Live in Orbit: No need to dodge space junk

NASA has determined that a large sheet of a spent rocket stage poses no risk of colliding with the joined International Space Station and shuttle Discovery early Friday, so there's no need to adjust the spacecrafts' orbits.

As tracking of the space junk's orbit continued overnight and became more accurate, analysts determined that "the probability of the two objects coming together was zero," Royce Renfrew, a station flight director, said this morning.

To require move, the probability must exceed 1 in 10,000.

The debris, believed to be about 200 square feet in size, was a piece of a spent Ariane 5 booster used to launch a satellite.

As of Wednesday, tracking showed it could zoom within two miles of the station-and-shuttle stack around 11 a.m. Friday.

"As we got closer and closer to the closest approach, the orbits started diverging enough that we got outside our flight rule limits," Renfrew said.

Discovery astronauts are set to wake up around 12:30 p.m. EDT.

Mission specialists Danny Olivas and Christer Fuglesang are scheduled to start the mission's second of three spacewalks at 5:19 p.m. They'll finish replacing ammonia tanks stored on the station's central truss.

Other crew members will continue transferring cargo in and out of the Leonardo cargo module and installing new equipment on the station, which is flying about 220 miles above Earth.

At one point Wednesday, there was concern that the approaching rocket debris could require a ducking maneuver that would delay the spacewalk and extend the planned 13-day mission by a day.

That move was deemed unnecessary, but managers said they might decide whether another maneuver was needed late in the spacewalk, around 11 p.m.

It turns out the space junk will miss the station by a safe margin, though Renfrew didn't provide an exact distance.

Discovery launched last Friday from Kennedy Space Center and docked with the space station Sunday.

The shuttle and seven astronauts are scheduled to return home next Thursday just after 7 p.m.