Tag: asteroids

New Horizons wants the public to help pick a nickname for its next target

9:12 pm

The New Horizons science team is asking the public to submit suggestions for a good nickname for 2014 MU69, the Kuiper Belt object that the spacecraft will fly past on January 1, 2019.

The naming campaign is hosted by the SETI Institute of Mountain View, California, and led by Mark Showalter, an institute fellow and member of the New Horizons science team. The website includes names currently under consideration; site visitors can vote for their favorites or nominate names they think should be added to the ballot. “The campaign is open to everyone,” Showalter said. “We are hoping that somebody out there proposes the perfect, inspiring name for MU69.”

The campaign will close at 3 p.m. EST/noon PST on Dec. 1. NASA and the New Horizons team will review the top vote-getters and announce their selection in early January.

The press release says that a more formal name for the object will be submitted to the IAU after the fly-by.

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An ancient ocean on Ceres?

10:03 am

Two studies released today by the Dawn science team suggest that the spacecraft has found evidence that an ancient ocean once existed on Ceres.

In one study, the Dawn team found Ceres’ crust is a mixture of ice, salts and hydrated materials that were subjected to past and possibly recent geologic activity, and 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.

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Rosetta’s capture of a dust jet from Comet 67P/C-G

9:26 am

Dust jet on Comet 67P/C-G

Cool image time! The Rosetta science team has released images and data gathered in July 2016 when the spacecraft successfully observed a dust outburst erupting from Comet 67P/C-G’s surface. The image on the right, slightly reduced in resolution, shows that outburst.

When the Sun rose over the Imhotep region of Rosetta’s comet on July 3, 2016, everything was just right: As the surface warmed and began to emit dust into space, Rosetta’s trajectory led the probe right through the cloud. At the same time, the view of the scientific camera system OSIRIS coincidentally focused precisely on the surface region of the comet from which the fountain originated. A total of five instruments on board the probe were able to document the outburst in the following hours.

As should be expected, the results did not match the models or predictions. The jet, instigated by water-ice just below the surface turning into gas when heated by the Sun, was much dustier than predicted. They have theories as to why, but it appears that no one likes these theories that much.

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The first large object identified coming from interstellar space

6:38 pm

Astronomers think they have spotted the first large object to come from beyond the solar system.

Based on its apparent brightness, dynamicist Bill Gray calculates that it would have a diameter of about 160 meters (525 feet) if it were a rock with a surface reflectivity of 10%. “It went past the Sun really fast,” Gray notes, “and may not have had time to heat up enough to break apart.”

Now it’s headed out of the solar system, never to return. It passed closest to Earth on October 14th at a distance of about 24,000,000 km (15,000,000 miles), and astronomers worldwide have been tracking it in the hopes of divining its true nature — especially whether it’s displaying any cometary activity.

…According to Gray, Comet PanSTARRS appears to have entered the solar system from the direction of the constellation Lyra, within a couple of degrees of right ascension 18h 50m, declination +35° 13′. That’s tantalizingly close to Vega — and eerily reminiscent of the plot of the movie Contact — but its exact path doesn’t (yet) appear to link any particular star.

This object entered the solar system moving at 26 km (16 miles) per second. At that speed, in 10 million years it would traverse 8,200,000,000,000,000 km — more than 850 light-years.

Reminds me of a really good science fiction novel I read recently. They should keep an eye on it for as long as they can, just in case it suddenly changes course and settles into a more circular orbit around the Sun. In the unlikely case it does that, it might just be the biggest discovery in history.

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NASA extends Dawn’s mission orbiting Ceres

2:11 pm

NASA has decided to extend the Dawn mission again, but have that extension remain in orbit around Ceres.

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.

They aim to get as close as 120 miles of the surface during this extension, half as close as the previous closest approach.

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Astronomers reduce estimate of still undiscovered dangerous asteroids

11:49 am

Astronomers have now reduced [pdf] their estimate of the number of still undiscovered dangerous Near Earth Asteroids (NEAs) that could impact the Earth from 100 to less than 40.

