Tag: asteroids

Hayabusa-2 completes rehearsal for MINERVA-II drop

9:58 am

Hayabusa-2 has successfully completed its rehearsal for its planned drop of its last MINERVA-II bouncer/rover, releasing two reflective targets in order to track how they spiral down to the surface of Ryugu.

Hayabusa 2’s cameras will track the movement of the two navigation aids as they fly in space around Ryugu over the next several days. Scientists expect Ryugu’s tenuous gravity will pull the target markers to the asteroid’s surface within a week.

The release of that last bouncer is now expected in about a month. After spending time obtaining the data from that drop, Hayabusa-2 will then head back to Earth by the end of the year.

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The never-ending snowstorm circling Saturn

10:21 am

New data suggests that the water being spewed out of Enceladus’s tiger stripes is depositing so much snow and ice on Saturn’s three inner moons, Mimas, Enceladus and Tethys, that these moons, as well as Enceladus, are about twice as bright in radar than previously thought.

Dr Le Gall and a team of researchers from France and the US have analysed 60 radar observations of Saturn’s inner moons, drawing from the full database of observations taken by the Cassini mission between 2004 and 2017. They found that previous reporting on these observations had underestimated the radar brightness by a factor of two.

Unprotected by any atmospheres, Saturn’s inner moons are bombarded by grains of various origins which alter their surface composition and texture. Cassini radar observations can help assess these effects by giving insights into the purity of the satellites’ water ice.

The extreme radar brightness is most likely related to the geysers that pump water from Enceladus’s internal ocean into the region in which the three moons orbit. Ultra-clean water ice particles fall back onto Enceladus itself and precipitate as snow on the other moons’ surfaces.

Dr Le Gall, of LATMOS-UVSQ, Paris, explained: “The super-bright radar signals that we observe require a snow cover that is at least a few tens of centimetres thick. However, the composition alone cannot explain the extremely bright levels recorded. Radar waves can penetrate transparent ice down to few meters and therefore have more opportunities to bounce off buried structures. The sub-surfaces of Saturn’s inner moons must contain highly efficient retro-reflectors that preferentially backscatter radar waves towards their source.”

While the new results suggest that the surfaces of these moons are much brighter that expected, I find the circumstances they describe far more fascinating: a never-ending snow storm in the orbits around Saturn and landing continually on these moons.

My, isn’t the universe wonderful?

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Stony-iron asteroid caused flash on Jupiter in August

11:26 am

According to an analysis of the data obtained from the light flash that occurred when an object hit Jupiter on August 7, scientists have estimated its probably make-up, mass, and size.

They estimate from the energy released by the flash that the impactor could have been an object around 12-16 metres in diameter and with a mass of about 450 tons that disintegrated in the upper atmosphere at an altitude of about 80 kilometres above Jupiter’s clouds. Sankar and Palotai’s models of the light-curve for the flash suggest the impactor had a density typical of stony-iron meteors, indicating that it was a small asteroid rather than a comet.

Their conclusions are strengthened because they were able to compare this flash with five other similar but not as bright flashes, all detected since 2010.

These recent detections, all by amateurs, are because of the higher quality equipment now available to ordinary people, including the use of computers and remote operation. This technology is making it possible for amateurs to discover things that once only professionals could find.

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First high quality image of interstellar comet

2:01 pm

Comet Borisov
Click for full image.

The Gemini Observatory on Mauna Kea has successfully taken the first high resolution image of comet C_2019 Q4, unofficially Comet Borisov (after its discoverer), the first interstellar comet ever discovered.

The image to right, cropped to post here, is that image. It clearly shows the growth of a coma and possible tail, indicating that as it is approaching the Sun it is releasing material from its surface.

Right now the comet is visually very close to the Sun, when looked at from the Earth, making observations difficult. As in the next few months it drops towards its closest approach of the Sun, and the Earth circles around in its own orbit, the viewing angle will improve.

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Interstellar comet discovered?

