"We should expect we will not be restoring functionality to Spirit for a significant amount of time -- many days, perhaps two weeks -- even in the best of circumstances," said Peter Theisinger, rover project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Spirit transmitted data to Earth today for the first time since early Wednesday. The information about the rover's status arrived during three sessions lasting 10 minutes, 20 minutes and 15 minutes. Engineers will be examining it overnight and developing a plan for obtaining more on Saturday morning.

Spirit's flight software is not functioning normally. It appears to have rebooted the rover's computer more than 60 times in the past three days. A motor that moves a mirror for the rover's infrared spectrometer was partway through an operation when the problem arose, so the possibility of a mechanical problem with that hardware will be one theory investigated.

"We believe, based on everything we know now, we can sustain the current state of the spacecraft from a health standpoint for an indefinite amount of time," Theisinger said. That will give the team time to work on the problem.

Meanwhile, Spirit's twin, Opportunity, will reach Mars at 05:05 Universal Time on Jan. 25 (12:05 a.m. Sunday EST or 9:05 p.m. Saturday PST) at a landing site on the opposite side of the planet from Spirit. Opportunity's landing site is on plains called Meridiani Planum within an Oklahoma-sized outcropping of gray hematite, a mineral that usually forms in the presence of water. Scientists plan to use the research instruments on Opportunity to determine whether the gray hematite layer comes from sediments of a long-gone ocean, from volcanic deposits altered by hot water, or from other ancient environmental conditions.

Analysis of Spirit's descent through Mars' atmosphere for its landing at Gusev has contributed to a decision by flight controllers to program Opportunity to open its parachute higher than had been planned earlier, said JPL's Dr. Wayne Lee, chief engineer for development of the rover's descent and landing systems.

The Mars Orbiter Camera on NASA's Mars Global Surveyor orbiter has taken an image of Spirit's landing region that shows the spacecraft's lander platform on the ground. The jettisoned parachute, backshell and heat shield are also visible, noted Dr. Michael Malin of Malin Space Science Systems, San Diego, lead investigator for the orbiter's camera and a member of the rover science team.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Office of Space Science, Washington, D.C. Images and additional information about the project are available from JPL at

http://marsrovers.jpl.nasa.gov

and from Cornell University, Ithaca, N.Y., at

http://athena.cornell.edu/ .