Dawn: Journey to the Asteroid Belt

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Dawn: Evidence for Organic Material on Ceres

Postby bystander » Fri Feb 17, 2017 3:36 pm

Dawn Discovers Evidence for Organic Material on Ceres
NASA | JPL-Caltech | Dawn | 2017 Feb 16

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.

The discovery adds to the growing list of bodies in the solar system where organics have been found. Organic compounds have been found in certain meteorites as well as inferred from telescopic observations of several asteroids. Ceres shares many commonalities with meteorites rich in water and organics -- in particular, a meteorite group called carbonaceous chondrites. This discovery further strengthens the connection between Ceres, these meteorites and their parent bodies. ...

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. ...

SwRI scientist studies geology of Ceres to understand origin of organics
Southwest Research Institute | 2017 Feb 16

Dawn spacecraft data suggest organic materials are native to the dwarf planet

organic-concentrations-ceres.jpg

NASA’s Dawn spacecraft recently detected organic-rich areas on Ceres. Scientists evaluated the geology of the regions to conclude that the organics are most likely native to the dwarf planet. Data from the spacecraft suggest that the interior of Ceres is the source of these organic materials, as opposed to arriving via impacting asteroids or comets ...

Ceres is believed to have originated about 4.5 billion years ago at the dawn of our solar system. Studying its organics can help explain the origin, evolution, and distribution of organic species across the solar system. Data from Dawn’s visible and infrared mapping spectrometer show an unusually high concentration of organic matter close to the 50-km diameter Ernutet crater in the northern hemisphere of Ceres. The distribution and characteristics of the organics seem to preclude association with any single crater. The largest concentration appears to drape discontinuously across the southwest floor and rim of Ernutet and onto an older, highly degraded crater. Other organic-rich areas are scattered to the northwest. While other scientists looked at the distribution and spectra of the materials, Marchi focused on the geological settings. ...

Localized aliphatic organic material on the surface of Ceres - M. C. De Sanctis et al
Resolved Spectrophotometric Properties of the Ceres Surface from Dawn Framing Camera Images - S. E. Schröder et al
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Re: Dawn: Evidence for Organic Material on Ceres

Postby neufer » Fri Feb 17, 2017 4:02 pm

https://en.wikipedia.org/wiki/Ceres_(mythology) wrote:
<<In ancient Roman religion, Ceres) was a goddess of agriculture, grain crops, fertility and motherly relationships. She was originally the central deity in Rome's so-called plebeian or Aventine Triad, then was paired with her daughter Proserpina in what Romans described as "the Greek rites of Ceres". Her seven-day April festival of Cerealia included the popular Ludi Ceriales (Ceres' games). She was also honoured in the May lustratio of the fields at the Ambarvalia festival, at harvest-time, and during Roman marriages and funeral rites.>>
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MPS: Cryovolcanism on Dwarf Planet Ceres

Postby bystander » Mon Mar 06, 2017 9:47 pm

Cryovolcanism on Dwarf Planet Ceres
Max Planck Institute for Solar System Research | 2017 Mar 06

Highly resolved images of Occator crater show evidence for long-lasting geologic activity.

Among the most striking features on the surface of Ceres are the bright spots in the center of Occator crater which stood out already as NASA’s space probe Dawn approached the dwarf planet. Scientists under the leadership of the Max Planck Institute for Solar System Research (MPS) have now for the first time determined the age of this bright material, which consists mainly of deposits of special mineral salts. With about four million years only, these deposits are about 30 million years younger than the crater itself. This, as well as the distribution and nature of the bright material within the crater, suggests that Occator crater has been the scene of eruptive outbursts of subsurface brine over a long period and until almost recently. Ceres is thus the body closest to the Sun that shows cryovolcanic activity.

