Jupiter's moon Europa is the best candidate for finding life off Earth

In 2015, NASA’s Hubble Space Telescope (HST) celebrated its 25 years of first being launched into orbit to bring us astonishing discoveries. Even though its successor – the James Webb Space Telescope – is set to launch in 2018, NASA decided to prolong Hubble’s service for another 5 years. And it continues to pay off. Astronomers spotted what appear to be water vapour plumes spewing from the icy surface of Jupiter’s moon Europa – which has been long believed to hold a global ocean beneath a thick layer of ice, potentially brimming with life.
This is not the first time we made this observation. In 2012, a team of researchers in San Antonio also detected evidence of vapour plumes on Europa. However, the new observation done by NASA indicates that it could be possible to sample the ocean without actually landing on the moon or drilling through the thick crust of ice on the surface. The astronomers captured a total of 10 images via Hubble – each time Europa passed in front of Jupiter over the course of 15 months. They believe they saw the evidence in three of them.

“Europa’s ocean is considered to be one of the most promising places that could potentially harbor life in the solar system. These plumes, if they do indeed exist, may provide another way to sample Europa’s subsurface.” said Geoff Yoder, the acting associate administrator for NASA’s Science Mission Directorate.

Even though the phenomenon has been observed twice with similar data on location and size of the plumes, NASA isn’t jumping the gun just yet. The plumes – granted they really do exist – are estimated to be erupting about 200 kilometers (125 miles) up.
The sheer excitement of scouting out a potential ocean for signs of life, atop one of Jupiter’s icy moon, has already led to some ambitious plots. Sometime in the 2020s, NASA’s Europa Clipper mission will leap at the chance of exploring Europa’s deep ocean, Motherboard reports. Kurt Retherford, staff scientist at the Southwest Research Institute in San Antonio, Texas, says about the mission: “The Clipper mission has a set of instruments that are all very capable of measuring plume composition. It won’t tell us if there are jellyfish or something else living in that sub-surface ocean, but rather, whether it might be habitable.“

This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. (Source: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center)

The astronomers will have more to say on the subject on Sept. 29, publishing their results in The Astrophysical Journal. Whether the water vapour plumes are really there or not, Europa does indeed seem like a prime candidate in our solar system for the search for life.