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Atlantis to Enter Dangerous Debris Field in Earth's Orbit

The crew of the space shuttle Atlantis has discovered a 53-centimeter stretch of nicks on a few thermal tiles on the bottom of the vehicle likely caused by debris that came off the fuel tank during launch Monday. But the mission is going forward and the crew may face more danger from debris before it is over.

The main objective of this space shuttle mission is to maintain and repair the orbiting Hubble telescope, but the seven astronauts on board Atlantis must also spend time ensuring the safety of their own craft and themselves. On Tuesday they found a series of nicks on four or five thermal tiles by using the shuttle's robotic arm, equipped with cameras and sensors. Damage to the heat shield caused the space shuttle Columbia to disintegrate as it returned to earth in 2003. Engineers at the Johnson Space Center here in Houston are analyzing the information sent by the astronauts to determine how much danger the nicks on the underside will pose.

The shuttle is expected to reach Hubble by Wednesday, while space agency officials in Houston keep a close eye on orbiting debris in the area near the telescope. Atlantis is around 12,000 kilometers from the Hubble, which is positioned in orbit 560 kilometers above the earth's surface. By comparison, the International Space Station orbits at 352 kilometers. Johnson Space Center spokesperson Bill Jeffs says small orbiting pieces of material from satellite collisions and rocket launches are making it more difficult to operate in high orbit.

"There is more debris in the space environment than there was a few years ago and we are traveling to a higher altitude where there is more debris," he said.

Jeffs tells VOA that the main concern is debris between the size of one centimeter in diameter and 10 centimeters in diameter because pieces of debris that size could cause significant damage and are hard to detect and track from earth. Larger objects can be tracked by the US Strategic Command, which assists NASA in warning the shuttle to maneuver away from the area, if necessary.

Bill Jeffs says the danger of this mission is also amplified by the amount of time the astronauts need to spend with Hubble to complete the needed repairs.

"Five space walks are planned over five consecutive days. They will be conducted by two pairs of space walkers. The space walks will begin on Thursday and end on Monday. The space walkers will be repairing some instruments on the Hubble and they will be installing some new instruments," he added.

Jeffs says the Atlantis crew will also deliver and install fresh batteries, new gyroscopes and a new computer that will replace one that developed problems last year. Just in case Atlantis is damaged by debris while carrying out the mission, NASA has prepared the space shuttle Endeavor for launch at the Kennedy Space Center in Florida so that it might be used to rescue the Atlantis crew.