Mission: Hayabusa 2 Options

[Explorer1]

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

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...

[pandaneko]

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

[pandaneko]

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

[pandaneko]

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

P

[Explorer1]

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

[Guest_mcmcmc_*]

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...

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/

[pandaneko]

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

[Guest_mcmcmc_*]

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.

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

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

Where do you get historical data?

[pandaneko]

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

[pandaneko]

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

[pandaneko]

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

[Paolo]

Completion of forward cruise ion engine operation

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

[Guest_mcmcmc_*]

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°

[pandaneko]

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

[Guest_mcmcmc_*]

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.