Tag: asteroids

New Horizons makes final big course correction

7:26 pm

New Horizons this week successfully made its final major course correction in preparation for its January 1st fly-by of the Kuiper Belt object the science team has dubbed Ultima Thule.

NASA’s New Horizons spacecraft carried out a short engine burn on Oct. 3 to home in on the location and timing of its New Year’s flyby of the Kuiper Belt object nicknamed Ultima Thule.

Word from the spacecraft that it had successfully performed the 3½-minute maneuver reached mission operations at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, at around 10:20 p.m. EDT. The maneuver slightly tweaked the spacecraft’s trajectory and bumped its speed by 2.1 meters per second – just about 4.6 miles per hour – keeping it on track to fly past Ultima (officially named 2014 MU69) at 12:33 am EST on Jan. 1, 2019.

As the spacecraft gets closer they will do more refinements, but right now they are a very precise course. The January 1st fly-by will end a spectacular fall season of planetary mission rendezvous, landings, fly-bys and sample gatherings.

Posted from Chicago.

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MASCOT ends its mission on Ryugu, as planned

10:52 pm

Hayabusa-2’s mini-lander MASCOT has ended its mission on Ryugu after seventeen hours, slightly longer than the planned sixteen hours.

The lander made one hop, and successfully transmitted all its data back to Hayabusa-2, which still has one more mini-lander on board that will be sent to Ryugu’s surface, probably after Hayabusa-2 makes its own landing.

Meanwhile, the two Minerva-2 bouncers continue to operate on Ryugu.

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Astronomers discover very distant object orbiting the Sun

9:32 am

Astronomers have discovered a very distant object in a solar orbit ranging from 6 billion to 213 billion miles from the Sun.

Designated 2015 TG387 and nicknamed “The Goblin” by its discoverers, this object resides in the inner Oort Cloud, a region beyond the Kuiper Belt that until now harbored only two other known bodies: the dwarf planet Sedna and the less well-known 2012 VP113.

The scientists estimate its size to be about 200 miles in diameter. Based on the existence of the three known objects in this region of space, the scientists estimate there could be as many as 2 million objects there bigger than 25 miles in diameter. There is a lot of uncertainty in that number.

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Hayabusa-2’s third mini-lander successfully lands on Ryugu

8:55 am

MASCOT image of Ryugu surface

Update: The image at right, reduced to post here, was taken by MASCOT during its descent. You can see the spacecraft’s shadow in the upper right. If you click on the image you can see the full resolution version.

Original post: The German/French-build mini-lander MASCOT has been successfully deployed by Hayabusa-2 and has successfully landed on the asteroid Ryugu.

MASCOT came to rest on the surface approximately 20 minutes after the separation. Now, the team is analysing the data that MASCOT is sending to Earth to understand the events occurring on the asteroid Ryugu. The lander should now be on the asteroid’s surface, in the correct position thanks to its swing arm, and have started to conduct measurements independently. There are four instruments on board: a DLR camera and radiometer, an infrared spectrometer from the Institut d’Astrophysique Spatiale and a magnetometer from the TU Braunschweig. Once MASCOT has performed all planned measurements, it is expected to hop to another measuring location. This is the first time that scientists will receive data from different locations on an asteroid.

The spacecraft took 20 pictures during its descent, which were beamed to Hayabusa-2 where they are presently stored.

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Deployment operations for Hayabusa-2’s MASCOT lander have begun

9:07 am

Engineers have begun the deployment sequence for Hayabusa-2’s MASCOT lander, with deployment planned for tomorrow.

Right now Hayabusa-2 is slowly moving closer to Ryugu, with live images appearing about once every half hour. More information about MASCOT can be found here. The lander can also hop like the MINERVA bouncers, but it can only do it once. Its battery life is about sixteen hours, so once it is deployed it will only operate on the surface for a short while.

Both the MINERVA and MASCOT mini-landers are mostly engineering tests for using small cubesat-sized spacecraft as probes. So far the MINERVA bouncers have been an unqualified success. Hopefully MASCOT will be as successfully.

