Fantastic visualisation from Roman Tkachenko http://www.youtube.com/watch?v=w_ownuA5KJ4

By the way, a new press conference and a pdf are up.

https://www.youtube.com/watch?v=2B5M9RWAfeM

http://fanfun.jaxa.jp/jaxatv/files/20180802_hayabusa2.pdf

Hayabusa 2 is back at its 20 km "home position"

Phil Plait posted an article correcting his earlier mistake about Haybusa 2 being in orbit around Ryugu: http://www.syfy.com/syfywire/mea-culpa-circling-ryugu

Here is my map of Ryugu.



BTW, as far as I understand, on the images from Hayabusa2 website north is towards the bottom. This means that the hemispheres on my previous image (Polar views of Asteroid Ryugu) are inverted.

yes, latest press release explains tha nort and south poles are determined by direction of rotation: seen from North Star, Earth rotates CCW; so bodies rotating CW are "upside-down".
On the press release there are also a couple of "shaded relief" maps taken from 3d models.

Yes - here is Roman's map merged with the colour topography. (Thanks for the map, Roman)

Phil

Click to view attachment

I am in WIFI difficult area. Still, what follows may be of interest.

P3
0. Hayabusa 2 mission outline
1. Project status and overall scheduling
2. Initial result of LIDAR
3. Initial result of NIRS3
4. Shape models
5. Mission schedule
6. Collaborations
7. Briefing schedule

P6 Where we are now

BOX-C operation was conducted between 17 and 25 July.

About one whole day was spent at an altitude of 6km.

Middle altitude operation was conducted between 31 July and 2 August, reaching an altitude of 5km (1 August).

From 5 August a free fall experiment will begin in order to estimate Ryugu's gravitational pull.

P7

2. Initial result from LIDAR and shape measurement

(upper)
Ryugu's shape estmated from one month (30 June to 25 July) LIDAR data

Very close to the shape obtained by picture data. Possible to identify craters and large boulders.

Most of data is focused on equatorial area as H2 is normally above this area.

P8

2. Initial result from LIDAR observation
(charts : horizontal is east-west distance in meter and vertical is height in meter)

(upper)

Crater temporary number 6: Diameter about 210m, depth about 30m, d/D ratio of about 0.14, crater edge height
is about 5m

(lower)

Crater temporary number 12: Diameter about 110m, depth about 17m, d/D ratio of about 0.16, crater edge
height is about 7m

P9

2. Initial result from LIDAR observation
Similarly, altogether 7 craters have been measured. From these result we see :

(*) d/D ratio is between 0.1 and 0.2:
This ratio is similar to the data from other asteroids
(**) Some craters have clear edges (about 5m in height)

We did not find this kind of edges on Itokawa, but this is not new and other asteroids have crater edges.

Crater shape : The reason for dispersed measurement points on upper left and lowe left is not due to error,
but due to H2 atitude and position when crossing craters.

More to follow.

P

A free fall experiment, very interesting. Let's see if people's estimates were right.

Phil Plait estimates that "if they just turned the thrusters off and let Hayabusa 2 fall toward the asteroid, it would take about a week to drop down all the way to it. [...] it would impact very near the escape velocity of Ryugu, which is a paltry 35 centimeters per second." http://www.syfy.com/syfywire/mea-culpa-circling-ryugu

P10

3. Initial result from NIRS3

NIRS3 : capable of detecting minerals which contain water and provide spatial distribution from reflection
spectrum covering the spectral range of 1.8 to 3.2 micro meters, detect infrared absorption around 3 micrometers
for water and hydroxy group of molecules.

