NASA astronauts Ron Garan (left) and Mike Fossum held a news conference from the space station Tuesday. NASA TV

Ground crews are making plans to possibly operate the International Space Station without crew for awhile, but preparations are not yet underway in space.

"The teams in Houston are in the preliminary stages of deciding everything from what ventilation we’re going to leave running, what lights we’re going to leave on, what condition of each particular experiment will be on, every tank, every valve, every hatch – there’s a lot to do," said NASA astronaut Mike Fossum at a news conference from the International Space Station with fellow NASA astronaut Ron Garan Tuesday.

The details will be shared with astronauts in the weeks ahead, he added, and they will have plenty of time to implement them.

In the meantime, the only preparations that the astronauts have been making so far is to document some of their space station work using video, in order to hand it over to the first crew to repopulate the space station. Up until now, all such handovers have been done face-to-face.

On Aug. 29, NASA had disclosed that following the crash of the Russian Progress unmanned cargo space ship on Aug. 24, some astronaut trips to and from the space station will be delayed.

The delays will give the Russian space agency time to investigate the accident and make sure the problem that caused it has been resolved. Following the retirement of NASA's shuttle fleet, astronauts are currently transported to the station aboard Soyuz spacecraft, which use the same rockets that failed during the Progress launch. U.S. and Russian space agency officials do not plan to make any manned launches until there have been at least one or two successful unmanned spacecraft launches with the rockets.

By the time that happens, all astronauts currently aboard the station may have already returned, leaving the space station crewless for the first time in more than 10 years.

Garan and two other astronauts are scheduled to return to Earth on Sept. 15, a week after their original planned return date of Sept. 8.

Fossum and the other two remaining astronauts on the space station are scheduled to return in mid-November.

Currently, the next Soyuz flight to the space station is scheduled to arrive on Nov. 2, before the return of Fossum's expedition.

But Fossum said the possibility that it will be delayed remains, as "there’s a lot of things that need to stack up to make that [flight] happen."

He noted that troubleshooting a rocket isn't easy and could take a long time if the problem doesn't involve obvious recent hardware, software or process changes.

If the space station does need to go crewless, the risk to the space station is low provided it remains crewless for a short time, Fossum said. The types of problems that are most likely to pose an issue without crew are things like the failure of a pump last year that knocked out half the station's cooling capability, which are not that serious in the short term but do reduce the station's ability to tolerate other failures.

"As that short gap turns into many months... it leads toward a greater possibility that we would have a problem up here that became very significant with nobody to take action."