Hayabusa-2 has begun approach to Ryugu

Ryugu during approach

Hayabusa-2 has begun its approach to Ryugu, aiming for a quick touchdown and sample grab at approximately 7:06 pm (Eastern) tonight. The image at the right is the most recent taken during the approach.

The risks? From the Hayabusa-2 website:

Our original schedule planned for touchdown in late October of last year (2018). However, Ryugu was revealed as a boulder strewn landscape that extended across the entire surface, with no flat or wide-open regions. Before arriving at Ryugu, it was assumed there would be flat areas around 100 meters in size. But far than finding this, we have not even seen flat planes 30 meters across!

During the scheduled time for touchdown in late October, we did not touchdown but descended and dropped a target marker near the intended landing site. We were able to drop the target marker in almost the planned spot and afterwards we examined the vicinity of the target marker landing site in detail. Finally, the area denoted L08-E1 was selected as the place for touchdown.

From the first link above you can see approach images as they are downloaded today, about once every half hour.

Hayabusa-2 prepares to land

Ryugu's northen hemisphere

The JAXA science team has released a set of images taken in January by Hayabusa-2 of its landing site on Ryugu, describing how those images helped map the region where touchdown will occur on February 22. The image on the right is one such image.

[It] shows a diagonally imaged photograph of Ryugu, captured by moving the spacecraft towards the direction of the north pole. The upper side of the image shows the north pole and reveals a landscape dominated with many large boulders. The white band extending to the left and right slightly below the center of the image is the equatorial ridge (Ryujin Ridge). The arrow tip marks the planned touchdown site and you can see this site is on the main ridge.

This is the first time we have images the northern hemisphere of Ryugu. In this observation, we acquired data on the equatorial region of Ryugu, the southern and northern hemisphere. Imaging the entire area is very important for creating accurate global shape models for Ryugu.

They should begin beaming images down of the landing approach sometime tomorrow, and will do so about every 30 minutes throughout the sequence.

Hayabusa-2 to attempt asteroid landing on February 22

JAXA, Japan’s space agency, today announced that Hayabusa-2 will attempt a landing on the asteroid Ryugu on February 22.

The landing was delayed from October because of the unexpected roughness of Ryugu’s surface, which literally has no spot smooth enough and large enough for Hayabusa-2, as planned. This landing will therefore be attempted in one of two places that are almost large enough, but not quite. It thus carries some additional risks.

Hayabusa-2 names features on Ryugu

The Hayabusa-2 science/engineering teams have now revealed the names they have given to all the significant features on Ryugu that they have photographed.

To name a place on a celestial body in the Solar System, you must first decide on a theme. For example, the theme for places on Venus is the “names of goddesses”. During discussions between the domestic and overseas project members, suggestions such as “names of castles around the world”, “word for ‘dragon’ in different languages” and the “names of deep-sea creatures” were proposed for the place name theme on Ryugu. After an intense debate, the theme was selected to be “names that appear in stories for children” and a theme proposal was put to the IAU WG. The proposal was accepted on September 25, after which the discussion moved to selecting the topographical features to be named and the choice of name.

The link provides a table describing the meaning of many of the names, which is often quite amusing. For example, Kolobok Crater comes from a Russian story about “A small round bread that ran away from home.”

Hayabusa-2 to grab asteroid samples in February

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.

Comparing Ryugu and Bennu

Link here. As much as they are alike, which is not surprising as they both come from the same asteroid family, the article notes the surprising differences.



Both asteroids are also liberally strewn with boulders – a challenge to mission planners on each team, who hope to descend close enough to scoop up samples for return to Earth. “It’s certainly more rugged than we had expected,” Lauretta says. 

But while boulders on Ryugu look to be unpleasantly ubiquitous, Bennu’s terrain is more varied, with more-obvious places where a safe touchdown might be possible. And, Lauretta notes, the OSIRIS-REx spacecraft is only recently arrived.

“We have a long time to explore and make the crucial decisions about where to go,” he says.

The biggest difference has to do with water. Even though scientists believe them to be portions of the same parent body, which broke apart between 800 million and one billion years ago, Bennu appears to be water rich, while Ryugu is less so. Within a week of arrival, infrared spectrometers on OSIRIS-REx were finding evidence of water-bearing minerals, and not just in localised patches. “We saw this in every single one of the spectra we have taken to date,” says Amy Simon, of NASA’s Goddard Space Flight Centre in Greenbelt, Maryland. 

One of the reasons Bennu was chosen as OSIRIS-REx’s target, Lauretta says, was the hope it would be rich in water, and possibly in organic compounds.

The similarities and differences in the samples both spacecraft will bring back will be most revealing.