Observers have been cataloging potentially hazardous asteroids for decades. Based on the number of finds, the area of sky explored, and the limiting brightness our telescopes and cameras can reach, researchers can estimate what fraction of the NEA population has been detected so far and how many more objects lurk undiscovered. Harris has published numerous such estimates over the years. Recently he realized that his estimates have been plagued by a seemingly innocuous but nonetheless consequential round-off error. Once corrected, the estimated number of large (diameter > 1 kilometer) NEAs remaining to be discovered decreases from more than 100 to less than 40.

To put it mildly, there is a lot of uncertainty here. This also reminds me of the cavers’ joke question: “How many miles of unexplored passages does this cave have?”

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Nearby asteroid orbits both the Earth and the Sun

11:42 am

Worlds without end: Astronomers have determined that a recently discovered object with a weird solar orbit that also has it loop around the Earth each year is an asteroid, not space junk.

The asteroid is dubbed 2016 HO3. What is most interesting about this story to me however was this tidbit:

“Of the near-Earth objects we know of, these types of objects would be the easiest to reach, so they could potentially make suitable targets for exploration,” said Veillet, director of the LBT Observatory. “With its binocular arrangement of two 8.4-meter mirrors, coupled with a very efficient pair of imagers and spectrographs like MODS, LBT is ideally suited to the characterization of these Earth’s companions.”

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Astronomers discover ring around object beyond Neptune

10:14 am

Observations of the trans-Neptunian object Haumea has revealed that not only is is shaped like a football due to its fast rotation, it has a ring.

Haumea is an interesting object: it rotates around the Sun in an elliptic orbit which takes it 284 years to complete (it presently lies fifty times further from the Sun than the Earth), and it takes 3.9 hours to rotate around its axis, much less than any other body measuring more than a hundred kilometers long in the entire Solar System. This rotational speed causes it to flatten out, giving it an ellipsoid shape similar to a rugby ball. The recently published data reveal that Haumea measures 2.320 kilometers in its largest axis – almost the same as Pluto – but lacks the global atmosphere that Pluto has.

“One of the most interesting and unexpected findings was the discovery of a ring around Haumea. Until a few years ago we only knew of the existence of rings around the giant planets; then, recently, our team discovered that two small bodies situated between Jupiter and Neptune, belonging to a group called centaurs, have dense rings around them, which came as a big surprise. Now we have discovered that bodies even farther away than the centaurs, bigger and with very different general characteristics, can also have rings,” says Pablo Santos-Sanz, another member of the IAA-CSIC team.

The more we see of these distant objects beyond Neptune the more I suspect that they are going to be puffy, not very dense, and surrounded by miscellaneous objects. The gravity and environment that far from the Sun simply allows them to not coalesce as happened in the inner solar system.

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Hubble spots most distance active comet yet

11:13 am

Comet C/2017 K2

Using the Hubble Space Telescope astronomers have imaged a comet that is sublimating material at a distance from the Sun farther than any previously known comet, out beyond Saturn.

“K2 is so far from the Sun and so cold, we know for sure that the activity — all the fuzzy stuff making it look like a comet — is not produced, as in other comets, by the evaporation of water ice,” said lead researcher David Jewitt of the University of California, Los Angeles. “Instead, we think the activity is due to the sublimation [a solid changing directly into a gas] of super-volatiles as K2 makes its maiden entry into the solar system’s planetary zone. That’s why it’s special. This comet is so far away and so incredibly cold that water ice there is frozen like a rock.”

Based on the Hubble observations of K2’s coma, Jewitt suggests that sunlight is heating frozen volatile gases – such as oxygen, nitrogen, carbon dioxide, and carbon monoxide – that coat the comet’s frigid surface. These icy volatiles lift off from the comet and release dust, forming the coma. Past studies of the composition of comets near the Sun have revealed the same mixture of volatile ices.

The significance here is that by studying the comet’s activity scientists will be able to identify some of these volatile gases, which in turn will tell them something about the make-up of the outermost fringes of the solar system.

