Jupiter’s moon Europa has long been regarded as one of the most likely places in the solar system where some form of life could exist outside of Earth. Evidence from visiting spacecraft has shown that it almost certainly has a liquid water ocean beneath its icy surface. That water is also thought to be similar to that in Earth’s salty oceans and rich in oxygen.
Obtaining any answers to the life question however will require further missions to be sent there, and that is the tricky part. The costs involved have pushed back such missions; the current mission proposal, the Europa Jupiter System Mission, would launch sometime within this decade. Europe would then follow with its own mission to Ganymede, another Jupiter moon thought to have a subsurface ocean.
The estimated cost of EJSM would be about $4.7 billion, not easy in this time of planetary budget cuts. There is now, however, another proposal being offered – split the costly single-spacecraft mission into three smaller missions. The idea was put forward by astrobiologist Pabulo Henrique Rampelotto at the Federal University of Pampa in Brazil.
His study was published in the July 13 issue of the journal Astrobiology. It calls for two orbiters and one other probe with impactors.
As Rampelotto notes, “Europa is considered the prime candidate in the search for life in our solar system. Its ocean may be in direct contact with the rocky mantle beneath, where the conditions could be similar to those on Earth’s biologically rich sea floor.”
The first orbiter would measure the thickness of the ice shell and the depth of the ocean below that. The second orbiter would map the surface in both visible and infrared light, searching for any organic molecules that may be present on the surface. Finally, the third probe would send impactors into the surface, similar to the Deep Impact cometary mission, which could penetrate between 3-33 feet into the ice and then analyze its composition. They wouldn’t be expected to reach the ocean itself or any of the other subsurface lakes also thought to be on Europa, but they could still analyze the water indirectly.
According to Rampelotto, “But, if delivered in potential landing sites where liquid water from the ocean could have recently reached the surface or near surface, we could analyze indirectly the ocean composition, including signals of life.”
Whatever form the Europa mission eventually (and hopefully) takes, it will be exciting. As recent findings from two of Saturn’s moons Enceladus and Titan also suggest, moons with subsurface oceans may be common in the universe. If any evidence of life were to be found on (or rather in) any of these moons in our own solar system, it would dramatically increase the chances of finding it elsewhere as well.
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