Science - jupiter-moon

Apr

2013

12:20pm, EDT

Jupiter's icy moon Europa holds ingredient for life

NASA / JPL / University of Arizona

These global views of Jupiter's icy moon Europa were captured by NASA's Galileo spacecraft in June 1997. The image on the left shows Europa in natural color, while the right-side image has enhanced colors to bring out subtle color differences to show differences between pure water ice (white and bluish white) and non-ice components (red, brown and yellow spots).

By Tariq Malik
Space.com

A potential energy source for life appears to be common on Jupiter's icy moon Europa, a new study suggests.

An analysis of infrared observations of Europa revealed that hydrogen peroxide is abundant on the ice-covered Jovian moon. If the hydrogen peroxide finds a way beneath Europa's surface and mixes with the moon's liquid water ocean, it could be a vital energy source for any life that might exist there, scientists said.

"Life as we know it needs liquid water, elements like carbon, nitrogen, phosphorus and sulfur, and it needs some form of chemical or light energy to get the business of life done," study leader Kevin Hand of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. "Europa has the liquid waterand elements, and we think that compounds like peroxide might be an important part of the energy requirement. The availability of oxidants like peroxide on Earth was a critical part of the rise of complex, multicellular life."

Planetary scientist Mike Brown of the California Institute of Technology in Pasadena co-authored the new study, which analyzed near-infrared observations of Europa collected in September 2011 by the Keck II telescope atop the Mauna Kea volcano in Hawaii. [See photos of Jupiter's icy moon Europa]

The study found that the highest concentration of hydrogen peroxide occurs on the leading side of Europa as it orbits Jupiter. The ice in those regions is almost pure water, and not contaminated by sulfur like other parts of Europa, NASA officials said.

Hydrogen peroxide is created on Europa due to the intense radiation bombardment of the moon's surface as it moves through Jupiter's powerful magnetic field. At its most concentrated, the chemical was found with a peroxide abundance of about 0.12 percent compared to water. That's about 20 times more diluted than the bottles of hydrogen peroxide for sale in drug stores on Earth, NASA officials said.

Hydrogen peroxide was first discovered on Europa by NASA's Galileo spacecraft, which studied Jupiter and its moons from 1995 to 2003. But Galileo's observations studied only a limited path of Europa. The new analysis covers a much broader region of Europa's surface.

"The Galileo measurements gave us tantalizing hints of what might be happening all over the surface of Europa, and we've now been able to quantify that with our Keck telescope observations," Brown said. "What we still don't know is how the surface and the ocean mix, which would provide a mechanism for any life to use the peroxide."

But the fact that so much peroxide exists on Europa is a boon for the potential habitability of the icy moon's water ocean. When mixed with water, peroxide releases oxygen.

"At Europa, abundant compounds like peroxide could help to satisfy the chemical energy requirement needed for life within the ocean, if the peroxide is mixed into the ocean," Hand said.

The research is detailed in a recent edition of the Astrophysical Journal Letters and was partially funded by NASA's Astrobiology Institute through its Icy Worlds team.

Email Tariq Malik at tmalik@space.com or follow him @tariqjmalik and Google+. Follow us @Spacedotcom, Facebook and Google+.

Mar

2013

4:25pm, EST

Ocean bubbles up to surface of Jupiter's moon Europa

NASA / JPL-Caltech

Based on new evidence from Jupiter's moon Europa, astronomers hypothesize that chloride salts bubble up from the icy moon's liquid ocean and reach the frozen surface, where the salts are bombarded with sulfur from volcanoes on Jupiter's moon Io.

By Mike Wall
Space.com

The huge ocean sloshing beneath the icy shell of Jupiter's moon Europa likely makes its way to the surface in some places, suggesting astronomers may not need to drill down deep to investigate it, a new study reports.

Scientists have detected chemicals on Europa's frozen surface that could only come from the global liquid-water ocean beneath, implying the two are in contact and potentially opening a window into an environment that may be capable of supporting life as we know it.

"We now have evidence that Europa's ocean is not isolated — that the ocean and the surface talk to each other and exchange chemicals," study lead author Mike Brown of Caltech in Pasadena said in a statement.

"That means that energy might be going into the ocean, which is important in terms of the possibilities for life there," Brown added. "It also means that if you’d like to know what’s in the ocean, you can just go to the surface and scrape some off." [Photos: Europa, Mysterious Icy Moon of Jupiter]

Studying Europa's icy shell
Brown and co-author Kevin Hand of NASA's Jet Propulsion Laboratory in Pasadena scrutinized Europa's surface with Hawaii's powerful Keck II Telescope, which sports an adaptive-optics system to compensate for the blurring caused by Earth's atmosphere.

Europa is tidally locked with Jupiter, meaning one hemisphere of the moon always leads in its orbit while the other one always trails. Keck detected a mysterious signal on Europa's trailing side that no other instrument had seen before, researchers said.

“We now have the best spectrum of this thing in the world,” Brown said. “Nobody knew there was this little dip in the spectrum because no one had the resolution to zoom in on it before.”

After much experimentation in the lab, Brown and Hand determined that the spectroscopic signal was caused by a magnesium sulfate salt called epsomite.

"Magnesium should not be on the surface of Europa unless it’s coming from the ocean," Brown said. "So that means ocean water gets onto the surface, and stuff on the surface presumably gets into the ocean water."

An Earth-like ocean?
But the astronomers don't think Europa's ocean, which is believed to be about 62 miles (100 kilometers) deep, is rich in magnesium sulfate.

That's because the epsomite signal comes only from Europa's trailing side, which is blasted with sulfur expelled by Jupiter's volcanic moon Io. If magnesium sulfate were bubbling up to the surface directly from the ocean, its signal should have been seen on the leading side, too, the reasoning goes.

Europa's ocean, Brown and Hand say, can be only one of two types — sulfate-rich or chlorine-rich. With sulfate-rich off the table, the oceanic magnesium source is likely magnesium chloride (which gets broken apart on the surface by radiation, leading to the formation of magnesium sulfate on the moon's trailing side after exposure to sulfur from Io).

Other chloride salts are probably in the water as well, such as sodium chloride and potassium chloride, the scientists added. Indeed, previous work by Brown showed that atomic sodium and potassium are present in Europa's wispy atmosphere.

The composition of Europa's ocean may thus be similar to that of Earth's seas, researchers said.

“If you could go swim down in the ocean of Europa and taste it, it would just taste like normal old salt," Brown said.

If that's the case, the 1,940-mile-wide (3,120 km) Europa would become even more intriguing to scientists searching for signs of life beyond our planet.

"If we’ve learned anything about life on Earth, it’s that where there’s liquid water, there’s generally life," Hand said. "And of course our ocean is a nice salty ocean. Perhaps Europa’s salty ocean is also a wonderful place for life."

The new study has been accepted for publication in the Astronomical Journal.

Follow Mike Wall on Twitter @michaeldwall. Follow us @Spacedotcom, Facebook or Google+. This article was first published on Space.com.