At about 11:22 a.m. ET, the Cassini spacecraft successfully flew through the icy plumes on the South Pole of Saturn’s moon Enceladus. In the much anticipated flyby, Cassini passed just 30 miles over the surface of the small moon.
While this isn’t the closest Cassini that has passed by Enceladus, it is the deepest dive the spacecraft has taken through the icy plumes. The purpose of this flyby is to assess the habitability of Enceladus. It will be some time before any of the results are published but hopefully we get an idea of what the results suggest soon.
Enceladus, of course, has a subsurface ocean below its thin icy crust, which is kept in liquid form by tidal effects caused be the gravitational pull of Saturn.
By passing through the plumes, Cassini was able to sample the water being ejected, which will give insight into what the conditions are like below the icy exterior. The presence of hydrogen can indicate hydrothermal activity. On Earth, extremophile life exists around hydrothermal vents, so if high quantities of hydrogen are found in the plumes of Enceladus, it may very well be habitable.
While Cassini doesn’t have the capability to identify life directly, it can detect organic molecules. The fact that the dive is so deep through the plume ensures more sensitivity of Cassini to detect larger molecules.
“With our much deeper dive through the plume, we’ll have a chance to sample potentially larger particles,” says Linda Spilker, project scientists of Cassini.
The flyby will also tell us about the nature of the plumes. They may be either single jets of long, curtain like plumes. By measuring the features of the plumes, the Cassini team can learn how the water in the plumes reaches the surface whether it is through a single crack going through the whole crust of a series of cracks.
If the results do suggest that the ocean of Enceladus is habitable, it could result in a new mission to visit the moon. It could take the form of an orbiter either with the capability of detecting signs of life in the plumes or that could return samples of the plume back to Earth. Another idea would be to send a lander equipped with a drill and some sort of “swim bot” that could explore the ocean first hand and look for signs of life.
The Cassini team says close up photographs of the plumes and surface of Enceladus will be released in the coming days.
Unfortunately, the Cassini mission is nearing its end. Cassini arrived at Saturn in 2004 and in its time has made some incredible discoveries including, in addition to the icy plumes of Enceladus, liquid lakes of methane and ethane on Titan and the dynamic nature of Saturn’s trademark rings. Cassini will orbit around Saturn 22 more times before it is intentionally crashed into the giant planet on September 15 2017.