https://twitter.com/haya2e_jaxa/status/1057065930927140864
HAYABUSA2@JAXA‏ @haya2e_jaxa
[BOX-C] Touchdown rehearsal, TD1-R3, is just over but we are beginning BOX-C operations. The spacecraft will perform low altitude observations at ~5km from today (October 30). After this, we plan to further lower the altitude for images near the touchdown candidate site, L08.
9:25 - 2018年10月30日

http://www.hayabusa2.jaxa.jp/topics/20181030_TD1R3_CAMH/

Image taken with a small monitor camera (cam-h) in touchdown 1 rehearsal 3 (TD1-R3). The photograph was taken from the altitude of about 21m, which began to rise on October 25, 2018 (JST) every second.
The rising speed is about 52cm/s. (Image credit: JAXA)

Jaw-dropping! Thanks for finding this, brightening up my morning Yoichi!
According to the English twitter, another target marker was dropped off and tracked autonomously.

press release in english
http://www.hayabusa2.jaxa.jp/en/topics/20181030e_TD1R3_CAMH/

Another map update to include dropping the second target marker.

Any corrections or additions including feature names are very welcome.

Phil

Click to view attachment

During past hours Hayabusa silently performed a low altitude mission, going down to 2300 m; now it's rising since 15 hours and it has reached 7400m altitude, and it's still rising at 20 cm/s.


No info about it on twitter and official site.

These images attempt showing the paths followed by H2 during TD1-R1A (right long blue path, ONC-W camera) and TD1-R3 (left short blue path, horn camera).
They are the result of the 3d reconstruction of landing site using 3DF Zephyr free, which also shows (but unfortunately does not export) calculated position of cameras.


This is the 3d reconstruction of the landing site:
https://sketchfab.com/models/95adee20ea9145...1064df8418b99c7

I don't get why they decided to land so close to a house-tall boulder.

Although not very scientific because I don't have all the needed tools and skills to perform a precise job, this model is interesting because it gives a sense of scale of the landing site:
https://sketchfab.com/models/f66ecf2b03b545...969b4d5aa81d99c

Mistery revealed (about low altitude mission of previous days): they were looking for the target maker, which is confirmed to be visible from 2.4 km away:
https://twitter.com/haya2_jaxa/status/1058612614924652544

Press release (English PDF) from 8/nov press conference:
http://www.hayabusa2.jaxa.jp/enjoy/materia...08_ver6_en2.pdf

During TD1-R3:
LIDAR active down to 25m, then LRF. Synchronization to Ryugu speed, short "quick" descent before target release, target release at 12m altitude, ascent to 20 m, marker tracking , ascent back to 20000m.


2018/11/18-2018/11/29: Preparation period - On November 23, 2018, the spacecraft will be placed into the conjunction transition orbit. During this period, communications are not reliable due to Sun radio interference.
2018/11/30-2018/12/21: No trajectory control is performed, but communication with the spacecraft is still attempted.
2018/12/22-2019/01/01: Reversion period - Home Position Return control (HPR) maneuver will be performed on December 29, 2018 to return the spacecraft to the home position.


* JAXA Space Exploration Innovation Hub unveils a simple version of the shape model.
* The Hayabusa2 Science Team is developing a precise shape model for Ryugu.
* Schedule for release with the publication of the associated paper.
Downloadable here: http://www.ihub-tansa.jaxa.jp/ryugu_mokei.html
Direct link: http://www.ihub-tansa.jaxa.jp/files/tansax..._mokei_2018.fbx
Model based on low-res images from june 2018.
· Number of vertices: 157,000
· Number of triangular patches : 52, 600
· File size: 4 MB, FBX Format
· km unit


Selected landing site: L08-B
http://www.planetary.org/multimedia/space-...nding-site.html


Next press conferences scheduled for 6/dec, 13/dec

A post in the Osiris-REx thread reminded me: is there any reason Hayabysa 2 has stayed in basically an equatorial 'hover' for all this time, rather than going into a proper orbit like Osiris-Rex will after finishing imaging of the poles this month (which is also something Hayabusa 2 has not done)?

Why did the spacecraft go on a distant excursion away from Ryugu during solar conjunction, when they could have just spent that time in orbit. Surely there would be no danger of a collision after mapping out the gravity field! Or were they worried about accidentally going into the asteroid's shadow?