(lower right)

Reflection spectrum of carbon containing meteorite in laboratory

P11

3. Initial result from NIRS3

1. Status of device: Normal and health is not questioned.

2. First detection of Ryugu on 21 June and continues to provide good quality data

3. Carried out measurements since 27 June at 20km altitude (BOX-A) equivalent to 4 self rotations by Ryugu and
at altitude of 7 to 12km (BOX-C) 2 rotations worth of data

4. Carried out scan measurements for one rotation each in BOX-A and BOX-C

5. Altogether so far obtained spectral data from 54,000 points of Ryugu

P12

3. Initial result from NIRS3

Observation Coverage

• scanning by atitude control and making use of self-rotation of Ryugu

• More than 90% of land surface covered

(lower right)

Observation frequency from BOX-A at each point of measurement, grey areas have not been covered yet

P13

3. Initial result from NIRS3

Main results at this point in time

1. Water absorption at around 3 micro meter has not yet been detected. Ryugu's surface seems to be dry.

Scientifc understandnings are:

1. Mother astronomical bodies did not have water in the first place

2. Secndary heating led to loss of water

However, polar regions have not been covered yet and it is also possible that water may exist undersurface.
We will be looking at these possibilities later on.

(a little more to follow, P)

Ryugu surface close up - from UTC 2018-08-06 22:53

After a few minutes the image of Ryugu's surface disappeared from the JAXA website: http://www.hayabusa2.jaxa.jp/en/galleries/onc/nav20180805/

Strange!

I am also perplexed and I looked at Hayabusa 2 main page and here is what I discovered. That also iritates me a lot.

Real time delivery of pictures from gravity measurement operation (finished)
Than you for watching. Real time delivery this time is now over )
(JST 2018/7 August 11:45)
We will carry these photos later when they are sorted out properly.
Here, we carry photos taken during gravity measurement operation (5-8 August 2018).
Gravity measurment operation ismeant to estimate the gravity to within 1% acuracy for the pricise descending7
operation. Spacecraft will free fall to 1.4km and we will estimate the parameter from its position and velocity.

Here, we carr real time photos by ONC-W1. Photos may be disrupted due to stability of transmission. Please take
kindly to this inconvenience.
Time is UTC, and add 9 hours if you want JST

All above can be found at the top of the current page of H2 main page (not the control panel like seperate web site).

I seems to me that JAXA added comments without deleting earlier comments. OK, fiinished, I understand it,
but does this mean JAXA did real time distrobution without ample notification. I do not look at H2 pages every
day and if there had been notice I must have missed out on it.

Another question is this. On the Haya2 web page (control panel like page) Ryugu seems larger. I vaguely
remember it was a tiny dot when I last looked at the window. Does this mean that we can watch it grow if we
keep watching it during gravity approach and other similar operations?

P

What remains of the latest press briefing.

P17


North/south of Ryugu

determined by direction of self rotation, north/south of the earth is solar system standard and both Itokawa and
Ryugu are upside down by earth standard.

Most of Ryugu's photos have been upside down in this respect.

P20

5. mission schedule

Immdeiate future operation plan

•Normal observation frm home position at 20km altitude = BOX-A

• Altitude lowering operation

BOX-C operation (17-25 July) with lowest altitude of 6km (20/21 July)

Middle altitude operation (31 July to 2 August) with lowest altitude of 5km on 1 August

Free fall operation (5-7 August) with lowest altitude of 1km on 7 August

Touring operation and BOX-B operation: end August

※ For BOX-B refer to attached materials

P35

Collaborative research on exploratuon hub

◆JAXA Space exploration Innovation Hub

P36

Press briefings

16:30-17:30 23 August
11:00-12:00 5 September
14:30-15:30 27 September

■ Out reach events for kids
14:00-16:00 2 September at Sagamihara City (where ISAS is located) Museum with internet viewing

P

Ryugu Close-up

What bothers me about JAXA's latest findings is the dryness of Ryugu.

JAXA were constantly saying, before arrival, that Ryugu had been chosen because it appears to be a water rich(?)
asteroid. The reason must be remote spectroscopy unless it was just their wishfull thinking and unlss there are
other means of guessing properties of asteroid surface.

So, my guess is that remote spectroscopy across billion km is not at all reliable. Is that right?

P

Thank you, Roman for the close up photo.

This makes me think. Look at the relatively large chunk of stone in the lower right of the photo. There appears
to be a slit down the whole length of it.

Can a physical feature like slits be born of collisions? I am trying to convince myself that anything can happen
in collisions.

