After 172 days and 431 million kilometers (268 million miles) of deep space stalking, Deep Impact successfully reached out and touched comet Tempel 1. The collision between the coffee table-sized impactor and city-sized comet occurred at 1:52 a.m. EDT.
"What a way to kick off America's Independence Day," said Deep Impact Project Manager Rick Grammier of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The challenges of this mission and teamwork that went into making it a success, should make all of us very proud."
Image right: This image from the flyby's medium-resolution camera shows the initial ejecta that resulted when NASA's Deep Impact probe collided with comet Tempel 1. It was taken by the spacecraft's medium-resolution camera 16 seconds after impact.
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"This mission is truly a smashing success," said Andy Dantzler, director of NASA's Solar System Division. "Tomorrow and in the days ahead we will know a lot more about the origins of our solar system."
Official word of the impact came 5 minutes after impact. At 1:57 a.m. EDT, an image from the spacecraft's medium resolution camera downlinked to the computer screens of the mission's science team showed the tell-tale signs of a high-speed impact.
"The image clearly shows a spectacular impact," said Deep Impact principal investigator Dr. Michael A'Hearn of the University of Maryland, College Park. "With this much data we have a long night ahead of us, but that is what we were hoping for. There is so much here it is difficult to know where to begin."
The celestial collision and ensuing data collection by the nearby Deep Impact mothership was the climax of a very active 24 hour period for the mission which began with impactor release at 2:07 a.m. EDT on July 3. Deep space maneuvers by the flyby, final checkout of both spacecraft and comet imaging took up most of the next 22 hours. Then, the impactor got down to its last two hours of life.
"The impactor kicked into its autonomous navigation mode right on time," said Deep Impact navigator Shyam Bhaskaran, of JPL. "Our preliminary analysis indicates the three impactor targeting maneuvers occurred on time at 90, 35 and 12.5 minutes before impact."
At the moment the impactor was vaporizing itself in its 10 kilometers per second (6.3 miles per second) collision with comet Tempel 1, the Deep Impact flyby spacecraft was monitoring events from nearby. For the following14 minutes the flyby collected and downlinked data as the comet loomed ever closer. Then, as expected at 2:05 a.m. EDT, the flyby stopped collecting data and entered a defensive posture called shield mode where its dust shields protect the spacecraft's vital components during its closest passage through the comet's inner coma. Shield mode ended at 2:32 a.m. EDT when mission control re-established the link with the flyby spacecraft.
"The flyby surviving closest approach and shield mode has put the cap on an outstanding day," said Grammier. "Soon, we will begin the process of downlinking all the encounter information in one batch and hand it to the science team."
The goal of the Deep Impact mission is to provide a glimpse beneath the surface of a comet, where material from the solar system's formation remains relatively unchanged. Mission scientists expect the project will answer basic questions about the formation of the solar system, by offering a better look at the nature and composition of the frozen celestial travelers known as comets.
The University of Maryland is responsible for overall Deep Impact mission science, and project management is handled by JPL. The spacecraft was built for NASA by Ball Aerospace & Technologies Corporation, Boulder, Colo.
For information about Deep Impact on the Internet, visit http://www.nasa.gov/deepimpact .