WASHINGTON – Russian and NASA engineers worked into the evening Thursday to figure out why two computer systems essential to the operation of the international space station crashed, and the agency began making contingency plans that include potentially abandoning the $100 billion facility if they should fail.

NASA officials said that the situation appeared to be improving and that some communication had been restored to the Russian computer system. But NASA’s space operations chief, William Gerstenmaier, said Thursday that the failure is complicated and will probably take days to fix.

“At this point, we don’t know the root cause of the problem,” he said. “Fortunately, we have a lot of flexibility in terms of timing.”

The computer systems, which began to have problems the day after new solar panels were deployed, creating an additional source of electric power, control thrusters that keep the station properly oriented. They are also used to control the oxygen-production and carbon-dioxide scrubbing systems for the air that the astronauts breathe.

The three-person crew of the station was joined this week by a seven-member team on the space shuttle Atlantis. NASA officials said they are currently in no danger.

Michael Suffredini, manager of the space station program at the Johnson Space Center in Houston, said intensive work to restore the computer functions began Thursday morning, when the station’s orbit brought it near its Russian control station, and would continue through the day.

He said the computers – which were made in Germany by Daimler-Benz and were donated by the European Space Agency – may be especially sensitive to “noise,” or variations in an electric signal that can cause static. That noise, he said, may have started after the new array of solar panels were connected.

Suffredini said he fully expected that the computer problem will be resolved. “I’m not thinking this is something we will not recover from,” he said.

As a precaution, he said, NASA is looking into options to further extend the shuttle’s stay, since its power and thrusters could be used to keep the station properly situated to keep the solar panels facing the sun. Mission Control had decided to extend the 11-day mission by two days to allow ample time to repair a damaged portion of the shuttle’s thermal insulation.

While Gerstenmaier acknowledged that the computer problem was serious, he said that the crew members and ground control were working out solutions.

“I think we’re stable,” he said. “In my world, this is space station operations.”