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New images from Hayabusa-2’s mini-bouncers

7:17 am

Three press releases from the Hayabusa-2 science team last night provide new images from the spacecraft’s MINERVA bouncers, presently on the surface of Ryugu, as well as new high resolution images from Hayabusa-2 during its recent close-in maneuvers.

The images from the first story also includes a ten second movie showing a very rocky surface with the sun moving across the sky. The last link shows the primary landing site candidate with two backup sites.

All told, these images suggest that Ryugu is nothing more than a rubble pile stuck together. If it was heading to Earth, it might be difficult to deflect it, as it might break apart caused by any stress.

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Minerva probes send back first pictures

12:51 pm

Ryugu's surface

Super cool images! The two Minerva probes released two days ago from Hayabusa-2 have both sent back spectacular images from the surface of Ryugu.

The image on the right was captured by the rover dubbed 1A. I have rotated it to show the surface on the bottom, but the actual picture was taking during one of the rover’s bounces while it was moving, so the returned picture had the surface on left. The white brightness is from sunlight. From the press release:

We have confirmed both rovers landed on the surface of asteroid Ryugu. The two rovers are in good condition and are transmitting images and data. Analysis of this information confirmed that at least one of the rovers is moving on the asteroid surface.

MINERVA-II1 is the world’s first rover (mobile exploration robot) to land on the surface of an asteroid. This is also the first time for autonomous movement and picture capture on an asteroid surface. MINERVA-II1 is therefore “the world’s first man-made object to explore movement on an asteroid surface”. We are also delighted that the two rovers both achieved this operation at the same time.

Other released images were taken just after release. One shows a blurred picture of Hayabusa-2, while the other sees Ryugu’s surface below.

Both of these rovers are designed to travel on the surface by a series of hops, taking advantage of Ryugu’s tiny gravity. There will be more images I’m sure from them in the coming days.

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Creeping into Ryugu

10:16 pm

Ryugu

Cool images! As Hayabusu-2 creeps to its closest approach to Ryugu in preparation to releasing its first two mini-landers, dubbed MINERVA-II-1 and 2, the images coming down about once every half hour show the asteroid increasingly closer, with the spectacular shadow of Hayabusa-2 with its solar panels clearly visible.

The image on the right was downloaded about 10 pm (Pacific) tonight. The boulder-strewn field of Ryugu is also clearly visible. The black areas are where data has not yet been downloaded. The bright area under the shadow is merely an optical illusion.

UPDATE: A look at this webpage provides some details. When this image was taken the spacecraft was about 60 100 meters above the surface, its closest approach yet. This was also when the MINERVA-II landers were to be deployed.

All later images at the first link above were from a greater distance.

UPDATE: I have corrected the post. They released both MINERVA-II rovers, and they did it about 100 meters distance from the asteroid, not 60. We will not know the mini-landers’ status until late today.

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Hayabusa-2 sees its shadow

9:24 am

Ryugu, with Hayabusa-2's shadow

During its aborted landing rehearsal last week Hayabusa-2 imaged its own shadow as it approached within 600 meters of Ryugu.

The shadow is only a little dot on the surface of the asteroid, but to have resolved it is quite impressive. The image on the right has been annotated by me to indicate the shadow.

They have not said when they will do another landing rehearsal. Meanwhile, two of the spacecraft’s mini-landers are expected to be released sometime in the next few days.

Update: Based on the raw navigation images being released in real time from Hayabusa-2, the release of the MINERVA-II-1 has begun, with Hayabusa-2 moving in towards Ryugu in preparation for that release.

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Cryo-volcanism had less influence on shaping Ceres than predicted

10:23 am

The uncertainty of science: A careful analysis of the Dawn data has found that though cryo-volcanism has occurred repeatedly on Ceres, it had less influence on the dwarf planet’s surface than previous models had predicted.

At the same time, the data also suggests that Ceres has been more active throughout its history than predicted. They found about 22 domes that are apparently past cryo-volcanoes that have flattened out.

