The crater diameter should be determined much more easily than Deep Impact (any prize for most accurate guess?)

What followd is the test firiing range movie.

https://youtu.be/lWnl_G3_N1Y

P

The hole created could be fairly deep too!

Wow! That is a LOT more powerful than I'd expected!

174000 km today! We are still sneaking up on Ryugu. I don't know when the first resolved image will be taken, but probably in the next couple of weeks or so.

Phil

Tokyo to London is 12 hours, so Hayabusa 2 is half the speed of an international flight, landing gear is not out yet, it is slow, very...

P

I have noticed something else on the main page of Hayabusa 2.

Marked with an yellow square is , apparently, the delay time in outbound/inbound
flight. As of today, it is 1941 seconds. What does it mean?

P

It means the time it takes for electromagnetic waves to make the round trip from Earth to Hayabusa 2 and back.

Schedule of mission events at the asteroid:

http://www.hayabusa2.jaxa.jp/topics/mission_schedule_e/

Phil

Cool list of activities, sounds like a lot of interesting events... Wishing them the best of luck

Thank you Charborob. I thought that it might be somehow related to the flight time. It is some time sice I last looked at the relative
velocity. A few weeks ago it was 100m/s and now it is now down to 60m/s. That must mean that the ion engines are pointing to Ryugu. It makes
me uneasy because by the look of the diagram both telephoto (once used to catch a glimpse of the asteroid, about 5,6 weeks ago?) and
the wide angle cameras are pointing perpendicular to the flight direction.

Haya2 web page shows that it is now the wide angle camera in use, but it is not looking forward, yet, I think. Display window is totally
dark. I was hoping that Haya 2's display window will show us continous image of approaching Ryugu, but it seems very unliklely,
unless they use chemical thrusters on and off for us. How soon will we be seeing anything at all?

P

They already confirmed where Ryugu was back in February, they would have to stop firing the engines to turn the craft and take pictures. They will wait to be close enough to resolve it, presumably.

I have had a look at a radar image of the target asteroid for OSIRIS-REX. The image looked a bit wobbly, but it looked just like those
comments made about it, its shape in particular. And, presumably, by triangulation and experience with mereorites they can
estimate its mass.

I have seen comments that not much is known about Ryugu. How then did they estimate the escape velocity for MASCOT? My guess is
that the design velocity is far below the thinkable upper limit, so that MASCOT is not lost into space after its first hop?

My general cuoriosity is simply, how do they know anything at all about these asteroids from such a distant place like earth.

P

There is a consolation, after all, except that we do not know when it will be.

Haya2's pop-up for the display window translates as follows:

"Asteroid position and size. In the final stage of approach to Ryugu Hayabusa 2 will be showing approaching Ryugu
in the display window."

Very irritating. They could tell us roughly when it will be. Very bad PR activity, I think. Anyway, the relative velocity is now
down to 50m/s.

P

15 May 2018. Star-tracker has detected Ryugu.

http://www.hayabusa2.jaxa.jp/topics/20180515_e2/

There is a short article about Hayabusa 2 on today's local newspaper here. JAXA told the municipality of Sagamihara where
ISAS (part of JAXA) is located. Students in ISAS control room are operating Hayabusa 2. It confirms that the arrival of
Hayabusa 2 (apparently to the altitude of 20km) is 21 June (as opposed to a longer window starting from 21 June).

P

Below really is for myself.

As of 20 May the relative velocity is 180km/h, already slower than shinkansen trains. The distance to be closed is
38,000km, about two round trips bet. Tokyo and London. If this speed is maintained Hayabusa will reach Ryugu in
8.8 days, i.e. before the end of this month.

How soon it is to slow down further remains to be seen.

P

Less than 24000 km to go! But who's counting? (hint: me!)

Another new world about to be revealed. This is going to be a very cool mission.

Phil

24 May (144km/h): 16/11/18/10/15/13/19/8/9/9/7/8

I want to continue , for some time to come, with this above to see if it is useful. This is the speed of Hayabusa 2
with chemical thrusters cumulative burn time (numbers are rounded). Neither Hayabusa 2 nor Haya2 web page
indicates significant changes in the flight in an easy to understand manner, so I decided to monitor what chemical
thrusters are doing.