11:51 pm

An amateur astronomer has discovered what appears right now to be an interstellar comet making its approach into the solar system.

[I]mages show that the incoming object sports a faint but distinct coma and the barest hint of a tail — something ‘Oumuamua lacked — and thus appears to be a comet. Astronomers are no doubt eager to get spectra of the new find to determine what compounds might be escaping from its surface.

Based on current observations, C/2019 Q4’s eccentricity is about 3.2 — definitely hyperbolic. Objects on hyperbolic orbits are unbound to the Sun. They’re most likely to hail from beyond the solar system, flying in from great distances to pay our neighborhood a brief visit before heading off for parts unknown.

If this result holds up, astronomers have an unprecedented opportunity to study a potentially interstellar object in great detail over a long span of time. Based on the comet’s current magnitude (~18) and distance from the Sun (2.7 a.u.), it appears to be a fairly large object — perhaps 10 km or more across, depending on the reflectivity of its surface.

There remains a great deal of uncertainty about comet’s path, which will be better resolved with time and better data.

If it is a comet from beyond the solar system, it will be a spectacular goldmine for scientists, because its coma and tail will allow them to gather a great deal of information about its make-up, far more than they were able to gather about Oumuamua.

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Hayabusa-2 in safe mode for one day on August 29

9:36 am

Japan’s Hayabusa-2 space probe automatically entered safe mode for one day on August 29, causing engineers to postpone a planned operation set for Sept 5.

Hayabusa2 is equipped with four reaction wheels that are used to control the posture of the spacecraft, and posture control is usually performed using three of these reaction wheels. On August 29, the back-up reaction wheel that has not been used since October last year was tested, and an abnormal value (an increased torque) as detected. The spacecraft therefore autonomously moved into the Safe-Hold state. Details of the cause of the abnormal torque value are currently under investigation. On August 30, restoration steps were taken and the spacecraft returned to normal. However, as the spacecraft moved away from the home position due to entering Safe-Hold, we are currently having to return to the home position. We will return to the home position this weekend.

The attitude of the spacecraft is controlled by three reaction wheels as before. Entering the Safe-Hold state is one of the functions employed to keep the spacecraft safe, which means that procedures have worked normally.

In this case it is very clear that this event actually demonstrated that the spacecraft’s systems are operating properly to prevent it from becoming lost. However, the event also underlined the urgency of getting its samples from the asteroid Ryugu back to Earth.

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OSIRIS-REx’s four candidate landing sites

9:07 am

The OSIRIS-REx engineering team has released a short video that flies over in close-up, showing the spacecraft’s four candidate sites on the asteroid Bennu, one of which will be where they will do a touch-and-go sample grab.

They continue to accumulate data on the four sites, all of which pose issues and risks because of nearby boulders and the looseness of Bennu’s rubble pile make-up.

Though all the sites are being considered, my sources in the industry suggest that the two dubbed Sandpiper and Nightingale are being favored. I like Osprey, because it is inside a crater and looks clear, but then, what do I know?

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Arecibo gets $19 million NASA research/education grant

5:25 pm

The Arecibo Observatory in Puerto Rico was today awarded an $19 million NASA research/education grant for studying near Earth asteroids.

NASA awarded the University of Central Florida (which manages the site on behalf of National Science Foundation) the four-year grant to observe and characterize near-Earth objects (NEO) that pose a potential hazard to Earth or that could be candidates for future space missions.

…The award also includes money to support STEM education among high school students in Puerto Rico. The Science, Technology And Research (STAR) Academy brings together 30 local high-school students per semester once a week for 16 classes to learn about science and research at the observatory.

This, plus the recent NSF grant, will keep the telescope operating for at least the next few years.

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Results from tiny MASCOT lander on Ryugu

9:21 pm

The scientists in charge of the tiny MASCOT lander dropped from Japan’s Hayabusa-2 spacecraft today released the results from the lander’s short seventeen hour observations of the surface of Ryugu.

They found that the asteroid has two different types of rocks (why is a mystery) and practically no dust.