“Given how small Ceres is, and how quickly it cooled off after its formation, it would be exciting to identify only one or two possible cryovolcanoes on the surface. To identify a large population of features that may be cryovolcanoes would suggest a long history of volcanism extending up to nearly the present day, which is tremendously exciting,” said Sizemore. “Ceres is a little world that ought to be ‘dead,’ but these new results suggest it might not be. Seeing so much potential evidence for cryovolcanism on Ceres also lends more weight to discussions of cryovolcanic processes on larger icy moons in the outer solar system, where it’s likely more vigorous.”

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Dress rehearsal of Hayabusa-2’s landing scrapped

9:22 am

The dress rehearsal of Hayabusa-2’s eventual landing on the asteroid Ryugu was cut short yesterday when the spacecraft found it could not get a reliable distance reading of the surface once it descended to 600 meters.

The problem was apparently due to the pitch black surface of the carbon-rich asteroid that made laser distance measurements difficult. JAXA says the Hayabusa 2 is in good condition, and the agency is considering changing landing procedures such as adjusting the configuration of measuring devices.

Despite the suspension, the altitude of 600 meters the explorer has descended to the asteroid is the closest ever recorded. JAXA had planned to bring down the probe to 30 meters and make detailed observations of a landing spot.

Just to clarify, this was a height record for Hayabusa-2 only.

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Astronomers use radio emissions from distant galaxy to observe asteroid

9:03 am

The wonders of science: Astronomers have successfully used the faint radio emissions from very distant galaxy to roughly determine the shape and size of a nearby asteroid.

In an unusual observation, astronomers used the National Science Foundation’s Very Long Baseline Array (VLBA) to study the effects on radio waves coming from a distant radio galaxy when an asteroid in our Solar System passed in front of the galaxy. The observation allowed them to measure the size of the asteroid, gain new information about its shape, and greatly improve the accuracy with which its orbital path can be calculated.

When the asteroid passed in front of the galaxy, radio waves coming from the galaxy were slightly bent around the asteroid’s edge, in a process called diffraction. As these waves interacted with each other, they produced a circular pattern of stronger and weaker waves, similar to the patterns of bright and dark circles produced in terrestrial laboratory experiments with light waves. “By analyzing the patterns of the diffracted radio waves during this event, we were able to learn much about the asteroid, including its size and precise position, and to get some valuable clues about its shape,” said Jorma Harju, of the University of Helsinki in Finland.

The amount of information is not great, and there is an enormous amount of uncertainty in the data. Nonetheless, this is an amazing and fascinating observation.

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The upcoming very busy planetary probe season

12:08 pm

The next few months are going to be very busy and exciting for the planetary science community. Seven different probes will be either flying past or landing on four different solar system objects, with interesting events happening every few weeks:

  • September 21: One of Hayabusa-2’s mini-landers, Minerva-II-1, will land on the asteroid Ryugu
  • October 3: Another Hayabusa-2 mini-lander, MASCOT, will land on Ryugu
  • Late October: Hayabusa-2 itself will land and grab a sample of Ryugu
  • November 26: The U.S. lander InSight will land on Mars.
  • December 3: OSIRIS-REx will arrive at the asteroid Bennu.
  • December: Chang’e-4 will land on the Moon’s far side.
  • January 1: New Horizons will fly past the Kuiper Belt object Ultima Thule.

In addition, another Hayabusa-2 mini-lander will also land on Ryugu, sometime after Hayabusa-2’s landing. Moreover, as OSIRIS-REx and New Horizons approach their targets we shall see daily new and increasingly sharper images of both Bennu and Ultima Thule, prior to their arrival.

I expect from September to January there will be many many very cool images coming from space, on almost a daily basis.

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Dates set for first landings on Ryugu

9:10 am

The science team for the Japanese probe Hayabusa-2 have set the dates for the first two landings on the asteroid Ryugu.

On 21 September, it will despatch the first of these piggybacked packages. A 3.3kg container known as Minerva II-1, which is mounted on the spacecraft, will deploy two robots known as Rover 1A and Rover 1B.

