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NASA Dawn Asteroid Mission Told to "Stand Back Up", Reinstated!
dvandorn
post Mar 28 2006, 07:58 AM
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Just 'cause I said I would... biggrin.gif biggrin.gif biggrin.gif biggrin.gif biggrin.gif biggrin.gif

Hopefully, though, this whole episode has made its point -- NASA isn't afraid to tell overbudget missions to stand down.

I just *really* wish we could get the magnetometer back on the beastie, though...

-the other Doug


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“The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Guest_BruceMoomaw_*
post Apr 2 2006, 08:13 PM
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That, in turn returns us to the question I mentioned a bit earlier: to what extent have all the asteroids, including the biggest ones, been busted up by impacts? Especially during the Belt's earliest days, when it is generally thought to have had MUCH more material in it -- perhaps including dozens of large protoplanetary "embryos", some of them perhaps as big as the Moon or Mars? Most of that material was eventually completely ejected from the Belt by Jupiter's gravitational perturbations, but in the meantime the situation there must have been wild indeed.

The trouble is that the evidence seems contradictory. The existence of a fair number of M-type asteroids -- some of which still appear to be iron-nickel, even in the latest revised near-IR compositional studies -- suggests that they were created from small, initially differentiated asteroids whose outer silicate mantles were completely stripped away, leaving their harder metal cores. There are also the asteroid "families" whose trajectories clearly show that they are the fragments of a bigger original body that got blasted to hellandgone at some point -- and eight of those families are big enough that they must have come from bodies over 200 km wide. But at the same time Vesta seems mostly covered by a basalt crust -- which must be the product of a particularly strong and complete differentiation process -- and most of that outer crust is still on it, instead of having been blasted away by impacts to expose the asteroid's underlying non-basalt mantle. (There are also the other really big remaining asteroids -- Ceres, Pallas, Hygeia. Did they also avoid a large number of impacts, or were they bashed into rubble but were still big enough that their gravity recompressed them again into solid material and spherical forms? If so, then the original ice in them could have been melted by those impacts, and the large part of it that they retained would then have refrozen again as their upper layer.)

There seem to be at least three different theories to explain this seeming contradiction on the Belt's collisional environment, and I'm currently trying to slog through abstracts and papers on the subject to try and get everyone's views properly sorted out. Once I get this done -- on top of the other things I'm trying to do right now -- I'll have more comments.
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Bob Shaw
post Apr 2 2006, 08:57 PM
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Bruce:

'Harder metal cores?' That's an interesting one. If the proto-asteroids were differentiated, presumably by virtue of the radiactive decay of Al, then would hot cores be more or less likely to be disrupted than undifferentiated bodies after big impacts? Similarly, if the early asteroid belt saw many impacts, would that not mean that some bodies might still have been warm after the last whack when they ran into something else?

Obviously, these days, a monolithic lump of cold nickel-iron (or some variant thereof) is going to be hugely more robust than a rubble pile - but what about *warm* objects?

And that's got me wondering about the effect of T-Tauri solar winds on both icy and rocky/metallic bodies... ...induced currents in rotating irons, leading to poor structural cohesion, maybe?