It may be that only ion engines are used until Hayabusa 2 comes to a halt and in that case no significant changes
will have been made to above matrix of numbers (right now only one row). This matrix will continue to build up unil
it is 7 rows. If nothing has happned by that time a new matrix will appear wih its first row being the latest
input into Hayabusa 2 web page.

That way, we may be able to know when the landing gear is out.

P

24 May (144km/h): 16/11/18/10/15/13/19/8/9/9/7/8
25 May (144km/h): 16/11/18/10/15/13/19/8/9/9/7/8

No change, yet...

P

Is the landing gear supposed to deploy THIS early? Thought it was going to spend some time in orbit surveying the asteroid before attempting to touch down.

just an analogy? Does it even have landing gear? I think the drogue chute might be enough.

Phil

The landing gear would be for touchdown on the asteroid, I think. Return capsule should indeed be just the aeroshell & chute, no legs.

I am unsure as it is now such a short distance to the target, but point taken and I will do it in my backyard!

P

I have been using "landing gear being out" to mean a significant reduction in speed. My matrix was
a means to feel the onset of slowing down, but overnight from yesterday to this morning
Hayabusa2's speed went down from 144km/h to 108km/h, and it is pretty clear, I think, that
the breaking power of ion engines alone is good enough to make Hayabusa2 to come to a halt
without relying on chemical thrusters.

I am excited to see this asteroid!!! 加油！！！

P

Me too! Though I wonder if the there is still a Lipovitan-D tradition among the team members. There will be some complex manouevres ahead, and they should start stocking up soon.

By my count (from http://spaceflight101.com/hayabusa-2/hayabusa-2/) , there are three mini-rovers (MINERVA-II), a lander (MASCOT), an impact module/projectile, a deployable camera, and 5 target markers! Do I have that correct? By the time we humans are through with Ryugu, it will be littered with our detritus! All in the name of science of course...

There is a twitter tag on the main Hayabusa 2 web page and what follows is the translation of the latest input as
of 27 May.


27 May @haya2_jaxa (by IES elder brother, sic)

We occasionally receive questions like:

1. Are ion engines being used for acceleration or decceleration?
2. Are we now approaching with RCS (chemical thrusters)?
3. Are you looking with your cameras everyday?

We answer as follows.

HY2 is approaching Ryugu from within the Ryugu orbit by enpanding HY2 orbit outwardly.

We are at the very last stage of navigation and we are firing the ion engines into the acceleration direction.
Consequently, there are times when HY2 speed increases momentarily (conversely, meaning a longer orbital
period in the longer run, leading to a decreased flight velocity, which is a very interesting aspect of orbital
dynamics)

As a result, matching of HY2 orbit and that of Ryugu becomes better and the relative distance between them
decreases.

We are also conducting optical navigation using cameras. However, "keeping Ryugu in field of view" and
"IES firing in the right direction" are contradictory to each other.

Naturally, we will be using cameras rather extensively during the final approach after ion engines are stopped.
‏
Optical navigation while ion engines are fired was conducted during 12 to 14 May (strictly speaking engines were
stopped while taking photos).

The result of this operation will be used for subtle orbit correction during the very final approach.
That is about all for now and we will try our best in the final approach!

P

I have found something else.


http://fanfun.jaxa.jp/countdown/hayabusa2/...sat33_fs_20.pdf

This is a fact sheet compiled by Hayabusa 2 project team and this latest version, ver. 2.0 is dated
19 April 2018. It is a 120+ page pdf document in Japanese. There is a table of relative distance to Ryugu.
According to this table, ion engines will be stopped on 5 June at a distance of 2500km from Ryugu.

P

According to the latest JAXA fact sheet on Hayabusa 2 the mission after Hayabusa 2 is a solar powered sail boat
to Jupiter.

P

Less than Earth's diameter in distance now... getting very close now!