Ralf Jaumann and his team were particularly surprised by the lack of dust: “Ryugu’s entire surface is littered with boulders, but we have not discovered dust anywhere. It should be present, due to the bombardment of the asteroid by micrometeorites over billions of years, and their weathering effect. However, as the asteroid has very low gravity – only one-sixtieth of that experienced on Earth’s surface – the dust has either disappeared into cavities on the asteroid or has escaped into space. This gives an indication of the complex geophysical processes occurring on the surface of this small asteroid.”

They also confirmed that the asteroid is a very fragile rubble pile.

“If Ryugu or another similar asteroid were ever to come dangerously close to Earth and an attempt had to be made to divert it, this would need to be done with great care. In the event that it was impacted with great force, the entire asteroid, weighing approximately half-a-billion tonnes, would break up into numerous fragments. Then, many individual parts weighing several tonnes would impact Earth,” says Jaumann, who is supervising the MASCam experiment, interpreting the observations. The asteroid is very similar to carbonaceous meteorites found on Earth, which date back 4.5 billion years. With an average density of just 1.2 grams per cubic centimetre, Ryugu is only a little ‘heavier’ than water ice. But as the asteroid is made up of numerous pieces of rock of different sizes, this means that much of its volume must be traversed by cavities, which probably makes this diamond-shaped body extremely fragile.

MASCOT was another example of a cubesat demonstrating that these tiny spacecraft can do very sophisticated science.

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Japan’s plan for returning Hayabusa-2’s Ryugu samples to Earth

10:07 am

Japan’s today provided an update on what it has done to prepare the location where Hayabusa-2’s samples from the asteroid Ryugu will land on Earth.

The landing site is in the Woomera Prohibited Area (WPA) in the outback of southern Australia. Japan has already signed an agreement with that country for the recovery, as well as done preliminary surface work

The recovery site is an Australian Government prohibited area and is not accessible to the public. As part of the preparatory work, a field survey of the proposed recovery site in the WPA was conducted with permission from the Australian Government. This preparatory work confirmed the suitability of both the proposed recovery site and the candidate site for the antenna station that will search for the capsule.

The landing of the recovery capsule is now scheduled for late in 2020.

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OSIRIS-REx team picks four finalist sample return sites on Bennu

3:31 pm

After months of photographing and analyzing the very rocky-shrewn surface of the rubble-pile asteroid Bennu, the OSIRIS-REx team has chosen four finalist sites, one of which they will do a touch-and-go sample grab.

This fall, OSIRIS-REx will begin detailed analyses of the four candidate sites during the mission’s reconnaissance phase. During the first stage of this phase, the spacecraft will execute high passes over each of the four sites from a distance of 0.8 miles (1.29 km) to confirm they are safe and contain sampleable material. Closeup imaging also will map the features and landmarks required for the spacecraft’s autonomous navigation to the asteroid’s surface. The team will use the data from these passes to select the final primary and backup sample collection sites in December.

The second and third stages of reconnaissance will begin in early 2020 when the spacecraft will perform passes over the final two sites at lower altitudes and take even higher resolution observations of the surface to identify features, such as groupings of rocks that will be used to navigate to the surface for sample collection. OSIRIS-REx sample collection is scheduled for the latter half of 2020, and the spacecraft will return the asteroid samples to Earth on Sept. 24, 2023.

They given the four sites the names Nightingale, Kingfisher, Osprey and Sandpiper.

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Possibility of meteorites from bright fireball in Ontario

1:54 pm

Astronomers were successfully able to track and photograph a bright fireball over Canada early today, and think it is strongly possible that pieces of it might have hit the ground.

Preliminary results indicate that the fireball first became visible just south of Oshawa over Lake Ontario at an altitude of 93 km. It traveled over Clarington and passed just west of Peterborough before extinguishing just west of Bancroft. The fireball rivaled the full moon in brightness and had a number of bright flares near the end of its flight. The meteoroid was roughly the size of a small beachball (approx. 30cm in diameter) and likely dropped a small number of meteorite fragments in the tens to hundreds of grams size-range on the ground.

