Tag: asteroids

3D image of Comet 67P/C-G

9:06 am

Do you own red-blue 3-D glasses? Get them out and go to this link. Rosetta scientists have created a 3-D image of Comet 67P/C-G, including the jets of material shooting out from its surface.

[C]reating a 3d anaglyph of dynamic events like this is notoriously difficult: often the jets are too faint or their duration is too short to find two high-quality images taken several minutes apart that are suitable to pair together to create this type of view. However, the OSIRIS team got lucky with this particular event, capturing two images separated by about two-and-a-half minutes.

The image shows a bright, collimated jet embedded in a broader emission structure. The three dimensional perspective also reveals the conical shape of the jet and that the collimated feature is emitted towards the observer.

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Sunlight rolled the rocks on an asteroid

8:53 am

Scientists studying the rounded rocks on the surface of the asteroid 25143 Itokawa, photographed by the Japanese probe Hayabusa, have concluded that sunlight combined with the asteroid’s tiny gravity caused them move and thus erode themselves.

As sunlight bounced off the orbiting boulders, photons provided a tiny push. As they radiated back outward as heat, they triggered a recoil effect that added a gentle spin. Over time, these slowly spinning boulders bumped into each other with enough force to wear their edges into smooth surfaces.

Warning! This is only a model, and thus could very well be wrong. It is reasonable however and worth considering as a factor in studying the early formation history of asteroids.

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NASA pulls funding from private asteroid hunter

10:57 pm

Because of a failure to meet its developmental deadlines, NASA has cut its ties with the privately funded Sentinel satellite, designed to spot 90% of all near Earth asteroids that might pose a threat to the Earth.

The problem for the B612 Foundation, the private company committed to building Sentinel, is that they haven’t clearly laid out a way any investors could make money from the satellite. Thus, they have so far raised only $1.6 million from private sources. They need almost half a billion to build it, according to their own budget numbers.

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Changes on the surface of Comet 67P/C-G

6:16 pm

In a science paper now accepted for publication, the Rosetta science team have described changes that have occurred on the surface of Comet 67P/C-G from May through July of this year as the comet moved closer to the Sun and activity increased.

The changes were seen in a smooth area dubbed Imhotep.

First evidence for a new, roughly round feature in Imhotep was seen in an image taken with Rosetta’s OSIRIS narrow-angle camera on 3 June. Subsequent images later in June showed this feature growing in size, and being joined by a second round feature. By 2 July, they had reached diameters of roughly 220 m and 140 m, respectively, and another new feature began to appear.

By the time of the last image used in this study, taken on 11 July, these three features had merged into one larger region and yet another two features had appeared.

Be sure to click on the link to see the images. The changes look like a surface layer is slowing evaporating away.

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Rivers and lakes on Pluto?

8:49 am

Cool image time! Though the New Horizons science team will likely not issue their next press release until Friday, they appear to be posting new images on their website on a daily basis. From those images I pulled out the one below, which to fit I have cropped and reduced slightly in size. Be sure to go to the full image.

Do you see what I see? It appears that there are meandering braided dry streambeds on Pluto, draining into what appears to be a large basin.

Rivers and lakes on Pluto?

Assuming my guess of what this is is correct, this is obviously not a streambed created by water. Earlier images showed nitrogen ice flows and glacier-like geology. It is possible this new image is observing evidence of past nitrogen riverbeds and nitrogen lakes.

Expect a very interesting press release from New Horizons later this week.

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Closing in on Ceres’s bright spots

9:33 am

Ceres's bright spots

Cool image time! The Dawn science team has released a new close-up of Ceres’s Double Bright Spot.

The new up-close view of Occator crater from Dawn’s current vantage point reveals better-defined shapes of the brightest, central spot and features on the crater floor. Because these spots are so much brighter than the rest of Ceres’ surface, the Dawn team combined two different images into a single composite view — one properly exposed for the bright spots, and one for the surrounding surface.

They have also released a detailed topographic map of the crater as well as a fly-around video, which I have posted below the fold. The interesting take-away from this new data is that, while the bright spots look at first glance remarkably like the snow-cap on a mountain-top, they are actually at the low spots in the crater. This suggests that they are instead material that has either bubbled up from below, or flowed downward to the crater bottom.

