Colliding with Deep Impact

After months on a precise interception course, NASA’s unmanned Deep Impact space probe meets up with Comet Tempel 1, firing a impactor into the comet’s nucleus to study the distribution and composition of the debris scattered by the resulting impact. The impactor had been released by the flyby spacecraft six days earlier, and transmitted its images and readings to the flyby vehicle, which records them and retransmits them to ground controllers on Earth. The two vehicles’ on-board software tracks the comet so precisely that the impact happens within a second of the anticipated timeline in the mission plan, kicking up enough cometary dust to obscure the view of the crater left on the comet’s nucleus. Following the Tempel 1 mission, the still-intact Deep Impact flyby vehicle is redirected for future missions to other objects in the solar system.