Tag: asteroids

Landslides on Ceres

9:31 am

Landslides on rim of Occator Crater

Cool image time! With Dawn completing its descent into its final low orbit only about 30 miles above the surface of Ceres, it is beginning to take some very spectacular images. Above is a cropped section from a full image taken on June 9th of the rim of Occator Crater from an altitude of 27 miles. It shows evidence of landslides on the crater’s rim, as well as at least two bright patches. If you click on it you can see the entire picture.

Crater on Ceres

Nor is this the only cool image released As Dawn descended to its new orbit, it took one very cool oblique image of the planet’s horizon. On the right I have cropped a small section out of one such image, taken on May 30th from an altitude of 280 miles. If you click on it you can see the full image, showing numerous other small craters all around it, to the horizon.

Note the bright streaks on the crater walls, suggestive of more landslides as well as seepage of the thought-to-exist brine from below the surface.

For the next year or so, as Dawn winds down its mission, expect a lot more very intriguing pictures of Ceres. I am especially eager to see close-ups of the bright spots at the center of Occator Crater.

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New analysis suggests Ceres has more organic molecules than previously estimated

12:11 pm

The uncertainty of science: A new analysis of data from Dawn now suggests that the surface of Ceres has a greater percentage of organic molecules than previously estimated.

To get an initial idea of how abundant those compounds might be, the original research team compared the VIR data from Ceres with laboratory reflectance spectra of organic material formed on Earth. Based on that standard, the researchers concluded that between six and 10 percent of the spectral signature they detected on Ceres could be explained by organic matter.

But for this new research, Kaplan and her colleagues wanted to re-examine those data using a different standard. Instead of relying on Earth rocks to interpret the data, the team turned to an extraterrestrial source: meteorites. Some meteorites — chunks of carbonaceous chondrite that have fallen to Earth after being ejected from primitive asteroids — have been shown to contain organic material that’s slightly different from what’s commonly found on our own planet. And Kaplan’s work shows that the spectral reflectance of the extraterrestrial organics is distinct from that of terrestrial counterparts.

“What we find is that if we model the Ceres data using extraterrestrial organics, which may be a more appropriate analog than those found on Earth, then we need a lot more organic matter on Ceres to explain the strength of the spectral absorption that we see there,” Kaplan said. “We estimate that as much as 40 to 50 percent of the spectral signal we see on Ceres is explained by organics. That’s a huge difference compared to the six to 10 percent previously reported based on terrestrial organic compounds.”

Please note: Both estimates depend on assumptions that could easily be wrong. Ceres might have less organics, or more, than either estimate. Or somewhere in the middle. These estimates are merely educated guesses.

And remember, organic molecules does not mean life. It only means the molecules use carbon as a component.

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Hayabusa-2 takes first photos of target asteroid Ryugu

8:34 am

On June 10 Hayabusa-2 took its first photos of Ryugu, the asteroid it will reach later this month.

The Sunday photos were taken when Hayabusa2 was about 930 miles (1,500 kilometers) from Ryugu. Last week, JAXA released a few ONC-T images taken on June 6, when the probe was 1,615 miles (2,600 km) from the space rock.

Hayabusa2, which launched in December 2014, is scheduled to arrive at Ryugu on or around June 27. At that time, the probe will begin orbiting the asteroid at an altitude of about 12 miles (20 km), JAXA officials have said.

Hayabusa2 will then start prepping for a series of complex, up-close studies of the space rock. If all goes according to plan, over the ensuing 12 months, the spacecraft will deploy three rovers and a lander on Ryugu’s surface, gouge out a small crater using an explosives-bearing impactor, and collect samples from the newly created crater.

The spacecraft will depart Ryugu in November or December 2019, and its collected samples will come back to Earth in a special return capsule in late 2020.

The image suggests that the asteroid is “not significantly elongated.”

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No giant planet needed in Kuiper Belt to shape orbits of outer known planets

9:27 am

Using computer models astronomers have found that the tiny objects in the Kuiper Belt could be sufficient, instead of one giant undiscovered planet, to provide the gravity necessary to explain the orbits of the solar system’s outer planets.

They call theorized giant planet “Planet Nine,” which seems silly since Pluto really still fills that role. Nonetheless, this work also might explain the process that flung some surprisingly large objects so far out into the Kuiper Belt.

