Tag Archives: Ryugu

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

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

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

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

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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Hayabusa’s 2nd sample grab on Ryugu

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

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

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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Hayabusa-2 completes close approach of target/manmade crater

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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Hayabusa-2 making close approach of target/manmade crater

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

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

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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Hayabusa-2’s second approach to artificial crater scheduled

Ryugu impact site
Click for full image.

Based on images obtained during the aborted early May close-in approach to the asteroid Ryugu, the Hayabusa-2 science team was able to get better imagery of the location of their man-made impact site,, and this has allowed them to both reschedule to May 28-30 the next close approach, as well as more accurately aim the spacecraft at that artificial crater.

The image on the right shows the artificial crater as the dark area inside the box labeled C01, their new target site. The S01 box was the target location for the mid-May aborted approach.

The goal of these close-in approaches is to drop a reflective target at the site, giving them a very precise reference point for the touch-and-go sample grab to follow. They were unable to make the drop on the aborted close-in approach, and will attempt it again in this week’s second attempt.

The second link above provides a detailed minute-by-minute outline of this week’s approach. As before, you can watch it happen with the live download of navigation images every thirty minutes or so. A link to that real-time image delivery will be found here.

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Hayabusa-2 aborts close-in drop of visual marker on Ryugu

Japan’s asteroid probe Hayabusa-2 automatically aborted a planned drop of a visual markee on the asteroid Ryugu at the site where the probe created a crater in April.

Thursday’s mission was to observe the targeted area in detail and drop a marker from an altitude of 10 meters. But officials say the probe automatically suspended the operation after it descended to about 50 meters above the surface. It then headed toward its standby position of 20 kilometers above Ryugu. Hayabusa2 is designed to automatically abort its landing if it detected any irregularity. The agency is looking into the cause of the arrested descent.

Once the marker is eventually in place, they will use it for guidance during a a second touchdown to grab further samples, this time hopefully of material churned up by the explosion that created the crater.

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Ten secondary craters produced on Ryugu by Hayabusa-2’s manmade impact

The Hayabusa-2 science team has announced that it has found ten additional secondary craters produced from ejecta from the manmade impact the spacecraft created on Ryugu on April 5.

The secondary craters appear to be about a yard across each, while the initial crater is about thirty feet wide with a depth of six to ten feet.

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The new man-made crater on Ryugu

Man-made crater on Ryugu

The Hayabusa-2 science team has released before and after images of the spot on Ryugu where the spacecraft’s explosive projectile caused the creation of a small crater.

On the left above is the before, with the new crater indicated by the circle on the right. Note the rocks in both pictures, some now partly covered with debris. They did not give a scale, but this is a very small area, probably less than a few feet across.

They now need to analyze whether they can safely touchdown at this spot and grab a sample.

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Hayabusa-2 confirms man-made crater on Ryugu

In a planned fly-over of Ryugu yesterday Hayabusa-2 took its first direct images of the location where it had fired an explosive projectile and thus confirmed the creation of a man-made crater by that projectile.

“The asteroid’s terrain has clearly been altered,” said Yuichi Tsuda, an associate professor at the Japan Aerospace Exploration Agency.

Hayabusa2, which began its descent toward the asteroid Wednesday afternoon, captured images of its surface to determine the existence of the crater after it successfully shot a metal projectile at Ryugu on April 5 in an experiment deemed the first of its kind.

According to the JAXA, the probe photographed the area hit by the projectile from a distance of 1.7 km. The agency compared images of the asteroid’s surface before and after the shooting of the projectile to determine the presence of a man-made crater.

They have not yet released any of these images. They will use them however for planning a touchdown and sample grab within this crater in next few months.

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Hayabusa-2 has begun close fly-in of man-made crater

Hayabusa-2 has begun its fly-in of Ryugu to make its first close observation of the man-made crater it created on the asteroid’s surface on April 4.

The link takes you to the images downloaded in real time from the spacecraft’s navigation camera. New images appear approximately every thirty minutes. The approach has only just begun, so Ryugu remains somewhat small in the images. This will change as the day proceeds.

