Research

NASA has fresh hope of finding signs of alien life

NASA has fresh hope of finding signs of alien life

Data gathered by NASA's Galileo spacecraft in 1997 may prove that it flew directly through a water plume from Jupiter's moon Europa.

Somebody call up Mulder and Scully because scientists just came one step closer to finding the likeliest source of alien life in our solar system.

Europa is covered in thick ice and also has super-salty water flowing under vast ice sheets. "There may be ways for material from that ocean to come out above that ice shell, and that means we'd be able to sample it". The model simulations that included plumes from Europa closely matched the Galileo data, but the model without them did not.

Now, in a new study, the researchers describe how they went back to the Galileo data after grainy images beamed home from the Hubble space telescope in 2016 showed what appeared to be plumes of water blasting from Europa's surface. NASA's Hubble Space Telescope in 2012 collected ultraviolet data suggestive of a plume.

But follow-up observations from Hubble were unable to confirm that idea. Even so, Europa's eruptions could be equally as dense as its cousin's, and easily visible by an orbiting spacecraft. In both cases, the data indicate plumes erupted from roughly the same region, a known thermal "hot spot" on the moon's surface.

Kivelson and Xianzhe Jia, associate professor in the department of climate and space sciences and engineering at the University of Michigan, Ann Arbor, chose to take a second look at those signatures. Why wait so long?

"When we look at those data carefully, what we found is there's some unusual magnetic signals in those data that have never been explained before", Jai says.

"There now seem to be too many lines of evidence to dismiss plumes at Europa", said Robert Pappalardo, Europa Clipper project scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena. During that pass, the spacecraft took about five minutes to traverse Europa's face. "There's liquid water, there's energy, there's some amount of carbon material, but the habitability of Europa is one of the big questions that we want to understand", says Elizabeth Turtle, a Johns Hopkins planetary scientist who is developing the imaging system for the Europa Clipper.

On its closest flyby, Galileo swept over Europa at more than 2,230 miles per hour.

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New research offers additional evidence of plumes emanating from Europa's subsurface ocean.

Some of the flybys indicated a higher density of particles near the surface - possible plumes.

The study, led by Xianzhe Jia, of the University of MI, seems to confirm an idea that had already arisen from observations of the Hubble Space Telescope taken in 2012. "We needed to see whether there was anything in the data that could tell us whether or not there was a plume". "So when you put those two together, that indicated that something very special had happened during that interval".

At 1,900 miles (3,100 kilometers) wide, Europa is slightly smaller than Earth's moon. But Jia and his team wanted to make sure. The Galileo observations matched the simulation nearly perfectly. "That's what is starting to convince people".

The Galileo data were collected in 1997 during a Europa flyby at an altitude of less than 250 miles.

"These results provide strong independent evidence of the presence of plumes at Europa", they wrote. How did it form in the Milky Way galaxy?

Many experts believe the hidden ocean surrounding Europa, warmed by powerful tidal forces caused by Jupiter's gravity, may have conditions favourable for life.

"Up until this paper, I was very skeptical that the plume existed, because all those Hubble measurements made before were at the sensitivity limit of the instruments". What it finds will be anyone's guess. "We can analyse the particles and the gases to get a detailed composition of Europa's interior".