P

Here is view from ONC-W1 and ONC-T (from your post Marcin)

Click to view attachment

JAXA has posted official locations for surface images: http://www.hayabusa2.jaxa.jp/topics/20180807/index.html

Do you see layers too?

My explanations for these possible layers from my post above:

1. stratified impact breccia

2. some kind of gravity sorting

3. image artifact

Ryugu as seen from an altitude of 1km

Since arriving on 27 June H2 has undergone BOX-C operation (20-21 July) and also on 1 August descended to an
altitude of 5km (middle altitude operation), and from 6 August went through 3rd descent in terms of a free fall
operation in order to estimate the gravitational constant of Ryugu.

In so doing we simply let H2 experience Ryugu's pull without controling its orbit or orientation (free fall and free
ascend). That way we can measure the precise movements of H2 to estimate Ryugu's influence.

H2 started descending at 11:00 JST on 6 August from its home position (20km from Ryugu) and reached
the altitude of 6km at around 20:30 on the same day where free fall started. H2 eventually reached the lowest
altitude so far of 851m at 08:10 on 7 August when the thrusters were fired for ascending motion.

(above is now on the front page of H2 main web page, P)

The plan was to boost delta-V on ascent to speed the return to the Home Position, but a major Typhoon is approaching Japan and they were concerned this would interfere with operations on the arrival at "Home" so they delayed the acceleration. They refered to this as a "typhoon avoidance manoeuvre".

IIRC the basis of the water detection is a feature at about 3 microns - a feature that can be notoriously hard to diagnose correctly. But I've also read that Ryugu is a g type (or cg type depending on classification system) which, again only from my imperfect memory, do not always have that 3 micron feature anyway?

Two things I have noted from the H２main web page are as follows.

1. Free fall operation.

They originally had 1400m as the target height where free fall stops, but in actuality H2 went down as low as 851m.
During the ascent phase they did not attmept to control attitude nor thrust up to 5km so that H2 while going up was
still experiencing free fall. Now, that is easy to follow.

What is not very well clear to me (and perhaps all other people except me know about it?) is:

2. http://www.hayabusa2.jaxa.jp/galleries/onc/nav20180805/

This gives us a series of photos taken by the wide angle camera. If you look at the very bottom photos the size of
Ryugu almost coincide with that we normally find on the ONC-W1 camera window of the control panel like web site.

So, I am guessing that if I had kept on watching this window I probably would have seen this series of photos
without gaps between them? Is that what this window will do for us? If this is the case I will be clinging on to
this window as H2 tries to land next. I hope that they will do it during civilised hours.

P

I looked at the English version of H2 main web page. There, you find Haya2Kun writing twitter articles about
operations. The problem with this fellow is that he sometimes writes in English, sometimes in Japanese. What follows
was written in Japanese and almost certainly confirms my nagging thought about ONC-W1 window.

Translation is as follows.

"Others.

We are again approaching Ryugu! This is the 3rd time. The difference this time is that other people can watch
the same Ryugu as I am watching almost at the same time as I do. It is Ryugu being seen all the way from Earth! "

"Almost at the same time" is perhaps the time it takes for the raw photos made easy for general public, I think.

P

Explosives could leave residue possibly contaminating the sample.

I don't know about layers but even a conglomerate could be interesting.

There was some "suspected transient sublimation activity" as well. Curiously, the signature was observed when Ryugu was at aphelion.

New candidates for active asteroids: main-belt (145) Adeona, (704) Interamnia, (779) Nina, (1474) Beira, and near-Earth (162173) Ryugu
Possible sublimation and dust activity on primitive NEAs: Example of (162173) Ryugu

pandaneko and Roman Tkachenko - thank you for your work and posts here!

What follows is from the witter section of the main Hayabusa 2 web page, two bits in one go.

Status of hayabusa2 （week starting on 6 August 2018）

We conducted a free fall experiment during 5 to 7 August. This was the same operation as landing and meant
it was the second near landing for H2.

