Dawn: Journey to the Asteroid Belt

[bystander]

Vesta, Tell Us About the Childhood of the Solar System
Italian National Institute for Astrophysics (INAF) | 2018 Oct 05

Artist view of a young Solar System -- Credit: NASA/FUSE/Lynette Cook

---

Investigating the earliest and least known phases of the history of the Solar System, when the young Sun was still enveloped by the disk of gas and dust where its planets began to form, is probably one of the most complex challenges in modern planetary science. The celestial bodies formed at the time that survived intact to now are few and in the majority of cases their "memory" of the ancient processes that marked the birth of the Solar System has been canceled or otherwise altered by the environments to which they were exposed or by the later events that shaped their evolution.

For decades the asteroid Vesta has been one of our most reliable witnesses of this ancient past: in particular, the survival of its thin volcanic crust to impacts provided a powerful constraint to how violent the Solar System was in its youth. Recently, however, the data collected by NASA’s Dawn mission, which is now coming to its end after successfully exploring also asteroid Ceres, raised the possibility that Vesta’s memory may not be as good as we thought.

On one hand, the craters produced by impacts on its surface in the last 4 billion years seem to have erased the traces of the much older ones formed in the circumsolar disk. On the other hand, the possible greater thickness of its crust with respect to what was suggested by the HED meteorites (which the Dawn mission confirmed being Vesta’s crust fragments that landed on Earth) makes the information provided by the crust survival very vague. ...

The Late Accretion and Erosion of Vesta’s Crust Recorded by Eucrites and Diogenites as an
Astrochemical Window into the Formation of Jupiter and the Early Evolution of the Solar System ~ D. Turrini et al

• Icarus 311:224 (Sept 2018) DOI: 10.1016/j.icarus.2018.04.004
  arXiv.org > astro-ph > arXiv:1804.06150 > 17 Apr 2018

[bystander]

Polar Wandering on Dwarf Planet Ceres Revealed
Planetary Science Institute | 2018 Oct 08

Ceres -- Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

---

Dwarf planet Ceres experienced an indirect polar reorientation of approximately 36 degrees, a new paper by Planetary Science Institute Senior Scientist Pasquale Tricarico says.

Using data from NASA’s Dawn mission, Tricarico determined the magnitude of the reorientation with three independent and corroborating lines of evidence. Global Gravity Inversion, from a paper Tricarico published in 2013, helped determine the density variations of Ceres, especially in the crust. This is what was used to find the equatorial density anomaly. Statistical analysis of topography was used for ridge analysis and the paleo-pole. And for matching the crustal fractures, a well-proven method by Matsuyama and Nimmo was used.

“The most surprising aspect of this paper is to me the observation that the pole of Ceres must have followed an indirect path to its current pole. A multi-step reorientation could mean that the equatorial density anomaly was still evolving during the reorientation, and this could be because the crust and mantle were weakly rotationally coupled, allowing the crust to start reorienting while the mantle would lag behind,” Tricarico said. “If crust and mantle are allowed to shift with respect to one another, that could point to a layer of reduced friction between crust and mantle, and one of the possible mechanisms to reduce friction could be an ancient water ocean beneath the crust.”

True Polar Wander of Ceres Due to Heterogeneous Crustal Density ~ P. Tricarico

• Nature Geoscience (online 08 Oct 2018) DOI: 10.1038/s41561-018-0232-3

[bystander]

Dawn Mission to Asteroid Belt Comes to End
NASA | JPL-Caltech | Dawn | 2018 Nov 01

Click to play embedded YouTube video.

NASA's Dawn spacecraft has gone silent, ending a historic mission that studied time capsules from the solar system's earliest chapter.

Dawn missed scheduled communications sessions with NASA's Deep Space Network on Wednesday, Oct. 31, and Thursday, Nov. 1. After the flight team eliminated other possible causes for the missed communications, mission managers concluded that the spacecraft finally ran out of hydrazine, the fuel that enables the spacecraft to control its pointing. Dawn can no longer keep its antennae trained on Earth to communicate with mission control or turn its solar panels to the Sun to recharge. ...

