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NASA steps closer to a Europa mission

The space community is buzzing with news of positive steps toward NASA’s planned mission to Jupiter’s fascinating moon Europa.

A composite of Europa made from images from the Galileo spacecraft, which orbited in the jovian system for eight years, beginning in 1995.  Image via NASA/JPL

A composite of Europa made from images from the Galileo spacecraft, which orbited in the jovian system for eight years, beginning in 1995. Areas that appear blue or white contain relatively pure water ice. Image via NASA/JPL

This week, as Earth passes between the sun and Jupiter, and the giant planet looms brightest in our sky for 2015, the space community is buzzing with news of positive steps toward NASA’s planned mission to Jupiter’s fascinating moon Europa. On Monday (February 2, 2015), NASA administrator Charles Bolden mentioned the start of a selection process for projects to accompany a Europa mission. On the same day, the White House announced its fiscal year 2016 budget request for NASA, allocating $18.5 billion to the space agency, half a billion more than last year, and including $30 million to formulate this mission. This is in addition to the $100 million added to NASA’s budget last year to begin design work for a Europa mission.

Europa was too far away for the Pioneer spacecraft in 1973 and 1974 to see clearly.  Image via history.nasa.gov

Europa was too far away for the Pioneer spacecraft to see clearly when they passed in 1973 and ’74. Image via history.nasa.gov

A mission to Jupiter’s moon Europa – which is about the same size as Earth’s moon – is a long-cherished dream of space scientists and space fans. We’ve all been fascinated by the little moon since the two Voyager spacecraft swept through the Jovian system in 1979, providing the first detailed images of Europa’s icy surface. Those images caused many scientists to begin to speculate about the possibility of a liquid ocean, and possibly life, below Europa’s ice.

NASA’s latest concept for a Europa mission is called Europa Clipper. It consists of a spacecraft that will orbit Jupiter and conduct 45 low-altitude flybys of Europa during its planned primary mission of 3.5 years. The aim of Europa Clipper will be to explore Europa, while investigating the potential for habitability. The mission will aid selecting sites for a future lander. The probe has been envisioned as carrying ice-penetrating radar, a short-wave infrared spectrometer, a topographical imager, and an ion- and neutral-mass spectrometer.

Europa is thought to have a crust of ice perhaps 100 kilometers (60 miles) thick. Below this crust, space scientists believe, there may be a vast hidden ocean, kept in liquid state by constant squeezing from the powerful gravity of nearby Jupiter.

In a way similar to its thick crust, the ocean layer on Europa may be some 100 kilometers deep. Think of that in contrast to the deepest part of Earth’s ocean, the Mariana Trench in the Pacific, a mere 11 kilometers (6.8 miles) deep. Europa’s ocean contains much more water than the oceans on Earth; it may contain some 3 times the amount of water as in all of Earth’s oceans. If it exists, it is likely vastly deeper than Earth’s oceans. And yet, scientists believe, there may be similarities between conditions in the Mariana Trench – where life can be found, even in the cold and dark – and in Europa’s ocean. On Europa, it’s believed, life may extract energy not from the sun via photosynthesis, but from hydrothermal vents, which are openings in the sea floor out of which heated mineral-rich water flows.

Astrobiologist Kevin Hand, JPL’s Deputy Chief Scientist for Solar System Exploration, said on Monday at a special JPL Icy Worlds media event:

Europa’s ocean, to the best of our knowledge, isn’t that harsh of an environment.

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This color image of the Jovian moon Europa was acquired by Voyager 2 during its close encounter on Monday morning, July 9, 1979. Europa, the size of our moon, is thought to have a crust of ice perhaps 100 kilometers thick which overlies the silicate crust. The complex array of streaks indicate that the crust has been fractured and filled by materials from the interior.

When Voyager passed Europa in 1979 … wow! The two Voyager spacecraft revolutionized our view of this little world and inspired decades of plans and dreams about space missions to Europa. Voyager 2 captured this image of Europa during its closest approach to the moon on July 9, 1979.

Above the thick, icy crust of Europa, though, it’s a different story. There, conditions are extremely harsh. At Europa’s distance from Jupiter, all space is awash in radiation from Jupiter’s vast radiation belts. The planned Europa Clipper spacecraft will have to dive into the radiation belts to fly over Europa’s surface.

If an unshielded human were aboard the craft, the amount of radiation in the vicinity of Europa is enough to cause severe illness or death after a single day’s exposure. A robotic spacecraft – like the Europa Clipper – will also have to be heavily shielded to endure the amount of radiation in this little moon’s vicinity.

How can life survive in these conditions, you might wonder? Europa’s thick, icy crust is thought to shield its ocean from the powerful radiation above.

The Europa Clipper concept is exciting, but it’s not likely to reveal life at Europa. It won’t be designed to search for life. Kevin Hand explained:

The way we framed the Europa mission science objectives is not to specifically look for life, but to understand habitability; the ingredients for life.

He said a search for life within Europa’s ocean isn’t technologically feasible at this time.

If everything goes according to plan, the Europa Clipper could be ready to launch as early as 2022 at a total cost of about $2 billion.

Europa rising above Jupiter's cloudtops, as captured by the New Horizons spacecraft - en route to Pluto - in 2007.  Image via NASA.

Europa rising above Jupiter’s cloudtops, as captured by the New Horizons spacecraft – en route to Pluto – in 2007. Image via NASA.

Bottom line: The space community is buzzing with news of positive steps toward NASA’s planned mission to Jupiter’s fascinating moon Europa. The mission is called Europa Clipper.

Deborah Byrd

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