[meteorite-list] NASA's Deep Impact Spacecraft Preps for July 4 Fireworks

[Ron Baalke]

DC Agle (818) 393-9011
Jet Propulsion Laboratory, Pasadena, Calif.

Dolores Beasley  (202) 358-1753
Headquarters, Washington 							

Lee Tune  (301) 405-4679
University of Maryland, College Park, Md.
 
NEWS RELEASE: 2005-107					      July 1, 2005

NASA'S DEEP IMPACT SPACECRAFT PREPS FOR JULY 4 FIREWORKS 

NASA's Deep Impact spacecraft continues to sail through its final checkout, 
as it hurtles toward comet Tempel 1. Impact with the comet is scheduled for 
1:52 a.m. EDT, July 4 (10:52 p.m. PDT, July 3). 

"The time of comet encounter is near and the major mission milestones are 
getting closer and closer together," said Rick Grammier, Deep Impact project 
manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "After all 
the years of design, training and simulations, we are where we want to be. 
The flight and science teams are working the mission plan, and we are good 
to go for encounter." 

Deep Impact consists of a subcompact-car-sized flyby spacecraft and an 
impactor, about the size of a washing machine. The dual spacecraft carry 
three imaging instruments, two on the flyby and one on the impactor. 

Several major mission milestones occurred during the past week. The mission's 
third trajectory correction maneuver was successfully executed on June 23. 
The burn of the spacecraft's motors changed Deep Impact's speed by 13 miles 
per hour. Another trajectory correction for final targeting before impactor 
release is scheduled for 8:00 p.m. EDT July 2 (5:00 p.m. PDT). 

Mission planners separated the spacecraft's flight operations into six mission 
phases. The phases are launch, commissioning, cruise, approach, encounter and 
playback. The five-day encounter phase incorporates the final approach to the 
comet and transmission to Earth of collected data.

"We've completed the final pre-release checkout of the impactor. The impactor 
probe will have a short, 24 hour life from release to impact, but an incredibly 
important role," said Dave Spencer, Deep Impact mission manager at JPL.

The impactor has an auto-navigation system that will make final corrections to 
its flight path just minutes before the scheduled collision. Scientists hope 
the resulting crater will expose fresh material from below the comet's surface 
and subsurface. 

"That is the whole point of Deep Impact," said mission principal investigator 
and University of Maryland astronomer Dr. Michael A'Hearn. "We want to find out 
what are the guts of a comet."

The flyby spacecraft will use medium and high resolution imagers and an infrared 
spectrometer to collect and send to Earth pictures and spectra of the event. 
Spaceborne science platforms will also be watching Deep Impact. These include 
NASA's Hubble and Spitzer space telescopes, the Chandra X-ray Observatory, the 
Swift and Submillimeter Wave Astronomy satellites, the European Space Agency's 
XMM-Newton X-ray observatory and Rosetta spacecraft. Observatories on Earth 
will view the impact and its aftermath.

The final prelude to impact begins early on July 3 EDT (July 2 PDT), when the 
flyby spacecraft releases the impactor into the path of the onrushing comet. 
The release is scheduled at 1:52 a.m. EDT, 24 hours before impact 
(10:52 p.m. PDT).

The 820-pound impactor will collide with the comet's nucleus at a closing speed 
of 37,000 kilometers per hour (23,000 miles per hour). Scientists expect the 
impact to create a large crater. The impact will eject ice, dust and gas from 
the crater and reveal the pristine material beneath. The impact will have no 
significant effect on the comet's orbit, which poses no threat to Earth.

The University of Maryland, College Park, conducts overall mission science for 
Deep Impact. JPL handles project management and mission operations. 
 
For information about Deep Impact on the Web, visit:

http://www.nasa.gov/deepimpact

For information about NASA and agency programs on the Web, visit:

http://www.nasa.gov/home/index.html

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