For nearly two years, the NASA’s space probe Dawn has been accompanying dwarf planet Ceres, which orbits the Sun within the asteroid belt between Mars and Jupiter. During the first part of the mission, the probe advanced to lower and lower orbits until between December 2015 and September 2016 only approximately 375 kilometers separated it from the surface. During this so-called Low Altitude Mapping Orbit the Dawn Framing Cameras produced highly resolved images of Ceres’ surface displaying a resolution of 35 meters per pixel. The Dawn Framing Cameras, Dawn’s scientific imaging system, were developed and built and are operated under the leadership of the MPS.

MPS researchers have now thoroughly investigated the complex geological structures that are shown in the detailed images of Occator crater. These structures include fractures, avalanches, and younger, smaller craters. "In these data, the origin and evolution of the crater as it presents itself today can be read more clearly than ever before”, says Andreas Nathues, Framing Camera Lead Investigator. Additional indications were provided by measurements of the infrared spectrometer VIR onboard Dawn. ...

Evolution of Occator Crater on (1) Ceres - A. Nathues et al
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Dawn Identifies Age of Ceres' Brightest Area

Postby bystander » Wed Mar 08, 2017 6:34 pm

Dawn Identifies Age of Ceres' Brightest Area
NASA | JPL-Caltech | Dawn | 2017 Mar 08

The bright central area of Ceres' Occator Crater, known as Cerealia Facula, is approximately 30 million years younger than the crater in which it lies, according to a new study in the Astronomical Journal. Scientists used data from NASA's Dawn spacecraft to analyze Occator's central dome in detail, concluding that this intriguing bright feature on the dwarf planet is only about 4 million years old -- quite recent in terms of geological history. ...

The new study supports earlier interpretations from the Dawn team that this reflective material -- comprising the brightest area on all of Ceres -- is made of carbonate salts, although it did not confirm a particular type of carbonate previously identified. The secondary, smaller bright areas of Occator, called Vinalia Faculae, are comprised of a mixture of carbonates and dark material, the study authors wrote.

New evidence also suggests that Occator's bright dome likely rose in a process that took place over a long period of time, rather than forming in a single event. They believe the initial trigger was the impact that dug out the crater itself, causing briny liquid to rise closer to the surface. Water and dissolved gases, such as carbon dioxide and methane, came up and created a vent system. These rising gases also could have forced carbonate-rich materials to ascend toward the surface. During this period, the bright material would have erupted through fractures, eventually forming the dome that we see today. ...
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Ice in Ceres' Shadowed Craters Linked to Tilt History

Postby bystander » Wed Mar 22, 2017 5:15 pm

Ice in Ceres' Shadowed Craters Linked to Tilt History
NASA | JPL-Caltech | Dawn | 2017 Mar 22

Dwarf planet Ceres may be hundreds of millions of miles from Jupiter, and even farther from Saturn, but the tremendous influence of gravity from these gas giants has an appreciable effect on Ceres' orientation. In a new study, researchers from NASA's Dawn mission calculate that the axial tilt of Ceres -- the angle at which it spins as it journeys around the sun -- varies widely over the course of about 24,500 years. Astronomers consider this to be a surprisingly short period of time for such dramatic deviations.

Changes in axial tilt, or "obliquity," over the history of Ceres are related to the larger question of where frozen water can be found on Ceres' surface, scientists report in the journal Geophysical Research Letters. Given conditions on Ceres, ice would only be able to survive at extremely cold temperatures -- for example, in areas that never see the sun. ...

Ceres's obliquity history and its implications for the permanently shadowed regions - A.I. Ermakov et al
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JPL: Ceres' Temporary Atmosphere Linked to Solar Activity

Postby bystander » Thu Apr 06, 2017 7:20 pm

Ceres' Temporary Atmosphere Linked to Solar Activity
NASA | JPL-Caltech | Dawn | 2017 Apr 06


NASA's Dawn spacecraft determined the hydrogen content of the upper yard,
or meter, of Ceres' surface. Blue indicates where hydrogen content is higher,
near the poles, while red indicates lower content at lower latitudes.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Scientists have long thought that Ceres may have a very weak, transient atmosphere, but mysteries lingered about its origin and why it's not always present. Now, researchers suggest that this temporary atmosphere appears to be related to the behavior of the sun, rather than Ceres' proximity to the sun. The study was conducted by scientists from NASA's Dawn mission and others who previously identified water vapor at Ceres using other observatories. ...