Probably more a matter of how confident they were that there would not be any problem during conjunction. Osiris-Rex doesn't have to worry about conjunction now, but they also might not want to stay in a low orbit for weeks without contact.

Phil

Gravity strength map released: http://www.hayabusa2.jaxa.jp/en/topics/201..._AstroDynamics/

There was a very brief news on H2 landing on this evening's NHK TV. H2 is now scheduled to
make the first landing attempt during the week starting on 18 February.

P

New map of many feature names, both IAU approved and colloquial ones from the team: https://twitter.com/haya2e_jaxa/status/1082952972181458944

I have added those new names to my map. There is one missing character to be filled in on the ridge name when I figure it out (any Japanese-speaking help would be appreciated - message me please!). In the previous version of the map I had marked two target markers but I see now that there was only one, the second descent was for imaging - please correct me if I am wrong about that.

Phil

Click to view attachment

EDIT - a forum member (and spouse) was able to help me - thanks very much. So the missing character has been added at the end of the name of the equatorial ridge. I replaced the map file with the corrected version.

I found this https://twitter.com/CiteEspace/status/1047166709906493441
Does anyone know: are these photos of Otohime Saxum anywhere officially published?

JAXA trains before shooting

http://www.hayabusa2.jaxa.jp/en/news/status/

There was an article in this morning's newspaper here that H2 will go down for sampling at 08:00 on 22nd this month. Time, I think, is JST.

P

It's start!

https://twitter.com/haya2e_jaxa

Thank you, Foe. Good luck!!!

GO HAYABUSA 2!!!

"Hayabusa2" Touchdown (TD1)（English）
https://www.youtube.com/watch?v=qeMwAdquDYM
Live relay from JAXA Sagamihara Campus: Feb 22, 06:45~ JST

https://www.youtube.com/watch?v=WkoVN_Bzkdo

this above is real timish, and not real, but it may be interesting to some people,
jointly produced by JAXA and NHK.

P

The touchdown is scheduled for 23:25 UTC on the 21st (today). A small slip from the original 23:06.

That would be 6:25 pm EST and 2:25 pm PST.

The full schedule of events is posted on the Hayabusa English site at this link.

I CAN'T FIND MY BOTTLE OF LIPOVITAN D

Confirmation that the spacecraft carried out it's sampling operation and, if I understood correctly, that the projectile was fired.
Edit: Confirmation that the projectile was commanded to fire, not necessarily that it did.

Yay, JAXA, and Doug!!!

Post-sampling conference (english):
https://www.youtube.com/watch?v=B2EvmOJa_-k

Temperature sensor showed a ten degree increase when the projectile was commanded to fire. This is being interpreted as confirmation of projectile firing.

They say thruster firings caused the dark marks. There may be debris near the spacecraft or on the camera lens (out of focus smudges). They're confident because of this image that sample-collection was successful and have commanded the sample canister chamber to seal this sample.

Waiting for more photos from the touchdown ...

Ryugu from a different perspective - older picture from January 24, 2019 - northern hemisphere and marked place of touchdown: http://www.hayabusa2.jaxa.jp/en/topics/20190220e_BoxB/

Some quotes in this article indicate the team is already preparing for the copper projectile firing (and future sample collection)!
https://spaceflightnow.com/2019/02/22/japan...capture-sample/

Regarding the dark spot left by the Hayabusa 2 on the surface of Ryugu - I wonder if it is the effect of a blast of engines? But there is no dust and sand on Ryugu like on Mars or the Moon! Or maybe there was a chemical reaction between the asteroids material and the fuel combustion products?

"But there is no dust and sand on Ryugu like on Mars or the Moon! "

We don't know that there is none at all. There might be a small amount.

Phil

Or maybe the effect of inverting small stones with this side up, which is unchanged by cosmic erosion upwards. In microgravity conditions

Small as it is, Ryugu doubtless still gets its share of micrometeoritic erosion over time. Of course there has to be at least some dust on the surface.

Apparently, the way H2 tocuhed down is something like this. H2 went down for the marker and stopped right above it.
It then tilted the solar panel. It then, with the tilted panel, slided down at an angle until it reached the surface.

