NASA - Chinese Space Debris Threatens ISS

The Expedition 27 crew aboard the International Space Station and the team in Mission Control Houston are monitoring a piece of orbital debris that might pass close to the station later today.

There isn’t enough time to steer the station out of the way, as was done last Friday for a different piece of debris, so if the probability of collision continues to remain in the “red” category, the crew will be asked to shelter inside the Soyuz TMA-20 that brought them up to the station in December. That spacecraft is currently docked with the Rassvet module.

The piece of debris is from the defunct Chinese FENGYUN 1C satellite, and flight controllers have been monitoring it since early this morning.

There is an imaginary box drawn around the station that measures a half a mile deep by 15 miles across by 15 miles long (.75 x 25 x 25 kilometers), and if a piece of orbital debris is going to cross within that, the flight team is notified and begins computing a probability of collision.

The last several tracking runs have shown a “red” probability, so they notified the crew at 7:01 a..m. EDT today that they are tracking it and that the crew would need to begin the shelter procedures if it remains on track. As of now, the debris is expected to pass about 4.5 km away from the station.

The time of closest approach is at 4:21 p.m. today, and the crew will start working the procedures about 1.5 hours ahead of time. They will remove the ventilation between the hatches and will close the U.S. hatches completely.

They will also configure all the communications channels to make sure they stay in touch with Houston and Moscow and will then crawl inside the Soyuz about 10-15 minutes ahead of the time of closest approach (TCA). They will stay inside until about 15 minutes after the debris passes.

Mission Control will continue to track the debris, and if the probability lessens and moves to either a “yellow” or “green” category, the crew will not have to shelter in the Soyuz.

For up to date information check here:› Orbital debris and the International Space Station