If left unfixed, the instrument could still determine the presence of iron-bearing minerals in the rocks and soil on the Martian surface, but not their relative abundance, said Steve Squyres, of Cornell University. Some of that information could be derived from the rover's other instruments, however.
Scientists hope that testing the minerals will help solve the riddle of whether Mars was ever a warmer, wetter place capable of sustaining life.
"We would be able to extract some science from the data — not everything, but some," said Squyres, lead scientist on the package of instruments carried on the rover, Spirit, and its twin, Opportunity.
Scientists do not understand the cause of the glitch, but have five months to come up with a remedy before the rover lands, Squyres said. Spirit is expected to make a Jan. 3 landing on Mars, followed by Opportunity on Jan. 24.
The instrument, called a Mossbauer spectrometer, malfunctioned during tests last week.
The National Aeronautics and Space Administration will continue to work on a long-distance fix to Spirit's instrument during the balance of its cruise to Mars.
"We will do the best we can to adjust the instrument so it delivers the maximum science," Squyres said.
The $800 million pair of rovers otherwise remain in excellent health, according to NASA.
The equipment troubles are not the first problems to plague the rovers. In fact, NASA's efforts to study mars have run into difficulty several times in recent years.
The launch of the second rover, Opportunity, was postponed more than a half-dozen times because of bad weather, a failed battery cell and a nagging problem with cork insulation failing to stick to the aluminum rocket.
Even on the countdown to the successful launch, officials halted the countdown with seven seconds left because of a problem with a valve on the rocket.
In 1999, the Mars Climate Orbiter apparently burned up in the Red Planet's atmosphere because of a metric mix-up, and the Mars Polar Lander failed to call home when it tried to land.