So far, images from a dozen flybys and distant probing by Earth-based observatories are available for study, but we still can't address some of the biggest questions being asked of Europa.
The paper, published in the journal Astrobiology, has kicked-off discussions for a future NASA surface mission to Europa.
In the paper's abstract, the priorities for any surface mission to Europa are laid out:
The highest priority is active sampling of Europa's non-ice material from at least two different depths (0.5–2 cm and 5–10 cm) to understand its detailed composition and chemistry and the specific nature of salts, any organic materials, and other contaminants. A secondary focus is geophysical prospecting of Europa, through seismology and magnetometry, to probe the satellite's ice shell and ocean. Finally, the surface geology can be characterized in situ at a human scale.
ANALYSIS: The Best Way to Explore Europa? Bomb It
This exciting news comes hot on the tail of the April announcement that $75 million of NASA's remaining 2013 budget allocation is intended "for pre-formulation and/or formulation activities for a mission that meets the science goals outlined for the Jupiter Europa mission in the most recent planetary science decadal survey."
Unfortunately, there's no word on whether a surface mission or the proposed "Europa Clipper" orbiter will get future funding. After all, NASA's planetary sciences budget has seen huge cuts, with the bulk of the existing attention focused on digging in the dry Martian dirt in the hope of turning up any vague clue on the potential for past habitability. While the search for life on Mars is important, it comes at the expense of sending a bold mission to a world that is known to have all the basic ingredients for life in abundance (liquid water, energy source, potentially organic chemistry).
In an interview with the Houston Chronicle's Eric Berger, University of Texas geophysicist Don Blankenship, who has had a hand in both the Europa Clipper and lander proposals, expressed his frustration at shrinking budgets and lack of support for planetary exploration beyond Mars. "For decades the United States has led the world - humanity has relied upon us to explore the outer planets," he said. "But now it seems we're checking out of the hotel."
But still, Europa waits, daring us to sample its ice, explore its surface and dive into its ocean in the hope of uncovering life's secrets.
"Landing on the surface of Europa would be a key step in the astrobiological investigation of that world," said Chris McKay, of NASA Ames Research Center and senior editor of the journal Astrobiology. "This paper outlines the science that could be done on such a lander. The hope would be that surface materials, possibly near the linear crack features, include biomarkers carried up from the ocean."
So, we wait in the hope that politics will re-prioritize science and space exploration. Sadly, it might be a long wait until we see a robotic mission set down on Europa's promising landscape.
The Astrobiology paper, "Science Potential from a Europa Lander," is now available online.
Image: An artist's impression for the view from Europa's surface. Credit: NASA/JPL-Caltech