Though the Deep Impact mission's impactor struck the Tempel 1 Comet back in July, research and discoveries continue for the mission's team, which includes Professor of Geological Sciences Peter Schultz.
Key among the team's most recent findings is that water ice exists on the surface of the comet.
"We've known that there must be ice in comets for a long time. We can see it in the atmosphere, but we didn't know where the ice was," said Jessica Sunshine '88 Sc.M. '89 Ph.D. '94, the lead author of a Feb. 2 article in the online edition of Science magazine that outlines the team's findings.
The water ice is located in three thin patches covering approximately 300,000 square feet of Tempel 1. The comet's surface area is about 45 square miles.
"We didn't expect to find significant concentrations of ice in certain areas," Sunshine said. "That really came as a surprise." In addition, it was discovered that water ice made up only 6 percent of the material found at these locations. "It's like a skating rink of icy dirt," Schultz said.
According to Sunshine, the ice discovered on the surface of the comet alone does not account for the concentrations of water ice found in the coma, the atmosphere that surrounds the comet. "There must be significant sources of water ice just below the surface," Sunshine said. According to Schultz, the Deep Impact research team also discovered that the ice blows out through "jets" in the comet and joins the coma. "This was the first time we could extend the ice found in the coma back to the nucleus itself," Schultz said.
The Deep Impact mission culminated in the smashing of an 820-pound impactor into the surface of the comet early in the morning on July 4, 2005. The composition of debris blown out by the impact was analyzed by a spectrometer, the results of which have been investigated by the Deep Impact team.
The team discovered evidence of a great deal of organic material within the comet, Sunshine said. "If you look at the coma before and after impact the organic material increased by a factor of 20," Sunshine said. "That strongly suggests that there must be more organic compounds beneath the surface than we would have assumed."
Ethane and HCN, two relatively simple organic compounds, were detected by the spectrometer, but there are probably more complex organic compounds as well, Schultz said, adding that learning about the organic compounds on Tempel 1 is an important step of the team's research. "Comets probably delivered the building blocks of life to the earth, so the more we understand what material is on these comets the better," Schultz said.
The Deep Impact project is an exciting one, according to Schultz. "When you think about it, this is the exact history of how we explored the planets," he said, mentioning how scientists have been able over time to investigate the composition of Mars and Venus. Comets are the next step in the process of analyzing the solar system, Schultz said.
