Space station repairs and Martian rovers? Heck, that’s playground stuff. The spacecraft Cassini was poking around Saturn and her moons back when JPL’s wunderkinds were watching Firefly. This is one of our Top Gun explorers. The data sent from Cassini to Earth is solid gold. So what about a springtime teaser? Cassini can deliver, folks. How about a huge body of water under the Saturn moon of Enceladus?
Enceladus is one of many satellites in the Saturn neighborhood, but also one of the most geologically active. After many flybys of Enceladus, Cassini has found atmospheric water vapor, particles of ice or dust, giant ice boulders, and fresh cracks in the surface filled with ice. Then, in 2005, Cassini witnessed plumes of icy material shooting out from the south pole. In 2011, the European Space Agency learned that these jets were actually dumping water into Saturn’s upper atmosphere at the rate of 250kg of vapor every second.
The mystery was further explored in analysis from Cassini and the Deep Space Network, NASA’s international collection of radio antennae, as described in the latest press release from NASA/JPL-CalTech:
The gravitational tug of a planetary body, such as Enceladus, alters a spacecraft’s flight path. Variations in the gravity field, such as those caused by mountains on the surface or differences in underground composition, can be detected as changes in the spacecraft’s velocity, measured from Earth.
The technique of analyzing a radio signal between Cassini and the Deep Space Network can detect changes in velocity as small as less than one foot per hour (90 microns per second). With this precision, the flyby data yielded evidence of a zone inside the southern end of the moon with higher density than other portions of the interior.
That anomalous zone is a depression in the southern pole, and possibly compensated by a denser, subsurface material. Liquid water was tapped as the probable cause and supports the notion that a big reservoir is under the ice. So, if Enceladus is the squirt gun of the Solar System, this might be its source. And where there’s water, there’s the chance of finding signs of life.
I couldn’t possibly do justice to the epic work of Cassini and Jet Propulsion Laboratory in a single post. Check out the NASA/JPL-CalTech release to learn more, and visit the links above for more info on this exciting moon. No doubt the folks at JPL will start a new page on exogeology. Just when you thought Saturn and Titan were hogging all the media, Enceladus gets a piece of the action!