A Jovian Mystery: It's Time to Land On Europa
Europa has only been seen from afar, but its aura of intrigue has inspired scientists to study ideas as to how to explore the icy Jovian moon.
In a new study published today (Aug. 7), a NASA-appointed science definition team lays out the rich tapestry of discovery facing any mission to study Europa, but what questions do we need answering?
“If one day humans send a robotic lander to the surface of Europa, we need to know what to look for and what tools it should carry,” said Robert Pappalardo, of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., and the study’s lead author. “There is still a lot of preparation that is needed before we could land on Europa, but studies like these will help us focus on the technologies required to get us there, and on the data needed to help us scout out possible landing locations. Europa is the most likely place in our solar system beyond Earth to have life today, and a landed mission would be the best way to search for signs of life.” (Emphasis added.)
Indeed, a mission to the Europan surface would be monumental. We know that the moon has a sub-surface liquid water ocean hidden beneath a icy crust. We also know that liquid lakes embedded below the ice cycle nutrients from the surface into the ocean below. To maintain Europa’s sub-surface liquid water oceans, there’s an internal heating mechanism driven by tidal interactions with its parent gas giant planet Jupiter.
In short, Europa has all the components to support life (as we know it). It seems that if the components are there, and basic organic chemistry is possible, then perhaps some form of extraterrestrial microbe could thrive. Some scientists have thrown caution into the wind and even speculated that complex lifeforms may cruise in the dark Europan ocean. (For more on that little fact, I wholeheartedly recommend you watching the newly-released movie Europa Report.)
Flybys of the moon by NASA’s Voyager 2 in 1979 and NASA’s Galileo spacecraft in the mid-to-late 1990s have shown Europa’s chaotic cracked surface to be mottled with red discoloration — what chemistry is causing these mysterious features? How thick is the ice? There appears to be fresh fractures, could these locations provide a hypothetical shortcut for a surface mission’s submersible? Is there organic chemistry on the surface? If so, did it leach from below the ice?
Depiction of the model lander implementation. Descriptions of the model payload are provided in the 2012 NASA lander study (Europa Study Team, 2012).
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.
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.
Image: An artist’s impression for the view from Europa’s surface. Credit: NASA/JPL-Caltech