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April 25 set for Hayabusa-2’s first observations of artificial crater

The Hayabusa-2’s science team has scheduled their first observations of the artificial crater the spacecraft made on the surface of the asteroid Ryugu for April 25.

The probe will observe the crater, which was generated during an impact experiment on April 5, from a height of 1.7 kilometers. JAXA will collate the data with photographs of the surface taken near the impact point to measure the size and location of the crater. It will also examine the dispersion of rocks and judge whether Hayabusa2 can land to take samples.

This is only their first assessment. Once they feel comfortable about getting closer, they will then plan the spacecraft’s second touchdown and sample collection, this time hopefully from within that crater.

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Hayabusa-2’s successfully bombs Ryugu

impact on Ryugu

Japan’s Hayabusa-2 probe yesterday successfully impacted an explosive charge on the surface of the asteroid Ryugu, creating a crater for observing the interior geology.

The image to the right was taken by a camera that has separated from Hayabusa-2 and stayed closer to the impact. It shows material flying off the asteroid’s surface, at the horizon line.

Hayabusa-2 — which moved to the other side of the asteroid to stay clear of any ejecta — will next arc around and get close to this impact site to study it. They first need to make sure the ejecta has cleared.

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Hayabusa-2 to take close look at planned explosive impact point on Ryugu

Flight plan for Hayabusa-2's rehearsal

Beginning today Hayabusa-2 will do a two-day close approach of Ryugu in order to get good baseline images of the point on the surface where they will fire an explosive projectile in the first week in April. As they note:

Currently, we have scheduled the small carry-on impactor operation (SCI operation) for the first week in April. The purpose of the SCI operation is to create a crater on the surface of Ryugu, and it is important to be able to compare the asteroid surface before and after the SCI operation.

The graph on the right shows the flight plan. I expect they will do the same for this maneuver as they have done with previous close approaches, and provide real-time images as they happen.

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Confirmed: Ryugu is a rubble pile

Close-up of Ryugu's surface
Click for source paper [pdf].

At a special session today dedicated to results from the Hayabusa-2 probe to the asteroid Ryugu at the 50th Lunar and Planetary Science Conference in Texas, scientists confirmed from numerous data and images that the asteroid has a low density, is covered with boulders and pebbles, is very porous, and is thus a rubble pile that is held together by gravity, barely.

From their lead presentation [pdf]:

The estimated total porosity is even higher than that of rubble-pile asteroid Itokawa (44 ± 4%), indicating that asteroid Ryugu is also a rubble pile. This is consistent with a theory arguing that all Solar System bodies with diameter of ~1 km should be rubble piles and might have formed from reaccumulation of fragments generated by catastrophic disruption events of ~100-km sized parent bodies.

They also posit that the asteroid’s diamond shape is caused by the asteroid’s 3.5 hour rotation, which causes its weak rubble pile structure to be easily pulled to the equator, and then outward.

Another paper [pdf] did crater counts, and found that there are fewer large craters than one would expect.

The density of large craters (D>100 m) on Ryugu is lower than the empirical saturation level and its slope is steeper than that of the saturated distribution, suggesting that craters larger than 100 m are not saturated and the size distribution reflects the crater production function. However, craters smaller than 100 m are significantly under-saturated, suggesting that some crater erasure processes such as seismic shaking and armoring effect are active on the Ryugu surface. Based on cratering chronology model for the main belt, the surface age of Ryugu is estimated to be 5–200 [million years] from the size–frequency distribution of craters larger than 100 m.

In other words, this rubble pile is constantly being shaken by its rotation and time and later impacts, which steadily rewrites the surface.

If this asteroid was headed to Earth, I imagine the only safe solution to prevent disaster would be to slowly and gently deflect it so it only flies past. To do this will require an arrival far in advance of the schedule impact, to give time for the deflection process to work.

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Hayabusa-2 schedules explosion on Ryugu

The Hayabusa-2 science team has scheduled April 5 for when it will use the spacecraft to fire an explosive device into Ryugu to create a crater and debris cloud.