Height reached was 851m and we were able to obtain a large number of close up photos. Right now, people are
flowing into ISAS in droves from within Japan and overseas and they are happily discussing new findings.
(13 August 2018)

(we do not seem to be viewing them, not in large numbers...., P)

"What bothers me about JAXA's latest findings is the dryness of Ryugu.

JAXA were constantly saying, before arrival, that Ryugu had been chosen because it appears to be a water rich(?)
asteroid. The reason must be remote spectroscopy unless it was just their wishfull thinking and unlss there are
other means of guessing properties of asteroid surface.

So, my guess is that remote spectroscopy across billion km is not at all reliable. Is that right?"


I was under the impression that it was chosen for being carbon-rich. Any thoughts about water would be an assumption, not based on direct evidence. Even so, it may contain water below a surface which has been dried by heating. Spectroscopy only tells us about the uppermost surface layer. So I would suggest waiting for later results.

Phil

Article on DLR's plans for the MASCOT landing: https://www.dlr.de/dlr/en/desktopdefault.as...#/gallery/31672

10 possible landing sites for MASCOT lander

10 possible landing sites for MASCOT lander (3D visualization)

I'm fond of saying 'If you laid all the near-infrared spectroscopists end-to-end, they'd reach across an ocean, but wouldn't reach a conclusion'.

The history of planetary science is full of claims and counterclaims on the interpretation of near-IR spectra, more so than any other type of data, I think, except perhaps geomorphology.
There are of course counterexamples where such spectra have been decisive and important.

Thank you, Roman, this rotating movie looks pretty good, and my guess is MA-4 for MASCOT landing. It is a crater rim and may have
something interesting. I really, really want to see photos from MASCOT!!!

P

There was an interesting article in today's local national newspaper. I will carry my translation in
two bits. Here goes the first bit.


Hayabusa 2, in addition to sampling operations, has 4 landers. Hayabusa-1 failed (lost its lander)
to land its only lander called Minerva and JAXA team is determined to make it a success this time.

These landers will be be seperated from H2 from September on.

H 1 had only one lander called Minerva, but this time H2 has 3 Japanese landers (3 of Minerva -2)
and one European lander called MASCOT jointly developped by DLR and CNES.

They will be seperated from H2 and gravitationally land on Ryugu. They are classified as
autonomous robots.

Naming of 3 Japanese landers is complicated. They are simply called, Minerva-1　and Minerva-2
and Minerva-1 consists of two landers.

Minerva-2 is a direct successor to the failed Minerva carried by Hayabusa which landed on Itokawa. Minerva-1 was newly and jointly developped by a group of 5 Japanese universities. JAXA developped two of Minerva-2 and they are called Minerva-2-1 and Minerva-2-2.

These names are complicated, so JAXA will name them properly if and when they managed to land
on Ryugu. Right now, they are simply,2-1 and 2-2.

Two of the 2-1 are very similar to the Minerva carried by Hayabusa 1(one). They are cylindrical
with a diam. of 17 cm and height 7cm, weighing 1 kg, only slightly larger than 12cm x 10cm x
600gm Minerva. They will be released at the same time.

These two has internal motors and jump as the original Minerva was intended to do. They do not
have wheels as it is feared that if they did they might fly out into deep space and also because
rokcs on asteroid surface will make it difficult for them to move about freely.

Indtead, two hooks, one above the robot body and one below will kick Ryugu surface, like in a
kicking motion, to move to next positions.

Each carries a couple of cameras and two of them are used to take photos of the same object
at the same time so that they can measure size of very small grains. In addition, they have light
direction, temp. and jump rotation sensors.

According to JAXA, they were made into a twin because they did not know the spin direction nor
surface temp. of Ryugu and they thought that one of them should not completely covered by
a solar panell so that heat will not accumulate too much inside the robot.

Also, two will have a better chance of success than a single robot.

Contrary to 2-2, 2-1 is more self propelling. 2-1 is powered by solar energy it will go into vacation
mode when night falls on Ryugu. When internal temp. exeeds 80 degrees it will go into
a siesta mode and stops its activities.

