Deep Impact (spacecraft) - Results

Results

Mission control did not become aware of the impactor's success until five minutes later at 0157 ET. Once news of a successful impact had taken place, the mission control team members applauded and hugged each other. Don Yeomans confirmed the results for the press, "We hit it just exactly where we wanted to" and JPL Director Charles Elachi stated "The success exceeded our expectations."

In the post-impact briefing at 0100 Pacific Daylight Time (08:00 UTC) on July 4, 2005, the first processed images revealed existing craters on the comet. NASA scientists stated they could not see the new crater that had formed from the impactor, but it was later discovered to be about 100 meters (328 ft) wide and up to 30 meters (98 ft) deep. Lucy McFadden, one of the co-investigators of the impact, stated "We didn't expect the success of one part of the mission to affect a second part . But that is part of the fun of science, to meet with the unexpected." Analysis of data from the Swift X-ray telescope showed that the comet continued outgassing from the impact for 13 days, with a peak five days after impact. A total of 5 million kilograms (11 million pounds) of water and between 10 and 25 million kilograms (22 and 55 million pounds) of dust were lost from the impact.

Initial results were surprising as the material excavated by the impact contained more dust and less ice than had been expected. The only models of cometary structure astronomers could positively rule out were the very porous models which had comets as loose aggregates of material. In addition, the material was finer than expected; scientists compared it to talcum powder rather than sand. Other materials found while studying the impact included clays, carbonates, sodium, and crystalline silicates which were found by studying the spectroscopy of the impact. Clays and carbonates usually require liquid water to form and sodium is rare in space. Observations also revealed that the comet was about 75% empty space, and one astronomer compared the outer layers of the comet to the same makeup of a snow bank. Astronomers have expressed interest in more missions to different comets to determine if they share similar compositions or if there are different materials found deeper within comets that were produced at the time of the solar system's formation.

Astronomers hypothesized, based on its interior chemistry, that the comet formed in the Uranus and Neptune Oort cloud region of the solar system. A comet which forms farther from the Sun is expected to have greater amounts of ices with low freezing temperatures, such as ethane, which was present in 9P/Tempel. Astronomers believe that other comets with compositions similar to Tempel 1 are likely to have formed in the same region.