A total amount of 11 separable payloads!
3 MINERVA-II rovers (1a, 1b, twins; 2, bigger)
1 MASCOT rover
1 Impact module (SCI)
1 deployable camera (DCAM3)
5 target markers

Rovers locomotion systems:
http://www.dlr.de/pf/Portaldata/6/Resource...t_Nagaoka_K.pdf
http://www.astro.mech.tohoku.ac.jp/~nagaok...iras_knaga1.pdf

I can't (yet) find info about DCAM3 propulsion system.

Mission status:

https://aliveuniverse.today/rubriche/missio...proccio-a-ryugu

http://www.hayabusa2.jaxa.jp/

According to JAXA ion engines will be stopped on 5 June at a distance of 2500km from Ryugu. That means Hayabusa 2 has 4800km
left to cover with ion engines. Right now, the relative velociyt is 72km/h and if this velocity is kept Hayabusa 2 will arrive at 2500km
point some time on 3 Junem, which is too early for the ion engines.

That in turn presumably means that the velocity at 2500km point is almost zero. I would have thought that there will be some
residual velocity so that chemical fuels are spared, but it looks like they are going to use chemicals. That is perhaps when my little matrix
may become handy only for once, momentarilly. It is looking like below now.

24 May (144km/h): 16/11/18/10/15/13/19/8/9/9/7/8
25 May (144km/h): 16/11/18/10/15/13/19/8/9/9/7/8
26 May (108km/h): 16/11/18/10/15/13/19/8/9/9/7/8
27 May (108km/h): 16/11/18/10/15/13/19/8/9/9/7/8
28 May (108km/h): 16/11/18/10/15/13/19/8/9/9/7/8
29 May ( 72km/h): 16/11/18/10/15/13/19/8/9/9/7/8
30 May ( 72km/h): 16/11/18/10/15/13/19/8/9/9/7/8
31 May ( 72km/h): 16/11/18/10/15/13/19/8/9/9/7/8

P

Landing gear?
There is no landing gear, neither on Hayabusa nor in the rovers:
http://www.asahi.com/special/rocket/hayabusa2_3d/

Downloadable model: http://win98.altervista.org/hayabusa2/hayabusa2-original.zip

"Rovers" are just "rollers": boxes with internal "misbalanced weight", moved to change center of mass and make the rovers move/roll around.

Updated status:

6800 km to go
20 m/s
1898 s roundtrip communication time


Where do you get historical data?

The data comes from Haya2 web page.

http://haya2now.jp/ Haya2NOW

The 12 (rounded) numbers are for 12 thrusters, 1 to 12 from left to right. The table on Haya2 is difficult to read when one or two thrusters
are used. That is why I wanted to line them up for easy detection of changes.

However, once chemical engines are used this table will become useless. It is ony meant for early detection of the use of chemical
thrusters. I am keeping a log and hope that I will be able to detect the onset of very final approach.

P

From the fact sheet of JAXA we know that they will start using chemical thrusters on 5 June at the 2500km point and that must
mean that cameras will be facing Ryugu.

Although the camera with Haya2 web page is a wide angle camera I think they will use the telephoto camera when Hayabusa 2
reaches 2500km point. From the specs of the telephoto camera my estimate is that Ryugu will be only about 10 pixels altogether.

It is not much, still only a dot size, is it not? I want to see a bigger picture!!!

P

As at 12:00 on 4 June JST Hayabusa 2 web page carries a note which says:

Data is being swapped

This is the best translation I can think of.

P

Completion of forward cruise ion engine operation

there are also frequent updates (in Japanese) on the mission twitter profile https://twitter.com/haya2_jaxa

For resolution calculations:
ONC-T: 1024x1024, 5.7°x5.7°
ONC-W1: 1024x1024, 60°x60°
ONC-W2: 1024x1024, 60°x60°
MASCOT: 1024x1024, 55°x55°
DCAM3: 2000x2000, 74°x74°

Thank you, Paolo. I opened up Japanese web pages, just about everywhere. There are lots and
lots of congratulatory remarks, but no important information on flight operation itself. In the
meantime, my little matrix is looking like (its usefulness is now over),

31 May ( 72km/h): 16/11/18/10/15/13/19/8/9/9/7/8
1 June ( 36km/h): 16/11/18/10/15/13/19/8/9/9/7/8
2 June ( 36km/h): 16/11/18/10/15/13/19/8/9/9/7/8
3 June ( 36km/h): 16/11/18/10/15/13/19/8/9/9/7/8
4 June ( ?km/h): 16/11/18/10/15/13/19/8/9/9/7/8

I did not know they stopped ion engines as early as 3 June, so Hayabusa 2 must be coasting at
36km/h now. They can now turn the satellite so that we can look into the right direction.

