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Europa, Jupiter's Moon

Are Scientists Set to Discover Life Beneath Europa’s Underground Ocean?

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Europa is one of Jupiter’s 79 moons. It is one of four large moons that revolve around the planet, and is slightly smaller in size than our moon. Europa was discovered in 1610 by Galileo Galilei, and has the distinction of being the first moon found orbiting another planet in our solar system.

While Europa was the first of Jupiter’s moons to be discovered, it is also the most intriguing from the perspective of planetary scientists. Oxygen and water have been detected in its thin atmosphere, and it is known to have a massive ocean somewhere below the depths of its frozen surface. Estimates are that this ocean is 100 kilometres deep and has twice the volume of water of all the oceans on Earth combined.

And where there’s water, there could be life. Planetary scientists know this, and that is why they’ve identified Europa as a place worthy of exploring.

The Plumes of Europa

In 2014 and again in 2016, scientists observing images from the Hubble space telescope found confirmation of water on Europa, and in significant amounts. They were shocked and delighted to see vast, arcing plumes of liquid water spurting from the surface of the planet. Estimates are that these plumes were between 50 and 100 kilometres in length, and in each occasion they emerged from the same location on the planet’s surface.

Europa rotates around Jupiter in an eccentric orbit, with the same side facing Jupiter all the time (just as our Moon faces Earth exclusively on one side). The eccentric rotation creates motion in the ocean underneath the surface and tidal waves due to gravity changes, which may cause cracks to form on the moon’s surface. If some type of underwater disturbance (perhaps tectonic plates shifting or volcanic activity) created enough excess pressure, it might send plumes of water shooting up through those cracks and high into the low-gravity Europan sky.

Deep space geysers had been seen before, emerging from the surface of Saturn’s moon Enceladus. But seeing them on Europa, which has generated so much excitement and anticipation among planetary scientists seeking possible sources of extraterrestrial life, has helped spur interest in examining this fascinating moon more closely.

Submarines, Lander and Orbiting Spacecraft: NASA Has Big Plans for Europa

Plans have been underway to explore Europa for a long time.

In 2013, scientists from NASA’s Jet Propulsion Laboratory in California and the Angstrom Space Technology Centre at Uppsala University in Sweden proposed an innovative solution to exploring the depths of Europa’s subsurface ocean. They developed blueprints for a tiny submarine that could drill a hole through Europa’s surface ice and enter the water below to search for life.

Because its moons are bombarded by powerful radiation from Jupiter’s massive magnetosphere, life would not be able to exist anywhere close to Europa’s surface. Consequently, microbial life would likely be found at a depth of several kilometres, which a tiny unmanned submarine equipped with small-scale scientific instrumentation would be able to explore.

More recently (in 2017), a separate team of NASA scientists has requested funding for the development of a Europan lander . Modeled after the various Martian landers, such a mobile machine could travel across the Europa landscape taking photographs and collecting samples. This lander would be equipped with a scoop that could burrow into the ice to a depth of about 10 centimetres, in order to collect core samples for later examination.

With this mission, there would be no expectation of finding anything alive. But the ice samples might contain the remnants of life, such as the frozen bodies of dead microbes or organic compounds like amino acids and lipids. Even the way inorganic compounds were distributed in the ice might give indications of how life was functioning in the ocean below.

While missions to send a lander to Europa are currently on hold, the Europa Clipper is set to leave Earth for Jupiter sometime between 2022 and 2025. The Europa Clipper is a satellite-style spacecraft that will park itself in orbit around Jupiter, and then spend the next 28 months examining Europa during a series of 45 flybys. NASA plans to outfit the Clipper with a plethora of scientific instruments, which will measure the thickness of Europa’s surface ice, the depth and salinity of its ocean and the characteristics (primarily the moisture content) of its atmosphere.

Like the proposed Europan lander, the Europa Clipper will not search for life directly. But the data it collects will allow scientists to evaluate the moon’s overall suitability for life, based on existing knowledge about the requirements that must be met for organic evolution to take place.

There are several other moons in our solar system, including Enceladus (Saturn) and Ganymede (Jupiter), that may also have liquid oceans beneath frozen surfaces. If conditions are ripe for life to evolve on Europa, these other moons might be capable of hosting microbial lifeforms (or something even bigger) as well.

“All These Worlds are Yours Except Europa. Attempt No Landing There.”

It has long been speculated that life may exist in the subsurface ocean of Europa. In fact, this concept was a key plot point in Arthur C. Clarke’s 1982 novel 2010: Odyssey Two , as well as in the movie version of the book (both were sequels to the classic 2001: A Space Odyssey ).

“All these worlds are yours except Europa. Attempt no landing there.”

In Clarke’s novel, this was the ominous message received by the spacecraft sent to Jupiter to explore the planet and its moons. In the epilogue of the book, set 18,000 years in the future, Europa’s native lifeforms have evolved so far that they’ve left the moon’s oceans to live on land, and have even formed a primitive society. Apparently we were being warned away in the past because aliens monitoring developments on the planet were afraid we’d somehow disrupt or corrupt this evolutionary process.

As of now, we have no idea if any type of life actually does exist on Europa. But the influence of Jupiter’s gravity is believed to be strong enough to cause hot hydrothermal vents to form on the bottom of Europa’s ocean, and some scientists believe these types of vents are the wellsprings from which life first evolved on Earth. If Europa’s ocean is salty and rich in minerals on the sea bottom, this along with the presence of hydrothermal vents would create ideal conditions for the development of life, according to current theories about the origins of life and its subsequent evolution .

Given how complex life became on Earth, once it first appeared, the possibility that intelligent life might manifest elsewhere in our solar system is not so farfetched. Where there’s an initial spark, miraculous things can happen.

We can only hope that if life does exist on Europa, we will exercise great caution and a sense of moral responsibility in our interactions with it. We cannot possibly know its ultimate destiny, any more than aliens visiting Earth a billion years ago could have guessed the microbial species they discovered would someday turn into us.

Top image: Jupiter’s moon Europa. Credit: dottedyeti / Adobe Stock

By Nathan Falde

 

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