Hayabusa-2’s highest resolution image so far

Ryugu up close

The Hayabusa-2 science team has released the highest resolution image taken by the spacecraft so far. The image on the right, reduced to post here, is that image. Click on it to see the full resolution version.

The image resolution is about 4.6mm/pixel. This is the highest resolution image that Hayabusa2 has taken so far and even small rocks with a diameter of 2 – 3cm are clearly visible. The maximum resolution of AMICA –the camera at the time of the first Hayabusa mission— was 6 mm/pixel, so even its resolution has now been exceeded. As the image captured of the asteroid surface from the spacecraft, it will be one of the highest resolution to be taken of Ryugu (MINERVA-II1 and MASCOT which landed on the surface, have captured even higher resolution images).

A feature from the image is the lack of regolith (sandy substance). This was suspected to be true from the images obtained so far, but it is more clearly seen in this high resolution photograph. There is also a collection of pebbles with different colors, which may be evidence that the surface material of Ryugu is mixed.

This was taken during the second landing rehearsal about two weeks ago. The image clearly shows the rubble pile that is Ryugu, lacking anything but cemented rocks. It also illustrates the landing problem faced by Hayabusa-2’s engineers. They need a flat smooth area to land, and they have not really found one that fits their needs.

Hayabusa-2 completes third Ryugu touchdown rehearsal

Ryugu up close

Hayabusa-2 today completed its third Ryugu touchdown rehearsal.

According to their operation schedule, they were planning to descent to about 20 meters of the surface, about 65 feet. The image on the right is the closest image taken during the rehearsal. You can see the shadow of Hayabusa-2 in the middle of the frame.

They have not released any information about the rehearsal results. The key here is how accurately they were able to get Hayabusa-2 to approach the asteroid’s largest flat spot, a tiny 20 meter wide spot less than half the size of their original planned landing diameter. From the image, it is unclear how successful they were.

They will now spend the next two months analyzing the data from their landing rehearsals in preparation for a landing attempt in January. During this time observations will be reduced because the Sun will be between the Earth and the asteroid.

Hayabusa-2 will do two touchdown rehearsals prior to landing in January

In order to test whether they can bring Hayabusa-2 down to the surface within a circle only 20 meters (65 feet) across (the largest smooth landing area they have found so far on Ryugu), their engineering team has decided to first do two more touchdown rehearsals in October.

In the area where the spacecraft will touchdown, it is dangerous to have boulders with a height greater than about 50cm. Since the length of the sampler horn is about 1m and the spacecraft will be to be slightly inclined during the touchdown, there is a possibility that if a boulder with a height above about 50cm is present, it will strike the main body of the spacecraft or the solar panels. Viewed from the position in Figure 2, there is no boulder larger than 50cm in the area L08-B. L08-B is the widest part within all the candidate sites without a boulder larger than 50cm.

The difficulty is that area L08-B is only about 20m in diameter. Originally, it was assumed that a safe region for touchdown would be a flat area with a radius of about 50m (100m in diameter). This has now become a radius of just 10m; a fairly severe constraint. On the other hand, during the descent to an altitude of about 50m during the MINERVA-II1 and MASCOT separation operations, we were able to confirm that the spacecraft can be guided within a position accuracy of about 10m for a height 50m above the surface of Ryugu (Figure 3). This is a promising feature for touchdown.

Although the spacecraft can be controlled with a position error of 10m at an altitude down to 50m, there remains the question of whether this accuracy can be retained as the spacecraft descends to the surface. This must be confirmed before touchdown operations. Therefore, the touchdown itself will be postponed until next year, during which time we will have two touchdown rehearsals; TD1-R1-A and TD1-R3.

After the rehearsals in October they must wait until January to do the landing because in November and December the sun will be in-between the Earth and the spacecraft, making operations more difficult. They want to also use this time to review the results of the rehearsals to better prepare for the January landing.

MASCOT’s journey on Ryugu

MASCOT's journey on Ryugu

MASCOT’s German science team has released a summary of the lander/hopper’s results and seventeen hour journey across the surface of the asteroid Ryugu. The image on the right, reduced and cropped to post here, shows the spacecraft approach, landing, and numerous hops across the surface. If you click on the image you can see the full high resolution image.

Having reconstructed the events that took place on asteroid Ryugu, the scientists are now busy analysing the first results from the acquired data and images. “What we saw from a distance already gave us an idea of what it might look like on the surface,” reports Ralf Jaumann from the DLR Institute of Planetary Research and scientific director of the MASCOT mission. “In fact, it is even crazier on the surface than expected. Everything is covered in rough blocks and strewn with boulders. How compact these blocks are and what they are composed of, we still do not know. But what was most surprising was that large accumulations of fine material are nowhere to be found – and we did not expect that. We have to investigate this in the next few weeks, because the cosmic weathering would actually have had to produce fine material,” continues Jaumann.