The 1kg “rovers” will actually move by hopping under the asteroid’s low gravity. Each one contains a motor-powered internal mass that rotates to generate force, propelling the robot across the surface. The rovers are equipped with wide-angle and stereo cameras to send back pictures from Ryugu.

Then, on 3 October, the mothership will deploy a lander called Mascot, which has been developed by the German Aerospace Center (DLR) in conjunction with the French Space Agency (CNES). Mascot, otherwise known as the Mobile Asteroid Surface Scout, is a 10kg instrument package that will gather a range of scientific data from the surface. It carries a wide-angle camera, a microscope to study the composition of minerals, a radiometer to measure temperature and a magnetometer to measure the magnetic field.

After it reaches the surface, Mascot can move its position only once, by jumping.

An earlier report had said that Hayabusa-2 would itself land late in October, but this report today leaves that landing date unstated.

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Scientist proposes aerobraking asteroids into Earth orbit

9:00 am

What could possibly go wrong? A scientist has proposed the use of the Earth’s atmosphere to aerobrake resource-rich asteroids into Earth orbit to make them easily available for mining.

In the new paper, Tan and colleagues propose using aerobraking to slow small asteroids enough that they don’t just shoot straight past Earth, but stay in orbit, where they could be mined for platinum or water. Those resources could then be taken to space stations to supply future missions or operations. Water, they write, could even be split into hydrogen and oxygen for fuel. All it would take is a precisely calculated push from an unmanned spacecraft, they report this month in Acta Astronautica.

And if the maneuver were done far enough from Earth—millions of kilometers, in most cases—it likely wouldn’t take much effort. That’s because a small push from far away would greatly change the angle of an incoming space rock’s path. Tan notes that each case would be different, depending on the trajectory of the target asteroid, and says that modifications might be necessary if the asteroid gets off track.

They propose doing this only with small asteroids, less than 100 feet in diameter.

I am sure my readers can outline the numerous problems with this proposal. From my perspective, the primary one is that it is almost impossible to predict the precise path of these kinds of asteroids. Their rotation and irregular shape combined with radiation pressure from the Sun tends to make their solar orbits somewhat chaotic and difficult to predict at the accuracy needed to safely nudge them into a close fly-by of the Earth.

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Hayabusa-1 sample pins down age of asteroid

9:19 am

Using particles gathered by Hayabusa-1 Japanese scientists have determined the age of the asteroid Itokawa.

Japanese scientists, including those from Osaka University, closely examined particles collected from the asteroid Itokawa by the spacecraft Hayabusa, finding that the parent body of Itokawa was formed about 4.6 billion years ago when the solar system was born and that it was destroyed by a collision with another asteroid about 1.5 billion years ago.

These results are only the beginning. As more samples return from more asteroids, scientists will start to add details to the overall history of the formation and evolution of the solar system, adding significant depth to the rough outline they presently have. And these new samples are already on the way, with both Hayabusa-2 and OSIRIS-REx approaching their target asteroids.

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Hayabusa-2 science team lay out Ryugu landing schedule

8:41 am

At a press conference yesterday the Hayabusa-2 science team laid out their landing schedule for the spacecraft and its three tiny landers.

The first lander will be one of its two tiny MINERVA-II probes, and will take place in September. This will be followed by the German/French MASCOT probe in early October, followed in turn in late October by Hayabusa-2 itself.

The landings of the first two probes will help them pick Hayabusa-2’s landing site, as well as the site for last MINERVA lander.

Mission planners faced tough choices because the body almost uniformly strewn with boulders. “Ryugu is beautiful, but challenging,” said Aurélie Moussi, a collaborator from the French space agency CNES in Toulouse, at a press conference in Sagamihara, Japan, on 23 August.

…To minimize risks for MASCOT, mission planners mapped the topography of Ryugu and the distribution and size of the boulders on its surface. They ran computer simulations to produce a shortlist of ten options, and then picked one spot on the asteroid’s southern hemisphere. The choice reflected a number of criteria, including average temperatures on the ground and the materials that MASCOT will analyse with its four on-board instruments. “The other sites would have been just as good, or just as difficult,” says MASCOT payload manager Stephan Ulamec of the German Aerospace Center in Cologne. “Wherever we look, there is a lot of big boulders.”

