The space shuttle Discovery and the International Space Station may not have to move to avoid an approaching piece of space junk, a NASA official said late Wednesday.

John McCullough, the chief of the flight director office, said it doesn’t look like the space station, which is is currently docked with the shuttle, will perform a "debris avoidance manoeuvre" to move into a higher orbit.

The shuttle and space station are currently circling the Earth at a height of 354 kilometres.

NASA said a final decision whether to move the station will be made during the last hour of a spacewalk planned for Thursday.

The piece of debris that is being tracked is approximately 19 square metres and is a leftover part of a booster from a three-year-old European Ariane 5 rocket.

NASA said the relatively large size of the space junk makes it relatively easy to track.

The space junk is expected to get as close as three kilometres from the station, at about 10:06 a.m. ET Friday. That is about eight kilometres closer than earlier projections.

With files from The Associated Press