[X] My Assistant

[abalone]

And those (few?) remnants that fortuitously don't achieve escape velocity have likely had centuries to land again.
Andy G

Anything that does not reach escape velocity will be launched into an eliptical orbit and return to its point of origin after one complete orbit. This will probably mean that it will hit the ground again quite quickly

[Bob Shaw]

Anything that does not reach escape velocity will be launched into an eliptical orbit and return to its point of origin after one complete orbit. This will probably mean that it will hit the ground again quite quickly

Except that the asteroid is irregular in shape, with a similarly irregular gravity field. I bet that between the rotating body and the funny gravity something knocked off could stay up for a while - or even meet a speeding part of the surface and be whacked again - and that applies doubly to a fragile littel spacecraft. The guys in Japan are being rightly cautious about getting too near - perhaps they'll power in down the axis of rotation...

[AndyG]

Except that the asteroid is irregular in shape, with a similarly irregular gravity field. I bet that between the rotating body and the funny gravity something knocked off could stay up for a while - or even meet a speeding part of the surface and be whacked again - and that applies doubly to a fragile littel spacecraft. The guys in Japan are being rightly cautious about getting too near - perhaps they'll power in down the axis of rotation...

The speeding part of the surface is only rotating at about 4cm/s compared to the centre of gravity...so maybe whacked isn't the right word. If the surface of Itokawa is dusty, covered with a reasonably deep and friable regolith, these sorts of ejecta impacts might be more of a s-s-s-splurge than a thwack.

As to closing on the object, the escape velocity and the rotation means that the highest speed a free-falling body could hit the surface at is...16cm/s. A third of a mile per hour, without using rockets to slow down. My car bumpers wouldn't notice that!

While approaching the axis of rotation makes some sense, it does limit what material sources you could retrieve. Given that the ion drive has enough umph to counter the local gravity, all the way down to the surface if need be, and the reaction rockets have the perhaps more useful momentary acceleration to adjust speeds relative to the surface (unlike the ion's ~900 seconds for 0-4cm/s), I don't see that there's necessarily a need to head only for the poles...as long as, of course, the autonomous control is up to the task.

Andy G

[RNeuhaus]

The ion engine is not well positioned for approaching and deviation off from Hayabusha asteroide. Its position is horizontal and their 4 chemical propulsors are on the bottom along with the horn and an Optical Navigation Camera (ONC), a LIght Detection And Ranging (LIDAR), a Laser Range Finder (LRF) and Fan Beam Sensors (FBS) to gather topographic and range information about the asteroid's surface.

Hence, I don't think that the ion engine will be utilized for descendent and ascending phases.

The spaceship will start to aim the landing when it is 100 meters above of Itokawa. Mmm... so close....

The enclosed article : To land upon and gather fragments from the surface of the asteroid, the spacecraft has optical autonomous navigation, guidance and control system, which employs ONC and LIDAR above 100m altitude. For the measurement of the relative position and attitude to the surface in the final landing phase under 100m altitude, ONC, LRF and a Target Marker ™, which is an artificial target and released at about 100m altitude, are used. FBSs are also used for obstacle detection.

For more details, Hayabusa Landing & Reentry.

Rodolfo

[Guest_BruceMoomaw_*]

There are indeed no shadows on the left end of Itokawa in that latest photo -- but the shadows on the entire right half look pretty good, and what they show is lots of debris bumps but no craters yet (with the possible exception of the one over on the mostly-shadowed far right end). At this relative resolution, Eros was showing far more craters. (Not that this strikes me as much of a mystery -- as I said, seismic shaking seems entirely adequate as an explanation.)

And, yes, Hayabusa will do all its maneuvering around the asteroid -- including landings -- using its small chemical thrusters. The ion drive is hopelessly unwieldy and sluggish for the purpose; its sole purpose is for really low-rate but long-term acceleration to get to the asteroid and back.

[Sym05]

New document: "Hayabusa arrived at Itokawa" (Sept 21):
http://www.hayabusa.isas.jaxa.jp/e/Hayabusa_SAC14SEP_e.pdf

and new page with proposals for surface features names (today):
http://www.hayabusa.isas.jaxa.jp/e/index.html

[djellison]

Muses Sea...that's BAD

(for those that dont know, Japan usually has a bland name for a spacecraft at launch, in this case Muses-C, and then renames it after launch, in this case to Hayabusa)

Doug

[Bob Shaw]

Muses Sea...that's BAD

(for those that dont know, Japan usually has a bland name for a spacecraft at launch, in this case Muses-C, and then renames it after launch, in this case to Hayabusa)

Doug

And here's the image:

Attached File(s)

 Names.bmp ( 21.95K ) Number of downloads: 586

 

[ElkGroveDan]

Muses Sea...that's BAD

More proof that the English language has become so universal in science. The Japanese are making puns in English (barring the unlikely possibility that "sea" and "C" are also homonyms in Japanese).

[tty]

More proof that the English language has become so universal in science.  The Japanese are making puns in English (barring the unlikely possibility that "sea" and "C" are also homonyms in Japanese).

I don't think so, I'm fairly sure that sea is "kai".

tty

[tedstryk]

I don't think so, I'm fairly sure that sea is "kai".

tty

Well in that case, the MUSES-C itself is the English import, - After all, the Muses (and other) series seem to be following our alphabet.

[maycm]

http://www.isas.jaxa.jp/e/enterp/missions/...usa/today.shtml

She's moved in a bit closer. Now only 16km away.

[Guest_Sunspot_*]

Sadly they've stopped posting images.

[SFJCody]

Now 12km

[Toma B]

Now only 10 km away...
But stil no new images...
AAAARRRGGGGHHH!!!!!