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Phoenix666 writes:

NASA is very publicly planning a mission to Europa in the 2020s, one that will soar over the intriguing moon dozens of times. Yet the reality is more thrilling. Quietly, the same engineers who masterminded the daring Curiosity landing on Mars in 2012 have been plotting how best to drop a lander onto the nightmare glacier. In early November, they presented their preliminary findings for a 230-kg lander to the one person in the world who can, and who dearly wants to, make that happen.

"I told them to do whatever it takes," said Representative John Culberson after meeting with the NASA scientists. "All of humanity is going to want to know what's under the ice."

The discovery of water on Mars seems to have whetted the appetite.

Original Submission

takyon writes:

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.

Original Submission

takyon writes:

Future Europa landers may be in danger of sinking into a surface less dense than freshly fallen snow:

Space scientists have every reason to be fascinated with Jupiter's moon Europa, and, in 2017, NASA and the European Space Agency (ESA) announced they are planning a joint mission to land there. As the video above explains, this little moon is thought to have a liquid ocean submerged beneath an icy crust. Scientists believe it could host extraterrestrial life. But Europa's surface is much more alien than any we've ever visited. With its extremely thin atmosphere, low gravity – and a surface temperature of some -350 degrees F. (–176 °C.) – Europa might not be kind to a landing spacecraft. The moon's surface might be unexpectedly hard. Or – as evidenced by a study from the Planetary Science Institute announced on January 24, 2018 – Europa's surface might be so porous that any craft trying to land would simply sink.

The study – published in the peer-reviewed journal Icarus – comes from scientist Robert Nelson. If you're a student of space history, its results might sound familiar. Nelson pointed out in his statement:

Of course, before the landing of the Luna 2 robotic spacecraft in 1959, there was concern that the moon might be covered in low density dust into which any future astronauts might sink.

Now Europa is the source of a similar scariness, with Nelson's study showing that Europa's surface could be as much as 95 percent porous.

Laboratory simulations of planetary surfaces: Understanding regolith physical properties from remote photopolarimetric observations (DOI: 10.1016/j.icarus.2017.11.021) (DX)

Original Submission

takyon writes:

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)