According to new data from researchers at Stanford University, the University of Arizona, the University of Texas and NASA's Jet Propulsion Laboratory, some eruptions may not occur from the depths of the oceans of Europa, the moon of Jupiter, but from water pockets embedded in the ice shell itself.
On Jupiter's icy moon, Europa, powerful eruptions can erupt into space, which raises a number of questions for hopeful astrobiologists on Earth: what could explode due to plumes several kilometers high? Could they contain signs of extraterrestrial life? How are they formed in Europe? The new explanation now points to a source closer to the frozen surface than scientists could expect.
Using images captured by NASA's Galileo spacecraft, the researchers developed a model to explain how the combination of freezing and pressurization could lead to a cryovolcanic eruption or water splash. The results, published Nov. 10 in Geophysical Research Letters, have implications for determining the habitability of Europa's underlying ocean, as well as explaining eruptions on other icy bodies in the solar system.
Scientists have long speculated that the vast ocean hidden under Europa's ice crust might contain the elements needed to sustain life. But other than sending an underwater vehicle to the moon for exploration, it's hard to say for sure. This is one of the reasons why Europa's plumes have generated so much interest: if eruptions originate from the bowels of the ocean, the elements can be more easily detected by a future mission spacecraft such as NASA's Europa Clipper.
But if the plumes originate in the moon's icy shell, they may be less conducive to life because it is more difficult to maintain the chemical energy to sustain life there. In this case, the chances of detecting habitability from space are reduced.
The researchers focused their analysis on Manannan, a 29-kilometer-wide crater in Europa that was formed by a collision with another celestial object tens of millions of years ago. Thinking that such a collision would generate a tremendous amount of heat, they modeled how the melting and subsequent freezing of a water pocket inside the ice shell could cause water to erupt.
The model shows that as Europa's water turned to ice in the later stages of the impact, pockets of water with increased salinity could have formed on the moon's surface. In addition, these pockets of salt water can migrate lengthwise through Europa's ice shell, obscuring adjoining areas of less salty ice, and therefore becomes even saltier in the process.