Ceres is the largest object in the asteroid belt that lies between Mars and Jupiter. When energetic particles from the sun hit exposed ice and ice near the surface of the dwarf planet, it transfers energy to the water molecules as they collide. This frees the water molecules from the ground, allowing them to escape and create a tenuous atmosphere that may last for a week or so. ...

Before Dawn arrived in orbit at Ceres in 2015, evidence for an atmosphere had been detected by some observatories at certain times, but not others, suggesting that it is a transient phenomenon. ...

The Dependence of the Cerean Exosphere on Solar Energetic Particle Events - M. N. Villarreal et al
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GA Tech: Landslides on Ceres Reflect Hidden Ice

Postby bystander » Wed Apr 19, 2017 3:46 pm

Landslides on Ceres Reflect Hidden Ice
Georgia Institute of Technology | 2017 Apr 18

Image
Type II features are the most common of Ceres’ landslides and look similar to deposits
left by avalanches on Earth. This one also looks similar to TV's Bart Simpson.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA, taken by Dawn Framing Camera

Massive landslides, similar to those found on Earth, are occurring on the asteroid Ceres. That’s according to a new study led by the Georgia Institute of Technology, adding to the growing evidence that Ceres retains a significant amount of water ice.

The study is published in the journal Nature Geoscience. It used data from NASA’s Dawn spacecraft to identify three different types of landslides, or flow features, on the Texas-sized asteroid.

Type I are relatively round, large and have thick "toes" at their ends. They look similar to rock glaciers and icy landslides in Earth’s arctic. Type I landslides are mostly found at high latitudes, which is also where the most ice is thought to reside near Ceres' surface.

Type II features are the most common of Ceres’ landslides and look similar to deposits left by avalanches on Earth. They are thinner and longer than Type I and found at mid-latitudes. The authors affectionately call one such Type II landslide "Bart" because of its resemblance to the elongated head of Bart Simpson from TV's "The Simpsons."

Ceres' Type III features appear to form when some of the ice is melted during impact events. These landslides at low latitudes are always found coming from large-impact craters. ...

Landslides on Ceres Reflect Ice Content
NASA | JPL-Caltech | Dawn | 2017 Apr 19

Geomorphological Evidence for Ground Ice on Dwarf Planet Ceres - Britney E. Schmidt et al
Last edited by bystander on Thu Apr 20, 2017 3:30 pm, edited 1 time in total.
Reason: Added NASA/JPL-Caltech/Dawn article links
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Re: GA Tech: Landslides on Ceres Reflect Hidden Ice

Postby neufer » Wed Apr 19, 2017 4:38 pm

Image
Type II features are the most common of Ceres’ landslides and look similar to deposits
left by avalanches on Earth. This one also looks similar to TV's Bart Simpson.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA, taken by Dawn Framing Camera

One can still see Homer's fingerprints on Bart's neck from years ago.


.
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Dawn: Movie Shows Ceres at Opposition from Sun

Postby bystander » Tue May 16, 2017 5:24 pm

Movie Shows Ceres at Opposition from Sun
NASA | JPL-Caltech | Dawn | 2017 May 16

PIA21405[1].gif
Ceres During 'Opposition Surge'
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

NASA's Dawn spacecraft successfully observed Ceres at opposition on April 29, taking images from a position exactly between the sun and Ceres’ surface. Mission specialists had carefully maneuvered Dawn into a special orbit so that the spacecraft could view Occator Crater, which contains the brightest area of Ceres, from this new perspective.

