[X] My Assistant

[Floyd]

NASA is appraising a human mission to a near-Earth asteroid—gauging the scientific merit of the endeavor while testing out spacecraft gear, as well as mastering techniques that could prove useful if a space rock ever took aim for our planet. Space.com


Floyd Dewhirst

[Guest_Myran_*]

Yes I noted it at Space.com also, and went to look if someone had posted about it - you had.

The idea are not entirely new, it was suggested as a follow up to the lunar program with one NEO as a target for the Apollo craft. By that time the idea was sold as a 'stepping stone' before going on to Mars. As we know in hindsight the Mars plans never got off the drawing table and even the Apollo program itself got a cut before it was finished.

(And yes, feel free to move this thread to 'Manned spaceflight')

[nprev]

What would really be interesting is a mission to a suspected ex-comet nucleus, if in fact any potential candidates are NEOs. Obviously we wouldn't want to send people to an active object for safety reasons, but the scientific return from extinct nucleus samples could be substantial indeed.

The other selling point here would be that, if the Moon truly lacks any useful volatiles, such an object could be a major candidate for early resource exploitation.

[edstrick]

Meteoritics 101 reminder. There are about 5 main types of objects (maybe 5 1/2) we're likely to find in the near-earth object population. ALL of them are well worth exploring, some are better sources of potential resources than others.

1.) Ordinary Chondritic meteorite parent bodies. Asteroids made of relatively raw inner-solar system "sediment" (rock and metal grit, plus frozen rock droplets - chondrules). They may vary from nearly pristine to highly metamorphosized by heat so everything's recrystalized. These appear to be the most commen objects made of stuff that's got enough mechanical strength to survive atmospheric entry.

2.) Stony Achondrite meteorite parent bodies. Inner portions or surface erupted lava flow portions of <probably> former chondrite parent bodies which heated up enough to melt and differentiate. Consists of olivine and/or pyroxene or basaltic <pyroxene, maybe olivine, and feldspar> rock. These are true igneous rocks from a micro-planet. These are rare.

3.) Stony-Iron (Pallasite) and Iron (actually nickle-iron alloy) parent bodies. These are the cores and core/mantle boundaries of fully differentiated micro- and mini-planets that have had their presumably chondritic crusts and achondritic mantles blown off them by impact, exposing the core. These are rare.

4a.)"dry" Carbonaceous Chondrite parent bodies, relatively raw "sediment", possibly from the "middle belt": silicate rock, with the metal oxidized and contained in the rock, some of the rock oxidized with more iron in Fe+3 state (ferric) than in ordinary chondrites, where it's all Fe+2 and Fe metal. Involatile carbon compounds and little water. Like the Allende carbonaceous chondrite. These are uncommon, but not rare.

4b.) "wet" Carbonaceous Chondrite parent bodies. "Sediment" from further out in the belt. Fe+3 rich silicates, some hydrates silicates, carbon and organic compounds. Like the Murchison carbonaceous chondrite (with amino acids) and in extreme variety, the Tagash Lake meteroite crumbly-bits. These are uncommon, at least in forms with enough strength to survive atmospheric entry, and probably uncommon in the NEO population.

5.) Extinct or nearly-extinct comets: Objects formed close to Jupiter's orbit or beyond, containing at least <unless sublimated away> water ice, and if formed further out, cryogenic ices like C02, volatile organic compounds, perhaps NH3, and in extreme cases, N2, C0 and the like. Mixed with silicate dust and organic materials. Nothing from these appears to have strength to survive atmospheric entry. These appear to be uncommon in the NEO population but are hard to recognize other than as "not odinary chondrite or rocky achondrite"

6.) None of the above. Unknown or poorly recognized natural small solar system bodies, hibernating Borg cubes, failed intersteller "generation" colony ships, Vgr-like unmanned interstellar probes, UFO's with Air-Force shrapnel in their interstellar drives, space whales, and mini-black holes. (this IS #6 of 5). The more intoxicated or mentally unbalanced you are, the more common these appear to be.

[nprev]

Thanks, Ed...great primer! Under category 6, you forgot to mention pieces of failed alien Von Neumann asteroid mining machines, though...

[MizarKey]

And also those miles long craft making the rings of saturn...oh, and the self replicating probes that can survey the galaxy long after the creator race is dead.

Actually, we should put some hardware on Earth's other moon - 3753 Cruithne.

[lyford]

Well, couldn't you really add some S-IVB's to category 6?

[tty]

There definitely are quite a few bits and pieces of Earth, Moon and Mars out there (and probably of Mercury and most gas-giant moons too), but I suppose most of them are quite small. There are blocks many meters in diameter in the Chicxulub ejecta blanket but I expect that only small rocks would be accelerated to escape velocity. Incidentally has anybody seen any research on this?

tty

[algorimancer]

A manned mission to Ceres would be particularly interesting, quite possibly on the order of Mars. It is probably easier to get to Mars, however. No comparison to a near-earth-asteroid mission, however; that's just good practice and basic science.