6 May 2005

NASA Spacecraft on Track to Strike Comet Tempel 1 on the Fourth of July

NASA's Deep Impact spacecraft is designed to intercept and collide with Comet Tempel 1 on 4 July 2005. The spacecraft, which is the size of a small car, was launched from Cape Canaveral on 5 January 2005 (Fig. 1). The craft has completed the commissioning and boost phase of its flight and is now cruising toward a rendezvous with Tempel 1. The spacecraft's trajectory following its first course correction was so successful that a second such maneuver scheduled for 31 March was canceled.

Deep Impact is a two-part spacecraft. The main craft will release a smaller impact body directly in the path of the comet (Fig. 2). If all goes well, the impactor will collide with the comet at a velocity of about 37,000 kilometers per hour (23,000 miles per hour). The impact is expected to produce a crater with a width somewhere between that of a typical house and an athletic field. Instruments on the flyby craft will then be pointed at the crater to gather data on the internal composition of the comet. More details are available at NASA's Deep Impact web site and the University of Maryland's Deep Impact site.

While some of the world's best Earth-based telescopes are also expected to be trained on the impact, there are also opportunities for amateur astronomers. To find out more, visit the Deep Impact Amateur Observers' Program. This site has Beginner, Intermediate and Advanced pages (Fig. 3). Serious amateur astronomers should go straight to the Advanced page. From there, they should visit the the Small Telescope Science Program (STSP).

This sophisticated program is an excellent example of amateur science being taken seriously by the professional community. STSP is a major worldwide collaboration of advanced amateur astronomers, private observatories, and professional astronomers. The key objective of STSP is to provide continuous monitoring of Tempel 1 to complement observations made by major telescopes.

The STSP web page lists specific objectives for the collaboration. Also provided are detailed observing procedures. Even casual amateur astronomers will find this web site of great interest.

Forrest M. Mims III

 
Figure 1. The Deep Impact spacecraft was launched from Cape Canaveral on 5 January 2005. NASA photograph.
 
Figure 2. This negative image of Comet 9P/Tempel 1 was captured during a 300-second exposure by the University of Hawaii's 2.2-meter telescope on the summit of Mauna Kea on the Big Island of Hawaii on 10 March 2005. The image sensor was a 2048 x 2048 pixel CCD imager with a dust-sensitive R-filter. The comet's coma extends about 70,000 km (approximately 43,500 miles) or about 100 arc seconds. Image courtesy of the University of Hawaii and the University of Maryland.
 
Figure 3. Serious amateur astronomers who participate in the Deep Impact Amateur Observers' Program can make important observations during the collision of the Deep Impact space craft impactor with Comet 9P/Tempel 1. Click image to enlarge.
   
Copyright 2005 by Society for Amateur Scientists