Hayabusa - The Return To Earth, The voyage home Options

[Guest_BruceMoomaw_*]

The article remarks (though with what evidence I don't know; it's a reference to some upcoming reports on Hayabusa's findings in "Science") that the regolith on Eros' surface is finer than that on Itokawa -- and in fact a comparison of those two photos suggests just that. Is it possible that this is because Itokawa's still lower gravity means that meteoroid impacts kick the smallest particles completely off that asteroid's surface, whereas most of them tend to fall back onto Eros?

[ElkGroveDan]

The article remarks (though with what evidence I don't know; it's a reference to some upcoming reports on Hayabusa's findings in "Science") that the regolith on Eros' surface is finer than that on Itokawa -- and in fact a comparison of those two photos suggests just that. Is it possible that this is because Itokawa's still lower gravity means that meteoroid impacts kick the smallest particles completely off that asteroid's surface, whereas most of them tend to fall back onto Eros?

That's a good possibility. Interestingly the article talks about "coarse gravel". Coarse indeed. Based on that 1-meter scale, I'd say those particles are the size of baseballs, small oranges or perhaps eggs. So if your theory holds, my guess is that the small particles "kicked off" include everything we think of as dust, sand, AND gravel. This could also end speculation of whether or not Haybusa captured anything. If there was no fine regolith on Itokawa then the projectile would have simply bounced off the more solid "basket full of oranges" that constitutes Itokowa's surface.

[Guest_BruceMoomaw_*]

I think it likely that the bullet -- if it DID fire -- probably did kick at least a few small bits of rock into the sample container; the Japanese had the foresight to lab-test it on mostly-rock surfaces as well as loose ones. And of course Earth labs can now do stupendous things with very tiny samples, as Stardust will shortly prove again. But this does indicate the superiority of the alternate sampling system proposed for the "Hera" near-Earth asteroid Discovery proposal. Namely, a bunch of pads, each one pressed into the surface and coated with a 1-cm thick layer of squishy silicone grease -- which in lab tests very nicely picks up 0.1 kg of debris up to the size of small pebbles, without contaminating it for the purposes of laboratory study.

[djellison]

From the LPSC papers - a stereo pair that I've anaglyphed, simulated from LIDAR I believe..

Attached thumbnail(s)

 

[Phil Stooke]

Very nice, Doug.

I was talking to Gaskell about this - they have lots of small maps but they are not sure how to combine them into a global map. The problem (illustrated nicely in some of the abstracts) is that one area (Shirikami) is such a steep slope that a radius from the centre of mass passes out of the surface below Shirikami, then hits the surface again at the top of Shirikami. Normally, we associate one elevation value with each lat/long location. But here there are three separate points on the surface lying along one radius. This problem occurs to a minor extent on Eros, and might on Toutatis - and DOES on Kleopatra. The solution I have suggested is to use a non-radial lat/long system - maybe cylindrical, with a point being defined by its azimuth around the axis plus its position along the axis. The end of the cylinder need special attention, though. Another approach is to map the surface onto the convex hull of the shape, not its true shape, which removes the problem.

Phil

[nop]

The problem (illustrated nicely in some of the abstracts) is that one area (Shirikami) is such a steep slope that a radius from the centre of mass passes out of the surface below Shirikami, then hits the surface again at the top of Shirikami.

FYI, It's not "Shirikami", but "Shirakami" Please check the LPSC abstracts to make sure.
"Shirikami" looks so funny to us because "Shiri" in Japanese means "buttocks".

Anyway, thanks for your fine and exciting montage map of Itokawa!

[TheChemist]

FYI, It's not "Shirikami", but "Shirakami" Please check the LPSC abstracts to make sure.
"Shirikami" looks so funny to us because "Shiri" in Japanese means "buttocks".

Hmm, that explains the steep slopes...

Edited to remove tasteless comment, apologies ...

