An unmanned Russian supply ship blasted off Sunday from Kazakhstan, bound for an international space station with an uncertain future after the loss of the space shuttle Columbia and the resulting suspension of shuttle flights.

The Progress M-47 lifted off from Baikonur Cosmodrome about 7 p.m. (8 a.m. ET) carrying supplies for the station's three-man crew.

Americans Ken Bowersox and Donald Pettit and Russian cosmonaut Nikolai Budarin had been due to return to Earth on March 1, when the shuttle Atlantis was scheduled to deliver a replacement crew.

But that mission - and all future shuttle flights - are on hold until investigators learn what caused Columbia to disintegrate 40 miles above Earth Saturday, killing all seven astronauts aboard.

"I hope that we get this situation resolved in the coming weeks, so that it isn't an extended period of time, but that remains to be seen," said shuttle program director Ron Dittemore. "In the near term, we know we have months of adequate supply on board the international space station, and we also know that we can help resupply them from our international partners' resources."

Dittemore said supplies aboard the station were sufficient to last through the end of June. NASA's space station managers reviewed the cargo list for Sunday's Progress launch, and pronounced the supplies "appropriate, given the fact that we may not be there for a while," he said.

Russian space agency spokesman Sergey Gorbunov said the station could face at least a temporary abandonment if the shuttle program suspension lasts too long.

Russia's Progress shuttles, Gorbunov said, cannot match the U.S. shuttles' capacities for cargo. The Progress carries about 2 tons of supplies, compared with the 30 tons a space shuttle can lift.

Additionally, he said, a U.S. shuttle with its three engines can make the trip in less time and at less cost than the single-engine Progress.

Transferring the bulk of resupplying missions to Russian spacecraft, Gorbunov said, would require construction of more Progress ships, at up to two years each - and more money from Russia's international partners, including the United States.

Still, Gorbunov said its three scheduled supply flights would be sufficient to keep the station operable for the rest of the year. And, he said, Russia has scheduled two flights of its Soyuz spacecraft to take crews of three people each to the station in April and October.

Bowersox, Pettit and Budarin - Expedition 6 to the space station - arrived at their orbital home November 25, 2002. Their mission was to have been the shortest stint to date. Expedition 4 stayed aboard for 195 days, the longest mission to the station.

Gorbunov said the Russian Space agency and NASA will have to reconsider the working plans for the station as well as the manned flights schedule in the wake of the Columbia disaster. He said the re-evaluation could lead to a decision to bring the crew back to Earth and leave the station unmanned to work automatically in order to save resources until the situation is resolved