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posted by martyb on Friday March 16 2018, @08:16AM   Printer-friendly
from the Roman-goddess-of-agriculture,-grain-crops,-fertility-and-motherly-relationships dept.

NASA Dawn Reveals Recent Changes in Ceres' Surface

NASA's Dawn mission has found recently exposed deposits that give us new information on the materials in the crust and how they are changing, according to two papers published March 14 in Science Advances that document the new findings.

Observations obtained by the visible and infrared mapping spectrometer (VIR) on the Dawn spacecraft previously found water ice in a dozen sites on Ceres. The new study revealed the abundance of ice on the northern wall of Juling Crater, a crater 12 miles (20 kilometers) in diameter. The new observations, conducted from April through October 2016, show an increase in the amount of ice on the crater wall.

"This is the first direct detection of change on the surface of Ceres," said Andrea Raponi of the Institute of Astrophysics and Planetary Science in Rome.

[...] In a second study, VIR observations also reveal new information about the variability of Ceres' crust, and suggest recent surface changes, in the form of newly exposed material.

[...] This study, led by Giacomo Carrozzo of the Institute of Astrophysics and Planetary Science, identified 12 sites rich in sodium carbonates and examined in detail several areas of a few square miles that show where water is present as part of the carbonate structure. The study marks the first time hydrated carbonate has been found on the surface of Ceres, or any other planetary body besides Earth, giving us new information about the dwarf planet's chemical evolution.

Ceres.

Variations in the amount of water ice on Ceres' surface suggest a seasonal water cycle (open, DOI: 10.1126/sciadv.aao3757) (DX)

Nature, formation, and distribution of carbonates on Ceres (open, DOI: 10.1126/sciadv.1701645) (DX)

Previously: Ceres's Cryovolcanoes Viscously Relax Into Nothingness
Organic Molecules Found on Ceres
Ceres May Have Had a Global Surface Ocean in the Past
Bright Areas on Ceres Suggest Geologic Activity


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Ceres's Cryovolcanoes Viscously Relax Into Nothingness 3 comments

Scientists theorize that Ceres's cryovolcanoes slowly flatten over time:

A recently discovered solitary ice volcano on the dwarf planet Ceres may have some hidden older siblings, say scientists who have tested a likely way such mountains of icy rock – called cryovolcanoes – might disappear over millions of years. NASA's Dawn spacecraft discovered Ceres's 4-kilometer (2.5-mile) tall Ahuna Mons cryovolcano in 2015. Other icy worlds in our solar system, like Pluto, Europa, Triton, Charon and Titan, may also have cryovolcanoes, but Ahuna Mons is conspicuously alone on Ceres. The dwarf planet, with an orbit between Mars and Jupiter, also lies far closer to the sun than other planetary bodies where cryovolcanoes have been found.

Now, scientists show there may have been cryovolcanoes other than Ahuna Mons on Ceres millions or billions of years ago, but these cryovolcanoes may have flattened out over time and become indistinguishable from the planet's surface. They report their findings in a new paper accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

[...] Ceres has no atmosphere, so the processes that wear down volcanoes on Earth – wind, rain and ice – aren't possible on the dwarf planet. Sori and his colleagues hypothesized that another process, called viscous relaxation, could be at work. Viscous relaxation is the idea that just about any solid will flow, given enough time. For example, a cold block of honey appears to be solid. But if given enough time, the block will flatten out until there is no sign left of the original block structure. On Earth, viscous relaxation is what makes glaciers flow, Sori explained. The process doesn't affect volcanoes on Earth because they are made of rock, but Ceres's volcanoes contain ice – making viscous relaxation possible. On Ceres, viscous relaxation could be causing older cryovolcanoes to flatten out over millions of years so they are hard to discern. Ceres's location close to the sun could make the process more pronounced, Sori said.

The vanishing cryovolcanoes of Ceres (open, DOI: 10.1002/2016GL072319) (DX)


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Organic Molecules Found on Ceres 12 comments

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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Ceres May Have Had a Global Surface Ocean in the Past 14 comments

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

Bright Areas on Ceres Suggest Geologic Activity 8 comments

Bright Areas on Ceres Suggest Geologic Activity

Since Dawn arrived in orbit at Ceres in March 2015, scientists have located more than 300 bright areas on Ceres. A new study in the journal Icarus, led by Nathan Stein, a doctoral researcher at Caltech in Pasadena, California, divides Ceres' features into four categories.