A new movie shows these opposition images, with contrast enhanced to highlight brightness differences. The bright spots of Occator stand out particularly well on an otherwise relatively bland surface. Dawn took these images from an altitude of about 12,000 miles (20,000 kilometers).

Based on data from ground-based telescopes and spacecraft that previously viewed planetary bodies at opposition, scientists correctly predicted that Ceres would appear brighter from this opposition configuration. This increase in brightness, or "surge," relates the size of the grains of material on the surface, as well as the porosity of those materials. ...
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Dawn Mission Celebrates 10 Years in Space

Postby bystander » Wed Sep 27, 2017 9:47 pm

Dawn Mission Celebrates 10 Years in Space
NASA | JPL-Caltech | Dawn | 2017 Sep 27

Click to play embedded YouTube video.
Fly Over Ceres with the Dawn Spacecraft (360 video)
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Ten years ago, NASA's Dawn spacecraft set sail for the two most massive bodies in the asteroid belt between Mars and Jupiter: giant asteroid Vesta and dwarf planet Ceres. The mission was designed to deliver new knowledge about these small but intricate worlds, which hold clues to the formation of planets in our solar system. ...

Since its launch on Sept. 27, 2007, Dawn has achieved numerous technical and scientific feats while traveling 4 billion miles (6 billion kilometers). It is the only spacecraft to orbit two extraterrestrial solar system targets. It is also the only spacecraft to orbit a dwarf planet, a milestone it achieved when in entered orbit around Ceres on March 6, 2015. The spacecraft's ion propulsion system enabled Dawn to study each of these worlds from a variety of vantage points and altitudes, creating an impressive scrapbook of 88,000 photos. Additionally, Dawn's suite of instruments enabled it to take a variety of other measurements of Vesta and Ceres, revealing the contrasting compositions and internal structures of these two bodies. ...
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Dawn Mission Extended at Ceres

Postby bystander » Sat Oct 21, 2017 3:35 pm

Dawn Mission Extended at Ceres
NASA | JPL-Caltech | Dawn | 2017 Oct 19

NASA has authorized a second extension of the Dawn mission at Ceres, the largest object in the asteroid belt between Mars and Jupiter. During this extension, the spacecraft will descend to lower altitudes than ever before at the dwarf planet, which it has been orbiting since March 2015. The spacecraft will continue at Ceres for the remainder of its science investigation and will remain in a stable orbit indefinitely after its hydrazine fuel runs out.

The Dawn flight team is studying ways to maneuver Dawn into a new elliptical orbit, which may take the spacecraft to less than 120 miles (200 kilometers) from the surface of Ceres at closest approach. Previously, Dawn's lowest altitude was 240 miles (385 kilometers).

A priority of the second Ceres mission extension is collecting data with Dawn's gamma ray and neutron spectrometer, which measures the number and energy of gamma rays and neutrons. This information is important for understanding the composition of Ceres' uppermost layer and how much ice it contains.

The spacecraft also will take visible-light images of Ceres' surface geology with its camera, as well as measurements of Ceres' mineralogy with its visible and infrared mapping spectrometer.

The extended mission at Ceres additionally allows Dawn to be in orbit while the dwarf planet goes through perihelion, its closest approach to the Sun, which will occur in April 2018. At closer proximity to the Sun, more ice on Ceres' surface may turn to water vapor, which may in turn contribute to the weak transient atmosphere detected by the European Space Agency's Herschel Space Observatory before Dawn's arrival. Building on Dawn's findings, the team has hypothesized that water vapor may be produced in part from energetic particles from the Sun interacting with ice in Ceres' shallow surface.Scientists will combine data from ground-based observatories with Dawn's observations to further study these phenomena as Ceres approaches perihelion. ...
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Re: Dawn Mission Extended at Ceres