Dawn launched in 2007 on a journey that put about 4.3 billion miles (6.9 billion kilometers) on its odometer. Propelled by ion engines, the spacecraft achieved many firsts along the way. In 2011, when Dawn arrived at Vesta, the second largest world in the main asteroid belt, the spacecraft became the first to orbit a body in the region between Mars and Jupiter. In 2015, when Dawn went into orbit around Ceres, a dwarf planet that is also the largest world in the asteroid belt, the mission became the first to visit a dwarf planet and go into orbit around two destinations beyond Earth. ...

Science Operations End for NASA's Dawn Spacecraft
Planetary Science Institute | 2018 Nov 01

Dawn Falls Silent -- A Successful Mission Comes to an End
German Aerospace Center (DLR) | 2018 Nov 09

[bystander]

Team Finds Evidence for Carbon-Rich Surface on Ceres
Southwest Research Institute | 2018 Dec 10

NASA’s Dawn spacecraft captured this 12.5-mile-across close-up of the central peak of the 99-mile-wide Urvara impact crater on Ceres. The remarkable 6,500-foot central ridge is made from materials uplifted from depth, arising from terrains enriched with products of rock-water interactions, such as carbonates. (Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

---

A team led by Southwest Research Institute has concluded that the surface of dwarf planet Ceres is rich in organic matter. Data from NASA’s Dawn spacecraft indicate that Ceres’ surface may contain several times the concentration of carbon than is present in the most carbon-rich, primitive meteorites found on Earth.

“Ceres is like a chemical factory,” said SwRI’s Dr. Simone Marchi, a principal scientist who was the lead author of research published in Nature Astronomy today. “Among inner solar system bodies, Ceres has a unique mineralogy, which appears to contain up to 20 percent carbon by mass in its near surface. Our analysis shows that carbon-rich compounds are intimately mixed with products of rock-water interactions, such as clays.”

Ceres is believed to have originated about 4.6 billion years ago at the dawn of our solar system. Dawn data previously revealed the presence of water and other volatiles, such as ammonium derived from ammonia, and now a high concentration of carbon. This chemistry suggests Ceres formed in a cold environment, perhaps outside the orbit of Jupiter. An ensuing shakeup in the orbits of the large planets would have pushed Ceres to its current location in the main asteroid belt, between the orbits of Mars and Jupiter.

“With these findings, Ceres has gained a pivotal role in assessing the origin, evolution and distribution of organic species across the inner solar system,” Marchi said. “One has to wonder about how this world may have driven organic chemistry pathways, and how these processes may have affected the make-up of larger planets like the Earth.” ...

An Aqueously Altered Carbon-Rich Ceres ~ Simone Marchi et al

• Nature Astronomy (online 10 Dec 2018) DOI: 10.1038/s41550-018-0656-0

[bystander]

Ahuna Mons on Ceres: A New and Unusual Type of Volcanic Activity
German Aerospace Center (DLR) | 2019 Jun 11

Ahuna Mons on Ceres ~ Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

---

When scientists first saw this structure on the images taken by their camera on the Dawn space probe, they could hardly believe their eyes: from the crater-strewn surface of the dwarf planet Ceres rises an even, smooth and steep-sided mountain, towering over 4,000 metres high. It is the highest mountain on the thousand kilometre-diameter, almost spherical dwarf planet, and one of the most remarkable structures in the entire Solar System. A study involving scientists from the German Aerospace Centre (DLR) has now solved the mystery of how Ahuna Mons, as the mountain is called, was formed, using gravity measurements and investigations of the geometrical form of Ceres. A bubble made of a mixture of salt water, mud and rock rose from within the dwarf planet. The bubble pushed the ice-rich crust upwards, and at a structural weak point the muddy substance, comprising salts and hydrogenated silicates, was pushed to the surface, solidified in the cold of space, in the absence of any atmosphere, and piled up to form a mountain. Ahuna Mons is an enormous mud volcano.