Brown and his collaborators at Western and the Royal Ontario Museum are interested in connecting with people from the area of the potential fall, who may have heard anything unusual, or who may have found possible meteorites.

…Meteorites can be recognized by their dark, often scalloped exterior. Usually they will be denser than a ‘normal’ rock and will often be attracted to a magnet due to their metal content. Meteorites are not dangerous, but if recovered, it is best to place them in a clean plastic bag or wrap them in aluminum foil. They should also be handled as little as possible to help preserve their scientific value. In Canada, meteorites belong to the owner of the land upon which they are found. If individuals plan to search, they should always obtain permission of the land-owner before venturing onto private land.

If you live up in that neck of the woods, take a look around. You might find something.

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Hayabusa-2: Carbon-rich asteroids too delicate to reach Earth surface

1:57 pm

New data from Hayabusa-2 has confirmed the long-held suspicions of astronomers that the reason they find so few fragments of C-class asteroids, such as Ryugu, on Earth is because they are too delicate to reach the Earth’s surface.

Ryugu and other asteroids of the common ‘C-class’ [chondritic] consist of more porous material than was previously thought. Small fragments of their material are therefore too fragile to survive entry into the atmosphere in the event of a collision with Earth.

…Until now, only a few chondritic meteorites found on Earth have been identified as fragments of C-type asteroids, which are very common in the Solar System (‘C’ is the chemical symbol for the element carbon). …”We can now confirm that fragments of these asteroids are very likely to break up further when they enter Earth’s atmosphere, and then usually burn up completely. This means that only the largest fragments reach the Earth’s surface,” explains Grott. “That is why meteorites from this type of asteroid are so rarely found on Earth.”

The good news is that, because of this, Earth’s atmosphere offers increased protection from C-type asteroids, which account for 75 percent of all asteroids. …However, further research is necessary to determine the maximum asteroid size for which this atmospheric protection is effective.

It is likely that even the largest rubble-pile C-asteroids will not pose much risk. Even if some pieces reach the Earth’s surface they are probably going to be small and unable to do much harm.

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Hayabusa-2’s second touchdown sample grab

9:17 am

Hayabusa touchdown sequence

The Hayabusa-2 science team yesterday released a series of close-up images taken just as the spacecraft touched down and then backed off from the surface of Ryugu.

I have cropped and annotated that sequence and placed all three images side-by-side above. The red arrows in the first two images highlight similar shadows in both pictures, with the appearance of dust visible in the lower center of the middle touchdown picture. I have not marked any comparable surface features in the third image because the uplift of material makes it too difficult.

That uplift however is exactly what the Hayabusa-2 science team needs, as it is some of this material that has hopefully been captured. Their fear was that this uplift posed a risk to the spacecraft itself, but they took precautions to minimize the risk and it appears that these precautions have worked.

We now must wait until the samples come back to Earth in December 2020 to see exactly what they caught.

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Hayabusa-2’s second touchdown an apparent success

9:16 am

Japan’s Hayabusa-2 probe has successfully completed its second touch-and-go sample grab on the asteroid Ryugu.

Japan’s Hayabusa2 successfully completed its second touchdown on the asteroid Ryugu and probably captured material from its interior that was exposed by firing a projectile into the asteroid earlier this year. It is the first collection of subsurface materials from a solar system body other than the moon.

Engineers and technicians in the spacecraft’s control room near Tokyo could be seen erupting into cheers and applause on a YouTube live stream when Project Manager Yuichi Tsuda proclaimed the operation a success just before 11 a.m. local time. At an afternoon press briefing, Tsuda said, “Everything went perfectly.” He joked that if a score of 100 indicated perfection, “I would give this a score of 1000.”

They will now begin the journey home, with the samples arriving on Earth in December 2020.

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Hayabusa-2 begins second touch&go sample grab on Ryugu

8:26 am

The Hayabusa-2 science team has begun the approach to Ryugu for the spacecraft’s second tough-and-go sample grab.

