Hayabusa2 MINERVA-II-1 operation, 20-21 September 2018 Options

[J.J.]

Congratulations to JAXA!

Much thanks to you, Pandaneko, for keeping us posted.

[djellison]

I'm wondering why any hopping activity was occurring without any commands sent from Earth

You would absolutely pre-program a long sequence of activities for them, including hops, imaging, temperature measurements and comm passes. Our situational awareness for them is poor. We don't know what way up they will land, if they'll get stuck under a boulder etc etc

Having an autonomous sequence of imaging and hopping would be the only rational way to execute a mission like this.

[PDP8E]

Well Done JAXA!
My poor little deconvolving suite struggle for about an hour to converge on a better image of H2 a few hundred feet away
No luck but here is a gif of its best try

[neo56]

Amazing pictures from a tiny world! Congratulations JAXA!

Here is an animation showing the approach of Hayabusa 2 from 20km to 80m:

[Guest_mcmcmc_*]

Outstanding!

I have one thing about which I am curious. The final of the three images states it was taken while its rover was in mid-hop. I'm wondering why any hopping activity was occurring without any commands sent from Earth -- I didn't see any indication of pre-programmed hopping set up in the deployment and landing timelines

I don't remember which one, but one rover has an "automatic temperature-triggered hopping engine": every time it passes from light to shadow and viceversa, the mechanism is triggered and the rover bounces.
For ever, as it does not use any fuel but the sun.
It is one out of 4 or 5 different hopping mechanisms being tested.

[Guest_mcmcmc_*]

I don't remember which one

Looks like it's the "next one":

Yamagata University was in charge of one of the moving mechanisms installed in MINERVA-II-2. We devised and developed an "environmentally driven" moving mechanism using bimetal as an actuator, utilizing large temperature difference caused by the presence or absence of sunshine. Bimetal is a laminate of two types of alloy thin plates with different expansion coefficients, and it is a buckling type (mainly developed by Mineki Laboratory) that tends to bend due to temperature change and momentarily warps to the opposite side when exceeding the limit point , And a magnetic latch type which momentarily warps off the magnet (mainly developed by Tsumiki Laboratory). Even if the ambient temperature varies depending on the MINERUVA - II - 2 's dropping position and surrounding conditions, the possibility of either of which can be coped with is raised by setting the operating temperature to be shifted to the high temperature area and the low temperature area respectively. The rotation period of this asteroid is about 8 hours, and hopping in random directions every 4 hours corresponding to morning and evening.

http://mineta-lab.yz.yamagata-u.ac.jp/HAYABUSA2.html

[Guest_mcmcmc_*]

I can't find anything about rovers "1", but quite a lot about rover "2".

Next rover (Minerva-II-2) hopping mechanisms which are going to be tested:

1) Eccentric motor, which consists of a brushless DC motor.
This actuator enables ROVER2 to micro-hop by the motor’s vibration force

2) Elastic cilia mechanism on the ROVER2 surface fosters micro-hopping capability, and thus this is expected to achieve precise locomotion in a micro-gravity asteroid. (by Kenji Nagaoka, Kazuya Yoshida)
Prof Kazuya Yoshida Facebook page (last post: 2014).

3) Magnetic permanent magnet mechanism using a DC brush-less motor.
This actuator consists of one movable magnet and two stationary magnets, and enables ROVER2 to hop by the impact force generated when the movable magnet sticks to the stationary magnet. This mechanism provides a large impact force in spite of low power consumption.

4) Metallic and thin leaf spring.
The actuator stores preliminarily the elastic energy of the spring by bending it. This enables ROVER2 to hop by the impact force generated when the bending energy releases. The stored bending energy is locked by “tegus” before its driving, and will be released all at once by burning off the tegus.
ROVER2 has two metallic springs. Each spring is non-reusable but is highly reliable in harsh space environment because of its simple mechanism.

5) Shape Memory Alloy (SMA).
The most advantage of this actuator is that it can work with a change of surrounding temperature. This enables ROVER2 to hop by the impact force generated when the SMA bends in a specific temperature condition. As for safety launch-lock, this is also locked by tegus so as not to drive in an unexpected situation. Unlike the third actuator using leaf springs, this actuator will be able to work semipermanently with temperature shift.

1A2-L08 Design of Environment Driven Rover for Asteroid(Space Engineering and Robotics and Mechatronics(1))
TSUMAKI Yuichi - Yamagata University
AKAIKE Takahiro - Yamagata University
MINETA Takashi - Yamagata University
TADAKUMA Riichiro - Yamagata University

2015.10.24 Mr. Minoda (Takashi Mineta?) gave a lecture on the MEMS device & Hayabusa 2 Jumping Actuator at the Yonezawa Industry Association Chiba Branch (Chiba City)

1P2-N02 Performance Evaluation of Ambient Temperature Driven Bimetall Buckling Actuator for Asteroid Exploration Rover (Space Robot)
Takashi Mine , Atsuhisa Sugai , Ryo Kazama , Yuichi Tsumaki

"Bimetallic actuator" = のバイメタルアクチュエ
"Hayabusa 2" = はやぶさ2

Google for のバイメタルアクチュエ はやぶさ2

5b) ROVER2 employs two different SMA mechanisms so that ROVER2 can move in different temperature ranges. Of particular note that the total weight of these four different types of actuators is just 88.1 g. The simplified system design of MINERVA-II2 enables to result in low cost missions.