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One last image from Rosetta

8:17 am

Rosetta's last image

Engineers reviewing the last bits of telemetry that was transmitted back to Earth by Rosetta just before it crashed on Comet 67P/C-G have discovered one last image of the comet’s surface.

That image is on the right. It is slightly blurred because of the limitations of Rosetta’s camera at this short range, and the incompleteness of the data received.

The image covers an area about a meter across, with a resolution of about two millimeters per pixel.

I imagine this surface is relatively soft, since the gravity holding the comet together is so slight. If you wanted to dig down, you would find it easy digging.

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Hubble finds binary asteroid that also acts like a comet

10:54 am

Worlds without end: Astronomers using the Hubble Space Telescope have identified a strange new object in the asteroid belt, two asteroids closely orbiting each other while also acting like a comet.

The images of 288P, which is located in the asteroid belt between Mars and Jupiter, revealed that it was actually not a single object, but two asteroids of almost the same mass and size, orbiting each other at a distance of about 100 kilometres. That discovery was in itself an important find; because they orbit each other, the masses of the objects in such systems can be measured.

But the observations also revealed ongoing activity in the binary system. “We detected strong indications of the sublimation of water ice due to the increased solar heating — similar to how the tail of a comet is created,” explains Jessica Agarwal (Max Planck Institute for Solar System Research, Germany), the team leader and main author of the research paper. This makes 288P the first known binary asteroid that is also classified as a main-belt comet.

The data also suggests that this binary has only existed as such for a few thousand years, and probably broke into two pieces because of its rotation. When this happened, it exposed water ice buried below the surface, which having been exposed to sunlight is sublimating away and producing the binary’s cometlike of a tail and coma.

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New research challenges theories on Earth formation

9:47 am

The uncertainty of science: New research about the Earth’s core contradicts the presently accepted theories about the Earth’s formation.

New geochemical research indicates that existing theories of the formation of the Earth may be mistaken. The results of experiments to show how zinc (Zn) relates to sulphur (S) under the conditions present at the time of the formation of the Earth more than 4 billion years ago, indicate that there is a substantial quantity of Zn in the Earth’s core, whereas previously there had been thought to be none. This implies that the building blocks of the Earth must be different to what has been supposed.

The research suggests that the Earth is made up of materials different than expected, which means that the materials from the solar system from which it formed are different than presently believed, which also means that present formation theories will need to be revised.

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MU69 is not round

5:43 pm

New data about 2014 MU69, the Kuiper Belt object that New Horizons plans to fly past on January 1, 2019, suggests that it is either elongated or made of two objects almost touching.

Recent observations suggest that the rock is no more than 20 miles long, and its shape is not round or elliptical, like most space rocks. Instead, the icy body is either shaped like a stretched football, called an “extreme prolate spheroid,” or like two rocks joined together. That creates a rubber ducky shape similar to the comet that the European Space Agency landed on two years ago.

It’s even possible that the object is, in fact, two objects — like a pair of rocks that are orbiting around each other, or are so close that they’re touching. If 2014 MU69 does turn out to be two objects, then each one is probably between nine and 12 miles in diameter, according to the New Horizons team.

I predict that this object will be even weirder in shape that predicted. The low gravity in the Kuiper Belt almost guarantees it.

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New Horizons’ next target might be smaller than predicted

10:43 am

The uncertainty of science: Because all attempts to observe an occultation of a star on June 3 by New Horizons’ next target failed, astronomers now think Kuiper Belt object 2014 MU69 is much smaller than previously believed.

The discovery observations using Hubble and other ground-based telescopes had estimated its size as between 12 to 25 miles in diameter. The null result from the June 3 event suggests it is smaller than that.

More occultations are upcoming, so stay tuned.

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NASA shuts down asteroid capture mission

10:49 pm

Faced with years of congressional disinterest, NASA this week finally decided to close out its asteroid redirect mission.

