ASPERA instrument, which was designed to test whether the solar wind is eroding Mars’s thin atmosphere, found a difference between the area of the atmosphere impacted by the solar wind and that shielded by Mars. During a stellar occultation, the SPICAM instrument measured the distribution of ozone and water vapor and found that water vapor is concentrated in areas with low ozone abundances.