It does appear that the boulder-strewn surface is posing a problem for the engineers.

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Oblique mosiac of bright spot on Ceres

9:40 am

Cerealia Facula on Ceres

Cool image time! With the Dawn spacecraft now swooping with 22 miles of the surface of Ceres every 27 hours, the science team has assembled a spectacular oblique image of Cerealia Facula, one of the dwarf planet’s bright spots thought to be brine deposits that at some point erupted up from below the surface.

The image on the right, reduced in resolution to show here, shows that mosaic. If you click on the image you can see the full resolution version. From the image webpage:

This mosaic of Cerealia Facula combines images obtained from altitudes as low as 22 miles (35 km) above Ceres’ surface. The mosaic is overlain on a topography model based on images obtained during Dawn’s low altitude mapping orbit (240 miles or 385 km altitude). No vertical exaggeration was applied.

There are a lot of intriguing details in the full resolution image. I have highlighted one feature, indicated by the white box and shown in full resolution below.
» Read more

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Ceres’ internal structure

10:21 am

The Dawn science team has released their first artist’s concept of the interior of Ceres, based on data gathered by the spacecraft.

Using information about Ceres’ gravity and topography, scientists found that Ceres is “differentiated,” which means that it has compositionally distinct layers at different depths. The most internal layer, the “mantle” is dominated by hydrated rocks, like clays. The external layer, the 24.85-mile (40-kilometer) thick crust, is a mixture of ice, salts, and hydrated minerals. Between the two is a layer that may contain a little bit of liquid rich in salts, called brine. It extends down at least 62 miles (100 kilometers). The Dawn observations cannot “see” below about 62 miles (100 kilometers) in depth. Hence, it is not possible to tell if Ceres’ deep interior contains more liquid or a core of dense material rich in metal.

The most intriguing part of this concept is the existence of a brine layer below the crust. I suspect it is this layer that they believe is the source of the white salty brine that produces Ceres’ ice volcanoes and bright spots.

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Perseid meteor shower this weekend

10:24 am

The annual Perseid meteor shower upcoming on August 12 is expected to be especially good this year because there will be no moon in the sky.

The Perseid meteors seem to come from a single point, the `radiant’, situated in the constellation Perseus, giving the shower its name. This is however just an effect of perspective, as the meteors move parallel to each other, much like drivers see when driving in heavy rain.

The radiant will be visible from around 10pm and at this time there will be the highest chance of seeing `Earth grazing meteors’. These are meteors that skim the Earth’s atmosphere and so have long, blazing tails.

Observers can expect to see a few tens of meteors per hour, or one every few minutes, once darkness has fallen on 12 August. The number of meteors will peak in the early hours of 13 August, when up to around seventy each hour should be visible.

It is worth it to find a nice dark place and stay up all night at least once in your life to watch this shower. Get a nice camp chair that allows you to lie back, make sure you are dressed comfortably, and sit back and enjoy.

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Tess captures comet, variable stars, asteroids, and Martian light

8:44 am

During its testing period prior to beginning science operations this month, the exoplanet space telescope TESS spotted in one series of images a comet, a host of variable stars, some asteroids, and even the faint hint of some reflected light from Mars.

Over the course of these tests, TESS took images of C/2018 N1, a comet discovered by NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) satellite on June 29. The comet, located about 29 million miles (48 million kilometers) from Earth in the southern constellation Piscis Austrinus, is seen to move across the frame from right to left as it orbits the Sun. The comet’s tail, which consists of gases carried away from the comet by an outflow from the Sun called the solar wind, extends to the top of the frame and gradually pivots as the comet glides across the field of view.

In addition to the comet, the images reveal a treasure trove of other astronomical activity. The stars appear to shift between white and black as a result of image processing. The shift also highlights variable stars — which change brightness either as a result of pulsation, rapid rotation, or by eclipsing binary neighbors. Asteroids in our solar system appear as small white dots moving across the field of view. Towards the end of the video, one can see a faint broad arc of light moving across the middle section of the frame from left to right. This is stray light from Mars, which is located outside the frame. The images were taken when Mars was at its brightest near opposition, or its closest distance, to Earth.

