In a recent briefing, John McCullough, chief of NASA's flight director office, said on Wednesday that with a piece of space debris likely to pass within two miles of the orbiting complex and its 13 astronauts on Friday, the International Space Station might have to fire its thrusters, if required.

According to NASA officials, the odds in the case, point to a rather distant possibility of the space junk - a piece of European rocket - either coming too close to the shuttle- station complex or even hitting the linked space shuttle Discovery and international space station. As such, Mission Control is keeping track of the debris.

As per the experts, the main threat from the debris is that such pieces of uncontrolled space junk can stray from their orbit. Moreover, the debris' expansive oval-shaped orbit, stretching nearly 20,000 miles, is causing difficulty in monitoring it.

Saying that the space junk will make its closest approach to the station at 11:06 a. m. EDT on Friday, NASA elaborated that it would not cause any unwarranted delay in the second of three spacewalks planned outside the station on Thursday.

If need be, NASA might "reboost" the space station from its present orbit 220 miles above the Earth after the completion of the second space walk, in an attempt to 'dodge' the debris' orbit.