Back on track

Deep Space 1, an experimental NASA probe aimed at a distant asteroid, finally
got going last week after an inauspicious start. Last month its xenon ion
propulsion drive failed only four and a half minutes after being turned on.
Engineers at the Jet Propulsion Laboratory in Pasadena suspect that metallic
debris contaminated the drive, causing it to shut down automatically. Whatever
the problem, the drive now seems to be working normally.