Going for Maximum Impact

Deep Impact's unique Impactor.

The Mission The Deep Impact mission, scheduled for launch in December 2004, will use a specially designed to excavate a football field-sized crater in comet Tempel 1. This first look inside a comet could shed light on the origins of our solar system. Deep Impact's objectives are to oobserve how the crater forms, measure the crater's depth, diameter and interior composition, as well as measure the changes in the natural outgassing produced by the impact.

The greatest challenge will be to target and hit comet Tempel 1. Traveling at a relative velocity of 10 km/s and from about 864,000 km (536,865 miles) away, the impactor must hit the 6 km (3.7 mile) diameter comet. The impact area also must be well lighted to allow the science instruments to take images of the impact and its aftermath.

The Technology
In conjunction with Ball Aerospace & Technologies Corporation, NASA's Jet Propulsion Laboratory is currently developing the Impactor with a high-precision camera, called the Impacting Targeting Sensor (ITS). This technology:

• is made of copper (49%) instead of aluminum (24%) to permit better analysis of the comet data
• The Impactor will separate from the flyby spacecraft 24 hours before hitting comet Tempel 1. The Impactor will relay comet images through the flyby spacecraft to Earth while targeting itself at the comet, ultimately impacting the comet while the flyby spacecraft observes, records data and relays it to Earth.
• delivers 19 Gigajoules (that's 4.8 tons of TNT) of kinetic energy to excavate crater
• acquires guidance data by measuring its flight path relative to the background stars and Tempel 1's nucleus using optical measurements by the ITS with an accuracy of better than 1? rad.

What's Unique About the Impactor?

The Impactor and Impactor Targeting Sensor will employ automatic navigation software originally developed for Deep Space 1, but specifically tailored for Deep Impact. The combination is unique in creating a separate "smart" spacecraft specifically to target and hit Tempel 1. Minor trajectory corrections and attitude control are available by using the impactor's small hydrazine propulsion system.

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