Postby neufer » Sat Oct 21, 2017 4:35 pm

bystander wrote:Dawn Mission Extended at Ceres
NASA | JPL-Caltech | Dawn | 2017 Oct 19
The extended mission at Ceres additionally allows Dawn to be in orbit while the dwarf planet goes through perihelion, its closest approach to the Sun, which will occur in April 2018. At closer proximity to the Sun, more ice on Ceres' surface may turn to water vapor, which may in turn contribute to the weak transient atmosphere detected by the European Space Agency's Herschel Space Observatory before Dawn's arrival. Building on Dawn's findings, the team has hypothesized that water vapor may be produced in part from energetic particles from the Sun interacting with ice in Ceres' shallow surface.Scientists will combine data from ground-based observatories with Dawn's observations to further study these phenomena as Ceres approaches perihelion. ...
https://en.wikipedia.org/wiki/Ceres_(dwarf_planet) wrote:
<<Ceres [obliquity/Axial tilt ~4°]follows an orbit between Mars and Jupiter, within the asteroid belt, with a period of 4.6 Earth years. The orbit is moderately inclined (i = 10.6° compared to 7° for Mercury and 17° for Pluto) and moderately eccentric (e = 0.08 compared to 0.09 for Mars). When Ceres has an opposition near the [2.5577 AU : Max surface temperature ~ -38° C] perihelion, it can reach a visual magnitude of +6.7. This is generally regarded as too dim to be seen with the naked eye, but under exceptional viewing conditions a very sharp-sighted person may be able to see it. The only other asteroids that can reach a similarly bright magnitude are 4 Vesta, and, during rare oppositions near perihelion, 2 Pallas and 7 Iris. It can thus be seen with binoculars whenever it is above the horizon of a fully dark sky.
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Dawn Finds Possible Ancient Ocean Remnants at Ceres

Postby bystander » Thu Oct 26, 2017 5:21 pm

Dawn Finds Possible Ancient Ocean Remnants at Ceres
NASA | JPL-Caltech | Dawn | 2017 Oct 26

PIA22083-16-640x350[1].gif

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. ...

The first of the two studies ... used shape and gravity data measurements from the Dawn mission to determine the internal structure and composition of Ceres. The measurements came from observing the spacecraft's motions with NASA's Deep Space Network to track small changes in the spacecraft's orbit. ...

The second study ... investigated the strength and composition of Ceres' crust and deeper interior by studying the dwarf planet's topography. ...

Constraints on Ceres’ Internal Structure and Evolution from
Its Shape and Gravity Measured by the Dawn Spacecraft
- A. I. Ermakov et al
The Interior Structure of Ceres as Revealed by Surface Topography - Roger R. Fu et al
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Dawn Explores Ceres' Interior Evolution

Postby bystander » Fri Nov 10, 2017 2:22 pm

Dawn Explores Ceres' Interior Evolution
NASA | JPL-Caltech | Dawn | 2017 Nov 09

Click to view full size image 1 or image 2
This image made with data from NASA's Dawn spacecraft shows
pit chains on dwarf planet Ceres called Samhain Catenae.
Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Surface features on Ceres -- the largest world between Mars and Jupiter -- and its interior evolution have a closer relationship than one might think.

A recent study, published in Geophysical Research Letters, analyzed Ceres' surface features to reveal clues about the dwarf planet's interior evolution. Specifically, the study explored linear features -- the chains of pits and small, secondary craters common on Ceres.

The findings align with the idea that, hundreds of millions (up to a billion) years ago, materials beneath Ceres' surface pushed upward toward the exterior, creating fractures in the crust.

"As this material moved upward from underneath Ceres' surface, portions of Ceres' outer layer were pulled apart, forming the fractures," said Jennifer Scully, lead study author and associate of the Dawn science team at NASA's Jet Propulsion Laboratory in Pasadena, California.

The indication of upwelling material under Ceres' surface allows for another perspective in establishing how the dwarf planet may have evolved. ...

Evidence for the Interior Evolution of Ceres from Geologic Analysis of Fractures - J. E. C. Scully et al
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