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."
Image right:Artist's concept of comet. Image credit: NASA/JPL-Caltech.
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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
"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:
For information about NASA and agency programs on the Web, visit:
DC Agle (818) 393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
Dolores Beasley (202) 358-1753
NASA Headquarters, Washington
Lee Tune (301) 405-4679
University of Maryland, College Park