The probe is scheduled to detach a device loaded with explosives some 500 meters away from Ryugu. The device will set off the explosives using a timer some 40 minutes later and launch a copper “impactor” weighing about 2 kilograms into the asteroid’s surface.

The target point is several hundreds of meters away from where the space probe first touched down. The mission will require the spacecraft to move quickly to the other side of the asteroid so it won’t get hit by flying shards from the blast. A detached camera will shoot the moment of impact.

JAXA will analyze the size and shape of the crater, and how rocks fly off in a bid to collect underground samples for possible clues to the origin of the solar system.

This is different than the touchdown last month, as the spacecraft itself will not get close to the asteroid.

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Hayabusa-2 to get close to Ryugu again to observe next touchdown point

Hayabusa-2’s engineering team has decided it will on March 8 do a close approach to within 75 feet of its next planned touchdown target site in order to inspect it.

The DO-S01 operation schedule is shown in Figure 2. The spacecraft will begin descending on March 7 at 13:27 (JST, onboard time: times below are stated similarly) at a speed of 0.4m/s. The speed will then be reduced to 0.1 m/s around 23:47 on the same day. Continuing descent at this rate, we will reach our lowest altitude at around 12:22 on March 8 and then immediately begin to rise. The altitude of this lowest point will be about 23m. Please note that the times stated here are the planned values but the actual operation times may differ.

As before, they will upload navigation images as this approach is happening.

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Video from Hayabusa-2’s touchdown

The Hayabusa-2 science team has released a video taken of the spacecraft’s quick touchdown and sample grab on the asteroid Ryugu.

I have embedded the video below the fold. It not only shows the incredible rockiness of Ryugu’s surface, with the spacecraft barely missing a large rock as it came down, it also clearly shows the resulting debris cloud and surface changes after touchdown and the firing of Hayabusa-2’s projectile into the surface to throw up material that the spacecdraft could catch. You can actually see pebbles flying about below and around the spacecraft as it quickly retreats.

The Hayabusa-2 science team plans another touchdown in the next few months, this time using a different technique to disturb the surface and grab the resulting ejecta.
» Read more

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Hayabusa-2 touchdown images released

Surface of Ryugu 1 minute after touchdown

The Hayabusa-2 science team today released images taken during its quick touchdown on the asteroid Ryugu last week.

The image to the right was taken:

roughly 1 minute after touchdown at an estimated altitude of about 25m (error is a few meter) [80 feet]. The color of the region beneath the spacecraft’s shadow differs from the surroundings and has been discolored by the touchdown. At the moment, the reason for the discoloration is unknown but it may be due to the grit that was blown upwards by the spacecraft thrusters or bullet (projectile).

The image proves that everything on Hayabusa-2 worked as planned, and it almost certainly captured some of that grit.

They are going to do at least two more touchdowns before they have Hayabusa-2 leave Ryugu and head back to Earth.

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Confirmed: Hayabusa-2 grabbed got a sample of Ryugu

The Hayabusa-2 science team has confirmed that in the spacecraft’s quick touchdown on the surface of the asteroid Ryugu today it successfully snagged an asteroid sample.

Mission team members announced at about 6:30 p.m. EST (2330 GMT) today that the order to fire the bullet had been issued, and that Hayabusa2 had moved away from Ryugu as planned. But it took a few more hours for them to confirm that the bullet had indeed fired, and that sample collection occurred.

…The collected samples are key to this objective: The Ryugu material will come down to Earth in a special return capsule in December 2020. Scientists in labs around the world can then scrutinize the stuff with far more advanced equipment than the Hayabusa2 team could pack onto a single spacecraft.

The sample bounty will include more than just the material Hayabusa2 collected today. The mothership is expected to grab two more samples in the coming weeks and months. The second sampling sortie will unfold much like today’s did, but the third will be dramatically different: Hayabusa2 will fire a copper projectile into Ryugu, wait a bit for the dust to clear, and then swoop in to grab material from the newly created crater. This formerly subsurface stuff will be pristine, unaffected by weathering from deep-space radiation.

More thrills to come, obviously.

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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.

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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.

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