P

I completed my post with my strictly amateur concept of the creation of a dark spot on Ryugu - assuming that since Minerva's and MASCOT did not detect even a single piece of dust on the surface, there is probably very little there (???) - only gravel of different sizes

Of course - there should be dust and sand. Where all the regolith has disappeared is probably one of Ryugu's biggest questions

Doesn't seem that mysterious. Just about any impact large enough to leave a meter-sized crater or so likely provides enough energy to eject a fair amount of small regolith constituents from at least the general area around the impact site at escape velocity, and possibly even on the antipodal side as well if the internal structure of Ryugu is such that foci exist. Over time the rate of loss probably is greater than the rate of formation.

And yet scientists and designers of Hayabusa 2 seemed quite surprised by the lack / deficiency of the smallest particles of regolith (dust and sand) on Ryugu's surface.
If the mechanism you describe works, and at least some of the small asteroids are considered a pile of debris, then one can expect that the smaller the asteroid, the larger the rocks on the surface. I am curious about the results from OSIRIS-REx at Bennu. A lot of explanations will also bring results from MASCOT if they finally appear. The copper projectile will also tell a lot about Ryugu's surface. And of course, with a bit of luck, the content of the return capsule - but it still requires a lot of patience...

Impact ejecta particles will have a wide range of velocities. Look at Tycho crater on the Moon, where some ejecta can travel across much of the near side of the Moon, or even possibly converge on its antipode, but much more of it by volume was only just able to get out of the crater and covered the surface as a thick continuous ejecta blanket. Some didn't even get out and slumped back into the crater. On Ryugu, some ejecta might fly out at escape volocity, but some impact energy goes into jostling the blocks near the impact, breaking them into smaller pieces and no doubt generating dust in the process. There should be dust, and impacts cannot preferentially remove it as ejecta.

Large particles are often observed to collect at the top of a container of mixed particle sizes (the 'brazil nut effect'). The chances are that there is plenty of dust on Ryugu, but the bigger chunks are concentrated at the surface and the dust drains down into the voids between them. I think that is what we are seeing at Ryugu. We woild only need a very thin layer of it on the surface blocks to produce a visible effect when thrusters blow it away, and that amount would not be visible in the kind of images we have been seeing of the surface.

Phil

I agree with you, Phil, that "BNF" (I mean the "Brazil Nuts Effect") is a good candidate to explain the situation on the surface of Ryugu.
But, as a complete amateur, I have two questions:
1. Does "BNF" operate without gravity or in very low gravity as on Ryugu?
2. Does "BNF" work without "walls of the container" (as on Ryugu)?

I also remember that even on such a large globe as the Moon, dust can electrostatically levitate just above the surface - contrary to the force of quite high gravity, and therefore, potentially against the settling in the voids in the depths of the asteroid too.

Marcin

press release in english.
http://fanfun.jaxa.jp/jaxatv/files/20190305_hayabusa2_en.pdf

https://www.youtube.com/watch?v=-3hO58HFa1M

I updated the map of Ryugu with information from the new press release - may I say here how great the Hayabusa 2 press releases have been, just incredibly informative and detailed.

Phil

Click to view attachment

I didn't realize that the impactor is going to target poor Mascot, more or less...

Astounding views of the sampling! Looks like plenty of debris could have gone into the funnel. Looks like some pieces hit the side of the spacecraft too, judging from the video.
Hard to believe, but the SCI impact next month will be even more impressive (from a safe distance!).

It appears from the press release that they may still release the final rover this summer. Even if it's not working properly, surely there's not point in lugging that mass back to Earth.

one question comes to my mind after seeing the video, that I have not seen addressed: are all of the flying debris still gravitationally bound to Ryugu? will they fall back on it? will they end up in orbit? are we witnessing the birth of a mini-moon? or, finally, will they end in separate solar orbit?

Why is it that the same fragments look shiny and then dark as they fly up rotating?

P

Almost all of the fragments will either have escape velocity and disappear or not quite enough and settle back on the surface. A single kick from the surface can put an object into orbit but this orbit will have a perigee that is the same as the point it was kick off the surface. To go into a stable orbit it needs a second kick at some altitude above the surface to raise it perigee off the asteroids surface. The escape velocity is about 0.38m/s or about 1.35 km/h. This is one of the reasons why a cannon shell can not be fired into a stable orbit.


Id say some are sun illuminated and some in shadow