The washing-machine-sized, copper-fortified impactor is expected
to make a good impression on the comet Tempel 1 at 0152 EDT July
4th. It was successfully released from the flyby spacecraft at
0207 EDT on Sunday. At release, the impactor was about 547,000
miles away from its target. Six hours prior to impactor release,
the Deep Impact spacecraft successfully performed its fourth
trajectory correction Soon after the trajectory maneuver was
completed, the impactor engineers began the final steps that
would lead to it being ready for free flight. In order to
release the impactor, separation pyros fired allowing a spring
to uncoil and separate the two spacecraft at a speed of about
0.78 mile per hour. With Tempel 1 approaching at about 6 miles
per second, there is little time for mission controllers to
admire their work. The flyby craft began a 14-minute long divert
burn to slow its velocity relative to the impactor by 227 miles
per hour, keeping it out of the path of the onrushing comet
nucleus and setting the s