A NASA report on the potential for future exploration of the Jovian moon Europa has been published:
A report on the potential science value of a lander on the surface of Jupiter's icy moon Europa has been delivered to NASA, and the agency is now engaging the broader science community to open a discussion about its findings.
[...] The report lists three science goals for the mission. The primary goal is to search for evidence of life on Europa. The other goals are to assess the habitability of Europa by directly analyzing material from the surface, and to characterize the surface and subsurface to support future robotic exploration of Europa and its ocean. The report also describes some of the notional instruments that could be expected to perform measurements in support of these goals.
Scientists agree that the evidence is quite strong that Europa, which is slightly smaller than Earth's moon, has a global saltwater ocean beneath its icy crust. This ocean has at least twice as much water as Earth's oceans. While recent discoveries have shown that many bodies in the solar system either have subsurface oceans now, or may have in the past, Europa is one of only two places where the ocean is understood to be in contact with a rocky seafloor (the other being Saturn's moon Enceladus). This rare circumstance makes Europa one of the highest priority targets in the search for present-day life beyond Earth.
Executive summary:
The Europa Lander Science Definition Team Report presents the integrated results of an intensive science and engineering team effort to develop and optimize a mission concept that would follow the Europa Multiple Flyby Mission and conduct the first in situ search for evidence of life on another world since the Viking spacecraft on Mars in the 1970s. The Europa Lander mission would be a pathfinder for characterizing the biological potential of Europa's ocean through direct study of any chemical, geological, and possibly biological, signatures as expressed on, and just below, the surface of Europa. The search for signs of life on Europa's surface requires an analytical payload that performs quantitative organic compositional, microscopic, and spectroscopic analysis on five samples acquired from at least 10 cm beneath the surface, with supporting context imaging observations. This mission would significantly advance our understanding of Europa as an ocean world, even in the absence of any definitive signs of life, and would provide the foundation for the future robotic exploration of Europa.
Europa Lander Study 2016 Report (264 pages) and older resources.
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Yuri Milner, the Russian billionaire backer of Breakthrough Initiatives and Breakthrough Prizes, has set his sights on Saturn's moon Enceladus:
Milner founded the $100 million Breakthrough Starshot project, an attempt to send small probes to Alpha Centauri. Now, he has announced plans to explore funding a mission to Enceladus.
[...] "Can we design a low-cost, privately funded mission to Enceladus which can be launched relatively soon, and that can look more thoroughly at those plumes, try to see what's going on there?" Milner asked the New Space Age conference in Seattle this week.
A probe to Enceladus could be done for well under $1 billion, but it likely wouldn't be able to drill through the icy surface.
The Cassini spacecraft already flew as close as 49 km above the surface of Enceladus, and flew through a plume of water vapor released by the satellite. A proposed mission such as the Enceladus Life Finder could repeatedly fly through plumes and use better sensors to attempt to detect evidence of organic materials or microbes.
Two upcoming missions will be studying Jupiter's moon Europa: the ESA's Jupiter Icy Moons Explorer and NASA's Europa Clipper. Europa is easier for spacecraft to reach than Enceladus, but has thicker ice blocking its internal ocean.
Also at Newsweek.
Related: NASA Releases Europa Lander Study 2016 Report
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Porous Core Could be Keeping Enceladus Warm
Europa Lander May Not Have to Dig Deep to Find Signs of Life
If signs of life exist on Jupiter's icy moon Europa, they might not be as hard to find as scientists had thought, a new study reports. [...] NASA aims to hunt for such samples in the not-too-distant future. The agency is developing a flyby mission called Europa Clipper, which is scheduled to launch in the early 2020s. Clipper will study Europa up close during dozens of flybys, some of which might be able to zoom through the moon's suspected water-vapor plumes. And NASA is also working on a possible post-Clipper lander mission that would search for evidence of life at or near the Europan surface.
It's unclear, however, just how deep a Europa lander would need to dig to have a chance of finding anything. That's because Europa orbits within Jupiter's radiation belts and is bombarded by fast-moving charged particles, which can turn amino acids and other possible biosignatures into mush.
That's where the new study comes in. NASA scientist Tom Nordheim and his colleagues modeled Europa's radiation environment in detail, laying out just how bad things get from place to place. They then combined these results with data from laboratory experiments documenting how quickly various radiation doses carve up amino acids (a stand-in here for complex biomolecules in general).
The researchers found significant variation, with some Europan locales (equatorial regions) getting about 10 times the radiation pounding of others (middle and high latitudes). At the most benign spots, the team determined, a lander would likely have to dig just 0.4 inches (1 centimeter) or so into the ice to find recognizable amino acids. In the high-blast zones, the target depth would be on the order of 4 to 8 inches (10 to 20 cm). (This is not to imply that potential Europan organisms would still be alive at such depths, however; doses there are high enough to cook even the hardiest Earth microbes, study team members said.)
Also at Motherboard and Gizmodo.
Preservation of potential biosignatures in the shallow subsurface of Europa (DOI: 10.1038/s41550-018-0499-8) (DX)
Biosignature hide and seek (DOI: 10.1038/s41550-018-0542-9) (DX)
Fields of five-story-high ice blades could complicate landing on Jupiter moon
Probes have shown that Europa's ice-bound surface is riven with fractures and ridges, and new work published today in Nature Geosciences suggests any robotic lander could face a nasty surprise [DOI: 10.1038/s41561-018-0235-0] [DX], in the form of vast fields of ice spikes, each standing as tall as a semitruck is long.
Such spikes are created on Earth in the frigid tropical peaks of the Andes Mountains, where they are called "pentinentes,"[sic] for their resemblance to devout white-clad monks. [...] Pentinentes[sic] have already been seen on Pluto. And by calculating other competing erosional processes on Europa, such as impacts and charged particle bombardment, the new work suggests the vaporization of ice would be dominant in its equatorial belt, forming pentitentes[sic] 15 meters tall spaced only 7 meters apart. Such formations could explain, the authors add, why radar observations of the planet dip in energy at its equator, the pentinentes[sic] scattering the response. But the ultimate proof of whether Europa's belly will be off limits to landing will come when the Clipper arrives in the mid-2020s.
[Update: It's penitentes. Ed.]
First it was slush. Now it's spikes. Attempt no landing there.
Also at Science News and The Verge.
Related:
NASA Releases Europa Lander Study 2016 Report
Amino Acids Could Exist Just Centimeters Under Europa's Surface
(Score: 1) by DmT on Friday February 10 2017, @10:39PM
10 cm is not enough. More depth required.
(Score: 0) by Anonymous Coward on Saturday February 11 2017, @01:52AM
TWSS
(Score: 1) by SandRider on Saturday February 11 2017, @04:09AM
While I have not yet read the report, the summary states that they are looking for signs of life, not the life itself. Europa has a recently active surface so it is entirely possible that evidence of life beneath the ice can be found near the surface.
At this point there is too much risk of contamination by terrestrial life forms if we were to directly probe the subsurface ocean.