I wonder how soon theywill do it for us.

P

English translation of telemetry page:

http://win98.altervista.org/hayabusa2/Haya2NOW.html

It can't show data, but it's useful for easier usage of original page.

Radio silence, well, almost...

Due here, I think, is a little poem in traditional Japanese Haiku way.

Hayabusa 2

Doubling Ryugu to

Christmas

P

1 June ( 36km/h): 16/11/18/10/15/13/19/8/9/9/7/8
2 June ( 36km/h): 16/11/18/10/15/13/19/8/9/9/7/8
3 June ( 36km/h): 16/11/18/10/15/13/19/8/9/9/7/8
4 June ( ?km/h): 16/11/18/10/15/13/19/8/9/9/7/8
5 June ( 9.2km/h): 16/11/18/10/15/13/19/8/9/9/ 8 /8

As we can see thruster 11 was used for one second. I will stop carrying this matrix here now
as we know that we are really into the final stage.

P

Questions?
http://planetary.jp/hayabusa2/FAQ/index.html


Upcoming press conference:

http://fanfun.jaxa.jp/jaxatv/detail/12042.html

Thank you, mcmcmc

The deadline for questions was 1 June, but I looked into Qs&As and found some are interesting. Some are more technical than you may
think, coming from amateurs. I will translate some over the next 10 days or so. After all, there is not much else I can usefully do.

In the meantime I now know from my log that 6 of the 12 chemical thrusters have been fired over the last 36 hours.

I will also translate the contents of tomorrow's press conference, if there is something interesting or new to us.

P

I didn't read anything about end date, so I tried compiling the form and it was accepted, so let's see.
Anyway there are several questions dated after 1 june.


That would be great, thanks.

What follows is an extrat from JAXA Q&A collection. More will follow during the next few days.

Q. When will we be able to see the shape of Ryugu?
June 03, 2018 - : 64 year old

A. We will be abe to see the rough shape in mid June. We can find its precise shape when
Hayabusa 2 arrives at the asteroid and get data. If the axis of rotation is not perpendicular to
the plane of the ecliptic it will take longer to get the whole view of Ryugu, meaning that it may
be up to a few months before we know its precise shape.

Q. What is the prediction by the project team about Ryugu's water?
June 02, 2018 - : 14 year old

A. Water will not exist in the form of liquid or solid water. Water molecules will be contained in the
minerals of Ryugu. So, we will not be finding Ryugu to be wet or affected by moisture in any way.

Q. When can we see clear pictures of Ryugu?
June 02, 2018 - : 47 year old

A. It will be when we get to Ryugu. Rough shape, we will be seeng in mid June.

P

PS. I realise that questions were perhaps accepted even after the deadline of 1 June,
by the look of the dates here.

Press conference outcome (in japanese):
http://fanfun.jaxa.jp/jaxatv/files/20180607_hayabusa2.pdf

Following URL has shapes and appearances of Ryugu as imagined by those people in the project
team.

http://www.hayabusa2.jaxa.jp/topics/20180605/

Each picture is numbered, and 4 to 10 (this 10th fellow is the person who does the twittering),
12 to 37 are all those people in the team.

Since the volume of the press conference itself is rather a lot I will translate only some of them.

P

On page 13 of the press conference report there is a picture of Ryugu as seen at 04:15 JST on
6 June by the telephoto camera, ONC-T.

Shape is unknown, exposure time of 0.09 second, one pixel is
equivalent to 22 arc second, 0.3 km at 2600km distance.

There are interesting remarks in this press report, most of it is already known to us, but there
are new inputs. I will translate them very soon.

P

According to the same JAXA press report of today there will be another press conference on
14 June with more detailed information. The arrival time is thought to be 27 June, but it may
be a few days earlier or few days later than 27th, according to this report.

P