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)

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.