This post has been edited by TheChemist: Feb 20 2006, 02:23 PM

[Phil Stooke]

Thanks, nop, for pointing out the Shirakami problem. I will fix it and replace the image very soon.

Phil

[Phil Stooke]

Here is a corrected version of the Itokawa names image.

I'm grateful to nop for correcting me on this. There is a bit more to the story as well. Another person who saw the image queried the name I had spelled incorrectly, pointing out the humorous and/or unfortunate interpretation of it. So naturally, instead of checking with the LPSC abstracts, the sources for my names, I simply googled the name as I had originally spelled it. And wouldn't you know, there were lots of pages with the name spelled in that wrong way, referring to a mountain or mountain range in Japan. So I assumed the wrong spelling was in fact correct. Well, let that be a lesson to me never to rely only on Google, which is just as effective at finding mistakes as facts.

Anyway, I do hope we will soon see some official Japanese maps of this lovely little world.

Phil

[nop]

Thank you for your quick revision, Phil.

I also tried googling "Shirikami". Most of the pages are intended to refer "Shirakami mountain" as one of UNESCO world heritage, but I found that there really exists a place named "Shirikami"! it was a new discovery to me

FYI, here are origins of the names (it's just my speculation and not the official announce of JAXA/ISAS):

Muses Sea: MUSES-C and greek goddess
Little Woomera: the place in Australia for capsule recovery
Uchinoura: Uchinoura Space Center. Hayabusa was launched from here
Sagamihara: the name of the city where ISAS is located
Yoshinodai: the name of the town where ISAS is located
Fuchinobe: the name of the nearest station to ISAS
Tsukuba: where the JAXA Space Center (old NASDA) is located
Usuda: JAXA Deep Space Center with 64m antenna
Yatsugatake: A mountain near Usuda
Shirakami: I'm not sure but it might be a mountain range near JAXA/ISAS Testing Center
Kamisunagawa: there was a facility for zero-gravity experiment (now there isn't)
Komaba: ISAS was here a decade ago
pencil boulder: the first Japanese rocket was called "pencil rocket", created by Dr. Hideo Itokawa

[ljk4-1]

The Hayabusa mission and its planetoid target are the cover
subjects of the latest The Planetary Society The Planetary Report:

Hayabusa: A Daring Sample Return Mission

Japan's ambitious mission to land on an asteroid, collect samples, and return them to Earth has had its ups and downs. The tiny but robust spacecraft, with its determined ground crew, worked through problem after problem on its way to sample asteroid Itokawa. In the end, the "little spacecraft that could" revealed for the first time the rocky surface of Itokawa, dropped a memento from Earth onto its surface, and may have collected a sample of surface dust to return to Earth. Although we don't yet know if engineers will be able to guide the spacecraft back to Earth for the sample return, the Hayabusa mission team has much to be proud of. Journalist A.J.S. Rayl has been reporting on the spacecraft since before its launch in 2003. Here, she tells the story of Hayabusa's harrowing adventure.

http://www.planetary.org/programs/planetary_report.html

[Bob Shaw]

JAXA has been in touch with Hayabusa, but the situation is far from resolved.

http://www.msnbc.msn.com/id/11713182/

(sigh)

Bob Shaw

[foe]

ISAS
http://www.isas.jaxa.jp/e/snews/2006/0308.shtml


LbyD,Matsuura's blog (Translation ver.)
http://jspace.misshie.jp/index.php?LbyD%2F20060307-1
http://jspace.misshie.jp/index.php?LbyD%2F20060307-2

[Bob Shaw]

Interesting article at http://www.spaceref.com/news/viewnews.html?id=1107 - see also NASAWatch for a great comparison between Itokawa and the ISS!

Bob Shaw

[paxdan]

Interesting article at http://www.spaceref.com/news/viewnews.html?id=1107 - see also NASAWatch for a great comparison between Itokawa and the ISS!

Bob Shaw

Here is the Link to the Itokawa-ISS comparison it really is a fantastic graphic and gives a real sense of the size of the thing.