Shuttle Discovery to Depart International Space Station

The astronauts aboard the orbiting shuttle Discovery and the International Space Station are about to part. The 13 astronauts will finish their job together, and then the hatches between their spacecraft will be closed. A ton of trash and discarded equipment will be delivered back aboard the Discovery. It was brought by the shuttle, fully loaded with supplies, and moved onto the space station last week. The shuttle will undock on Tuesday and is due back at the Kennedy Space Center in Florida on Thursday, New York Times reports.

News agencies also report, Shuttle Discovery today plans to depart the International Space Station as it arrived more than a week ago, with careful firings of its powerful and noisy primary jets.

"When those 870-pound thrusters fire, it definitely gives the shuttle a little kick, and you just feel a little twang throughout the whole orbiter," shuttle pilot Kevin Ford said in a news conference last week.

Discovery is flying without the aid of the six smaller steering jets normally used during docking and undocking maneuvers. They were shut down because of a suspected fuel leak hours after the shuttle's Aug. 28 launch from Kennedy Space Center.

Commander Rick "C.J." Sturckow successfully docked the shuttle two days later -- a first without the so-called "vernier" jets -- and mission managers have been devising new procedures for today's planned 3:36 p.m. undocking.

The goal is to not to damage to the station, especially four sets of delicate solar array wings, with a plume of rocket fuel or excessive force.

The primary jets should fire just enough to push the shuttle about 75 feet from its port, then shut down for several hundred feet.

Ford then will the guide the shuttle in a loop around the outpost orbiting about 220 miles above Earth before starting the journey home, Florida Today reports.

In the meantime, NASA is tracking a piece of leftover space junk from a 2007 Chinese anti-satellite test that is expected to fly near the International Space Station twice on Wednesday, a day after the shuttle Discovery leaves the orbiting lab.

The satellite debris is expected to come within 31 miles (50 km) of the space station at about 4:30 a.m. EDT (0830 GMT) Wednesday morning, then zip around again two hours later to pass within 15 miles (25 km), NASA officials said.

Shuttle flight director Tony Ceccacci said NASA engineers are tracking the orbital debris to determine whether it could pose a threat to the space station. If so, the space station would have to fire its thrusters to in order to dodge the satellite remnant after Discovery undocks Tuesday afternoon.

Space.com quoted Ceccacci as saying, "The latest and greatest confidence is that it probably won't be a concern. We won't really know until we get the latest tracking this evening and determine what the probability of collision is."