Be sure you click on the link and look at the full resolution image.
» Read more

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Data from New Horizons does not match what is seen from Earth

9:10 am

The uncertainty of science: Planetary geologists are presently baffled by a conflict in the atmospheric data between New Horizons and data gathered from Earth.

On 29 June, a few weeks before the fly-by, Young organized astronomers across New Zealand and Australia to watch Pluto as it passed in front of a distant star. Tracking how the star’s light faded during the passage provided information on how much gas is in Pluto’s atmosphere. Using the same method, planetary scientists have seen the atmosphere grow denser since 1988 — and analysis of the 29 June observations shows that the trend remains intact. Young calculates that the current atmospheric pressure at Pluto’s surface is 22 microbars (0.022 pascals), or 22-millionths the pressure at sea level on Earth.

But on 14 July, New Horizons measured Pluto’s surface pressure as much lower than that ­— just 5 microbars. “How we link the two, we’re still working on,” says Cathy Olkin, a deputy project scientist for New Horizons at SwRI.

The difference could simply be that Pluto’s atmosphere is not smooth, that some regions are dense while others are thin, and New Horizons happened to look at a thin place. The Earth observations don’t have the resolution to separate the two.

There are other proposals to explain the problem. Regardless, the answer is likely hidden in the data from New Horizons that has still not been downloaded back to Earth. In a few months, all might very well become clear.

Or not, as is the natural state of science.

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New Horizons team picks its next Kuiper Belt target

3:07 pm

The New Horizons science team has picked its next Kuiper Belt fly-by target beyond Pluto.

New Horizons will perform a series of four maneuvers in late October and early November to set its course toward 2014 MU69 – nicknamed “PT1” (for “Potential Target 1”) – which it expects to reach on January 1, 2019. Any delays from those dates would cost precious fuel and add mission risk. “2014 MU69 is a great choice because it is just the kind of ancient KBO, formed where it orbits now, that the Decadal Survey desired us to fly by,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute (SwRI) in Boulder, Colorado. “Moreover, this KBO costs less fuel to reach [than other candidate targets], leaving more fuel for the flyby, for ancillary science, and greater fuel reserves to protect against the unforeseen.”

The press release includes some silly gobbly-gook about how the science team can’t announce this as its official target because they still have to write up a proposal to submit to NASA, which then must ponder their decision and decree it valid. We all know this is ridiculous. Will NASA sit and ponder and make them miss their target? I doubt it.

The fly-by itself will be really exciting, because this object will truly be the most unusual we will have ever gotten a close look at, as it has spent its entire existence far out in the dim reaches of the solar system.

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New sharp images of Ceres from Dawn

9:13 am

The Lonely Mountain on Ceres/>

Cool image time! The Dawn science team has released new images of Ceres, including one of a single mountain they have dubbed the Lonely Mountain.

The mountain, located in the southern hemisphere, stands 4 miles (6 kilometers) high. Its perimeter is sharply defined, with almost no accumulated debris at the base of the brightly streaked slope with bright streaks. The image was taken on August 19, 2015. The resolution of the image is 450 feet (140 meters) per pixel.

I have cropped the image and posted it on the right. Be sure to look at the full resolution version. Not only does the mountain have no debris at its base, it truly is lonely. There are no similar features anywhere near it. It almost looks like someone took a shovel of material out of the ground to create the crater immediately to the south and then dumped that material to create the mountain.

Note that the mountain is more like a mesa, with a flat top, which suggests it is the remains of a higher elevation surface that eroded away in the distant past. The geological processes that could have done this however remain quite puzzling at this point.

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Haze spotted over Ceres’ double bright spot

9:15 am

Dawn, in orbit around Ceres, has detected a haze above the dwarf planet’s double bright spot, suggesting that the tiny asteroid/planet is still geologically active.

Haze on Ceres would be the first ever observed directly in the asteroid belt. In 2014, researchers using the European Space Agency’s Herschel Space Observatory reported seeing water vapour spraying off Ceres, which suggested that it was geologically active1. At least one-quarter of Ceres’s mass is water, a much greater proportion than seen in most asteroids.