They ran supercomputer simulations of how bodies might interact in the outer Solar System far beyond Pluto, in the icy region known as the Kuiper belt. They found that a flock of Moon-sized worlds could do many of the same things as Planet Nine.

Over millions of years, the collective gravity of these smaller worlds would nudge the orbits of distant objects. The worlds would jostle one another like bumper cars and, occasionally, cause an object to move into a very distant orbit. Their simulations suggest that more-massive objects would be flung into the most distant orbits — as some observations have suggested.

We must also remind ourselves that this conclusion is based on a computer model, and is filled with uncertainty. We also do not yet have a full census of objects in the Kuiper Belt, which means this model required many assumptions.

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Boulder-sized asteroid discovered just before it hit Earth

8:59 am

The Catalina Sky Survey, designed to find asteroid with the potential of hitting the Earth, discovered a boulder-sized such asteroid this past weekend just hours before it burned up in the atmosphere.

Although there was not enough tracking data to make precise predictions ahead of time, a swath of possible locations was calculated stretching from Southern Africa, across the Indian Ocean, and onto New Guinea. Reports of a bright fireball above Botswana, Africa, early Saturday evening match up with the predicted trajectory for the asteroid. The asteroid entered Earth’s atmosphere at the high speed of 10 miles per second (38,000 mph, or 17 kilometers per second) at about 16:44 UTC (9:44 a.m. PDT, 12:44 p.m. EDT,6:44 p.m. local Botswana time) and disintegrated several miles above the surface, creating a bright fireball that lit up the evening sky. The event was witnessed by a number of observers and was caught on webcam video.

When it was first detected, the asteroid was nearly as far away as the Moon’s orbit, although that was not initially known. The asteroid appeared as a streak in the series of time-exposure images taken by the Catalina telescope . As is the case for all asteroid-hunting projects, the data were quickly sent to the Minor Planet Center in Cambridge, Massachusetts, which calculated a preliminary trajectory indicating the possibility of an Earth impact. The data were in turn sent to the Center for Near-Earth Object Studies (CNEOS) at NASA’s Jet Propulsion Laboratory in Pasadena, California, where the automated Scout system also found a high probability that the asteroid was on an impact trajectory. Automated alerts were sent out to the community of asteroid observers to obtain further observations, and to the Planetary Defense Coordination Office at NASA Headquarters in Washington. However, since the asteroid was determined to be so small and therefore harmless, no further impact alerts were issued by NASA.

The video at the link makes it appear that the asteroid has hit the ground, but that is not what happened.

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The surface properties of 122 asteroids revealed

1:12 pm

Using archive data produced by the Wide-field Infrared Explorer telescope (WISE, renamed NEOWISE) astronomers have been able to estimate the surface properties of 122 small asteroids located in the asteroid belt.

“Using archived data from the NEOWISE mission and our previously derived shape models, we were able to create highly detailed thermophysical models of 122 main belt asteroids,” said Hanuš, lead author of the paper. “We now have a better idea of the properties of the surface regolith and show that small asteroids, as well as fast rotating asteroids, have little, if any, dust covering their surfaces.” (Regolith is the term for the broken rocks and dust on the surface.)

It could be difficult for fast-rotating asteroids to retain very fine regolith grains because their low gravity and high spin rates tend to fling small particles off their surfaces and into space. Also, it could be that fast-rotating asteroids do not experience large temperature changes because the sun’s rays are more rapidly distributed across their surfaces. That would reduce or prevent the thermal cracking of an asteroid’s surface material that could cause the generation of fine grains of regolith. [emphasis mine]

If this conclusion holds, it means that mining these asteroids might be much easier. Dust can be a big problem, as it can clog up equipment and interfere with operations. It also acts to hide the underlying material, making it harder to find the good stuff.

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Pluto formed from a billion comets?

9:09 am

Scientists have come up with a new theory for the origin of Pluto, based on data from New Horizons and Rosetta, that suggests the planets formed from the accretion of a billion comets or Kuiper Belt objects.

“We’ve developed what we call ‘the giant comet’ cosmochemical model of Pluto formation,” said Dr. Christopher Glein of SwRI’s Space Science and Engineering Division. The research is described in a paper published online today in Icarus. At the heart of the research is the nitrogen-rich ice in Sputnik Planitia, a large glacier that forms the left lobe of the bright Tombaugh Regio feature on Pluto’s surface. “We found an intriguing consistency between the estimated amount of nitrogen inside the glacier and the amount that would be expected if Pluto was formed by the agglomeration of roughly a billion comets or other Kuiper Belt objects similar in chemical composition to 67P, the comet explored by Rosetta.”

