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dx3bydt3 writes:

Silicon-rich nanometer scale particles have been detected by Cassini’s Cosmic Dust Analyser in ice plumes of Saturn's moon Enceladus. The presence of these minerals suggests that the water in the plumes interacted with rock at the core of Enceladus.

From the ESA website:

takyon writes:

Scientists using imagery from the Dawn spacecraft have found evidence of organic material on the surface of the dwarf planet Ceres:

NASA's Dawn mission has found evidence for organic material on Ceres, a dwarf planet and the largest body in the main asteroid belt between Mars and Jupiter. Scientists using the spacecraft's visible and infrared mapping spectrometer (VIR) detected the material in and around a northern-hemisphere crater called Ernutet. Organic molecules are interesting to scientists because they are necessary, though not sufficient, components of life on Earth.

[...] "This is the first clear detection of organic molecules from orbit on a main belt body," said Maria Cristina De Sanctis, lead author of the study, based at the National Institute of Astrophysics, Rome. The discovery is reported in the journal Science. Data presented in the Science paper support the idea that the organic materials are native to Ceres. The carbonates and clays previously identified on Ceres provide evidence for chemical activity in the presence of water and heat. This raises the possibility that the organics were similarly processed in a warm water-rich environment.

[...] Having completed nearly two years of observations in orbit at Ceres, Dawn is now in a highly elliptical orbit at Ceres, going from an altitude of 4,670 miles (7,520 kilometers) up to almost 5,810 miles (9,350 kilometers). On Feb. 23, it will make its way to a new altitude of around 12,400 miles (20,000 kilometers), about the height of GPS satellites above Earth, and to a different orbital plane. This will put Dawn in a position to study Ceres in a new geometry. In late spring, Dawn will view Ceres with the sun directly behind the spacecraft, such that Ceres will appear brighter than before, and perhaps reveal more clues about its nature.

Localized aliphatic organic material on the surface of Ceres (DOI: 10.1126/science.aaj2305) (DX)

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takyon writes:

At a NASA press conference on Thursday, scientists from the Jet Propulsion Laboratory, NASA's D.C. Headquarters, and the Space Telescope Science Institute announced new observations about the "ocean worlds" Enceladus and Europa. At Enceladus, one of Saturn's moons, the Cassini spacecraft has measured emissions of hydrogen gas that could indicate a source of chemical energy for life forms. 2016 Hubble observations of Jupiter's moon Europa have found evidence of a water plume emanating from the same location as a plume measured in 2014.

The Cassini spacecraft took a "deep dive" into one of the Enceladus plumes on Oct. 28, 2015. The plume contains about 98% water, 0.4-1.4% hydrogen, and a mixture of carbon dioxide, methane, ammonia, and other molecules. The findings support the conclusion of hot water interacting with rock at hydrothermal vents on the seafloor, a type of habitat known to support life without the need for sunlight. NASA scientists have concluded that Enceladus has all of the conditions and ingredients necessary to support life, although the detection of hydrogen gas does not prove that the internal ocean currently contains life forms, and phosphorus and sulfur have yet to be measured.

The new Hubble images of Europa show that the height of the plume is about twice that of the one measured in 2014. The location of this periodic plume corresponds with a thermal hotspot on Europa's surface found by the Galileo spacecraft in the 1990s, which was once dismissed as an anomaly. The lack of craters on Europa's surface indicates that water is spraying out of the internal ocean through cracks and reshaping the surface. However, Europa's ice shell is thought to be thicker than that of Enceladus, with water vapor escaping the crust less often. NASA is currently developing a Europa Clipper mission that would conduct a series of 45 or more flybys of Europa, with the possibility of flying directly through water vapor plumes for sampling. The European Space Agency's Jupiter Icy Moons Explorer will study Europa and Callisto, but end its mission by orbiting Ganymede.

The same chemistry detected at Enceladus could also be taking place in interior oceans on other icy worlds, such as Ceres, Titan, Ganymede, Callisto, Dione, Rhea, Titania, Triton, Pluto, Eris, Sedna, etc.

Here's the press briefing (48m16s). Also at Science Magazine, BBC, Space.com, and Popular Mechanics (mhajicek's link).

Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes (open, DOI: 10.1126/science.aai8703) (DX)

Active Cryovolcanism on Europa? (DOI: 10.3847/2041-8213/aa67f8) (DX)

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Phoenix666 writes:

Saturn's icy moon Enceladus is best known for its numerous geysers ejecting plumes of water and ice. These eruptive fountains perplex researchers searching for signs of microbial life beyond Earth. A dedicated spacecraft designed to study the plume-like features spewing from Enceladus could definitely tell us whether or not they contain alien microorganisms.

"We need a spacecraft to travel to Enceladus, fly through a geyser plume, and analyze the water that is immediately accessible," Geoffrey Marcy, a retired professor of astronomy at the University of California, Berkeley, told Astrowatch.net.

Marcy is a renowned exoplanet researcher who discovered many extrasolar worlds. He was one of the co-investigators of NASA's Kepler planet-hunting mission that detected more than 4,000 exoworlds.
...
"The remarkable aspect of the search for microbes in the water spurting from geysers is that the spacecraft only needs to fly through the plume, well above the surface of Enceladus. No lander is needed—just a succession of flybys through the plumes as it orbits Enceladus," Marcy said.

He noted that such spacecraft should be fitted with a mass spectrometer to detect organic compounds that could be signs of microbial life. The spectrometer will look for amino acids and the structure of any organic molecules, especially fatty acids such as those composing cell membranes. It could also measure the relative amounts of isotopes of carbon (12 and 14) to detect non-natural anomalies due to biological processes.

Moreover, the mission to Enceladus would measure the properties of the water such as pH, oxidation and temperature, therefore assessing its suitability for organic life.

Marcy believes assembling "a brilliant team of billionaires" is the key to making such a mission possible. Lucky for him the monolith said nothing about Enceladus.

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Phoenix666 writes:

The hunt for habitable (and already inhabited) worlds has largely focused on a "Goldilocks zone" around a star, where it's neither too hot nor too cold for liquid water to exist. But astrobiologists have begun to broaden their search – thanks to discoveries by NASA's Cassini orbiter.

Saturn sits too far from the sun for its rays to melt ice, and yet Cassini discovered that one of the planet's moons, Enceladus, has a vast ocean sloshing beneath its icy crust. Instead of sunlight, tidal forces keep Enceladus's ocean warm. The gravity of Saturn pulls at Enceladus's core, driving thermal processes that create a new Goldilocks zone inside the moon itself.

"It's definitely been a paradigm shift in where you might find life," says Cassini project scientist Linda Spilker.

Still, it takes a lot more than water to make a place habitable. But here, too, Enceladus delivers. Icy geysers fueled by Enceladus's ocean shoot out from cracks in the moon's surface, allowing the Cassini spacecraft to sample them directly during flybys. What it found is that Enceladus has almost everything required for life as we know it: a source of energy, a source of carbon, and salts and minerals.

Thank goodness for Cassini, after that whole thing about being banned from Europa.

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takyon writes:

Timeline of Cassini–Huygens

NASA's Cassini Spacecraft Ends Its Historic Exploration of Saturn

Telemetry received during the plunge indicates that, as expected, Cassini entered Saturn's atmosphere with its thrusters firing to maintain stability, as it sent back a unique final set of science observations. Loss of contact with the Cassini spacecraft occurred at 7:55 a.m. EDT (4:55 a.m. PDT), with the signal received by NASA's Deep Space Network antenna complex in Canberra, Australia.

[...] As planned, data from eight of Cassini's science instruments was beamed back to Earth. Mission scientists will examine the spacecraft's final observations in the coming weeks for new insights about Saturn, including hints about the planet's formation and evolution, and processes occurring in its atmosphere.

[...] Cassini launched in 1997 from Cape Canaveral Air Force Station in Florida and arrived at Saturn in 2004. NASA extended its mission twice – first for two years, and then for seven more. The second mission extension provided dozens of flybys of the planet's icy moons, using the spacecraft's remaining rocket propellant along the way. Cassini finished its tour of the Saturn system with its Grand Finale, capped by Friday's intentional plunge into the planet to ensure Saturn's moons – particularly Enceladus, with its subsurface ocean and signs of hydrothermal activity – remain pristine for future exploration.

