The general sense of the spirit I was picking up was Hayabusa was the equal of NEAR for less money, or that it actually accomplished far more in certain areas such as infrared remote sensing. Hayabusa had the advantage of superior technology and the prior experience of NEAR to draw on in making it's specs for it's instrumentation, along with all the other flight operations planning.



Your opinions about my post are duly noted, Joffan. Thank you very much.

There is no doubt that Hayabusa has made a significant contribution to the study of NEOs, and has paved the way for more successful missions in the future, which the Japanese by all rights should be in the forefront of pursuing.

I earlier made a rather snide comment in one posting about the possibility of what kind of sample Hayabusa would be bringing back. This was during a time of frustration over all the problems it was having. I also earlier voted on a poll in this forum on whether Hayabusa would succeed in returning to earth with a sample. I voted "no". I'm more confident in that vote than ever. I trust most of you (certainly not all of you) will believe me when I say I will take no joy in it if I turn out to be right, and would be happy to be wrong.

And NEAR never found a Red Light District, either.
I, too, hope to be wrong, but I don't hold much hope for our little friend. Let us hope that the engineering lessons JAXA has learned include what to do and what NOT to do in the future.

Also, it mapped the whole asteroid except those parts that were seasonally in shadow. And, most importantly, it lasted as long as it was designed to last - had NEAR not arrived late, the nominal mission would have been over by the time it failed.

Holder of the Two Leashes:
"...One other thing I don't understand, though, is what your whole point is. ..."

I guess my points is that NEAR was the first of the Smaller, Cheaper, Faster, Better missions, but there is an ongoing debate on whether it was even good enough to accomplish what I thought was it's primary mission objective: determining whether S-type asteroids are or are not the parent bodies of ordinary chondrite meteorites. While the indications of a space-weathering modified surface were at least somewhat expected to cause potential problems in linking the two, the mission that was flown carried instruments that simply did not have the signal-to-noise ratio AND the resolution to clearly sort out what appear to be end-members of the weathering sequence. It was good, but like Boris, it wasn't good-enough.

Where NEAR really shined is in photo-geology, where it mostly made up for it's dinky camera with scads and scads of images that can be mosaiced into global coverage, and revolutionized our understanding of geologic processes on asteroids.

Both missions were successful. Note that they were quite different operationally in that NEAR orbited Eros, while Hayabusa more or less "escorted" Itokawa, and so far as I have seen, ended up with mainly high phase angle images. Of course, this was part of the mission design.

I would think that in retrospect, one might try to emulate NEAR again staying rather close to the mission's goals/money ratio, whereas Hayabusa was a bit too far over the edge for a novel spacecraft... perhaps with legacy components a future mission could be as ambitious and as cheap, but clearly the mission had more than one failure to execute -- the blessing is that it suceeded in every way needed to produce good science. Was it by design or luck that the "optional" portions of the mission were the ones to fail? Contrast Nozomi, which had lots of systems operational, but the one that failed to execute meant no Mars encounter at all.

NEAR had the advantage of treating Eros like it was a planet, but alternately easier (since light thrusters could perform the manuevers) and harder (strange gravity field made it). Hayabusa had a different challenge, and one felt as though it was awkwardly dancing with the asteroid. We can divide future asteroid missions between those that can orbit their worlds and those that must undertake many, frequent propulsive manuevers to execute. Given speed-of-light time, an autonomous system that was foolproof in gracefully dancing with its target would be a tremendous accomplishment.

One accomplishment of Hayabusa was in showing us an entirely new kind of world, at the smallest-yet end of the spectrum, whereas Eros looks on the whole like Gaspra, and is not too different from Phobos, the first "small" world seen by spacecraft. In a sense, Hayabusa "finished" the size spectrum, because yet smaller "worlds" are likely to be boulder heaps like Hayabusa in every way but the reading on the tape measure -- Hayabusa is clearly at the point where gravity ceases to rework the "world" in any way except to hold it together and pool its dust.

Hmmm. Okay.

You'll please forgive my earlier lashing out. NEAR was a mission I had a great fondness for. I perceived some slights directed at John Hopkins APL and the NEAR team, whom I thought pulled off a remarkable mission given the resources at hand, and reacted defensively. I believe the merits of Hayabusa can stand on their own without much comparision to specific previous missions, but rather what was gained in comparison to everything we had before.

NEAR was able to narrow things down. Eros appears to be a type L or type LL chondrite. Bear in mind, no one had examined an asteriod from this close a range before, and it was inevitable that a lot of lessons were going to be learned on how asteroid missions should be conducted in the future.

Persons close to the Hayabusa team have reported in here before, and I would love to hear what they think in regards to how NEAR influenced the planning for their mission. In the meantime, here is what I can note ostensively -

Some of the most interesting and intriguing images from Eros were the very last ones at closest range. It's obvious the Hayabusa team wanted very close and very detailed images from several points on Itokawa, hence Minerva.