Bright spots pepper Ceres’s surface, but the haze has so far been seen in only one location — a crater named Occator, which has a large bright area at its centre and several smaller spots nearby. Mission scientists have been trying to work out whether the bright spots are made of ice, evaporated salts or other minerals, or something else entirely.

Some team members had been leaning towards the salt explanation, but the discovery of haze suggests the presence of sublimating ice. “At noontime, if you look at a glancing angle, you can see what seems to be haze,” Russell says. “It comes back in a regular pattern.” The haze covers about half of the crater and stops at the rim.

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A closer close-up of Ceres’ double bright spot

9:19 am

Closer look at Ceres' double bright spot

Cool image time! In a new press release, the Dawn science team has unveiled a new close-up of Ceres’ double bright spot, shown on the right.

At least eight spots can be seen next to the largest bright area, which scientists think is approximately 6 miles (9 kilometers) wide. A highly reflective material is responsible for these spots — ice and salt are leading possibilities, but scientists are considering other options, too.

In other words, they still have not confirmed through spectroscopy, that these bright spots are ice.

Note also that they have reduced the image’s brightness so that the bright spots do not over expose as much as in past images. This not only allows more details to come out, but it portrays Ceres’ very dark surface more accurately. Even so, the image still shows that surface as brighter than it actually is.

A mountain on Ceres

The press release also described a second image, showing a single lonely mountain on the planet’s horizon, rising up three miles from the planet’s surface, shown in the cropped image to the left. Overall this image, as well as the others, suggest that the surface of Ceres is generally far less rough than we should expect.

Another science mystery to unravel!

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New close-up image of Ceres’s double bright spots

9:32 am

close-up of Ceres's bright spots

Cool image time! The Dawn science team has released a some new close-up images of Ceres, including a much higher resolution image of the dwarf planet’s double bright spot, which now resolves itself into a cluster of two larger spots with a half dozen smaller spots scattered nearby.

The region with the brightest spots is in a crater about 55 miles (90 kilometers) across. The spots consist of many individual bright points of differing sizes, with a central cluster. So far, scientists have found no obvious explanation for their observed locations or brightness levels.

“The bright spots in this configuration make Ceres unique from anything we’ve seen before in the solar system. The science team is working to understand their source. Reflection from ice is the leading candidate in my mind, but the team continues to consider alternate possibilities, such as salt. With closer views from the new orbit and multiple view angles, we soon will be better able to determine the nature of this enigmatic phenomenon,” said Chris Russell, principal investigator for the Dawn mission based at the University of California, Los Angeles.

To my eye, these bright areas resemble a wide flat caldera of a volcano. Instead of being at the top of a peak, the caldera is like a lava pool, almost like a large lake. In this case, the large spots are lakes of frozen ice that periodically melt and flow. The smaller spots are likely smaller vents where water can bubble up from below during active periods. When not active, the water will be frozen. Since ice is white and Ceres is very dark, the pools and vents appear extremely bright in these images.

I am speculating however. We will have to wait for much better images to know for sure.

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Rare large meteorite stolen from Australian museum

11:18 am

In a heist reminiscent of a Hollywood movie, two thieves in hooded jumpers and white masks stole a 25 pound meteorite the size of a soccer ball on Monday.

The only value of such a meteorite is among collectors, but to sell such a large and unique meteorite without being noticed would be impossible. It is theorized that the thieves might chop it up and sell the pieces to collectors instead.

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Dawn makes a movie of Ceres

9:28 am

Cool image time! Using images that Dawn has accumulated since it entered orbit around Ceres, scientists have created an animation showing the dwarf planet as it rotates.

Video below the fold. Note that this is an animation. They have filled in the gaps between images to make the rotation smooth, exaggerated the scale two times to bring out details, and added a background of stars that is not visible in the original images. Even so, this video is scientifically useful, as it shows Ceres in its entirety. It is also very spectacular.
» Read more

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Rosetta team proposes landing on comet to finish mission

4:14 pm

Rather than simply turn off the spacecraft when its funding runs out at the end of 2015, Rosetta’s science team have proposed that the mission get a nine month extension, during which they will slowly spiral into the comet and gently land.

