Russian officials say the wreckage of two large communication satellites that collided earlier this week, poses no current threat to the International Space Station or its crew.
The space station operates at an orbit lower than the ones used by the ill-fated communications satellites.
Pentagon spokesman Bryan Whitman says the U.S. military has not identified any threats to its satellites from the debris, but he says there are limits to the ability to track objects in space.
Scientists say it will take some time to plot the future courses of the debris left from the collision between the one-ton Russian satellite and the 560-kilogram commercial satellite operated by the Iridium company.
This is the first time two complete spacecraft have crashed into each other. Orbiting objects travel at tens of thousands of kilometers per hour, so such collisions can be devastating.
Even before the collision earlier this week, there were thousands of objects four centimeters in diameter and larger scattered in orbit, and even more smaller pieces of junk floating there.
The U.S.-based Iridium company operated one of the satellites that was destroyed. The firm has spares among the dozens of satellites it has in space, and can move a replacement into the old satellite's orbit in about 30 days.