"In this region, the interior of Ceres is not solid and rigid, but moving and at least partially fluid," explains Wladimir Neumann ... "This ‘bubble’ that formed in the mantle of Ceres beneath Ahuna Mons is a mixture of saline water and rock components." ... Ceres is a dwarf planet on the outer edge of the asteroid belt. The largest body in this zone between Mars and Jupiter, populated by minor planets, consists primarily of siliceous rocks, but also, to a considerable extent, of ice and presumably layers of water. The scientists are working on the assumption that up to a quarter of the mass of Ceres is ice or water – an even higher proportion than Earth's reserves of freshwater and ice. ...

The interior of Ceres is not homogeneous, but rather, to use geologists' terminology, partially 'differentiated', which means that after the formation of the celestial body, its components have become segregated and separated, at least to a certain degree. Components with a higher proportion of heavy elements, such as magnesium or iron, sank into the centre of the body, while lighter components like rocks with a high aluminium silicate or water content rose. Bubbles and domes are being created due to the heat that is still being generated today, four-and-a-half billion years after the formation of Ceres, by the decay of radioactive elements. The presence of liquids has influenced the inner formation differently to the usual rocky planets. As a result of their lower specific weight compared to the surrounding materials, these bubbles rise and press against the crust from below. The kilometre-high domes deform the crust, and once they break through it, fluid material penetrates the surface. ...

Slurry Extrusion on Ceres from a Convective Mud-bearing Mantle ~ Ottaviano Ruesch et al

• Nature Geoscience (online 10 Jun 2019) DOI: 10.1038/s41561-019-0378-7

[bystander]

Mystery Solved: Bright Areas on Ceres Come From Salty Water Below
NASA | JPL-Caltech | Dawn | 2020 Aug 10

Data from NASA's recent Dawn mission answers two long-unresolved questions: Is there liquid inside Ceres, and how long ago was the dwarf planet geologically active?

This mosaic image uses false color to highlight the recently exposed brine, or salty liquids, that were pushed up from a deep reservoir under Ceres' crust. In this view of a region of Occator Crater, they appear reddish. Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

---

NASA's Dawn spacecraft gave scientists extraordinary close-up views of the dwarf planet Ceres, which lies in the main asteroid belt between Mars and Jupiter. By the time the mission ended in October 2018, the orbiter had dipped to less than 22 miles (35 kilometers) above the surface, revealing crisp details of the mysterious bright regions Ceres had become known for.

Scientists had figured out that the bright areas were deposits made mostly of sodium carbonate - a compound of sodium, carbon, and oxygen. They likely came from liquid that percolated up to the surface and evaporated, leaving behind a highly reflective salt crust. But what they hadn't yet determined was where that liquid came from.

By analyzing data collected near the end of the mission, Dawn scientists have concluded that the liquid came from a deep reservoir of brine, or salt-enriched water. By studying Ceres' gravity, scientists learned more about the dwarf planet's internal structure and were able to determine that the brine reservoir is about 25 miles (40 kilometers) deep and hundreds of miles wide.

Ceres doesn't benefit from internal heating generated by gravitational interactions with a large planet, as is the case for some of the icy moons of the outer solar system. But the new research, which focuses on Ceres' 57-mile-wide (92-kilometer-wide) Occator Crater - home to the most extensive bright areas - confirms that Ceres is a water-rich world like these other icy bodies. ...

Bright Hydrothermal Deposits on Dwarf Planet Ceres Have a Style All Their Own
Universities Space Research Association | 2020 Aug 10

Cryovolcanism on Ceres
Max Planck Institute for Solar System Research | 2020 Aug 10

A revealing last glance at Ceres
Nature Astronomy | Editorial | 2020 Aug 10

Recent Cryovolcanic Activity at Occator Crater on Ceres ~ A. Nathues et al

• Nature Astronomy 4(8):794 (Aug 2020) DOI: 10.1038/s41550-020-1146-8

Impact-Driven Mobilization of Deep Crustal Brines on Dwarf Planet Ceres ~ C. A. Raymond et al

• Nature Astronomy 4(8):741 (Aug 2020) DOI: 10.1038/s41550-020-1168-2

Evidence of Non-Uniform Crust of Ceres from Dawn's High-Resolution Gravity Data ~ R. S. Park et al