The link outlines the plan and timing of the operation. You can view real-time images taken by the probe’s navigation camera here. The actual touchdown will take place on July 11 (Japan time).

You can also view a set of stereoscopic images of Ryugu produced by Brian May, lead guitarist of Queen who clearly wants to return to his roots as a trained astrophysicist.

As they note at the first link:

The 2nd touchdown is the last big operation at Ryugu for the Hayabusa2 project. We will proceed with caution and the upmost care. Please wish us success…!

If successful, their next big operation will be getting those samples back to Earth.

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Astronomers find kilometer-sized asteroid with shortest year

10:10 am

Astronomers have found a kilometer-sized asteroid with a year only 151 days long, the shortest year of any asteroid.

The asteroid has been dubbed 2019 LF6.

In its orbit, the asteroid swings out beyond Venus and, at times, comes closer in than Mercury, which circles the sun every 88 days. 2019 LF6 is one of only 20 known “Atira” asteroids, which are objects whose orbits fall entirely within Earth’s.

Atira asteroids are difficult to find because they are so close to the Sun, which makes observations difficult if not impossible. Expect more such discoveries as the technology to make these observations improves.

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Hayabusa’s 2nd sample grab on Ryugu

8:11 am

Target 2nd landing site on Ryugu
Click for full resolution image.

The Hayabusa-2 science team today posted detailed information in two posts about the process that led to the decision to attempt a second touch-and-go sample grab on the surface of Ryugu. The first part outlined in detail what they have learned about the target landing site. The second part described the decision making process.

The image to the right, reduced to post here, is from the second part. It shows the crater they created with a projectile and the target landing site, labeled C01-C. The dark areas show the changes on the surface following the impact. Their analysis of the target site found that, first, they can land there without undue risk to the spacecraft, and, second, they have a high probability of getting ejecta thrown up from the crater in their sample.

Based on all this information, they decided to attempt it, on July 11. I especially like how they stated this decision:

The second touchdown will be attempted on July 11. We will proceed with our mission with care, but boldly go. [emphasis mine]

I am sure my readers will recognize the literary reference.

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Hayabusa-2 to attempt 2nd sample grab

9:02 am

The new colonial movement: The Hayabusa-2 science team has decided to attempt a second touch-and-go sample grab from the man-made crater they created on the surface of the rubble-pile asteroid Ryugu.

JAXA engineers confirmed that the probe’s camera and other equipment that were slightly damaged by the first landing are usable, and that there are no big rocks at the candidate site. They gave the go-ahead for a landing on July 11.

Hayabusa2 is scheduled to begin its descent from an altitude of 20,000 meters at around 10 a.m. on July 10 Japan time, and touch down on the asteroid’s surface about 25 hours later.

This is the first time I have heard of any damage to the spacecraft from the first touch-and-go landing. Regardless, they have decided they can risk another sample grab and still have the ability to return the samples to Earth.

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Planning Hayabusa-2’s next sample grab on Ryugu

10:47 am

Target and man-made crater on Ryugu
Click for full image.

The Hayabusa-2 science team today released a mosaic image created using the images taken during the four close approaches to the site of the man made crater put there by a projectile fired from the spacecraft. The image on the right, reduced and cropped to post here, shows this area, with the white spot being the target they dropped onto the site during the most recent close approach. As they note in their release:

In order to collect this material, we need a second touchdown for which the project has been steadily preparing. At this point, it has not yet been decided whether or not to go ahead with a second touchdown, but here we will introduce our preparations in the “Approach to the second touchdown”.

After the operation to form the artificial crater, the spacecraft descended a total of four times above or near the crater site. These descent operations allowed us to obtain detailed data of the region near the artificial crater. In addition, we succeeded in dropping a target marker in the area close to the artificial crater on May 30. Combined, these operations mean that the situation around the artificial crater is now well understood.