The video that was compiled from these images is embedded below the fold.
» Read more

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More close-up images of Ceres

9:19 am

Dome and fractures in Occator Crater

Strange image time! The Dawn science team today released a set of new images taken by the spacecraft in its new very close orbit of Ceres. The image on the right is a cropped section of one of those images, and shows some fractures and a dome in Occator Crater. The image was taken from 28 miles altitude, and if you click on it you can see the entire photograph.

What immediately stands out in this image is the strange bright flow on top of the dome. At first glance it looks like someone put a seashell there. In reality I think it is showing us a landslide of bright material flowing downward, towards the top of the image. The flow was significant enough that it piled up as it went down, which is why it created a cliff edge and shadow line at its base.

Everything we see here is influenced by Ceres’s tiny gravity. It is not unusual to see fractures in the floor of a crater, the nature of these fractures and domes is different, and will require a lot of work by scientists to interpret, because of the different environment.

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No water as yet detected on Ryugu

9:05 am

The Hayabusa-2 science team today said that their first preliminary survey of Ryugu has yet to detect evidence of water.

The Japan Aerospace Exploration Agency (JAXA) said Aug. 2 that data collected from the space probe showed no water on the boulders scattered on the surface of Ryugu.

Ryugu is a C-type asteroid, which is rich in carbon. Many C-type asteroids are known to contain moisture in their surface boulders, and experts hoped that Ryugu would be one of them.

Hayabusa-2’s visit has just begun. I still expect surprises.

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Ryugu as seen by Hayabusa-2 from less than 4 miles

8:41 am

Ryugu from less than 4 miles distance

The image on the right as a cropped section of an image taken by Hayabusa-2 from only 3.7 miles distance from the asteroid Ryugu. If you click on the link you can see the full image. I picked this section to crop out because it shows the asteroid’s limb, an interesting boulder field, and part of a the asteroid’s largest crater, on the lower right. As noted by the Hayabusa-2 science team in describing details in the full image:

The resolution in Figure 1 is about 3.4 times higher than the images taken from the Home Position [20 kilometers distance] so far. 1 pixel in Figure 1 corresponds to about 60cm. The largest crater on the surface of Ryugu is situated near the center of the image and you can see that it has a shape like a “mortar”. You can also see that the surface of Ryugu is covered with a large number of boulders. This picture will provide important information as we choose the landing site.

The smallest objects visible are thus about two feet across.

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Hayabusa-2 finds Ryugu covered with scattered large boulders

11:02 pm

Hayabusa-2 has found that the asteroid Ryugu is covered with many scattered large boulders.

The Hayabusa 2 space probe discovered many boulders scattered on the asteroid Ryugu, suggesting it was formed from fragments of other celestial bodies, the Japan Aerospace Exploration Agency (JAXA) said July 19. More than 100 rocks larger than 8 meters in length were confirmed on the surface of the “spinning top” asteroid from images captured by Hayabusa 2, according to JAXA. The largest boulder was about 130 meters in length near the south pole.

The rocks are likely too big to be meteor fragments from collisions with Ryugu, which has a diameter of about 900 meters. “(The finding) is compelling evidence to prove that the Ryugu asteroid was formed by fragments of larger celestial bodies,” said Seiichiro Watanabe, head of the study team and professor of Nagoya University.

The asteroid’s slightly tilted axis of rotation gives Ryugu two seasons: summer and winter. Hayabusa 2 found the temperature ranged from about 20 to 100 degrees on Ryugu’s surface.

Surprise! This finding makes Ryugu very different from every other asteroid previously visited. Most have had relatively smooth surfaces, with lots of dust.

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New close-up images of Ceres

12:15 pm

Cerealia Facula on Ceres

Cool image time! The image on the right, cropped and reduced in resolution to post here, is one of two images released today by the Dawn science team of the double bright spots found in Occator Crater, taken from the spacecraft’s tight final orbit above Ceres. This image shows what they have dubbed Cerealia Facula. The second image shows Vinalia Faculae.

