Spacecraft on course for encounter with comet

Nasa’s Deep Impact spacecraft is on course for a July 4 encounter with comet Tempel 1, but mission officials are trying to determine why one of the probe’s telescopes has not focused properly, the space agency said.

The problem was discovered after a process called a ”bake-out”, in which heat is used to remove residual moisture from the telescope, which absorbed moisture as the spacecraft waited on the launch pad and flew through the atmosphere into space.