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Data From Mauna Kea Confirms Water On Jupiter's Moon

David Ladd
NASA Goddard Space Flight Center
An artist rendering of water geysers on Europa, one of Jupiter's 79 moons.

Scientists from NASA have confirmed the presence of water millions of miles from Earth. The observations were made using the W.M. Keck Observatory on Mauna Kea.

Scientists have long believed the ice-covered surface of Jupiter’s moon Europa is covering a vast ocean of liquid water.

Cracks in the ice were photographed by the Voyager probe in the 1970s. Twenty years later, the Galileo spacecraft detected fluctuations in Jupiter’s magnetic field, evidence of liquid underneath Europa’s icy crust.

When the Hubble Space Telescope later detected evidence of water vapor above Europa, it led to the theory that geysers could be ejecting water from the subsurface ocean into space. Until this month, direct proof of that water remained elusive

Using mas spectroscopy data collected at the W.M. Keck Observatory on Mauna Kea, a team from NASA’s Goddard Space Flight Lab was able observe the molecular signature of water vapor. John O’Meara, chief scientist at Keck, describes that as direct evidence of water plumes emanating from Europa.

Credit W. M. Keck Observatory
The twin telescopes of the Keck Observatory. Confirmation of the Europan water plumes was achieved through a technique called infrared observation. Mauna Kea is considered the premier site in the Northern Hemisphere for that type of astronomy.

This is apparently not an extremely common occurrence. It took the NASA team 17 attempts before it was able to catch one of the geysers in action. But the evidence supports prior theories of a massive quantity of water beneath Europa’ visible surface. NASA says enough water was released to fill an Olympic-sized swimming pool in just a few minutes.

The water was observed in vapor form, but supports the idea of a large body of liquid water below the ice. The surface temperature on Europa never climbs above -260°F, which makes the presence of water below the surface somewhat remarkable.

According to O’Meara, the immense gravitational force coming from Jupiter, Europa’s gigantic neighbor, exerts enough force on the moon that heat is generated in the interior.

“Those forces are actually increasing the temperature inside of those moons. And that heat is keeping huge amounts of liquid water just below the surface,” he said.

Credit NASA Astrobiology Institute
An image of Europe captured by the Galileo spacecraft in the 1990's. Europa was first observed by Galileo in 1610.

That water is held in place by the outer layer of ice, estimated to be anywhere from 10 to 15 miles thick. The liquid ocean could be up to 100 miles deep. By comparison, the deepest point in Earth’s ocean is just 7 miles below the surface.

By some estimates, there is more liquid water on Europa than in all of Earth’s oceans combined. According to NASA, that ocean is the most promising place to find extraterrestrial life in our solar system -- so promising that NASA is planning to send a new probe to make detailed observations of the icy moon. But with the possibility of life comes a major risk: contamination from Earth.

Richard Greenberg, a retired professor of planetary science with the University of Arizona, says there is always the chance of a stray microorganism hitching a ride on a spacecraft outbound from Earth.

An international treaty already governs the contamination of space and other celestial bodies. To prevent such an occurrence, NASA spacecraft are sterilized before launch.

But as far back as 2001, Greenberg warned that contamination protocols may not be sufficient, especially for an environment like Europa that harbors the building blocks of life.

“If you drop Earth germs on to another planet and then you discover life there, then you don't really know whether you're just finding Earth life that you put there or something that was there before,” Greenberg said in an interview with HPR.

He also points out that not only could the exporting of Earth life lead to a false positive in the search for extraterrestrial lifeforms, it could also be a danger to those organism.

Countless examples of this can be found here on Earth. When plant and animal species are transported from one continent to another by human activity, the invasive often wreaks havoc on an ecosystem that is not adapted for its presence.

There are currently no plans to land a spacecraft on Europa, so the risk of contamination is much lower. But the hazard may be unavoidable on Mars, as more robotic landers and even bacteria-carrying humans venture into space and intensify the search for life beyond our world.

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