This mosaic of Cerealia Facula is based on images obtained by NASA’s Dawn spacecraft in its second extended mission, from an altitude as low as about 21 miles (34 kilometers). The contrast in resolution obtained by the two phases is visible here, reflected by a few gaps in the high-resolution coverage. This image is superposed to a similar scene acquired in the low-altitude mapping orbit of the mission from an altitude of about 240 miles (385 km).

Inset of Cerealia Facula

The second image on the left is a crop at full resolution of the area in the white box above. This gives you a taste of the many interesting things found in the full resolution image. For example, the bright spots scattered throughout this image suggest they are recent upwellings from below. The ridgelines in the upper right are either the remains of the water-ice volcano they think once stood here but subsequently slumped back down to form a depression, or pressure ridges being pushed up by later upwellings.

The full image has lots more. So does the image of Vinalia Faculae. Check them out.

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Astronomers discover 10 more Jupiter moons

9:48 am

Worlds without end: Astronomers, while searching for objects in the Kuiper Belt, have discovered 10 more Jupiter moons.

All the newfound moons are small, between about 1 and 3 kilometres across. Seven of them travel in remote orbits more than 20 million kilometres away from Jupiter, and in the opposite direction from the planet’s rotation. That puts them in the category known as retrograde moons.

The eighth moon stands out because it travels in the same region of space as the retrograde moons, but in the opposite direction (that is, in the same direction as Jupiter’s spin). Its orbit is also tilted with respect to those of the retrograde moons. That means it could easily smash into the retrograde moons, pulverizing itself into oblivion. It may be the leftovers of a bigger cosmic collision in the past, Sheppard says.

Jupiter’s moons are named after gods with connections to the mythological Jupiter or Zeus. Sheppard has proposed naming the oddball Valetudo, after one of Jupiter’s descendants, the Roman goddess of hygiene and health.

The ninth and tenth newfound moons orbit closer to Jupiter, moving in the same direction as the planet.

I predict that these are not the last moons of Jupiter to be discovered. As our observing skills improve, more are certain to pop up.

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Binary asteroid imaged by radio telescopes

10:18 am

Three radio telescopes have successfully imaged the rotation of a binary asteroid, the fourth such binary so far discovered.

On June 21, the asteroid 2017 YE5 made its closest approach to Earth for at least the next 170 years, coming to within 3.7 million miles (6 million kilometers) of Earth, or about 16 times the distance between Earth and the Moon. On June 21 and 22, observations by NASA’s Goldstone Solar System Radar (GSSR) in California showed the first signs that 2017 YE5 could be a binary system. The observations revealed two distinct lobes, but the asteroid’s orientation was such that scientists could not see if the two bodies were separate or joined. Eventually, the two objects rotated to expose a distinct gap between them.

Scientists at the Arecibo Observatory in Puerto Rico had already planned to observe 2017 YE5, and they were alerted by their colleagues at Goldstone of the asteroid’s unique properties. On June 24, the scientists teamed up with researchers at the Green Bank Observatory (GBO) in West Virginia and used the two observatories together in a bi-static radar configuration (in which Arecibo transmits the radar signal and Green Bank receives the return signal). Together, they were able to confirm that 2017 YE5 consists of two separated objects. By June 26, both Goldstone and Arecibo had independently confirmed the asteroid’s binary nature.

The new observations obtained between June 21 and 26 indicate that the two objects revolve around each other once every 20 to 24 hours. This was confirmed with visible-light observations of brightness variations by Brian Warner at the Center for Solar System Studies in Rancho Cucamonga, California.

I have embedded below the fold a short video that includes the radio images showing this rotation. Most cool!
» Read more

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3D image of Ryugu

4:57 pm

The lead guitarist of the rock band Queen, Brian May, is also an astronomer, and he has taken Hayabusa-2’s first full close-up image of Ryugu and produced a 3D image of the asteroid.

If you have red/blue 3D glasses you should definitely click on the link and view the image. The asteroid appears much more elongated back to front than it appears in the flat image.

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