Farewell, Cassini: a 20 year mission to Saturn comes to a life-protecting end

During the Jovian flyby, Cassini performed scientific observations of the planet, showing that Jupiter's cloud belts were areas of "net-rising atmospheric motion."

This observation contradicted previous hypotheses about Jupiter's dark and light belts and served to highlight differences in planetary weather systems.

During the flyby, Cassini was also able to study Jupiter's thin ring system, revealing that Jupiter's rings were composed of irregularly shaped particles that likely originated as ejecta from micrometeorite impacts with the moons Metis and Adrastea.

Cassini: The legend and legacy of one of NASA's most prolific missions

Previously:

takyon writes:

A study has found that a "porous"/sandy/muddy core can increase the energy released by gravitational tidal friction inside Saturn's moon Enceladus. This could explain why the interior of the icy moon has not cooled down after billions of years:

A paper published in Nature Astronomy today presents the first concept that explains the key characteristics of 500 km-diameter Enceladus as observed by the international Cassini spacecraft over the course of its mission, which concluded in September.

This includes a global salty ocean below an ice shell with an average thickness of 20–25 km, thinning to just 1–5 km over the south polar region. There, jets of water vapour and icy grains are launched through fissures in the ice. The composition of the ejected material measured by Cassini included salts and silica dust, suggesting they form through hot water – at least 90ºC – interacting with rock in the porous core.

These observations require a huge source of heat, about 100 times more than is expected to be generated by the natural decay of radioactive elements in rocks in its core, as well as a means of focusing activity at the south pole.

The tidal effect from Saturn is thought to be at the origin of the eruptions deforming the icy shell by push-pull motions as the moon follows an elliptical path around the giant planet. But the energy produced by tidal friction in the ice, by itself, would be too weak to counterbalance the heat loss seen from the ocean – the globe would freeze within 30 million years.

[...] In the new simulations the core is made of unconsolidated, easily deformable, porous rock that water can easily permeate. As such, cool liquid water from the ocean can seep into the core and gradually heat up through tidal friction between sliding rock fragments, as it gets deeper.

Powering prolonged hydrothermal activity inside Enceladus (DOI: 10.1038/s41550-017-0289-8) (DX)

Previously: Hydrogen Emitted by Enceladus, More Evidence of Plumes at Europa
Cassini Finds Evidence of Change in Enceladus's Spin Axis
Could a Dedicated Mission to Enceladus Detect Microbial Life There?
How the Cassini Mission Led a 'Paradigm Shift' in Search for Alien Life

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takyon writes:

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
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

Original Submission

takyon writes:

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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Thexalon writes:

NASA's Curiosity rover has discovered ancient organic molecules on Mars. That plus the methane is strongly suggesting that life may have existed on Mars back when liquid water existed on the surface.

NASA's Curiosity rover has found new evidence preserved in rocks on Mars that suggests the planet could have supported ancient life, as well as new evidence in the Martian atmosphere that relates to the search for current life on the Red Planet. While not necessarily evidence of life itself, these findings are a good sign for future missions exploring the planet's surface and subsurface.

The new findings – "tough" organic molecules in three-billion-year-old sedimentary rocks near the surface, as well as seasonal variations in the levels of methane in the atmosphere – appear in the June 8 edition of the journal Science.

Organic molecules contain carbon and hydrogen, and also may include oxygen, nitrogen and other elements. While commonly associated with life, organic molecules also can be created by non-biological processes and are not necessarily indicators of life.

"With these new findings, Mars is telling us to stay the course and keep searching for evidence of life," said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters, in Washington. "I'm confident that our ongoing and planned missions will unlock even more breathtaking discoveries on the Red Planet."

Original Submission

takyon writes:

Organic Matter on Dwarf Planet Ceres More Abundant than Thought

A new analysis of data collected by NASA's Dawn orbiter suggests that organic molecules may exist in surprisingly high concentrations on the surface of Ceres. The study [DOI: 10.1029/2018GL077913] [DX] appears in the journal Geophysical Research Letters.

[...] To get an initial idea of how abundant those compounds might be, researchers compared the [Visible and Infrared Spectrometer] data from Ceres with lab reflectance spectra of organic material formed on Earth. Based on that standard, they concluded that 6-10% of the spectral signature they detected on Ceres could be explained by organic matter.

