WASHINGTON – NASA officials said Thursday the international space station is running so low on food that its two crewmen have had to cut back on their eating and may have to abandon the orbiting laboratory if a scheduled supply flight fails to arrive on Christmas Day.

The space station’s program manager, William Gerstenmaier, said U.S. astronaut Leroy Chaio and Russian cosmonaut Salizhan Sharipov had enough food to last one to two weeks beyond Christmas. “We haven’t picked an exact time or an exact day, but if we need to bring the crew home, we’ll bring the crew home,” Gerstenmaier said.

Crew commander Chaio, 44, a chemical engineer from California, and Sharipov, 40, a colonel in the Russian air force, left Kazakhstan’s Baikonur Cosmodrome Oct. 13 aboard a Russian Soyuz spacecraft and docked at the space station three days later for a six-month stay.

Gerstenmaier told reporters in a televised news conference that flight planners knew when the mission began that food supplies could be “extremely tight” at times for Chaio and Sharipov, “and we were tracking this all the time.”

Resupplying the space station with food, water, spare parts and other consumables has become a constant challenge since last year’s Columbia disaster grounded the workhorse space shuttle. The first post-Columbia shuttle launch is scheduled for May.