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Spy Satellite to Hit Earth by late February to March
tty
post Feb 15 2008, 01:36 PM
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If this was launched on a Delta 2 it must have been more-or-less an "end of the line" item. In earlier programs such satellites have frequently been cobbled together from engineering test articles and similar that have been updated and flight rated. Might have some bearing on why it failed.
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Jim from NSF.com
post Feb 15 2008, 05:03 PM
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Highly doubtful

1. NRO hasn't used a west coast Delta II, there is no "end of the line" since there was no beginning
2. It could have been test or new type of spacecraft
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Jim from NSF.com
post Feb 15 2008, 05:05 PM
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QUOTE (helvick @ Feb 15 2008, 03:58 AM) *
The one thing that surprises me about the whole situation is that this seems to imply that there is no self destruct capability on this satellite - I know nothing about spy sats



That isn't a US practice. Adds more complexity and hazards to the spacecraft and reduces available mass
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Jim from NSF.com
post Feb 15 2008, 05:08 PM
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QUOTE (nprev @ Feb 15 2008, 05:53 AM) *
I was wondering why they'd design the thing with such a massive load of scary nasty hazmat in a re-entry survivable container,



That is standard spacecraft design.

What do you think would happen to MSL or Phoenix if the upperstages didn't fire?
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Tom Tamlyn
post Feb 15 2008, 07:16 PM
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Ed,

Thanks for that thoughtful and knowledgeable analysis.

>>As a camouflaged test of an anti-sat system (which the moonbats will be screaming
>>is the purpose of the operation), it's a hell of a lousy test.

To me the more interesting question is whether success at what might be called a moderately challenging problem in orbital rendezvous tells us anything useful about the performance of systems intended to intercept unscheduled ballistic missiles.

Here is some amusing commentary on aspects of the story which are off-topic for umsf.com.

TTT

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nprev
post Feb 15 2008, 08:55 PM
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QUOTE (Jim from NSF.com @ Feb 15 2008, 09:08 AM) *
That is standard spacecraft design.

What do you think would happen to MSL or Phoenix if the upperstages didn't fire?


Understood. However, these vehicles are designed to land on Mars, so reentry into Earth's atmosphere, while still a risk, isn't part of the planned mission timeline. I don't know if there's a material that could be used to hold NH4 (nasty, corrosive stuff that it is) and also assuredly distintegrate at a safe altitude, but seems like it's something that should be thought about.

Titanium's wonderful stuff, but in this case it's too wonderful. sad.gif


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djellison
post Feb 15 2008, 11:25 PM
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Strong enough to maintain pressure on orbit, but weak enough to break apart on re-entry is probably a specification overlap that doesn't exist I would imagine.

Doug
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nprev
post Feb 15 2008, 11:57 PM
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I was thinking of something with a lower melting point than Ti that might have sufficient structural integrity; an alloy? If the tank is mounted on the exterior surface of the spacecraft, then it could get a favorable burnthrough at the right altitude. The main issue is getting the hazmat out of the tank well before it hits the ground.

One other idea is coating the exterior of the tank with something that might act as an accelerant during reentry to promote a burnthrough, sort of an anti-heat shield.

One of the most formidable obstacles, though, remains finding a material that is both resistant to NH4 and light enough to be used for this application. Any metallurgists in the house?

EDIT: CNN now reporting that the interception may cost as much as US$60 million; sounds like they're low-balling it to me, hopefully not. Lots of equipment modifications required per the article, lots of engineering support...



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edstrick
post Feb 16 2008, 10:02 AM
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The problem is that there is NO good replacement for hydrazine.

Space storable, non-cryogenic propellants are pretty much all nasty. About the only one that isn't nasty doubled is CONCENTRATED hydrogen peroxide.
You can have a dual propellant system.. another hydrazine and an oxidizer like nitrogen tetroxide <gak! gag! croak!>... less total nasty stuff but twice as complicated a propulsion system.

I don't know anything that has a decent "bounce per ounce" that isn't nasty.
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mchan
post Feb 16 2008, 05:04 PM
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Well, it's good that the US has the capability and will expend the costs to mitigate the hydrazine hazard, particularly since it can fall on other countries as well as the US. It is nasty stuff. I commiserate with the Kazakhstan folks downrange of Baikonur when a Proton is having a bad day.

BTW, nprev, NH4 is ammonium, usually ionized, and in solution or compound. Not quite as nasty without another N.
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nprev
post Feb 16 2008, 05:25 PM
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Ahh, I'm chemically illiterate...I meant N2H4, of course, thanks, mchan!

Yeah, Ed, I'm not advocating trying to do without hydrazine; can't see any other practical alternatives either. What's needed is a way to dump the stuff safely from a dead bird, which implies a passive method, presumably triggered by reentry heating. Perhaps high-threshold (500 deg C)/high-volume bimetallic dump valves hooked directly to the tank, similar to what I proposed for on-orbit dead booster venting awhile back?


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mchan
post Feb 16 2008, 05:55 PM
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If the intercept is successful in mitigating the hazard material problem, then it could be used for future similar cases without incurring development costs of an on-board hazard reduction mechanism and the associated mass penalty. The incremental cost of the intercept would be expended only if the contingency actually occurred rather than adding the cost to the spacecraft in anticipation of the contingency.

The intercept option would not work for hazard from a re-entry immediately following a late launch failure. Not too bad if the impact zone is over water, but very crappy if over land.
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nprev
post Feb 16 2008, 06:10 PM
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I don't know if the US Navy, nor the DoD itself, would be happy about maintaining the Lake Erie and its support ships in a unique hardware & software configuration ready for extremely infrequent use in this way, though. The missile mods are one thing, but from what I've read the ships themselves will have to be de-modified in order to reestablish their core mission capabilities.

However, I guess they could conceivably refine the whole process into a portfolio of quick-reaction kit mods after the scramble to get US-193 handled is over & there's time to work out the logistics.


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Jim from NSF.com
post Feb 16 2008, 10:27 PM
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QUOTE (nprev @ Feb 16 2008, 12:25 PM) *
Ahh, I'm chemically illiterate...I meant N2H4, of course, thanks, mchan!

Yeah, Ed, I'm not advocating trying to do without hydrazine; can't see any other practical alternatives either. What's needed is a way to dump the stuff safely from a dead bird, which implies a passive method, presumably triggered by reentry heating. Perhaps high-threshold (500 deg C)/high-volume bimetallic dump valves hooked directly to the tank, similar to what I proposed for on-orbit dead booster venting awhile back?



There is no need for this. This situation is rare. It is not worth the effort to mitigate this nonproblem
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nprev
post Feb 16 2008, 11:17 PM
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wink.gif ...NRO might see it differently, Jim; bet that they're just loving all this wonderful publicity...


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