Enceladus, Saturn’s sixth largest moon, formed about 4.5 billion years ago. The Hot Start model (life can begin near a hot volcanic vent containing water and matter) states that Enceladus got its start when ice and rock, both containing radioactive isotopes of iron and aluminum, mixed together.

Over a period of about seven million years the radioactive isotopes decayed, which produced large amounts of heat. The heat sent rocky material to the moon's center, while ice moved to cover the rocky core. The process of radioactivity continued to warm and melt its interior, along with help from Saturn's gravitational forces, for billions of years.

The team heading up the Cassini spacecraft now conjectures that radioactive decay played an important part in developing Enceladus’ warm South Polar Region (SPR), where geysers of water vapor and ice crystals vent. The Cassini spacecraft flew by Enceladus in 2005, at which time it discovered a watery plume venting from the SPR. Also, when the scientists found internal heat escaping from this region and a lack of impact craters, the team concluded that Enceladus was geologically active in the past, and is still active today.

The warm section of Enceladus, the South Polar Region, could support life, according to members of the Cassini team. Project scientist Dennis Matson said, “It tells us that conditions inside Enceladus either were or still are conducive to biochemical reactions.” [Associated Press]

Because of this exciting information, Cassini has been directed to fly within 23 kilometers (14 miles) of Enceladus in March 2008. It will also fly by the moon seven times between July 2008 and July 2010.

The Cassini mission is an international project between NASA, the European Space Agency (ESA), the Italian Space Agency, and other academic and commercial organizations. It was named for French-Italian astronomer Jean-Dominique Cassini, who discovered a gap in Saturn's main rings—what is now called the Cassini Division.

The Cassini spacecraft began its mission on October 15, 1997. It traveled about 2.175 billion miles (3.5 billion kilometers) in order to reach Saturn and its system of rings and moons on June 30, 2004.

These discoveries on Enceladus will be published in the April issue of the astronomical journal Icarus. The information have already been presented before the annual Lunar and Planetary Science Conference in Houston, Texas.

More information about the Cassini-Huygens mission can be obtained at: (NASA) http://www.nasa.gov/mission_pages/cassini/main/ and (NASA Jet Propulsion Laboratory) http://saturn.jpl.nasa.gov/home/index.cfm.

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ESA  NASA  Research  Science  Solar system  Space  William Atkins