The X-ray spectrometer on NEAR performed brilliantly. A similar device was included on Hayabusa.

The gamma ray spectrometer on NEAR was a real problem child. It never got the data it was designed for until after they pulled off that unlikely landing on Eros, and it had sat there for a week. Hayabusa didn't carry any similar instrument.

The magnetometer on NEAR never detected any intrinsic magnetic signature at EROS. When it failed to do so even after the landing, it was quickly and unceremoniously turned off. Hayabusa carried no magnetometer.

The NIS performed well according to it's design. As you have pointed out so well, edstrick, the reality of Eros was that more resolution, even from it's planned 35 km orbital results, would have been highly desirable. Hayabusa carried an instrument with improved resolution.

After all was said and done, the comparison of Eros with meterorite samples was not definitive. Hayabusa bringing back two samples from Itokawa would absolutely NAIL the comparisons, along with much else.

Part of what I was trying to allude to with my "scraping NEAR and Deep Space 1" remarks was to point out that Hayabusa would have been a very differently designed, and undoubtedly more costly, mission had it not had previous experience to draw on. Part of what was learned this time around was that Eros and Itokawa were more different than expected, which created some problems for Hayabusa's landing attempts. This points to a need for a CONTOUR type mission to visit several different NEAs.

Hawaii's Jeffrey Bell has been telling me for years that remote sensing -- even with high-quality instruments -- simply isn't adequate to answer the "ordinary chondrite" question, and that a sample return will be necessary. The evidence seems to be growing that he's right -- simple element measurements and near-IR spectra don't seem to be adequate to nail it -- and this is one reason why I regard "Hera" as one of the more likely candidates for selection in the next Discovery AO.

Can you point me to a good paper on this?

I just noticed this, though it may not be brand new. I don't think I had seen the false-color view at the bottom of the first page before this.

Phil

http://www.jaxa.jp/news_topics/column/special-4/index_e.html

Maybe if we wait a few million years, we'll get all the samples of Itokawa we will ever need - or want:

Smooth Sections on Asteroid Itokawa

Credit & Copyright: ISAS, JAXA

Explanation: Why are parts of this asteroid's surface so smooth? No one is yet sure, but it may have to do with the dynamics of an asteroid that is a loose pile of rubble rather than a solid rock. The unusual asteroid is currently being visited by the Japanese spacecraft Hayabusa that is documenting its unusual structure and mysterious lack of craters. Last month, Hayabusa actually touched down on one of the smooth patches, dubbed the MUSES Sea, and collected soil samples that will eventually be returned to Earth for analysis. Unfortunately, the robot Hayabusa craft has been experiencing communications problems and so its departure for Earth has been delayed until 2007.

Computer simulations show that 500-meter asteroid Itokawa may impact the Earth within the next few million years.

http://antwrp.gsfc.nasa.gov/apod/ap051228.html

From the January 12, 2006, issue of Nature: "So near yet so far."

Here's an excerpt from the article that, I believe, sums it up:

Coming back here after a hiatus... since Volcanopele pointed out in another thread that there are good abstracts on Hayabusa results at the Lunar and Planetary Science Conference:

http://www.lpi.usra.edu/meetings/lpsc2006/pdf/program.pdf

(near the bottom- check both the Hayabusa session and the posters)

Yes, there are, and they illustrate how successful JAXA has been in the remote sensing side of the mission. Some papers should appear in Science soon.

I went through all the abstracts and compiled a list of all the publicly announced feature names. None are official yet. Here they are shown over a montage of images which were released earlier, courtesy JAXA/ISAS. I look forward to seeing the first map of Itokawa.

Phil

Oh, yes. Two particularly striking photos that I've never seen before:

(1) http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2463.pdf (Fig. 3): The closest photo taken yet of an asteroid's surface -- with a resolution of only 6 mm/pixel -- showing the surface of the "Muses Sea" where Hayabusa landed for its sampling runs, and revealing that the "pond" is filled not with fine dust but with coarse gravel. (The abstract reveals that the gravel gets gradually and progressively smaller as one moves toward the center of the pond. Definitely size-sorting by seismic shaking.)

(2) http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1022.pdf (Fig. 1), making dramatically clear just how incredibly small Itokawa is compared with Eros. The similarity of their surface processes is thus even more striking.

Good find Bruce.
For a resolution of 6mm per pixel in this image (which according to their scale is about 6.5 meters wide) the original before re-scaling for the pdf it was extracted from, would have been about 1110 pixels wide.

The final NEAR photo was 537 pixels over a similar field of view (6 meters), so the Hayabusa image is nearly twice the resolution of NEAR's best of (11 mmpp).