Figure 1 [the image to the right] shows an image taken during the low altitude descent observation operation (PPTD-TM1B) conducted from June 11 – 13. The target marker was captured in the image and you can get a handle on the state of the surface. [emphasis mine]

Unfortunately they do not show us exactly where the man made crater is located in this mosaic. Nor was I able to locate it by comparing today’s image to a previous image that did indicate the location.

The only place that seems acceptable for their touch-and-go sample grab seems to be just above or to the left of the target. Whether this will get them any interior material thrown up during the impact however is unclear.

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Bennu from 2,200 feet

7:56 am

Bennu from about 2,200 feet
Click for full image.

The OSIRIS-REx science team today released one of the first images taken of Bennu after the spacecraft lowered itself into its closest orbit in early June. I have reduced and cropped slightly that image slightly to post here on the right. As they note,

From the spacecraft’s vantage point in orbit, half of Bennu is sunlit and half is in shadow. Bennu’s largest boulder can also be seen protruding from the southern hemisphere. The image was taken from a distance of 0.4 miles (690 m) above the asteroid’s surface by NavCam 1, one of three navigation cameras that comprise the spacecraft’s TAGCAMS (the Touch-and-Go Camera System) suite. At this distance, details as small as 1.6 ft (0.5 m) across can be resolved in the center of the image.

In other words, if a person was moving across the asteroid’s surface you could see them.

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Hayabusa-2 completes close approach of target/manmade crater

9:21 am

Target on Ryugu's surface

Hayabusa-2 has successfully completed its close approach and reconnaissance of the positioning target it had placed on May 30 near the crater it had created on Ryugu on April 4.

The image to the right is the last navigational image taken at the spacecraft’s closest point. You can clearly see the navigational target as the bright point near the upper center of the image, to the right of the three larger rocks. This location also appears to be inside the manmade crater, based on earlier reconnaissance of that crater. The crater is in an area they have labeled C01, which is where they have successfully placed the target. It also appears that this is the smoothest area in C01, which will greatly facilitate their planned sample grab.

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OSIRIS-REx’s new orbit of Bennu only half mile high

8:39 am

OSIRIS-REx has moved into its next phase of research by lowering its orbit around the asteroid Bennu to only 2,231 feet above the surface.

Upon arrival at Bennu, the team observed particles ejecting into space from the asteroid’s surface. To better understand why this is occurring, the first two weeks of Orbital B will be devoted to observing these events by taking frequent images of the asteroid’s horizon. For the remaining five weeks, the spacecraft will map the entire asteroid using most of its onboard science instruments: the OSIRIS-REx Laser Altimeter (OLA) will produce a full terrain map; PolyCam will form a high-resolution, global image mosaic; and the OSIRIS-REx Thermal Emission Spectrometer (OTES) and the REgolith X-ray Imaging Spectrometer (REXIS) will produce global maps in the infrared and X-ray bands. All of these measurements are essential for selecting the best sample collection site on Bennu’s surface.

The goal is to narrow to four the possible touch-and-go landing sites for grabbing a surface sample. They will pick the final choice in a reconnaissance phase now scheduled for the fall.

The present research phase will last until the middle of August, when they will raise the orbit slightly to give them a different perspective of its surface and the particles being released from it.

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Hayabusa-2 making close approach of target/manmade crater

5:56 pm

Ryugu during close approach

The Hayabusa-2 science team is right now conducting a close approach of the manmade impact crater they created to get a firm idea of exactly where the navigation target dropped to the surface during the last close approach landed.

The image on the right is the most recent navigation image, taken just a short time ago, and posted here in real time.

Once they have a precise location, they can then plan the touch-and-go sample grab within that man-made crater.

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The big water volcano on Ceres

8:38 am

Scientists have proposed a new detailed model to explain the formation of the large mountain Ahuna Mons on the asteroid Ceres.

The new theory doesn’t change the generally accepted idea that this mountain is a ice volcano, formed by the rise of a brine from below. It simply provides some details about the process.