The project was first pushed by President Obama as a mission to send astronauts to an asteroid. Then they downgraded it to using an unmanned spacecraft to bring a large asteroid back to lunar space, where astronauts would then visit it. Then they downgraded this to bringing back a small asteroid, which was later downgraded to bringing back a small boulder. In the process the manned mission got pushed farther and farther into the future, until it dwindled out of sight.

The mission never had any congressional support, so it was never going to happen. With the end of the Obama administration NASA can now finally stop making believe that it might happen and shut it down.

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More near Earth objects found by WISE

12:05 pm

NASA’s Wide-Field Infrared Explorer (WISE) has released its third year of survey data, including the discovery of 97 previously unknown objects.

Of those, 28 were near-Earth objects, 64 were main belt asteroids and five were comets. The spacecraft has now characterized a total of 693 near-Earth objects since the mission was re-started in December 2013.

For reasons that baffle me, NASA added “Near-Earth Object” to the telescope’s name when they restarted the mission, making its official name now NEOWISE.

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LRO hit by meteoriod in 2014

5:35 pm

LRO as it was hit by a meteor

While taking an image in October 2014, Lunar Reconnaissance Orbiter had apparently been hit by some small object, causing it to vibrate and create the zig-zag distortions seen on the image, a cropped section of which is shown on the right.

Clearly there was a brief violent movement of the left NAC [Narrow Angle Camera]. The only logical explanation is that the NAC was hit by a meteoroid! How big was the meteoroid, and where did it hit? The physical properties and vibration modes of the NAC are very well known – during development a detailed computer model was made to ensure the NAC would not fail during the vibrations caused by the launch, which are severe. The computer model was tested before launch by attaching the NAC to a vibration table that simulates launch. The model was solid, both NACs survived the test, and launch.

Most of each NAC is sequestered inside the spacecraft structure, so only the leading edge of the baffle and the radiator are exposed to space, and thus are potential targets for impactors. From the detailed computer model, the LROC team ran simulations to see if we could reproduce the distortions seen the image. Assuming an impact velocity of 7 kilometers per second and a density 2.7 g/cm3, an impacting particle would have been 0.8 mm in diameter (~half the size of a pinhead). If the velocity was faster, then the particle would have been smaller, and if slower then larger.

For comparison, the muzzle velocity of a bullet fired from a rifle is typically 0.5 to 1.0 kilometers per second. So the meteoroid was traveling much faster than a speeding bullet. In this case LROC did not dodge a speeding bullet, but rather survived a speeding bullet!

The image is fascinating because you can see the vibrations slowly disappear as the zig-zags shrink and fade.

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The face of Ceres

9:35 am

The face of Ceres

Cool image time! The image on the right, reduced in resolution to show here, was taken by Dawn on April 29, 2017, when the spacecraft had been positioned between the Sun and the dwarf planet at a moment when its entire surface was lit. They have enhanced the colors to bring out the contrasts.

Images combining these different color filter perspectives reveal fine details of Ceres’ surface. For example, they emphasize the distinct compositions and textures of the material ejected from craters. The brightest region on Ceres, called Cerealia Facula, is highlighted in Occator Crater in the center of this image. Vinalia Faculae, the set of secondary bright spots in the same crater, are located to the right of Cerealia Facula.

One of the darkest regions on Ceres is next to Occator, and represents ejected material from the impact that formed the crater. The ejected material forms a large arc that extends over several hundred kilometers, below the center of Ceres in this image. That material’s distribution is partly determined by Ceres’ rotation.

Be sure to take a close look at the full image. It isn’t super high resolution, but it reveals a lot of interesting details

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Moon discovered around Kuiper belt dwarf planet

11:28 am

Astronomers have discovered a moon orbiting 2007 OR10, one of the Kuiper Belt’s larger objects.

With this discovery, most of the known dwarf planets in the Kuiper Belt larger than 600 miles across have companions. These bodies provide insight into how moons formed in the young solar system. “The discovery of satellites around all of the known large dwarf planets — except for Sedna — means that at the time these bodies formed billions of years ago, collisions must have been more frequent, and that’s a constraint on the formation models,” said Csaba Kiss of the Konkoly Observatory in Budapest, Hungary. He is the lead author of the science paper announcing the moon’s discovery. “If there were frequent collisions, then it was quite easy to form these satellites.”