This is only a hypothesis, but it is intriguing. It suggests that Pluto’s make-up came only from the outer parts of the solar system, thus constraining how much mixing between the solar system’s inner and outer regions occurred. For scientists trying to understand the formation of the entire solar system, this lack of mixing would be significant. It means that the gas giants, while migrating inward, never migrated outward.

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Why jets formed on Comet 67P/C-G

9:02 am

Scientists analyzing the data produced by Rosetta while it was flying in formation with Comet 67P/C-G have determined that the comet’s complex topology acted almost like nozzles to encourage evaporating material to form jets.

The new study shows for the first time that mainly the unusual shape and jagged topography of the comet are responsible for this phenomenon. The researchers analyzed images at different observation geometries of the Hapi region located on the “neck” of the comet, the narrow part connecting its two lobes. In computer simulations, they were able to reproduce these images thus gaining a better understanding of the driving processes.

In particular, two effects proved to be decisive. Some regions on the surface are located at lower altitudes or in the shade. The first rays of sunlight reach them later. In contrast, the frost evaporates particularly efficiently from the early and strongly illuminated regions. In addition, pits and other concave structures virtually concentrate gas and dust emissions – much like an optical lens.

This means that predicting the evaporation patterns on other comets will require first obtaining a detailed map of the surface, showing both its topography and make-up. This also means that any future explorers will first have to send a robot scouting mission so that they can plan a safe arrival during active periods.

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Asteroid that formed in the inner solar system discovered in Kuiper Belt

9:24 am

Astronomers have discovered a carbonaceous asteroid in the distant Kuiper Belt beyond Pluto, even though it likely formed in the inner solar system.

The asteroid’s existence serves to confirm models of the solar system’s formation that say that the orbits of gas giants migrate inward and outward during the formation process, and as they do so they can fling material out of the inner solar system. This asteroid is the first evidence of this process.

At the same time, the data here is quite slim. They have only found one such asteroid. It could be that it was flung into the Kuiper Belt by other processes. If the formation model is correct, many more such Kuiper Belt asteroids will be eventually be found.

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Diamonds from space!

9:46 am

Researchers have discovered nano-sized diamonds inside a recovered meteorite that suggest a formation process deep within a planet at least the size of Mercury.

The researchers used transmission electron microscopes to determine their composition and morphology, and found that the diamonds contained inclusions (impurities) made of chromite, phosphate and iron-nickel sulfides.

These inclusions are common in diamonds formed underground here on Earth, but this marks the first time they’ve been found in alien rocks. That’s interesting enough on its own, but it has much bigger implications – the team calculated that these diamonds could only have formed under pressure of more than 20 gigapascals. That means they must have been born inside a planet at least as big as Mercury, and possibly up to the size of Mars.

But there’s still more to the story. The fact these diamonds made it to Earth implies that their home planet, whatever it may have been, is no longer with us, since it would take quite a cataclysm to wrench them out of their birthplace deep underground and fling them into space. Instead, the team believes the diamonds came from a planetary embryo.

Not so fast. Though the researchers themselves, in the released paper, assume that the diamonds could only have formed from inside a now destroyed large planet, this leaves out the possibility that the diamonds formed inside one of the existing terrestrial planets, were moved upward toward the surface by later geological process (as happens to diamonds are here on Earth), and then were thrown from the planet by a later nearby impact. This scenario is just as likely.

Nonetheless, this discovery is fascinating. More than anything, it illustrates the inconceivable amount of time that has passed in creating our solar system. Any of these scenarios requires time, time in quantities that no human can really understand or conceptualize.

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Star’s close approach 70,000 years ago pinned to cometary orbits

10:03 am

Astronomers now think they have pinned the orbits of about 340 comets to another star’s close approach to our solar system 70,000 years ago.

About 70,000 years ago, when the human species was already on Earth, a small reddish star approached our solar system and gravitationally disturbed comets and asteroids. Astronomers from the Complutense University of Madrid and the University of Cambridge have verified that the movement of some of these objects is still marked by that stellar encounter. At a time when modern humans were beginning to leave Africa and the Neanderthals were living on our planet, Scholz’s star – named after the German astronomer who discovered it – approached less than a light-year from the Sun. Nowadays it is almost 20 light-years away, but 70,000 years ago it entered the Oort cloud, a reservoir of trans-Neptunian objects located at the confines of the solar system.

