Or all the other more then 20, 00 pieces of orbital debris like Spent Rocket Boosters left in space that can no longer be moved by a control center on Earth.
It said that, although Nasa was taking steps to protect the shuttle from orbital debris such as spent rocket bodies, satellite fragments and paint chips - there was a real risk that a collision could cripple the shuttle or threaten the safety of the crew.
The Orbital Sciences Corporation (OSC) will shortly test its new Antares rocket before undertaking its own ISS demonstration with a robotic vessel called Cygnus.
The U.S. military's Space Surveillance Network tracks roughly 22, 000 pieces of orbital debris larger than 4 inches (10 centimeters), which include broken satellite parts and spent rocket bodies.