The first group of bright spots contains the most reflective material on Ceres, which is found on crater floors. The most iconic examples are in Occator Crater, which hosts two prominent bright areas. Cerealia Facula, in the center of the crater, consists of bright material covering a 6-mile-wide (10-kilometer-wide) pit, within which sits a small dome. East of the center is a collection of slightly less reflective and more diffuse features called Vinalia Faculae. All the bright material in Occator Crater is made of salt-rich material, which was likely once mixed in water. Although Cerealia Facula is the brightest area on all of Ceres, it would resemble dirty snow to the human eye.

More commonly, in the second category, bright material is found on the rims of craters, streaking down toward the floors. Impacting bodies likely exposed bright material that was already in the subsurface or had formed in a previous impact event.

Separately, in the third category, bright material can be found in the material ejected when craters were formed.

The mountain Ahuna Mons gets its own fourth category -- the one instance on Ceres where bright material is unaffiliated with any impact crater. This likely cryovolcano, a volcano formed by the gradual accumulation of thick, slowly flowing icy materials, has prominent bright streaks on its flanks.

Ceres and cryovolcanos.

The formation and evolution of bright spots on Ceres (open, DOI: 10.1016/j.icarus.2017.10.014) (DX)

Previously: A Closer Look At Mystery Spots On Dwarf Planet Ceres
NASA's Dawn Orbiter Finds a Mountain on Ceres
Ceres's Cryovolcanoes Viscously Relax Into Nothingness
Organic Molecules Found on Ceres
Dawn Mission Extended at Ceres
Ceres May Have Had a Global Surface Ocean in the Past


Original Submission

Dawn's Orbit Around Ceres: A New Low 9 comments

Previously, NASA planned to lower the closest approach to Ceres of the Dawn spacecraft to around 120 miles (200 km) from 239 miles (385 km). Now, the XMO7 orbit will reach an altitude of just 22 miles (35 km) above Ceres. The images returned should be over 9000 times better than what Hubble can capture. This is the final orbit planned:

NASA's Dawn spacecraft is maneuvering to its lowest-ever orbit for a close-up examination of the inner solar system's only dwarf planet.

In early June, Dawn will reach its new, final orbit above Ceres. Soon after, it will begin collecting images and other science data from an unprecedented vantage point. This orbit will be less than 30 miles (50 kilometers) above the surface of Ceres -- 10 times closer than the spacecraft has ever been.

Dawn will collect gamma ray and neutron spectra, which help scientists understand variations in the chemical makeup of Ceres' uppermost layer. That very low orbit also will garner some of Dawn's closest images yet.

The transfer from Dawn's previous orbit to its final one is not as simple as making a lane change. Dawn's operations team worked for months to plot the course for this second extended mission of the veteran spacecraft, which is propelled by an ion engine. Engineers mapped out more than 45,000 possible trajectories before devising a plan that will allow the best science observations.

Previously: Dawn Mission Extended at Ceres

Related: Ceres May Have Had a Global Surface Ocean in the Past
Evidence of a Seasonal Water Cycle and Surface Changes Found on Ceres


Original Submission

Dawn's Orbit Around Ceres: First Images 3 comments

The Dawn spacecraft has entered its lowest-ever orbit around Ceres:

Dawn entered orbit around 1 Ceres on March 6, 2015. Up until this year, Dawn's orbits brought it no closer than 483 kilometers (300 miles) from the rock's surface. The complicated process of entering the new 27-hour, 13-minute orbit around the asteroid began on April 16th, when NASA engineers instructed Dawn to fire its ion engines. The new orbit has a periapsis of less than 48 km above the pockmarked surface of Ceres and an apoapsis of 4,000 km.

