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Europa or bust: possible mission to icy moon in fy 2015 budget proposal

Europa peeking out from Jupiter’s limb, as seen by Voyager 2 on July 3, 1979.
Europa peeking out from Jupiter’s limb, as seen by Voyager 2 on July 3, 1979.
NASA / JPL / Daniel Macháček

For scientists and space enthusiasts who have been advocating a mission to Jupiter’s moon Europa, there was some good news last week from NASA. A mission to Europa has been officially included in the NASA 2015 Budget request. The inclusion is a reason for cautious optimism; while naming it as a target for a future robotic mission in the 2020s, NASA also wants to do that mission as cheaply as possible. Given the current economic climate, that may not be surprising, but what would reduced cost mean in terms of science?

Europa is one of the most fascinating worlds in the outer solar system. Europa has a global subsurface ocean, which is thought to share many characteristics with our own oceans (although it has been estimated Europa’s ocean is larger than Earth’s oceans combined). A more recent discovery of possible water plumes erupting from the surface is similar to Saturn’s moon Enceladus. These and other findings are the main reason Europa has become a primary focus for the search for extraterrestrial life.

Earlier Europa mission concepts called for an orbiter as well as a possible lander. While such a mission would be exciting and challenging – it would also be very expensive Estimates place the cost of such a mission at about $4.7 billion. An even more ambitious idea for farther in the future would be to send a lander which could drill through the surface ice layer to the water below.

But what could we realistically do now to explore Europa? The Europa Clipper mission concept has gained a lot of support and points toward a template as to what might be possible. Estimated at $2.1 billion, the spacecraft would fly past Europa about 50 times over a few years. It would be able to map the surface and also obtain data regarding the nature of the ocean below. NASA’s Juno spacecraft is currently en route to Jupiter, but it will focus primarily on studying the gas giant planet itself.

It takes a long time to get to Jupiter, about six years, so any mission to Europa should be able to do as much scientific study of the moon as possible, especially because of the possible astrobiological implications.

A Europa Clipper-type mission would go a long way towards increasing our understanding of the ocean environment on Europa, but not so much in terms of looking for direct evidence of life itself unless the probe could be flown directly through the water vapour plumes, just as Cassini has done at Enceladus (and so far has found water vapour, ice crystals and complex organic molecules). The mission would have to be modified a bit to accomplish this, but it can be done. It will also require a better understanding of the plumes, which appear to happen sporadically.

It would benefit the odds of a Europa mission being a success if more funds could be allocated for it (the final amount is still yet to be determined). This would also ensure more science could be accomplished. Large outer solar system missions such as this are less frequently attempted as opposed to missions to Mars or other inner solar system planets.

Europa is considered to be one of the best places to look for possible alien life that we know of. Scientists have worked for some time to have just such a mission take place. With this past week’s announcement it appears that the likelihood of such an expedition is likely to take place.

This article was first published on Spaceflight Insider.

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