Bob Shaw


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Posts in this topic
- dvandorn   NASA Dawn Asteroid Mission Told to "Stand Back Up"   Mar 28 2006, 07:58 AM
- - Holder of the Two Leashes   Does anyone know how much it would cost to reinsta...   Mar 28 2006, 03:32 PM
|- - Marz   yee haw!! Has the mission timeline be...   Mar 28 2006, 04:15 PM
- - J.J.   ^ The launch has been pushed back to July 2007. T...   Mar 28 2006, 04:27 PM
|- - Marz   QUOTE (J.J. @ Mar 28 2006, 10:27 AM) ^ Th...   Mar 28 2006, 10:01 PM
|- - mchan   QUOTE (Marz @ Mar 28 2006, 02:01 PM) 3. a...   Mar 28 2006, 10:39 PM
|- - AlexBlackwell   QUOTE (Marz @ Mar 28 2006, 10:01 PM) 3. a...   Mar 28 2006, 10:55 PM
|- - The Messenger   QUOTE (Marz @ Mar 28 2006, 03:01 PM) Oh, ...   Mar 29 2006, 04:08 PM
|- - AlexBlackwell   QUOTE (The Messenger @ Mar 29 2006, 04:08...   Mar 29 2006, 07:04 PM
||- - SFJCody   Magnetometer or not, 2015 will put a significant c...   Mar 29 2006, 08:01 PM
||- - The Messenger   QUOTE (AlexBlackwell @ Mar 29 2006, 12:04...   Mar 29 2006, 08:05 PM
||- - AlexBlackwell   QUOTE (The Messenger @ Mar 29 2006, 08:05...   Mar 29 2006, 08:08 PM
||- - SFJCody   QUOTE (The Messenger @ Mar 29 2006, 09:05...   Mar 29 2006, 08:10 PM
|- - BruceMoomaw   QUOTE (The Messenger @ Mar 29 2006, 04:08...   Apr 1 2006, 12:48 AM
|- - AlexBlackwell   QUOTE (BruceMoomaw @ Apr 1 2006, 12:48 AM...   Apr 1 2006, 01:36 AM
|- - tedstryk   QUOTE (BruceMoomaw @ Apr 1 2006, 12:48 AM...   Apr 2 2006, 04:53 PM
- - AlexBlackwell   QUOTE (dvandorn @ Mar 28 2006, 07:58 AM) ...   Mar 28 2006, 04:49 PM
|- - SFJCody   QUOTE (AlexBlackwell @ Mar 28 2006, 05:49...   Mar 28 2006, 04:58 PM
||- - JRehling   QUOTE (SFJCody @ Mar 28 2006, 08:58 AM) I...   Mar 28 2006, 05:58 PM
|- - elakdawalla   QUOTE (AlexBlackwell @ Mar 28 2006, 08:49...   Mar 28 2006, 05:45 PM
|- - AlexBlackwell   QUOTE (elakdawalla @ Mar 28 2006, 05:45 P...   Mar 28 2006, 06:02 PM
- - gpurcell   http://dawn.jpl.nasa.gov/science/technology.asp S...   Mar 28 2006, 05:40 PM
- - peter59   I checked my calendar but it is not April Fool...   Mar 28 2006, 05:46 PM
- - BruceMoomaw   It is, I imagine, well too late to reinstall eithe...   Mar 28 2006, 08:11 PM
|- - AlexBlackwell   QUOTE (BruceMoomaw @ Mar 28 2006, 08:11 P...   Mar 28 2006, 09:30 PM
- - elakdawalla   Colleen Hartman said yesterday that the arrival da...   Mar 28 2006, 10:08 PM
|- - JRehling   QUOTE (elakdawalla @ Mar 28 2006, 02:08 P...   Mar 28 2006, 11:24 PM
|- - ElkGroveDan   QUOTE (JRehling @ Mar 28 2006, 11:24 PM) ...   Mar 28 2006, 11:39 PM
|- - dvandorn   QUOTE (JRehling @ Mar 28 2006, 05:24 PM) ...   Mar 29 2006, 02:26 AM
|- - antoniseb   QUOTE (dvandorn @ Mar 28 2006, 09:26 PM) ...   Mar 29 2006, 01:45 PM
|- - Bob Shaw   QUOTE (antoniseb @ Mar 29 2006, 02:45 PM)...   Mar 29 2006, 02:21 PM
- - mars loon   QUOTE (dvandorn @ Mar 28 2006, 07:58 AM) ...   Mar 29 2006, 12:47 AM
