Tag: asteroids

Moon hit by small meteorite during eclipse

12:57 pm

During the lunar eclipse two days ago on January 20, 2018 amateur astronomers were able to record the impact of a small meteorite.

The MIDAS survey is a Moon-watching that scours video of its surface in the hopes of detecting the tiny flashes associated with meteorite impacts. In this case, MIDAS scored a home run, and it was the first time the system was able to spot an impact during a total lunar eclipse.

“In total I spent almost two days without sleeping, including the monitoring time during the eclipse,” [Jose] Madiedo explained to Gizmodo. “I was exhausted when the eclipse ended—but when the automatic detection software notified me of a bright flash, I jumped out of my chair. It was a very exciting moment because I knew such a thing had never been recorded before.”

The meteorite itself wasn’t terribly large, and is estimated to have only been around 22 pounds.

I have embedded the video of the impact below the fold. It is very short, and the flash is not very impressive, but it still is quite cool.
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No Planet X needed

9:11 am

The uncertainty of science: New computer models now suggest that the orbits of the known Kuiper Belt objects can be explained without the need for the theorized large Planet X.

The weirdly clustered orbits of some far-flung bodies in our solar system can be explained without invoking a big, undiscovered “Planet Nine,” a new study suggests.

The shepherding gravitational pull could come from many fellow trans-Neptunian objects (TNOs) rather than a single massive world, according to the research.

“If you remove Planet Nine from the model, and instead allow for lots of small objects scattered across a wide area, collective attractions between those objects could just as easily account for the eccentric orbits we see in some TNOs,” study lead author Antranik Sefilian, a doctoral student in the Department of Applied Mathematics and Theoretical Physics at Cambridge University in England, said in a statement.

When you think about it, having many many scattered small objects in the Kuiper Belt makes much more sense than a few giant planets. Out there, it would be difficult for large objects to coalesce from the solar system’s initial accretion disk. The density of material would be too low. However, you might get a lot of small objects from that disk, which once formed would be too far apart to accrete into larger planets.

The use of the term “Planet Nine” by these scientists however is somewhat annoying, and that has less to do with Pluto and more to do with the general understanding of what it means to be a planet that has been evolving in the past two decades. There are clearly more than eight planets known in the solar system now. The large moons of the gas giants as well as the larger dwarf planets, such as Ceres, have been shown to have all the complex features of planets. And fundamentally, they are large enough to be spheres, not misshaped asteroids.

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Ceres’ bright spots in Occator Crater

9:26 am

Occator Crater bright spot

Cool image time! The Dawn science team has released some additional images taken shortly before the mission’s conclusion when Dawn was in its closest orbit of the dwarf planet Ceres. On the right is a tiny cropped portion of a much larger mosaic of the bright spots on the floor of Occator Crater, focusing on one large bright spot that also includes a fissure cutting across it. If you click on the image you can see the entire mosaic, covering an additional four more bright areas.

The mosaic was taken in June 2018 from a distance of 21 miles.

The press release describes these bright areas as “deposits of salts, in particular sodium carbonate, possibly extruded through fractures connecting the surface to a deep reservoir of salty liquid.” That surely looks confirmed by the fissures in the image to the right.

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Hayabusa-2 to grab asteroid samples in February

9:36 am

The Hayabusa-2 science team has decided that it will make their first attempt to land and grab samples from the asteroid Ryugu in February.

“The time has finally come,” JAXA senior project member Takashi Kubota said at a news conference on Jan. 8. “Two candidate landing spots have their own advantages and drawbacks, but we will robustly try to collect samples.” The two sites are near the equator of the asteroid. JAXA said it will pick one by early February.

Between Feb. 18 and Feb. 23, the Hayabusa 2 will start descending from its “home position” at an altitude of 20 kilometers from the asteroid. JAXA will use “target markers,” which will be dropped on Ryugu beforehand, to guide the probe.

Hayabusa 2 is scheduled to make three touch-and-go landings.

There are clearly risks here, since the asteroid is strewn so completely with rocks and boulders.

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More results from New Horizons

1:42 pm

Today’s press conference did not release any significantly new images. In fact, they did not provide much new information at all. They noted that based on the data obtained so far, they have confirmed that Ultima Thule has no moons closer than 100 miles, or further than 500 miles, but they have not yet gotten the data that looks in that gap.

They created a stereoscopic image using two images produced thirty minutes apart. This helps tell us where the bumps and depressions are on the surface, something that cannot be clearly determined from the first image because the sun was shining directly on it, producing no shadows. From this it appears that the smaller lobe has a very significant bump. More data from New Horizons will have to be downloaded to confirm this.

The reddish color of Ultima Thule places it in the center of a class of Kuiper Belt objects dubbed cold classical objects. This will help them better determine its make-up as more data arrives.

Overall, this press conference was mostly hype. They don’t yet have enough data from the spacecraft, and won’t have it for weeks. I’m therefore puzzled why they bothered today, unless they did it simply to keep the hype up about the mission so as to encourage funding to look for another object to fly past.

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OSIRIS-REx’s first survey of Bennu

8:33 am

The OSIRIS-REx science team has released a short movie of Bennu made up of images taken by the spacecraft’s navigation camera during its preliminary approaches to the asteroid from November 30 to December 31, 2018.

You can watch it here. Because this is the navigation camera, the view is generally from far away. Nonetheless, you can see that during the passes over the north pole, the equator, and the south pole, the asteroid’s entire surface became visible as the asteroid rotated. From this they will be able to use the images taken by the high resolution cameras to create an excellent detailed global.

