A piece of space junk from a broken Soviet satellite is not expected to collide with the International Space Station after all, NASA said Monday.

"Mission Control says the space debris is not going to come close to the space station -- no need for an avoidance maneuver," NASA said in a message on the microblogging site Twitter.

The US space agency said Sunday that it was tracking the debris and that early information indicated it could have been on a collision course with the orbiting outpost, where the shuttle Atlantis just docked on its final mission.

The space junk is part of Cosmos 375, a satellite launched in 1970 by the former Soviet Union and which collided with another satellite and broke apart, NASA said.

Flight controllers are monitoring more than 500,000 pieces of debris in Earth's orbit, NASA said.

"It is not uncommon. There is a lot of junk in orbit and there are a lot of objects that are being tracked," deputy manager of the space shuttle program LeRoy Cain said on Sunday.

earlier related report
NASA adds extra day to Atlantis's final mission
Washington (AFP) July 11, 2011 - Astronauts aboard the shuttle Atlantis will get one extra day in space as they restock the International Space Station with a year's worth of food and supplies, NASA said Monday.

The final shuttle mission before the US program formally ends after 30 years will now last 13 days, returning to Earth on July 21, deputy shuttle program manager LeRoy Cain told reporters.

"There is a lot of good work that we can help this space station program with," said Cain.

NASA's damage assessment team also concluded that the shuttle heat shield sustained no major harm during liftoff and would not need a more focused inspection, which Cain described as "really good news."

Meanwhile, the combined crew of six aboard the space station and four who arrived on Atlantis prepared for the last-ever spacewalk of the shuttle era, set to take place early on Tuesday.

American astronauts Ron Garan and Mike Fossum, who are part of Expedition 28 aboard the ISS, will step out at 8:44 am (1244 GMT) to retrieve a failed ammonia pump from the station for return to Earth.

The shuttle crew will support the six and a half hour spacewalk. Garan and Fossum have already stepped out together on three spacewalks in June 2008 as part of the STS-124 mission that delivered the Japanese Kibo lab to the ISS.

On Tuesday they will also attach a Robotic Refueling Module to the lab.

Earlier Monday the Atlantis crew began work with their six colleagues at the ISS to transfer a year's worth of food and spare parts -- nearly five tons' worth -- to the orbiting outpost.

Other supply ships from Europe, Japan and Russia will be able to stock the ISS when the shuttle program retires after Atlantis's mission, but the amount of cargo space available aboard the shuttle is unparalleled.

The Raffaello multipurpose logistics module was lifted out of the shuttle's cargo bay and placed with the help of a Canadian robotic arm onto the space station's Harmony node at 6:46 am (1046 GMT).

The container is "packed with 9,403 pounds (4,265 kilograms) of spare parts, spare equipment, and other supplies -- including 2,677 pounds (1,215 kilograms) of food -- that will sustain space station operations for a year," NASA said.

Over the coming days, the combined crew will be transferring items from the Raffaello to the station and moving more than 5,600 pounds (2,540 kilograms) of old station gear back into the module for return to Earth.

"It is pretty much all hands on deck," said flight director Jerry Jason. "It is going to be a very busy time period."

Atlantis's flight marks the end of an era for NASA, leaving Americans with no actively operating government-run human spaceflight program and no method for sending astronauts to space until private industry comes up with a new capsule, likely by 2015 at the earliest.

With the shuttle gone, only Russia's three-seat Soyuz capsules will be capable of carrying astronauts to the ISS at a cost of more than $50 million per seat.

After being granted the extra day in space, Atlantis is now scheduled to land back on Earth July 21 at 5:56 am (0956 GMT), mission control in Houston said.