|- - Bjorn Jonsson   QUOTE (mars loon @ Mar 29 2006, 12:47 AM)...   Mar 29 2006, 12:48 PM
- - punkboi   All that matters is... The 'Send your name to ...   Mar 29 2006, 04:24 AM
- - nprev   You know, all these "Dawn ocean" jokes a...   Mar 29 2006, 06:40 AM
- - Myran   Ok great its back on track. And no more ocean joke...   Mar 29 2006, 11:34 AM
|- - dvandorn   QUOTE (Myran @ Mar 29 2006, 05:34 AM) ......   Mar 29 2006, 11:01 PM
- - BruceMoomaw   There's a great deal on this subject scattered...   Mar 29 2006, 06:52 PM
- - Mariner9   I second SFJCody's comment about a capstone ev...   Mar 29 2006, 08:45 PM
|- - SFJCody   QUOTE (Mariner9 @ Mar 29 2006, 09:45 PM) ...   Mar 29 2006, 09:51 PM
|- - JRehling   QUOTE (Mariner9 @ Mar 29 2006, 09:45 PM)W...   Mar 29 2006, 10:19 PM
- - BruceMoomaw   Actually, we still won't have done that. We h...   Mar 29 2006, 09:51 PM
- - Mariner9   Sigh. I considered putting in a caveate about th...   Mar 29 2006, 11:00 PM
- - BruceMoomaw   Actually, the Moomaw was just trying to point out ...   Mar 30 2006, 02:52 AM
|- - JRehling   I have a long-standing belief that I haven't h...   Mar 30 2006, 03:47 PM
- - Myran   QUOTE dvandorn said: in space, no one can hear you...   Mar 30 2006, 05:06 PM
|- - JRehling   QUOTE (Myran @ Mar 30 2006, 09:06 AM) Are...   Mar 30 2006, 05:12 PM
- - BruceMoomaw   One of the major mysteries of the belt is how Vest...   Mar 30 2006, 06:31 PM
- - Myran   QUOTE JRehling wrote: The total mass of the main b...   Mar 30 2006, 06:36 PM
|- - tedstryk   I think that it depends on how one defines samples...   Mar 30 2006, 08:39 PM
|- - JRehling   QUOTE (Myran @ Mar 30 2006, 10:36 AM) But...   Mar 30 2006, 11:39 PM
- - Mariner9   I remember in one of the earlier Discovery mission...   Mar 31 2006, 03:47 PM
|- - JRehling   QUOTE (Mariner9 @ Mar 31 2006, 07:47 AM) ...   Mar 31 2006, 05:47 PM
|- - Bob Shaw   QUOTE (JRehling @ Mar 31 2006, 06:47 PM) ...   Mar 31 2006, 10:57 PM
|- - David   Not me, but one thing occurs to me: aren't the...   Apr 1 2006, 12:06 AM
|- - JRehling   QUOTE (David @ Mar 31 2006, 04:06 PM) Not...   Apr 1 2006, 12:32 AM
- - BruceMoomaw   It's certainly an idea. One might even combin...   Mar 31 2006, 08:12 PM
- - BruceMoomaw   Oh, yes. Might be worth doing anyway, though, if ...   Apr 1 2006, 12:16 AM
- - BruceMoomaw   I've considered trying to look into the questi...   Apr 1 2006, 02:22 AM
- - BruceMoomaw   That, in turn returns us to the question I mention...   Apr 2 2006, 08:13 PM
|- - Bob Shaw   Bruce: 'Harder metal cores?' That's a...   Apr 2 2006, 08:57 PM
- - BruceMoomaw   As a matter of fact, the fact that a lot of the as...   Apr 2 2006, 11:34 PM
- - Bart   A new edition of the Dawn's Early Light newsle...   Apr 6 2006, 10:23 PM
|- - mchan   The newsletter notes what was posted earlier in th...   Apr 8 2006, 02:16 AM