• Nature Astronomy 4(8):748 (Aug 2020) DOI: 10.1038/s41550-020-1019-1

Fresh Emplacement of Hydrated Sodium Chloride on Ceres from Ascending Salty Fluids ~ M. C. De Sanctis et al

• Nature Astronomy 4(8):786 (Aug 2020) DOI: 10.1038/s41550-020-1138-8

Impact Heat Driven Volatile Redistribution at Occator Crater
on Ceres as a Comparative Planetary Process ~ P. Schenk et al

• Nature Communications 11:3679 (10 Aug 2020) DOI: 10.1038/s41467-020-17184-7

The Varied Sources of Faculae-Forming Brines in Ceres' Occator
Crater Emplaced via Hydrothermal Brine Effusion ~ J. E. C. Scully et al

• Nature Communications 11:3680 (10 Aug 2020) DOI: 10.1038/s41467-020-15973-8

Post-Impact Cryo-Hydrologic Formation of Small Mounds and Hills in Ceres's Occator Crater ~ B. E. Schmidt et al

• Nature Geoscience (online 10 Aug 2020) DOI: 10.1038/s41561-020-0581-6

[neufer]

Mystery Solved: Bright Areas on Ceres Come From Salty Water Below
NASA | JPL-Caltech | Dawn | 2020 Aug 10

NASA's Dawn spacecraft gave scientists extraordinary close-up views of the dwarf planet Ceres, which lies in the main asteroid belt between Mars and Jupiter. By the time the mission ended in October 2018, the orbiter had dipped to less than 35 kilometers above the surface, revealing crisp details of the mysterious bright regions Ceres had become known for. Scientists had figured out that the bright areas were deposits made mostly of sodium carbonate - a compound of sodium, carbon, and oxygen. They likely came from liquid that percolated up to the surface and evaporated, leaving behind a highly reflective salt crust. But what they hadn't yet determined was where that liquid came from. By analyzing data collected near the end of the mission, Dawn scientists have concluded that the liquid came from a deep reservoir of brine, or salt-enriched water. By studying Ceres' gravity, scientists learned more about the dwarf planet's internal structure and were able to determine that the brine reservoir is about 40 kilometers deep and hundreds of kilometers wide. Ceres doesn't benefit from internal heating generated by gravitational interactions with a large planet, as is the case for some of the icy moons of the outer solar system. But the new research, which focuses on Ceres' 92-kilometer-wide Occator Crater - home to the most extensive bright areas - confirms that Ceres is a water-rich world like these other icy bodies. ...

Terraform Ceres with Sea-Monkeys and leave a small 5G monolith.

.
<<Sea-Monkeys are a novelty aquarium pet, a type of brine shrimp that undergoes cryptobiosis. Developed in the United States in 1957, by Harold von Braunhut, the shrimp are intended to be added to water, and almost always come bundled in a 3-pouch kit with other required pouches and instructions. Sometimes a small tank and/or supplementary pouches may also be included with the product. The product was heavily marketed in the 1960s and 70s, especially in comic books, and remains a presence in popular culture.

The animals sold as Sea-Monkeys are claimed to be an artificial breed known as Artemia NYOS, formed by hybridising different species of Artemia. They are also claimed to live longer and grow bigger than ordinary brine shrimp, however there are no references to these claims outside marketing material from the manufacturer. They undergo cryptobiosis or anhydrobiosis, a condition of apparent lifelessness which allows them to survive the desiccation of the temporary pools in which they live.

Astronaut John Glenn took Sea-Monkeys into space on October 29, 1998, aboard Space Shuttle Discovery during mission STS-95. After nine days in space, they were returned to Earth, and hatched eight weeks later apparently unaffected by their travels. However, earlier experiments on Apollo 16 and Apollo 17, where the eggs (along with other biological systems in a state of rest, such as spores, seeds and cysts) traveled to the Moon and back and were exposed to significant cosmic rays, observed a high sensitivity to cosmic radiation in the Artemia salina eggs; only 10% of the embryos which were induced to develop from eggs survived to adulthood. The most common mutations found during the developmental stages of the irradiated eggs were deformations of the abdomen or deformations on the swimming appendages and naupliar eye of the nauplius.>>