The spacecraft apparently bounced eight times after first contact, then executed three hops. The rubble pile nature that is observed I think explains why the Hayabusa-2 science team decided to delay its own landing for a few months so they could figure out a plan. It really appears that Ryugu does not have any smooth flat spots, as expect.

Hayabusa-2 landing on Ryugu delayed until January

Because of the roughness of the surface of Ryugu, the Hayabusa-2 science team has decided to delay the landing of the spacecraft on the asteroid from the end of this month until late January at the earliest.

JAXA project manager Yuichi Tsuda said they needed more time to prepare the landing as the latest data showed the asteroid surface was more rugged than expected.

“The mission … is to land without hitting rocks,” Tsuda said, adding this was a “most difficult” operation. “We had expected the surface would be smooth … but it seems there’s no flat area.”

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This decision is a wise one. They will have the ability to land very precisely, and this will give them time to find the least risky spot. It does indicate however that the landing itself is going to be risky, which is probably why they want more time to gather data beforehand. Should the landing fail, the mission will essentially be over. This way they can maximize what they learn.

Images of Mascot by Hayabusa released

MASCOT descending towards Ryugu

The Hayabusa-2 science team today released images taken of MASCOT as it descended to the surface of Ryugu, including images showing where it landed.

In the image on the right, reduced slightly to post here, you can see MASCOT as it slowly moves downward towards the asteroid shortly after its release from Hayabusa-2. At the link there is another image showing the mini-lander as a white dot when it was still about 115 feet above the surface. Other images show its location on the surface where it operated for seventeen hours and completed three hops.

The next big event from Hayabusa-2 will be the spacecraft’s own landing, sometime later this month.

MASCOT ends its mission on Ryugu, as planned

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.

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

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.

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

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.

New images from Hayabusa-2’s mini-bouncers

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.

Creeping into Ryugu

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.

Hayabusa-2 sees its shadow

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.

Dress rehearsal of Hayabusa-2’s landing scrapped

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.

Hayabusa-2 scientists release updated landing schedule

The science team for Hayabusa-2 has released an updated landing schedule.

Two of the landers developed by the Japanese space agency will be deployed together by Hayabusa 2 on Sept. 21, and another landing probe provided by German and French scientists is set for its descent to Ryugu on Oct. 3.

Those landing attempts will be preceded by a landing rehearsal using the Hayabusa 2 spacecraft to approach within 100 feet (30 meters) of Ryugu next week. The spacecraft is scheduled to reach its closest point to the asteroid Sept. 12, low enough to fire and test its laser range finder, a navigation sensor to be used on future touch-and-go maneuvers to snag a sample of Ryugu for return to Earth.

Below is the very busy planetary probe schedule through January:

  • Week of September 12: Hayabusa-2 will do dress rehearsal of its Ryugu landing
  • September 21: Two of Hayabusa-2’s three Minerva-II mini-landers will land on Ryugu
  • October 3: Another Hayabusa-2 mini-lander, MASCOT, will land on Ryugu
  • October 3: The Parker Solar Probe makes first fly-by of Venus
  • 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.

During this time period Curiosity will also make two more drill attempts, and then resume its climb up Mount Sharp.

Dates set for first landings on Ryugu

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.

Hayabusa-2 science team lay out Ryugu landing schedule

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.

No water as yet detected on Ryugu

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.

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

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.

Hayabusa-2 finds Ryugu covered with scattered large boulders

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.

3D image of Ryugu

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.

Ryugu from 25 miles

Ryugu from 25 miles

The Hayabusa-2 science team has released its first image of Ryugu, posted to the right, from a distance of only 25 miles. From the project manager:

The shape of Ryugu is now revealed. From a distance, Ryugu initially appeared round, then gradually turned into a square before becoming a beautiful shape similar to fluorite [known as the ‘firefly stone’ in Japanese]. Now, craters are visible, rocks are visible and the geographical features are seen to vary from place to place. This form of Ryugu is scientifically surprising and also poses a few engineering challenges.

First of all, the rotation axis of the asteroid is perpendicular to the orbit. This fact increases the degrees of freedom for landing and the rover decent operations. On the other hand, there is a peak in the vicinity of the equator and a number of large craters, which makes the selection of the landing points both interesting and difficult. Globally, the asteroid also has a shape like fluorite (or maybe an abacus bead?). This means we expect the direction of the gravitational force on the wide areas of the asteroid surface to not point directly down. We therefore need a detailed investigation of these properties to formulate our future operation plans.

They are going to have to spend some time in orbit to figure out not only where to land, but how to do it. More information on the mission can be found here.

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