This discovery was made public in 2015 by a team of astronomers led by Professor Eric Mamajek of the University of Rochester (USA). The details of that stellar flyby, the closest documented so far, were presented in The Astrophysical Journal Letters.

Now two astronomers from the Complutense University of Madrid, the brothers Carlos and Raúl de la Fuente Marcos, together with the researcher Sverre J. Aarseth of the University of Cambridge (United Kingdom), have analyzed for the first time the nearly 340 objects of the solar system with hyperbolic orbits (very open V-shaped, not the typical elliptical), and in doing so they have detected that the trajectory of some of them is influenced by the passage of Scholz´s star.

It is likely that the close approach influenced a lot more objects, many of which might not have yet arrived in the inner solar system. Moreover, their computer models suggest that the star might have come closer to the Sun than 0.6 light years.

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Scientists theorize that Oumuamua came from a binary star system

8:17 am

Based on statistics and computer modeling, some scientists believe that the interstellar object Oumuamau likely came from stellar binary system.

For the new study, published in the journal Monthly Notices of the Royal Astronomical Society, Jackson and his co-authors set about testing how efficient binary star systems are at ejecting objects. They also looked at how common these star systems are in the Galaxy. They found that rocky objects like ‘Oumuamua are far more likely to come from binary than single star systems. They were also able to determine that rocky objects are ejected from binary systems in comparable numbers to icy objects.

Their conclusion does make sense, though any good scientist would retain a gigantic sense of skepticism. While it is statistically reasonable to conclude that a majority of interstellar objects should come from binary systems, there is no guarantee that Oumuamua in particular did so. Even if the odds were one in a million, there is always that one, and the universe often seems prone to fooling us.

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Dawn finds recent changes on Ceres

4:28 pm

New data from Dawn has found at least one spot on Ceres where recent changes appear to have occurred on the surface.

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.

Raponi led the new study, which found changes in the amount of ice exposed on the dwarf planet. “The combination of Ceres moving closer to the sun in its orbit, along with seasonal change, triggers the release of water vapor from the subsurface, which then condenses on the cold crater wall. This causes an increase in the amount of exposed ice. The warming might also cause landslides on the crater walls that expose fresh ice patches.”

There is a certain irony here. For eons, the only alien body that humans were able to get a good look at, the Moon, was also an object where almost nothing changed. Even today, after humans have visited its surface and numerous orbiting spacecraft have photographed its surface in numbing detail, the Moon has generally been found to be stable and unchanging. Though impacts do occur, and the surface does evolve over time, the Moon is probably one of the most static bodies in the solar system.

The irony is that this lunar stability gave us an incorrect impression of the rest of the solar system. Based on the Moon, it was assumed that airless or almost airless bodies like Mercury, Mars, Pluto, the large moons of Jupiter and Saturn, and asteroids like Ceres would also be stable and unchanging. What we have instead found is that the Moon is the exception that proves the rule. Most of these other worlds are unlike the Moon. They show a lot of surface evolution, over relatively short time scales. They change.

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Funding shortfall causes Planetary Resources to cut back

8:32 am

Because of their failure to close a round of investment fund-raising, Planetary Resources has been forced to cut back, including some layoffs and delaying several proposed later missions.

The delayed investment, though, forced Planetary Resources to lay off some of its employees. Lewicki declined to say how many were let go from a peak of 70 employees prior to the layoffs.

That setback also affects the schedule for future asteroid prospecting missions. In his conference talk, Lewicki showed a video of a planned mission where several small spacecraft, launched as secondary payloads, fly to near Earth asteroids to measure their water content. In past presentations featuring that video, company officials said the mission was scheduled for launch in 2020.

However, Lewicki didn’t state in this talk when that mission would launch, and acknowledged later the funding problems would delay it until some time after 2020. “The 2020 date was assuming we would get all the necessary financing on schedule last year,” he said.

To me, this article illustrates why Planetary Resources failed to obtain its investment funds. They pitch themselves as an asteroid mining company, but very little of what they are doing has anything to do with actual mining, or obtaining profits from that mining. At the moment, they remain an Earth observation company with capabilities not as good as a host of other similar companies expressly dedicated to this task.

