By some accounts, Enceladus is the number one place in our solar system to search for life. Sure, it looks icy on the outside, but it’s what’s on the inside that counts. And what’s inside Enceladus is a liquid ocean that may contain more water than all of Earth.
On Wednesday morning, the Cassini spacecraft will find out what that subsurface ocean is made of.
As Saturn’s gravity tugs on the small moon, it deforms the moon’s core, causing friction and heat. This ‘tidal heating’ is thought to be the source of Enceladus’ liquid ocean. So the small moon has heat and water– two main ingredients for life. Does it have the rest of what it takes?
In 2005, the Cassini spacecraft discovered geysers erupting from Enceladus’ south pole. Scientists think these frozen volcanoes (“cryovolcanoes”) are venting from the subsurface ocean. The icy plumes contain organic molecules–a promising finding when it comes to searching for alien life.
On October 28, Cassini will swoop in to search for more organics and take more accurate measurements of the geysers’ composition and volume. At 11:22 a.m. EDT, the spacecraft will come within 30 miles of the surface for its closest-ever look at the geysers.
“We will collect the best samples ever from an ocean beyond Earth,” said Curt Niebur, a program scientist for the Cassini mission, during a press conference.
Although Cassini isn’t equipped to find out whether there’s life in Enceladus’ ocean, this week’s flyby could tell us whether it’s got the ingredients needed to support life.
The deep dive will theoretically allow the spacecraft to ‘taste’ some of the heavier molecules spewing from the cryovolcano–including, maybe, complex organic molecules. The spacecraft will also be keeping an eye out for hydrogen.
This week’s flyby could tell us whether Enceladus has the ingredients needed to support life.
Hydrogen could indicate that hydrothermal activity is taking place at the bottom of Enceladus’ ocean. Earth’s hydrothermal vents support life even in the darkest regions of the ocean, infusing the local area with energy and nutrients. Perhaps the same could be true for Enceladus.
“Confirmation of molecular hydrogen in the plume would be an independent line of evidence that hydrothermal activity is taking place in the Enceladus ocean, on the seafloor,” Hunter Waite, from the Southwest Research Institute, said in a press release. “The amount of hydrogen would reveal how much hydrothermal activity is going on.”
The spacecraft, traveling at 19,000 miles an hour, will plunge through the plumes in a matter of seconds, but the findings from the flyby won’t be announced for several months. The scientists want to make sure the findings get peer reviewed and published in a journal before going public. But we can expect to see some great pictures by the end of this week.
If Enceladus is home to some kind of extraterrestrial life, it is probably simple–like the creatures that inhabit Earth’s ocean vents, said Cassini scientist Linda Spilker during the press conference. But Niebur pointed out that even tiny, simple organisms would change the way we view our place in the cosmos–because if life arose twice in our own solar system, how many times might it have evolved on the billions of other solar systems in our galaxy?
Update 10/26/2015 at 3pm: This post was updated to include information from a press teleconference.