Deep Impact
Deep Impact was a NASA mission that fired an impactor into comet Tempel 1 in 2005 to see what lay beneath its surface.
Deep Impact was a NASA mission launched in January 2005. On 4 July 2005, it released a 370-kilogram copper-rich impactor into the path of comet 9P/Tempel 1. The impactor struck at about 10 kilometres per second, and the main spacecraft watched the resulting flash and plume of debris from a safe distance.
The impact threw out a cloud of very fine dust, showing that the comet's surface layer was fluffy and powdery. Instruments detected water ice, carbonates, clays and organic material in the ejecta. The dust hid the crater from view, but in 2011 the Stardust spacecraft, on an extended mission, revisited Tempel 1 and photographed the impact site.
Renamed EPOXI, the Deep Impact spacecraft went on to fly past comet Hartley 2 in 2010. The mission pioneered the idea of deliberately hitting a small body, an approach later used in planetary defence by DART.
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