Saturday's disastrous shuttle mission has no direct affect on the space station, but NASA will want to determine the cause of the disaster before sending one of Columbia's sister vehicles into space. Meanwhile, many officials inside and outside NASA made it clear that the shuttle program does not have the luxury of a lengthy wait, such as the two-year grounding that occurred after the 1986 Challenger disaster.

Ron Dittemore, NASA's shuttle program manager, said during a press conference Saturday that a previously planned Russian launch of a unmanned Progress supply ship would go as planned Sunday.

Dittemore said he had spoken with ISS officials about the contents of the Progress shipment.

"Those contents are appropriate given the fact that we will not be there for awhile," Dittemore said. "They have enough consumables and supplies for the crew to go through the latter part of June without having a shuttle visit. So there's some time for us to work through this."

The station crew, called Expedition Six, has been aboard since November. The next visit had been planned for March 1, when the Space Shuttle Atlantis was to take a new crew to the station and bring the present crew home.

The station crew includes NASA astronauts Ken Bowersox and Don Pettit, along with Russian Soyuz Commander Nikolai Budarin.

If needed, the crew could return to Earth aboard a Soyuz vehicle that is attached to the orbiting outpost and reserved for emergencies. For now, NASA officials say the ISS crew will have to sit tight until decisions are made about the next steps in spaceflight.

Dittemore said once the root cause of the Columbia problem is determined, a decision can be made whether other flights should be free to go or if modifications to the rest of the shuttle fleet might be needed. He said it's too early to tell how long that review process will take.