Big Questions for Deep Impact
The Deep Impact mission was selected as a Discovery mission in 1999. The spacecraft was launched aboard a Delta II rocket on January 12, 2005 and left Earth’s orbit toward Comet Tempel 1. The spacecraft consists of two main sections, the 370 kg copper-core "smart impactor" which impacted the comet, and the "flyby" section, which imaged the comet from a safe distance during the encounter. After imaging the comet, in early July 2005 the larger “flyby” spacecraft pointed high-precision tracking telescopes at Tempel 1 and released the “impactor” spacecraft into the comet’s path for a planned collision to the icy body’s sunlit side. This mission is part of SMD's Discovery program.
- How did the solar system evolve to its current diverse state?
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Many of the other solar systems have massive Jupiter like planets close to their Sun, closer even than Mercury. Many scientists now believe that these gas giants could not have formed there. Rather, they must have began out where our Jupiter is, and moved inwards, scattering the smaller planets with their powerful gravity as they went. Why is it that our Jupiter and Saturn did not migrate inward? We are trying to learn more about our outer solar system by sending probes there. We sent Galileo to Jupiter, Cassini is at Saturn right now, and New Horizons is on its way to Pluto even as you read this.
- How did the sun's family of planets and minor bodies originate?
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For the first time in human history we know of planets around other stars and many of those other planetary systems look quite different from our own. Many have a planet like Jupiter, or even bigger, nearest to the Sun. If we are to understand why this is the case, and how likely it is that there are Earth-like planets elsewhere, we need to better understand how planets form.
- How did life begin and evolve on Earth, and has it evolved elsewhere in the Solar System?
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Microbial life forms have been discovered on Earth that can survive and even thrive at extremes of high and low temperature and pressure, and in conditions of acidity, salinity, alkalinity, and concentrations of heavy metals that would have been regarded as lethal just a few years ago. These discoveries include the wide diversity of life near sea–floor hydrothermal vent systems, where some organisms live essentially on chemical energy in the absence of sunlight. Similar environments may be present elsewhere in the Solar System.