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takyon writes:

The Dawn spacecraft has found evidence of magnesium sulphate (epsom salts) on Ceres, causing the mysterious bright spots:

The US space agency's Dawn satellite continues to return remarkable images from the dwarf planet Ceres. Now just 385km above the surface (lower than the space station is above Earth), the probe has revealed new features inside the mini-world's Occator Crater. This is the 92km-wide depression that has multiple bright spots of what are thought to be exposed salts.

[...] "The intricate geometry of the crater interior suggests geologic activity in the recent past, but we will need to complete detailed geologic mapping of the crater in order to test hypotheses for its formation." Scientists think the bright spots are deposits of epsom salts (magnesium sulphate), the trace remains of briny water-ice that at one time became exposed on the surface.

With no atmosphere on the dwarf planet, the water content would have rapidly vaporised, leaving only the magnesium sulphate spots. Ceres likely has quite a lot of buried water-ice. This idea is being investigated by the satellite's GRaND instrument, which senses neutrons and gamma rays produced by cosmic ray interactions with surface materials. It is a means to understand the chemistry of the top metre or so of Ceres' rocky "soil".

Lunar and Planetary Science Conference.

Original Submission

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)

Original Submission

takyon writes:

Dawn Finds Possible Ancient Ocean Remnants at Ceres

Minerals containing water are widespread on Ceres, suggesting the dwarf planet may have had a global ocean in the past. What became of that ocean? Could Ceres still have liquid today? Two new studies from NASA's Dawn mission shed light on these questions.

The Dawn team found that Ceres' crust is a mixture of ice, salts and hydrated materials that were subjected to past and possibly recent geologic activity, and that this crust represents most of that ancient ocean. The second study builds off the first and suggests there is a softer, easily deformable layer beneath Ceres' rigid surface crust, which could be the signature of residual liquid left over from the ocean, too.

"More and more, we are learning that Ceres is a complex, dynamic world that may have hosted a lot of liquid water in the past, and may still have some underground," said Julie Castillo-Rogez, Dawn project scientist and co-author of the studies, based at NASA's Jet Propulsion Laboratory, Pasadena, California.

Ceres.

Constraints on Ceres' internal structure and evolution from its shape and gravity measured by the Dawn spacecraft (open, DOI: 10.1002/2017JE005302) (DX)

The interior structure of Ceres as revealed by surface topography (DOI: 10.1016/j.epsl.2017.07.053) (DX)

Previously: Dawn Spies Magnesium Sulphate and Possible Geological Activity on Ceres
Ceres's Cryovolcanoes Viscously Relax Into Nothingness
Organic Molecules Found on Ceres
Early Asteroids May Have Been Made of Mud Rather Than Rock
Dawn Mission Extended at Ceres

Original Submission

takyon writes:

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

Original Submission

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