Deep Impact
The missionDeep Impact is a NASA mission to comet Tempel-1. Launch was on 12 January 2005. Impact on comet Tempel 1 occurred on 4 July 2005 at 06:52 BST.
Science objectives
The Deep Impact mission was designed to produce an artificial crater in comet Tempel 1, to release
pristine material from under the surface. The event was witnessed by a flyby spacecraft
('mothership') and from telescopes on Earth. An Impactor
spacecraft (370kg) was aimed at the comet and struck with a relative speed of 10 km/s. The
impact produced a crater; pre-impact estimates predicted a scale metres to hundreds of metres. This released
pristine cometary material from underneath the comet's crust.
Comets are thought to be 'dirty snowballs' containing material unaltered from
the formation of our solar system. When a comet comes close to the Sun in its orbit, volatile material
sublimes away from the nucleus taking dust with it. This probably leaves a surface crust which may
be stronger than the icy interior. The scale of crater formation depends on the strength of the crust.
Spacecraft
observations at three comets so far (Halley, Borrelly and Wild 2) have shown many natural craters
on these bodies but Deep Impact will produce the first artificial crater.
MSSL-UCL is involved in the ground based observations, using time allocated on the UK Schmidt
(Australia) and Isaac Newton (La Palma) telescopes. This is part of an international programme of
collaborative space and ground based observations of the impact (proposals are collaborations with
Geraint Jones, JPL, Casey Lisse, U.Maryland, and others). We are particularly interested in the sudden
increase of cometary activity expected, in compostition changes and in effects on the plasma tail.
Further Information
The Deep Impact homepage at University of Maryland