I say this not because I am against asteroid mining, or think it cannot make a profit. I just think Planetary Resources has oversold itself, which can be deadly in the harsh competitive market.

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Interstellar object Oumuamua tumbling chaotically

8:46 am

A new analysis of the data obtained when the interstellar object Oumuamua flew through the solar system in October 2016 suggests that it is tumbling in a chaotic manner, and that the surface is spotty.

Straight away, they discovered that ‘Oumuamua wasn’t spinning periodically like most of the small asteroids and bodies that we see in our solar system. Instead, it is tumbling, or spinning chaotically, and could have been for many billions of years.

While it is difficult to pinpoint the exact reason for this, it is thought that `Oumuamua impacted with another asteroid before it was fiercely thrown out of its system and into interstellar space. Dr Fraser explains: “Our modelling of this body suggests the tumbling will last for many billions of years to hundreds of billions of years before internal stresses cause it to rotate normally again.

To me, this data settles the question about whether Oumuamua is not an artificial structure. It is not. If it were, an impact that would have caused this kind of tumbling would have almost certainly destroyed it. Instead, it likely broke the original bolide up, producing many fragments, including Oumuamua and its elongated shape.

As for the object’s spottiness:

Dr Fraser explains: “Most of the surface reflects neutrally but one of its long faces has a large red region. This argues for broad compositional variations, which is unusual for such a small body.”

It is really a shame we couldn’t get a closer look before it sped away.

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New Horizons takes the most distant pictures from Earth ever taken

8:43 am

Kuiper Belt Object 2012 HE85

The New Horizons science team has released three images taken by the spacecraft from almost 3.8 billion miles from Earth, the most distant images ever taken.

The routine calibration frame of the “Wishing Well” galactic open star cluster, made by the Long Range Reconnaissance Imager (LORRI) on Dec. 5, was taken when New Horizons was 3.79 billion miles (6.12 billion kilometers, or 40.9 astronomical units) from Earth – making it, for a time, the farthest image ever made from Earth.

…LORRI broke its own record just two hours later with images of Kuiper Belt objects 2012 HZ84 and 2012 HE85 – further demonstrating how nothing stands still when you’re covering more than 700,000 miles (1.1 million kilometers) of space each day.

The images themselves are not spectacular to look at, though the two images of two different Kuiper Belt objects are the best ever taken of such objects, and certainly contain data that scientists will be able to use. The image on the right is one of these objects, 2012 HE85. For example, note how it does not appear to be round.

This exercise is in preparation for the January 1, 2019 fly-by of 2014 MU69, where the images will be sharp and detailed, and provide us a good look at such a distant object.

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Fractures in the floor of Occator Crater

9:42 am

Fractures in floor of Occator Crater

Cool image time! The Dawn science team has released an image of Ceres, cropped to post here in the right, that shows a spiderweb of fractures radiating out from a single point in the floor of Occator Crater.

These fractures have been interpreted as evidence that material came up from below and formed a dome shape, as if a piston was pushing Occator’s floor from beneath the surface. This may be due to the upwelling of material coming from Ceres’ deep interior. An alternative hypothesis is that the deformation is due to volume changes inside a reservoir of icy magma in the shallow subsurface that is in the process of freezing, similar to the change in volume that a bottle of water experiences when put in a freezer.

In the image sunlight is coming from the right. This fractured area can be seen in this earlier simulated oblique image of Occator Crater, in the southwest corner of the crater floor, well away from the crater’s more well known bright areas.

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Arecibo returns to operation with images of asteroid Phaethon

10:02 am

The Arecibo Observatory in Puerto Rico has resumed science observations after recovering from Hurricane Maria with new radio images of the asteroid Phaethon.

After several months of downtime after Hurricane Maria blew through, the Arecibo Observatory Planetary Radar has returned to normal operation, providing the highest-resolution images to date of near-Earth asteroid 3200 Phaethon during its Dec. 16 flyby of Earth. The radar images, which are subtle at the available resolution, reveal the asteroid is spheroidal in shape and has a large concavity at least several hundred meters in extent near the leading edge, and a conspicuous dark, circular feature near one of the poles. Arecibo’s radar images of Phaethon have resolutions as fine as about 250 feet (75 meters) per pixel.

The images also revealed that Phaethon, which is considered a potentially hazardous near Earth asteroid, is about 3.6 miles across and is about a half mile larger than previously believed.

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