NASA’s Deep Impact mission deliberately impacted comet Tempel 1 in 2005 to expose material beneath its surface.
Deep Impact launched on January 12, 2005, carrying a flyby spacecraft and a separate impactor. On July 4, 2005, the impactor struck Tempel 1 while the flyby spacecraft observed the resulting plume with cameras and spectrometers.
The experiment gave scientists a view beneath the comet’s weathered outer layer. Observations revealed dust and ice-related material, helping researchers investigate how comets formed and how their interiors differ from their surfaces.
Deep Impact is distinct from Stardust, which collected particles from Comet Wild 2 and returned them to Earth. It is also different from Rosetta, a European Space Agency mission that orbited and landed an instrument on Comet 67P. NASA later extended Deep Impact for additional comet and exoplanet observations, but the Tempel 1 collision was its defining experiment.