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Landslides on Ceres reveal presence of ice

4:37 pm

An analysis of data from Dawn has shown that Ceres’s landslides are distributed in greater numbers towards the poles, which suggests the presence of water ice just below the surface.

Georgia Tech Assistant Professor and Dawn Science Team Associate Britney Schmidt led the study. She believes it provides more proof that the asteroid’s shallow subsurface is a mixture of rock and ice. “Landslides cover more area in the poles than at the equator, but most surface processes generally don’t care about latitude,” said Schmidt, a faculty member in the School of Earth and Atmospheric Sciences. “That’s one reason why we think it’s ice affecting the flow processes. There’s no other good way to explain why the poles have huge, thick landslides; mid-latitudes have a mixture of sheeted and thick landslides; and low latitudes have just a few.”

The data also showed that Ceres has far more landslides than expected, which also supports the idea that the shallow subsurface has a lot of water ice in it, as much as 10% to 50% by volume.

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The changes seen by Rosetta on Comet 67P/C-G

1:51 pm

A new study released today describes in detail the many changes seen by scientists in the data collected by Rosetta during its two years in close proximity to Comet 67P/C-G.

“We saw a massive cliff collapse and a large crack in the neck of the comet get bigger and bigger,” said El-Maarry. “And we discovered that boulders the size of a large truck could be moved across the comet’s surface a distance as long as one-and-a-half football fields.”

In the case of the boulder, Rosetta’s cameras observed a 282-million-pound (130-million-kilogram), 100-feet-wide (30-meter) space rock to have moved 150 yards (460 feet, or 140 meters) from its original position on the comet’s nucleus. The massive space rock probably moved as a result of several outburst events that were detected close to its original position.

The warming of 67P also caused the comet’s rotation rate to speed up. The comet’s increasing spin rate in the lead-up to perihelion is thought to be responsible for a 1,600-foot-long (500-meters) fracture spotted in August 2014 that runs through the comet’s neck. The fracture, which originally extended a bit longer than the Empire State Building is high, was found to have increased in width by about 100 feet (30 meters) by December 2014. Furthermore, in images taken in June 2016, a new 500- to 1,000-foot-long (150 to 300 meters) fracture was identified parallel to the original fracture.

“The large crack was in the ‘neck’ of the comet — a small central part that connects the two lobes,” said El-Maarry. “The crack was extending–indicating that the comet may split up one day.”

It is almost a shame that Rosetta did not see that break-up. The images would have been breath-taking, and the science learned priceless.

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Asteroid breaks in two, each piece develops a tail

2:08 pm

Astronomers have discovered a main belt asteroid that six years ago broke in two, after which both pieces developed tails resembling comets.

“The results derived from the evolution of the orbit show that the asteroid fragmented approximately six years ago, which makes it the youngest known asteroid pair in the Solar System to date,” says Fernando Moreno, researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC), in charge of the project.

P/2016 J1 presents another important peculiarity, which makes it very unusual. “Both fragments are activated, i.e., they display dust structures similar to comets. This is the first time we observe an asteroid pair with simultaneous activity,” says Fernando Moreno (IAA-CSIC).

Analyses revealed that the asteroids were activated near their perihelion – the point on the orbit nearest to de Sun – between the end of 2015 and the beginning of 2016, and that they remained for a period of between six and nine months. The span of time between the moment of fragmentation and their bout of activity implies that the two events are not related. In fact, the data suggests that the fragmentation also happened near the perihelion but during the previous orbit (it takes P/2016 J1 5.65 years to spin around the Sun). “In all likelihood, the dust emission is due to the sublimation of ice that was left exposed after the fragmentation,” says Moreno (IAA-CSIC).

I suspect that the more we learn about asteroids and comets the more we will blur the line that separates them.

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China considering multi-asteroid mission

7:16 pm

The competition heats up: China is considering an unmanned probe to visit three different asteroids, including Apophis.

