The Cassini spacecraft, which is full of scientific instruments and cameras, has been orbiting Saturn and its moons since 2004. Its mission this week is to dip down into the icy plume of gases spewing out of the south pole of Saturn's moon Enceladus to take samples. The spacecraft will blast past the moon at 19,000 miles per hour, coming within 30 miles of the surface of Enceladus. You cans see the plumes in the picture below, courtesy of NASA/JPL/Space Science Institute.
According to earthsky.com, the source of the plume is believed to be an underground global ocean. Since the plume contains water vapor, ice and organic molecules, the mission is to take a sample to see if the underground ocean could support life.
This week, NASA unveiled seven key facts about Cassini's upcoming Enceladus plume dive. Here is what they had to say:
1. Early in its mission, Cassini discovered Enceladus has remarkable geologic activity, including a towering plume of ice, water vapor and organic molecules spraying from its south polar region. Cassini later determined the moon has a global ocean and likely hydrothermal activity, meaning it could have the ingredients needed to support simple life.
2. The flyby will be Cassini's deepest-ever dive through the Enceladus plume, which is thought to come from the ocean below. The spacecraft has flown closer to the surface of Enceladus before, but never this low directly through the active plume.
3. The flyby is not intended to detect life, but it will provide powerful new insights about how habitable the ocean environment is within Enceladus.
4. Cassini scientists are hopeful the flyby will provide insights about how much hydrothermal activity – that is, chemistry involving rock and hot water – is occurring within Enceladus. This activity could have important implications for the potential habitability of the ocean for simple forms of life. The critical measurement for these questions is the detection of molecular hydrogen by the spacecraft.
5. Scientists also expect to better understand the chemistry of the plume as a result of the flyby. The low altitude of the encounter is, in part, intended to afford Cassini greater sensitivity to heavier, more massive molecules, including organics, than the spacecraft has observed during previous, higher-altitude passes through the plume.
6. The flyby will help solve the mystery of whether the plume is composed of column-like, individual jets, or sinuous, icy curtain eruptions — or a combination of both. The answer would make clearer how material is getting to the surface from the ocean below.
7. Researchers are not sure how much icy material the plumes are actually spraying into space. The amount of activity has major implications for how long Enceladus might have been active.
Here is a short video on the subject.