There are many shades on Ryugu and if 2-1 happend to enter shaded areas it will go into
"if it is dark-mode" and immediately jumps back to its earlier lighted position.

Its cameras will record, at pe-determined intervals, only meaningful objects and delete dark space
etc. before sending data to Hayabusa 2.

It will also be taught about the minimum and maximum jumping limit given by the now available
Ryugu's gravitational constant so that it will not shoot out into deep space.

Their life time is about a few days. Mierva-2, in particular, will have a difficult life as it is solar
powered and if solar panel surface is affected by sands etc.it will meet a premature death.

2-2 was jointly developped by a group of 5 universities and is meant to serve as an engineering
test robot (15cm. diam x 16cm height x 1kg weight) and carries 4 different types of moving
mechanisms for evaluation.　

P

Thank you for doing this. It is very useful and interesting.

Phil

August 2 press conference, PDF in english.
http://global.jaxa.jp/projects/sat/hayabus...ss20180719e.pdf

What follows is the second part of the newspaper story about Ryugu landers.

MASCOT is much larger at 10kg, 30cmx30cmx20cm.

It was originally designed for a joint ESA/JAXA Marco Polo project. Marco Polo was not chosen and it was instead placed on Hayabusa 2.
It can make, limited to once only, a very big jump (200m maximum).

With autonomous robots of this kind it is a big advantage if asteroid surface can be examined to millimeter level and acuracy by moving
to different locations.

JAXA think that Minerva 2 technology will be useful in future explorations of planets. Larger landers will take time to develop and cost
a lot of money and cannot take the risk of landing in tricky places.

However, smaller ones typically up to 10kg can take these risky chances and a few of them can be placed in areas of interest without
sacrificing too much resources.

JAXA hope to use these small robots with their MMX project (Phobos sample return, 2024) and SLIM project (small moon lander, 2021).

Lessons learnt from Minerva 1 (one) with Hayabusa 1 (one)

Hayabusa seperated its Minerva lander in Novmber 2005, but it failed to land. The reason was as follows.

Hayabusa started to go up with its chemical thrusters before the command from the ground station for seperating Minerva reached it.

Consequently, Minerva could not approach Itokawa and the only result was the photo of Hayabusa solar panell.
　
It was XXX of JAXA who sent this seperation command to Hayabusa. His thought at that time was that the command from the earth
will be more reliable than Hayabusa's autonomous judgment about separation timing.

In reality , Hayabusa started its chemical thrusters earlier than expected. His thought when this happned was "OMG, we had it!"

From this lesson Minerva 2 seperation will be done completely autonomously by giving prior commands to Hayabusa 2 such as
seperation height and speed.

JAXA are now determined never ever to send further commands about Minerva seperation.

P

The latest press conference PDF contains slides in English along with Japanese: http://fanfun.jaxa.jp/jaxatv/files/20180823_hayabusa2.pdf
All focused on the touchdown planning.

Thank you, Wildespace, for this. There was an article in a local newspaper today. It mentions something not stated in this document.
The height during rehearsal is between 20m and 30m.

P

Landing site selection seems to be complete, both for Minerva II landers and MASCOT. http://astronomy2018.cosmoquest.org/newspa...asteroid-ryugu/

That article also mentions the mission scientists commenting on the hydration of the minerals being less than expected.

Interesting article discussing what was revealed by the first Hayabusa mission:

Particles collected by Hayabusa give absolute age of asteroid Itokawa

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

Read more at: https://phys.org/news/2018-08-particles-hay...teroid.html#jCp

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

MINERVA II 1 set for landing September 23rd, MASCOT landing for October 3rd! They are not waiting around!

Many images of Ryugu on this page.

I realise that there is a discrepancy between Japanese and English top pages. I will translate captions on the top page photos tomorrow.

P

Ryugu from an altitude of 6km

Captions of the latest photos of Hayabusa 2 main page are as follows.

3rd photo from left of the main page top. Its caption is:

As it has turned out there are more boulders on Ryugu than anticipated.
There were also many of them on Itokawa, but boulder density may be larger on Ryugu.