According to details that have previously emerged, one proposal is for a launch via Long March 3B rocket to take place in early 2022, with rendezvous with Apophis a year later and spend 220 days in orbit.

Then the probe would depart Apophis for a flyby of 2002 EX11 in 2025, and finally landing on 1996 FG3 in 2027, where it would, in Ji’s words, “conduct in-situ sampling analysis on the surface”.

The proposal is only in the design stage, but it should definitely be taken seriously. China is committing more and more of its resources to its space program, as that program is giving that government a big payoff in international recognition.

Posted in the airport in Dallas, where I have to wait an extra three hours because American Airlines practically shut the door to my connecting flight in my face. Their flight from Belize was late, and then Customs and the TSA conspired to create giant lines for no reason. Even though I had a friend at the gate with whom we were in contact by text who could tell them I was only a minute away, they shut the door anyway.

I have avoided American for more than a decade because they did something as obnoxious to me before. I think it might be a decade before I fly them again.

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The vanishing volcanoes of Ceres

10:02 am

New research based on Dawn data suggests that volcanoes on Ceres flatten and disappear over time.

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. “We think we have a very good case that there have been lots of cryovolcanoes on Ceres but they have deformed,” said Michael Sori of the Lunar and Planetary Laboratory at the University of Arizona in Tucson, and lead author of the new paper.

The cause of the flattening?

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.

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NASA approves two new asteroid missions

3:05 pm

NASA has approved two new unmanned missions aimed at studying the asteroids.

Lucy will take a close look at six Trojan asteroids orbiting near Jupiter, after first visiting a main belt asteroid.

Lucy, a robotic spacecraft, is scheduled to launch in October 2021. It’s slated to arrive at its first destination, a main belt asteroid, in 2025. From 2027 to 2033, Lucy will explore six Jupiter Trojan asteroids. These asteroids are trapped by Jupiter’s gravity in two swarms that share the planet’s orbit, one leading and one trailing Jupiter in its 12-year circuit around the sun. The Trojans are thought to be relics of a much earlier era in the history of the solar system, and may have formed far beyond Jupiter’s current orbit.

Psyche will visit 16 Psyche, an unusual metal-rich asteroid made up mostly of iron and nickel.

While Psyche will use an ion engine, allowing it great freedom and even the potential to go elsewhere, like Dawn, when its primary mission is complete, I have not been able to determine whether Lucy will use conventional chemical altitude thrusters or an ion-type engine.

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Flying over Occator Crater on Ceres

12:23 am

Cool movie time! Using data from Dawn the German Aerospace Center (DLR) has produced a short animation that gives a 3D flyover of Occator Crater on Ceres.

The animated flyover includes topographic and enhanced-color views of the crater, highlighting the central dome feature. The central area has been named Cerealia Facula. Occator’s secondary group of bright spots is called Vinalia Faculae.

The movie is definitely worth watching, especially the sections that show in close-up the bright areas near the crater’s center.

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Lots of ice on Ceres

12:34 pm

New data from Dawn now suggests that Ceres contains a large amount of ice on or near its surface.

“On Ceres, ice is not just localized to a few craters. It’s everywhere, and nearer to the surface with higher latitudes,” said Thomas Prettyman, principal investigator of Dawn’s gamma ray and neutron detector (GRaND), based at the Planetary Science Institute, Tucson, Arizona. Researchers used the GRaND instrument to determine the concentrations of hydrogen, iron and potassium in the uppermost yard (or meter) of Ceres. GRaND measures the number and energy of gamma rays and neutrons coming from Ceres. Neutrons are produced as galactic cosmic rays interact with Ceres’ surface. Some neutrons get absorbed into the surface, while others escape. Since hydrogen slows down neutrons, it is associated with a fewer neutrons escaping. On Ceres, hydrogen is likely to be in the form of frozen water (which is made of two hydrogen atoms and one oxygen atom).

Rather than a solid ice layer, there is likely to be a porous mixture of rocky materials in which ice fills the pores, researchers found. The GRaND data show that the mixture is about 10 percent ice by weight.

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