- - gpurcell   Looks like they whacked the program managers from ...   Apr 7 2006, 04:23 PM
- - Marz   So Oct 31, 2007 is a scary date indeed! I...   Apr 9 2006, 02:58 PM
- - BruceMoomaw   Andy Dantzler just provided an "explanation...   Apr 11 2006, 08:37 PM
- - gpurcell   QUOTE The other thing is when you do overrun - if ...   Apr 11 2006, 10:38 PM
|- - BruceMoomaw   [quote name= quote in reply - removed [/quote] No...   Apr 12 2006, 12:05 AM
- - gpurcell   Well, if he can still get two new vehicles out of ...   Apr 12 2006, 03:07 PM
- - Analyst   What has been the problem with the Discovery 11 AO...   Apr 18 2006, 10:59 AM
|- - BruceMoomaw   QUOTE (Analyst @ Apr 18 2006, 10:59 AM) W...   Apr 18 2006, 09:48 PM
|- - ugordan   QUOTE (BruceMoomaw @ Apr 18 2006, 10:48 P...   Apr 20 2006, 09:31 AM
- - monitorlizard   Without trying to provoke anger, I think Dawn was ...   Apr 18 2006, 12:38 PM
|- - Bob Shaw   QUOTE (monitorlizard @ Apr 18 2006, 01:38...   Apr 18 2006, 01:12 PM
|- - tedstryk   QUOTE (monitorlizard @ Apr 18 2006, 12:38...   Apr 18 2006, 02:48 PM
- - Analyst   Thank you, Bruce.   Apr 20 2006, 08:00 AM
- - Analyst   I guess it's not rising but falling demand. A ...   Apr 20 2006, 03:17 PM
- - BruceMoomaw   "Analyst" is correct -- as the demand fo...   Apr 20 2006, 08:31 PM
|- - Bob Shaw   Bruce: SeaLaunch on Zenit-2. Bob Shaw   Apr 20 2006, 08:40 PM
|- - RNeuhaus   QUOTE (Bob Shaw @ Apr 20 2006, 03:40 PM) ...   Apr 22 2006, 02:19 AM
|- - tedstryk   [quote name='RNeuhaus' _quote in reply -re...   Apr 22 2006, 02:21 AM
- - djellison   Sea Launch is 5200kg to GTO Delta II Heavy - 2064 ...   Apr 20 2006, 10:36 PM
|- - Bob Shaw   QUOTE (djellison @ Apr 20 2006, 11:36 PM)...   Apr 21 2006, 07:43 PM
|- - Jim from NSF.com   QUOTE (Bob Shaw @ Apr 21 2006, 03:43 PM) ...   Apr 22 2006, 07:57 PM
- - edstrick   The europeans ran into the same "oops.... how...   Apr 21 2006, 10:40 AM
- - BruceMoomaw   Yeah, but most Solar System launches have limited ...   Apr 22 2006, 02:06 AM
- - remcook   zenit is the rocket model   Apr 22 2006, 03:46 PM
- - tty   How about Long March 2 - 3370 kg to GTO tty   Apr 22 2006, 05:13 PM
- - ljk4-1   Mark Rayman has created his first log of the renew...   Apr 27 2006, 01:54 PM
- - Rakhir   Dawn Team Looking Good For Launch Next Year http:...   Jun 1 2006, 08:38 AM
|- - Marz   QUOTE (Rakhir @ Jun 1 2006, 03:38 AM) Daw...   Jun 1 2006, 03:50 PM
- - PhilHorzempa   Some recently posted images on DAWN website showin...   Jun 29 2006, 03:43 AM
|- - punkboi   QUOTE (PhilHorzempa @ Jun 28 2006, 08:43 ...   Jun 29 2006, 05:42 PM
- - PhilHorzempa   There have been several very good photos of DAWN r...   Aug 1 2006, 03:38 AM
- - djellison   Is it really necessary to attach these images to t...   Aug 1 2006, 08:53 AM
- - punkboi   Last day to send your name to the asteroid belt is...   Sep 13 2006, 07:46 AM


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