[...] Attaining a low orbit around Ceres object is no mean feat, as the asteroid's gravitational field is lumpy due to the asteroid's uneven composition. NASA engineers looked at over 45,000 possible trajectories before settling on the solution. A lower orbit will allow researchers to map Ceres's gravitational field and hence its internal mass distribution. Surprises may be in store, though: Dawn's reaction wheels failed earlier this year, so it now uses its hydrazine-fueled thrusters to control its orientation in space.

[...] We can enjoy the final closeups of Ceres before Dawn falls silent later this year. Then, the excitement in asteroid exploration will shift towards the arrival of the Japanese Aerospace Exploration Agency's Hayabusa-2 at 162173 Ryugu this July, as well as Osiris-REX's arrival at 101955 Bennu this August.

Check out Landslides Along Occator Crater's Rim and other recent images.

162173 Ryugu and 101955 Bennu.

Previously: Dawn Mission Extended at Ceres
Dawn's Orbit Around Ceres: A New Low

Related: Ceres May Have Had a Global Surface Ocean in the Past
Evidence of a Seasonal Water Cycle and Surface Changes Found on Ceres


Original Submission

Dawn Spacecraft Captures Closest-Ever Images of Ceres' Shiny Occator Crater

Dawn spacecraft captures new images of Ceres' Occator Crater

NASA's Dawn spacecraft has entered into its final planned orbital position from which it will study the dwarf planet Ceres, the lowest the probe has descended to the tiny world since it arrived in orbit on March 6, 2015.

The probe is powered by three xenon ion thrusters and it enter[ed] into its new orbit around the dwarf planet on June 6, 2018. Since then, the spacecraft has begun beaming back to Earth stunning new and closer images of this tiny worldlet.

One of Dawn's targets is Occator Crater. While the name might not ring a bell even among space enthusiasts, the "bright spots" contained within the crater should. These deposits are thought to be salt from briny water that erupted from the dwarf planet's surface before sublimating. It was found that the bright regions were comprised of sodium carbonate. On Earth, these salts are left behind when water evaporates.

Dawn was instructed to fire its ion engine—for what could be the last time—last week. By carrying out this maneuver, the probe flew closer to the dwarf planet's Cerealia Facula. This is the region of Occator Crater that contains a large deposit of sodium carbonate.

Perhaps more important than the cool photographs will be the data collected by the spacecraft's two other instruments, and particularly the Gamma Ray and Neutron Detector (GRaND).

Previously: Ceres Bright Spots Seen Closer Than Ever
Life On Ceres? Mysterious Changes in the Bright Spots Still Baffle Scientists
Bright Areas on Ceres Suggest Geologic Activity
Evidence of a Seasonal Water Cycle and Surface Changes Found on Ceres
Dawn's Orbit Around Ceres: A New Low
Dawn's Orbit Around Ceres: First Images


Original Submission

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  • (Score: 0, Troll) by cocaine overdose on Friday March 16 2018, @12:54PM (3 children)

    Space nerds find intergalactic ice, cream pants. Nearby, a herd of fat, virgin women complain that pre-mature ejaculation is unmanly, and that cumming to Ceres is sexual harassment. One notably voracious (in all respects possible) cattle of the flock points out that Playboy bunny polo [editor's note: bought at the goodwill] and should be fired.
    • (Score: 2) by Bot on Friday March 16 2018, @05:47PM (2 children)

      by Bot (3902) on Friday March 16 2018, @05:47PM (#653706) Journal

      Sorry but good trollish posts need to feature a gentle progression from normal to absurd or offensive, not a stream of consciousness summed up in the subject.

      The article is interesting because it confirms other studies where it was determined that indeed surface changes affect Ceres: the foam at the top of the beer glass tends to get slimmer with time.

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      Account abandoned.
      • (Score: 0) by Anonymous Coward on Saturday March 17 2018, @02:17AM (1 child)

        by Anonymous Coward on Saturday March 17 2018, @02:17AM (#653908)

        If you reply at a score of 2, then you prevent the parent post from getting folded out of sight when it is rated at -1

        • (Score: 2) by Bot on Saturday March 17 2018, @08:27PM

          by Bot (3902) on Saturday March 17 2018, @08:27PM (#654203) Journal

          Thank you I did not ever consider that, you mean I can unearth any troll? wow let me see past articles now.

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