These two photos are based on those taken from the home position on 30 June. Green crosses are marked on boulders between
8 and 10 meters across.

Photo 1: Longtitude 300 degrees and the north pole is up. Photo 1 shows a lessor dense surface and photo 2 denser surface.

(However, this analysis may change later as more is conducted). Either way there are hundreds of them on both photos, and their
distribution may be a clue to the kind of impact Ryugu had in the past.

Photo 2: Taken of longtitude 60 degrees surface.

--------------------

2nd photo from left of the main page top. Its caption is:

Hayabusa 2 is now looking at Ryugu with its thermal infrared camera and photo 1 was taken from the home position (20km height) on
30 June 2018 (16:02-23:45 JST). Image was taken at 8 minutes interval for one complete self-revolution and one pixel corresponds
to about 20m. Ryugu was at 0.987au from the Sun.

(Credits now include DLR, Max Planck and Stiring Unibersity. P)


Red areas are hotter. TIR photos can show even shade areas which cannot be seen on visible light pictures. Even craters and large
boulders show up thermal signatures.


We also notice temp. difference between northern and southern hemispheres due to the tilted spin　axis. Right now, upper hemisphere
(souther hemisphere) is in summer time, showing seasonal variation in temperature.

Highest temp. is about 100 degrees C and lowest at around room temp. on earth.

Hayabusa 2 's mission includes asteroid formation histroy from the surface property found by TIR.
TIR data also shows us possible location of landing sites with millimeter sized particles.

What follows is an interview with a former JAXA member now at a university. He was involved in Hayabusa 2 project right from
its conception.

Q.： What kind of work were you involved at JAXA?

A.: I was responsible for TIR and NIRS3. Actual making of the devices was done by Meisei Denki company in the town of Isezaki in
Gunma prefecture. I visited them many, many times to check everythig about the devices.

Q.：What can Hayabusa 2 tell us?

A.: These asteroids are supposed to retain features soon after their formation in the solar system because they lack atmosphere and
convection.Of particular interest is water (H2O) and it was anticipated that asteroids like Ryugu had more water than earth in terms of
weight ratio.

Earth rather has less water and it is a problem to be clarified. Where has the water difference gone to and if water was
supplied later during the evolutional history of earth what were its mechanisms.

Several different scinarions have been proposed and Hayabusa 2 will be looking at these problems.

Q.： What will you be doing from now?

A.：NIRS3 apart, I will be looking at thermographical pictures of Ryugu. I have made a GIF movie of Ryugu based on the data obtained
on 30 June.

Continous data acqusition of surface temp. can show thermal and physical properties of surface materials.
Rcent discovery of organic compounds contained in meteorites may mean that we can find them even on Ryugu.
RIR can guide us to lower temp. regions where organic compounds may still survive and also help us find termally safe landing locations
for sampling.

-------------------------

1st photo from left of the main page top. Its caption is:

It is more than one month since LIDAR was first activated.
The photo shows location of laser reflections from Ryugu.。

Usually, Hayabusa's attitude is such that LIDAR faces equatorial regions.
We have changed this attitude twice by now along the spin axis (attitude scanning). We still have much less data on polar regions,
but we are starting to see global pictures of Ryugu in so doing.

In ordert to obtain accurate pictures we must make sure that we know Hayabusa's orbit accurately. Right now its uncertainty is a few
hundred meters. Yes, it is amazing that we know Hayabusa's orbit this accurately whe it is so far away from us, but this uncertainty is
too much to measure the shape of Ryugu accurately enough as Ryugu is ony 900 meter across.

So, we do LIDAR data to improve on orbital accuracy and this improved orbital information has been provided to other teams
so that they can also better decide on landing locations etc.

P

I wonder if there can be gentle collisions between asteroids.

P

Not since the early days of the solar system, when accretion as still happening. Relative velocities are far too different now, or else a planet would have accreted there. Contrast with comet 67P, which is thought to be the product of a slow collision between two smaller bodies (see: https://arxiv.org/abs/1505.07021 )