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“We have a snow-man!”

12:30 pm

Ultima Thule, the snowman

The quote in the headline comes from Alan Stern, the principle scientist for New Horizons, during today’s press conference revealing the first high resolution images of Ultima Thule. The press release for this conference is now online. The image on the right is a reduced cropped version of the main release image today. If you click on it you can see the full resolution version.

The images reveal that Ultima Thule actually is two objects in contact with each other. In addition, the snowman description is apt, as it has a mottled appearance as if it was shaped roughly and somewhat gently over time. Tiny pebbles and rocks softly came together to form two snowballs that then eventually came to touch and join.

They describe this as the most primitive object ever observed. It is also dark, and red in color, like dark reddish dirt.

More images and data is still coming in, to be released in another press conference tomorrow.

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Another image of Ultima Thule

9:47 am

Ultima Thule again

The image on the right was released during this morning’s first briefing outlining the successful confirmation of New Horizons’ fly-by of Ultima Thule (still on-going as I post this). It, along with other data, has provided an explanation for why the scientists have not detected a significant variation in brightness: Our view is looking down at the object’s poles

Images taken during the spacecraft’s approach — which brought New Horizons to within just 2,200 miles (3,500 kilometers) of Ultima at 12:33 a.m. EST — revealed that the Kuiper Belt object may have a shape similar to a bowling pin, spinning end over end, with dimensions of approximately 20 by 10 miles (32 by 16 kilometers). Another possibility is Ultima could be two objects orbiting each other. Flyby data have already solved one of Ultima’s mysteries, showing that the Kuiper Belt object is spinning like a propeller with the axis pointing approximately toward New Horizons. This explains why, in earlier images taken before Ultima was resolved, its brightness didn’t appear to vary as it rotated. The team has still not determined the rotation period.

They note that the highest resolution images will not arrive until February, though they do expect some good images by tomorrow.

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“We have a healthy spacecraft.”

8:44 am

The words above were just announced in the control room for New Horizons. They have confirmation that the spacecraft survived the fly-by of Ultima Thule, and is now ready to begin downloading the data it obtained.

It will take literally a year to get all of that data. They will be holding a first press conference within an hour to outline in greater detail the spacecraft’s status, followed by another briefing at 2 pm Eastern where they will likely release the first images.

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First faint image of Ultima Thule

8:09 am

Ultima Thule, first image

In anticipation of receiving data from the fly-by just past midnight last night, the New Horizons team has released the image above, taken 24 hours earlier.

Just over 24 hours before its closest approach to Kuiper Belt object Ultima Thule, the New Horizons spacecraft has sent back the first images that begin to reveal Ultima’s shape. The original images have a pixel size of 6 miles (10 kilometers), not much smaller than Ultima’s estimated size of 20 miles (30 kilometers), so Ultima is only about 3 pixels across (left panel). However, image-sharpening techniques combining multiple images show that it is elongated, perhaps twice as long as it is wide (right panel). This shape roughly matches the outline of Ultima’s shadow that was seen in observations of the object passing in front of a star made from Argentina in 2017 and Senegal in 2018.

This object is definitely strangely shaped.

New Horizons is traveling fast, which is why we won’t get good images until practically the instant the fly-by happens. And the first downloads from that fly-by are due to arrive within the next two hours. Keep your fingers crossed that the spacecraft operated as programmed and captured Ultima Thule in all its weird glory.

One point about the sad state of journalism these days. Numerous media publications posted stories last night celebrating that fly-by, as if they knew it was a success. This is bunk. We won’t know what happened until this morning. To imply we do is the hallmark of fake news.

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OSIRIS-REx moves into close orbit with Bennu

4:02 pm

OSIRIS-REx has successfully completed an eight second engine burn to place it into a close orbit with the asteroid Bennu.

Now, the spacecraft will circle Bennu about a mile (1.75 kilometers) from its center, closer than any other spacecraft has come to its celestial object of study. (Previously the closest orbit of a planetary body was in May 2016, when the Rosetta spacecraft orbited about four miles (seven kilometers) from the center of the comet 67P/Churyumov-Gerasimenko.) The comfortable distance is necessary to keep the spacecraft locked to Bennu, which has a gravity force only 5-millionths as strong as Earth’s. The spacecraft is scheduled to orbit Bennu through mid-February at a leisurely 62 hours per orbit.

There is a bit of hype here. Other spacecraft have gotten far closer (NEAR, Hayabusa-1, Hayabusa-2) but then retreated for a variety of reasons. What makes this different is the plan to stay this close while they compile detailed data about Bennu’s surface in preparation for touchdown to grab a sample.

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OSIRIS-REx flies over Bennu’s north pole

10:09 am

Bennu's north pole

Cool movie time! OSIRIS-REx has completed its first planned fly-over of Bennu, this time above its north pole, and the science team has released a short movie showing part of that fly-over. I have embedded the movie below the fold.

This series of MapCam images was taken over the course of about four hours and 19 minutes on Dec. 4, 2018, as OSIRIS-REx made its first pass over Bennu’s north pole. The images were captured as the spacecraft was inbound toward Bennu, shortly before its closest approach of the asteroid’s pole. As the asteroid rotates and grows larger in the field of view, the range to the center of Bennu shrinks from about 7.1 to 5.8 miles (11.4 to 9.3 km).

They have four more fly-overs of the asteroid’s poles and equator as they assemble a detailed map of its surface.
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