A study involving scientists from the German Aerospace Centre (DLR) has now solved the mystery of how Ahuna Mons, as the mountain is called, was formed, using gravity measurements and investigations of the geometrical form of Ceres. A bubble made of a mixture of salt water, mud and rock rose from within the dwarf planet. The bubble pushed the ice-rich crust upwards, and at a structural weak point the muddy substance, comprising salts and hydrogenated silicates, was pushed to the surface, solidified in the cold of space, in the absence of any atmosphere, and piled up to form a mountain. Ahuna Mons is an enormous mud volcano.

The bubble would be the equivalent of a magma chamber of lava here on Earth.

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On the precipice on Bennu

10:00 am

Truck-sized boulder on a crater rim on Bennu
Click for full image.

Cool image from OSIRIS-REx. The picture on the right, cropped to post here, was taken by OSIRIS-REx and shows a square boulder about the size of a 15-passenger van, precariously perched on the rim of a large crater on the asteroid Bennu. The picture was taken April 11 from about 2.9 miles distance.

This scale is human-sized. If that rock is a 15 passenger van, then the small rocks around it are about the size of a person and that cliff is about 20-30 feet high. I can imagine strolling down the slope to check out the cliff face, though I would make sure I gave a wide berth to the part of the cliff directly below that boulder.

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VLT snaps image of double asteroid zipping past Earth

9:04 am

Double asteroid imaged by VLT

The Very Large Telescope (VLT) in Chile was successfully able to photograph the double asteroid that flew past the Earth on May 25 at a distance of 3.2 million miles and a speed of 43 thousand miles per hour.

The left image on the right is the raw image, while the right image is their reconstruction after applying adaptive-optics (AO) to the raw image. From the press release:

Bin Yang, VLT astronomer, declared “When we saw the satellite in the AO-corrected images, we were extremely thrilled. At that moment, we felt that all the pain, all the efforts were worth it.” Mathias Jones, another VLT astronomer involved in these observations, elaborated on the difficulties. “During the observations the atmospheric conditions were a bit unstable. In addition, the asteroid was relatively faint and moving very fast in the sky, making these observations particularly challenging, and causing the AO system to crash several times. It was great to see our hard work pay off despite the difficulties!”

To put it mildly, that right image is a fantasy. Astronomers love to tout the wonders of adaptive optics, but no matter how good it might be, it still is garbage-in-garbage-out, a computer simulation based on their guess at what the object would look like if there was no atmosphere in the way. In this particular case, they are being especially fantastic, and guaranteed to be wrong. It is impossible for them to extrapolate such minute surface details from the fuzzy image on the left.

Still, getting an image of this asteroid as it zipped by at that speed using such a large telescope is an achievement, and bodes well for the use of ground-based astronomy of near Earth asteroids.

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Hayabusa-2 successfully places reference target at man-made crater

8:48 am

Close-up during Hayabusa-2's close approach

Hayabusa-2 has successfully dropped a small reference target at the man-made crater on Ryugu, getting within 10 meters of the surface.

The image to the right is the last image taken by the spacecraft’s navigation camera during the operation. Unfortunately, the science team did not provide any further information, such as the height from which this image was taken, nor the scale of the features. Based on the sequence of images, it clearly occurred at the moment of closest approach.

I have tried to see if I could pinpoint the crater in the image by comparing it to the planning image post here. Unfortunately, I have been unable to identify comparable features.

Either way with the successful placement of the reference target on the surface, they can now begin planning the sample grab touch-and-go at this location.

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Hayabusa-2 has begun approach to Ryugu

9:05 am

Ryugu during approach

Hayabusa-2 has begun its approach to the man-made impact site on Ryugu in order to drop a reflective reference target there in preparation for a later touch-and-go landing.

The link provides real time delivery of the images taken by the spacecraft’s navigation camera, released approximately once every thirty minutes. The image on the right, brightened slightly to post here, is the most recent image as I write this post.

The approach will take almost twenty-four hours, so viewing the changes at the link will be somewhat equivalent to watching paint dry. I suggest returning every few hours to see the closer images of the asteroid.

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