This image shows how Deep Impact's impactor targeted comet Tempel 1 as the
spacecraft made its final approach in the early morning hours of July 4,
Eastern time. The autonomous navigation system on the probe was designed
to make as many as three impactor targeting maneuvers, identified as ITMs
in this picture, to correct its course to the comet.
The upper left dot indicates where the probe would have passed the comet's
nucleus if no maneuvers were performed. The dot below the nucleus shows
where the probe would have flown past the comet if only the first maneuver
was made. The leftmost dot on the nucleus marks the spot where the probe
would have crunched the comet if only the first two maneuvers had been
performed. The lower dot on the nucleus indicates the vicinity where, once
the third maneuver was performed, the probe met its final reward and
collided with the comet.