Development of MINERVA-II2, a Micro-Robot for Asteroid Surface Exploration with Innovative Mobility
Nagaoka, K., Tohoku University
https://www.dlr.de/pf/Portaldata/6/Resource...t_Nagaoka_K.pdf


Minerva-II-2 paper (in Japanese) about camera:
http://www.kimura-lab.net/wp-content/uploa...S-2013-4744.pdf
Shinichi Kimura (Tokyo University of Science)

[Guest_mcmcmc_*]

Maybe found details about rovers II-1:

Some rover packages named MINERVA-II are proposed to install in Hayabusa2 spacecraft. Since the target asteroid parameters may be different from the previous target, the rover design has to be made from the beginning. Technical challenging matters are arisen from the point of the distance from the Sun as well as the surface cruel temperature of low-albedo body.

MINERVA in Hayabusa mission <previous mission, previous rover>has two actuators inside in order to move. One of them is used as a torque. By rotating the torque, a reaction force against the asteroid surface makes the rover hop with a significant horizontal velocity. After hopping into the free space, it moves ballistically. Based on this mechanism, by changing the magnitude of torque, the hopping speed can be altered, so as not to exceed over the escape velocity from the asteroid surface.

The primary rover <II-1 in Hayabusa 2?> of the packages has the totally same kind of the mobile system[/b]. This time two torquers are aligned orthogonally. By simultaneously rotating the torquers, both the hopping speed and direction are controlled. The hopping speed is basically dominated by the magnitude of torques, while the hopping direction is set by he ratio of two torquers.

Intelligent Rover with Hopping Mechanism for Asteroid Exploration
Takashi Kubota
Institute of Space and Astronautical Science
Japan Aerospace Exploration Agency - Sagamihara, Japan
Kubota@isas.jaxa.jp

Tetsuo Yoshimitsu
Institute of Space and Astronautical Science
Japan Aerospace Exploration Agency - Sagamihara, Japan
kikko@nnl.isas.jaxa.j

[Guest_mcmcmc_*]

HAYABUSA 2 press conference
2018/09/27 15:30-16:30(JST)
2018/09/27 06:30-07:30(GMT)
https://www.youtube.com/watch?v=pJOxlZPlL6o

[Guest_mcmcmc_*]

Amazing images in the press release 20180927_hayabusa2.pdf , but I can't yet find official link, I downloaded it from another forum.
A dozen of images taken by bouncing rovers!
And plenty of technical data both about MINERVA and MASCOT.

[RonCatwanson]

Amazing images in the press release 20180927_hayabusa2.pdf , but I can't yet find official link, I downloaded it from another forum.
A dozen of images taken by bouncing rovers!
And plenty of technical data both about MINERVA and MASCOT.

That's it http://fanfun.jaxa.jp/jaxatv/files/20180927_hayabusa2_e.pdf

Link was published in official press-conference stream description https://www.youtube.com/watch?v=pJOxlZPlL6o

[Guest_mcmcmc_*]

Pictures:

2018/09/21 06:02 - ONC-W1 just before release, 70 m (page 18)
2018/09/21 06:07 - Rover 1B - p.9
2018/09/21 06:08 - Rover 1A - p.8
2018/09/22 04:44 - Rover 1A - p.10
2018/09/23 02:50 - Rover 1B hop - p.11
2018/09/23 02:55 - Rover 1B hop - p.11
2018/09/23 03:00 - Rover 1B hop - p.11
2018/09/23 02:43 - Rover 1A - p.14
2018/09/23 02:48 - Rover 1A - p.15-16
2018/09/23 03:10 - Rover 1B landing - p.13
2018/09/23 03:34-04:48 - Rover 1B movie (15 frames in 74 minutes, 1 every 5 minutes) - p.17

Does anybody can find the rover movie?!?

[RonCatwanson]

2018/09/21 06:02 - ONC-W1 just before release, 70 m (page 18)
2018/09/21 06:07 - Rover 1B - p.9
2018/09/21 06:08 - Rover 1A - p.8
2018/09/22 04:44 - Rover 1A - p.10
2018/09/23 02:50 - Rover 1B hop - p.11
2018/09/23 02:55 - Rover 1B hop - p.11
2018/09/23 03:00 - Rover 1B hop - p.11
2018/09/23 02:43 - Rover 1A - p.14
2018/09/23 02:48 - Rover 1A - p.15-16
2018/09/23 03:10 - Rover 1B landing - p.13
2018/09/23 03:34-04:48 - Rover 1B movie (15 frames in 74 minutes, 1 every 5 minutes) - p.17

Does anybody can find the rover movie?!?

here is link with time-stamp. hope JAXA is going to release it. whole movie or by frames
https://www.youtube.com/watch?v=pJOxlZPlL6o...be&t=20m18s

[Therion]

Here are the individual images extracted from press release.

[Guest_mcmcmc_*]

Rover movie!
https://twitter.com/Bottlaeric/status/1045222683221340160

(but I expected better resolution and 15 frames rather than 7)