NASA officials admitted that next month's shuttle Atlantis shuttle mission to fix the Hubble Space Telescope faces increased danger from possible junk floating in space.  The higher the elevation, the more likely it is for a space shuttle to encounter space debris from abandoned satellites and rockets. 

The ISS is orbiting 220 miles above the surface of the Earth, while Hubble is more than 350 miles away from Earth.

Furthermore, since most shuttles are sent to the International Space Station (ISS), shuttles are somewhat protected from space debris and other small objects that could impact the exterior of the shuttle.  But there will be no such luxury when Atlantis is sent to the Hubble.  According to program manager John Shannon, one out of every 300 space shuttle missions can expect to be ended due to space debris.  The odds are lower for shuttle Atlantis, which has a 1-in-185 risk of being destroyed by space debris during its mission.

Shuttle Atlantis is scheduled to launch October 10 from Cape Canaveral, Florida.  The launch marks the final repair mission for the 18-year-old telescope, which is facing retirement in the very near future.

Astronauts on the ISS were forced to fire boosters on the European Space Agency's Automated Transfer Vehicle, which helped lower the orbit of the ISS by one mile.  The incident marked the first time in five years in which astronauts had to fire boosters to avoid possible space debris.

Even a small metal shard can cause severe damage to the space shuttle because it is hurtling through space at thousands of miles per hour, astronomers noted.  Space has become increasingly cluttered with remnants of satellite and rocket mishaps from American, Russian and Chinese space missions.  The two latest problems include last year's controversial satellite destruction test by a Chinese missile and the self-destructed Russian spy satellite earlier this year.