Their proposal is similar to what American scientists did with their NEAR spacecraft, which hadn’t been designed to land on an asteroid but was successfully eased onto the surface of Eros, where it operated for a very short time.

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It looks like the Moon!

9:03 am

craters on Ceres

Cool image time! Dawn has now swooped down to 3,200 miles, and provided a very nice image of the cratered surface of Ceres. Though it does appear to resemble the Moon, there are some differences that come to mind if you take a close look at the full resolution image. The surface appears smoother. All of the craters appear worn or eroded or less rugged. Also, there are no mountains. The terrain resembles the Moon’s lowlands or maria, but more so.

Note that the region in this picture is tantalizingly close to the double bright spot, but does not include it. Because Dawn is still easing its way into its first survey orbit of 2,700 miles elevation, it only takes pictures when it stops firing its ion engine, which it is doing almost all the time to get where it wants to be. Thus, they apparently only had time for this image.

The spacecraft enters its mapping orbit on June 3. Expect some cool images, including the first good images of the double bright spots, shortly thereafter.

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New Horizons spots all of Pluto’s 5 known moons

7:46 am

New Horizons has now been able to image all of Pluto’s known moons.

Pluto’s five known satellites are Charon, Hydra, Nix, Kerberos and Styx. At 648 miles (1,043 km) in diameter, Charon is nearly half as wide as Pluto itself, but the other four moons are minuscule. Kerberos and Styx, for example, are thought to be just 4 to 13 miles (7 to 21 km) and 6 to 20 miles (10 to 32 km) wide, respectively.

That the spacecraft has been able to spot them all this soon bodes well for what it will see when if flies past Pluto in July.

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New images of Dawn’s double bright spot

8:42 am

The double spot on Ceres

Cool image time! Dawn has released a new animation made from images taken in early May, showing more details of the dwarf planet’s double bright spot.

As they note at the link, the double spot is now “revealed to be composed of many smaller spots.” As they also add, “Their exact nature remains unknown.”

Dawn’s engineers are now beginning to ease the spacecraft down to its survey orbit, about 2,700 miles above the surface.

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New studies struggle to explain the origin of the Moon

10:03 am

The uncertainty of science: Three new studies on the mystery of the origin of the Moon all appear to better confirm the theory that it was created when the Earth collided with a Mars-sized planet.

It is important to be aware of the uncertainties here. All these studies were done to try to address problems with the impact theory, and though they kind of answer the questions, they leave behind some important doubts.

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ALMA captures the rotation of the large asteroid Juno

8:52 am

The large ground-based telescope ALMA has captured a series of images of the large asteroid Juno, allowing scientists to estimate its rotation and overall shape.

Linked together into a brief animation, these high-resolution images show the asteroid rotating through space as it shines in millimeter-wavelength light. “In contrast to optical telescopes, which capture the reflected light from the Sun, the new ALMA images show the actual millimeter-wavelength light emitted by the asteroid,” said Todd Hunter, an astronomer with the National Radio Astronomy Observatory (NRAO) in Charlottesville, Va.

…The complete ALMA observation, which includes 10 separate images, documents about 60 percent of one rotation of the asteroid. It was conducted over the course of four hours on 19 October 2014 when Juno was approximately 295 million kilometers from Earth. In these images, the asteroid’s axis of rotation is tilted away from the Earth, revealing its southern hemisphere most prominently.

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Dawn’s chief engineer gives us a detailed update

9:00 am

Link here. Chief engineer Marc Rayman loves to write about Dawn, and his posts on the Dawn blog are probably the most information-packed of any spacecraft blog I have ever read. Key quote this time:

Dawn’s extensive photographic coverage of the sunlit terrain in early May will include these bright spots. They will not be in view, however, when Dawn spies the thin crescent of Ceres in its next optical navigation session, scheduled for April 10.

The orientation of the spacecraft and asteroid now are such that there is no point taking pictures, as most of the asteroid is in darkness.

Read it all, however. He gives a masterful overview of what is going to happen in the coming months.

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