While water plumes have been imaged on Saturn's icy moon Enceladus by the Cassini spacecraft, evidence for plumes on Jupiter's moon Europa has been scarce. But a new analysis found that a magnetometer aboard the Galileo spacecraft recorded signs of a plume in 1997, years before the Cassini spacecraft encountered plumes:
Scientists have new evidence that there are plumes of water erupting from the surface of Jupiter's icy moon Europa — plumes that could, maybe, possibly contain signs of life. The evidence comes from data collected by the now-defunct Galileo spacecraft. Although the data has been available since it was collected in 1997, it's only now that an analysis confirms the existence of water plumes.
For more than two decades, scientists have been convinced Europa has a liquid water ocean sloshing around beneath its icy outer crust. In the past six years, two teams of researchers using the Hubble Space Telescope reported the possible existence of plumes. But as powerful as Hubble is, seeing something as small as a plume on a moon more than 380-million miles away is difficult. "We're looking for effects that are relatively small, and are pushing the spatial resolution of the telescope," says astrophysicist Susana Deutsua of the Space Telescope Science Institute.
Congressman John Culberson, known for his support for the Europa Clipper mission, broke the research embargo in a recent hearing on NASA's budget.
Also at Ars Technica and The Verge.
Evidence of a plume on Europa from Galileo magnetic and plasma wave signatures (open, DOI: 10.1038/s41550-018-0450-z) (DX)
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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)
Saturn moon a step closer to hosting life
Scientists have found complex carbon-based molecules in the waters of Saturn's moon Enceladus.
Compounds like this have only previously been found on Earth, and in some meteorites. They are thought to have formed in reactions between water and warm rock at the base of the moon's subsurface ocean.
Though not a sign of life, their presence suggests Enceladus could play host to living organisms. The discovery came from data gathered by the Cassini spacecraft.
Also at SwRI, ScienceAlert, Space.com, National Geographic, Popular Mechanics, and The Guardian.
Macromolecular organic compounds from the depths of Enceladus (DOI: 10.1038/s41586-018-0246-4) (DX)
Related: Minerals In Plumes of Enceladus Indicate Hydrothermal Activity
Hydrogen Emitted by Enceladus, More Evidence of Plumes at Europa
Could a Dedicated Mission to Enceladus Detect Microbial Life There?
How the Cassini Mission Led a 'Paradigm Shift' in Search for Alien Life
Cassini Spacecraft Post-Mortem
Porous Core Could be Keeping Enceladus Warm
Yuri Milner Considering Privately Funded Mission to Enceladus
Organic Molecules Found on Ceres
NASA Finds Evidence of Water Plume on Europa
Organic Matter Found on Mars
Study Finds Evidence of More Organic Material on Ceres
Europa volcanism & interior heating modeled in detail, offers research targets for upcoming missions
Europa, an icy Jovian moon that likely possesses an ocean beneath its icy crust, may have an interior that is hot enough to produce volcanic activity on its seafloor. New research provides evidence that this seafloor volcanism likely occurred in the moon's past and [may be] ongoing at present as well.
The team of researchers, led by Dr. Marie Běhounková of Charles University in the Czech Republic, developed their own 3D models of Europa's interior and heating transfer properties to investigate the possibility of volcanism on Europa's ocean floor given other volcanism seen in the Jovian system.
[...] These volcanoes would form due to the melting of Europa's interior and heat transfer from the rocky interior of Europa to the seafloor. Models developed by Běhounková et al. show that many different factors — including radiogenic power and tidal forces — contribute to the melting of the icy moon's interior.
[...] A Laplace resonance is a phenomenon that occurs when three planetary bodies with an orbital period ratio of 1:2:4 exert regular and periodic gravitational effects on each other. These nudges create tidal forces that translate to the heating of the body's interior.
It's that interaction that led Běhounková et al.'s research toward the conclusion that this resonance and the associate tidal forces can cause increased periods of volcanic activity — called magmatic pulses — on Europa.
Journal Reference:
Marie Běhounková, Gabriel Tobie, Gaël Choblet, et al. Tidally Induced Magmatic Pulses on the Oceanic Floor of Jupiter's Moon Europa, Geophysical Research Letters (DOI: 10.1029/2020GL090077)
Previously: Hydrogen Emitted by Enceladus, More Evidence of Plumes at Europa
Plate Tectonics on Europa and Subsurface Oceans in the Outer Solar System
NASA Finds Evidence of Water Plume on Europa
Europa Plume Sites Lack Expected Heat Signatures
Jupiter's Watery Moon, Europa, Is Covered in Table Salt
Jupiter's Ocean Moon Europa Probably Glows in the Dark
(Score: 3, Informative) by Sulla on Tuesday May 15 2018, @04:44PM (1 child)
Although articles like this might not get much discussion I am happy to see them when they show up.
Ceterum censeo Sinae esse delendam
(Score: 3, Touché) by aristarchus on Tuesday May 15 2018, @10:48PM
What makes Sulla happy makes me happy, except when it doesn't. I guess we both like erupting water plumes.