But for this the new study, Southwest Research Institute researcher Hannah Kaplan and co-authors wanted to re-examine those data using a different standard. Instead of relying on Earth rocks to interpret the data, they turned to an extraterrestrial source: meteorites. Some meteorites have been shown to contain organic material that's slightly different from what's commonly found on our own planet. And the new analysis shows that the spectral reflectance of the extraterrestrial organics is distinct from that of terrestrial counterparts. [...] "We estimate that as much as 40-50% of the spectral signal we see on Ceres is explained by organics. That's a huge difference compared to the 6-10% previously reported based on terrestrial organic compounds."

[...] There are two competing possibilities for where Ceres' organics may have come from. They could have been produced internally on Ceres and then exposed on the surface, or they could have been delivered to the surface by an impact from an organic-rich comet or asteroid.

Previously: Organic Molecules Found on Ceres

Related: Dawn Spies Magnesium Sulphate and Possible Geological Activity on Ceres
Ceres May Have Had a Global Surface Ocean in the Past

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takyon writes:

NASA may have burned best proof of life on Mars by accident over 40 years ago

Viking landers sent to Mars in 1976 to search for organic matter reported finding nothing, a conclusion that shocked scientists at the time. New research published in the Journal of Geophysical Research Planets [DOI: 10.1029/2018JE005544] [DX], suggests the Vikings' main instrument might have actually discovered the organic matter but burned it while collecting soil samples, an article in New Scientist notes.

The primary instrument on the Viking landers, a gas chromatograph-mass spectrometer, used heat to try and find these molecules. That was big a mistake. Because of a now-known chemical in the soil perchlorate, the landers would have destroyed any organics in the process. NASA's Phoenix lander found perchlorate on Mars in 2008, Space.com notes.

Perchlorate on Mars.

Previously: Organic Matter Found on Mars

Related: NASA Discovers Evidence for Liquid Water on Mars
UV Radiation and Perchlorates Could be a Toxic Combination for Potential Mars Bacteria
Study Finds Evidence of More Organic Material on Ceres
Complex Organic Molecules Found on Enceladus

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)

takyon writes:

NASA to support initial studies of privately funded Enceladus mission

NASA signed an agreement in September with a foundation to support initial studies of a privately funded mission to a potentially habitable moon of Saturn. The unfunded Space Act Agreement between NASA and the Breakthrough Prize Foundation, initiated with little public fanfare, covers NASA support for initial concept studies, known in NASA programmatic parlance as "Pre-Phase A," for a mission to the moon Enceladus, an icy world believed to have a subsurface ocean of liquid water and plumes that eject that water through the surface into space.

The agreement, the seven-page document posted on a NASA website states, "shall be for the purpose of cooperating on the Breakthrough Pre-Phase A activities for Breakthrough's Enceladus Mission." That includes supporting a series of reviews that leads up to what NASA calls Key Decision Point (KDP) A, "to determine progress to Phase A, for further formation of the Enceladus Mission's concept and technology development."

[...] Most of the study work would be done by Breakthrough. NASA, under the agreement, would use "reasonable efforts" to offer scientific and technical consulting for the study, including expertise in a range of scientific fields and in planetary projection. NASA will also advise "in the development of Phase A plans for a life signature mission to Enceladus." The agreement between NASA and Breakthrough involves no exchange of funds. NASA estimates its cost of carrying out its responsibilities under the agreement to be $72,384.

The agreement, first reported by New Scientist, offers few details about the proposed mission itself. A companion document for the agreement notes that the foundation's Breakthrough Watch program "seeks to evaluate near-term missions to objects in the Solar System, including Enceladus," that would search for signs of life there. "The Enceladus Mission is considering novel low-cost approaches, one of which uses solar sail technology to flyby the moon of Saturn to collect scientific data.

However, foundation officials have publicly discussed their interest in an Enceladus mission for a year. "We formed a little workshop around this idea," said Yuri Milner, the Russian billionaire who funds the foundation, at an event in Seattle in November 2017. "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 to try to see what's going on there?"

Also at Space.com.

Previously: Yuri Milner Considering Privately Funded Mission to Enceladus

Related: Underground Ocean on Enceladus May be Close to the Surface
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
Porous Core Could be Keeping Enceladus Warm
Complex Organic Molecules Found on Enceladus

Original Submission