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Unmanned Spaceflight.com _ Earth Observations _ Spy Satellite to Hit Earth by late February to March

Posted by: Bobby Jan 27 2008, 04:47 AM

Just read at MSNBC that a large U.S. spy satellite will hit Earth by the end of February or early March.
Better keep our hard hats ready??? rolleyes.gif

Here is the article:

http://www.msnbc.msn.com/id/22857051/

Posted by: PhilCo126 Jan 27 2008, 01:01 PM

CNN also has the story: http://www.cnn.com/2008/TECH/space/01/26/dead.satellite.ap/index.html
And these guys observe all Sats:
http://www.satobs.org/seesat/Jan-2008/index.html#204

Posted by: ElkGroveDan Jan 27 2008, 03:58 PM

Of course there's the obligatory sensational AP headline http://Disabled%20spy%20satellite%20threatens%20Earth that sounds like a 1950's sci-fi movie.

It's interesting that as they go through the "history" of satellite reentry they seem to have missed http://en.wikipedia.org/wiki/Image:Cosmos-954_debris_cropped.png which left a swath of radioactive debris over northern Canada in 1978. Give it time and I'm sure that will become part of all these stories.




Posted by: nprev Jan 28 2008, 04:00 AM

Cosmos 954 was the first thing I thought of as well, Dan. Correct me if I'm wrong, but humanity seems to have survived...I'm still trying to figure out how to get rid of you all!!! tongue.gif

Posted by: Tman Jan 28 2008, 01:06 PM

Hi, according http://www.calsky.com/observer/csrender.cgi?object=Satellite&number=3&obs=99330761686815&tdt=2454540.07899579&sat=29651&tracker=&lang=en it seems to be satellite "USA 193 / NROL-21 (2006-057A)" that failed to work. The link shows the momentary estimated time and location of the fall.

Posted by: PDP8E Jan 30 2008, 08:37 PM

Here are the images of US-193 in orbit.

Credit John Locker of Great Britain.
He says that the solar wings that are so visible with other sats are not visible in his images

He thinks they failed to deploy

image us-193-1 is during September at a range of 340km
image us-193-2 is a high elevation morning pass in December at ~300km





cheers


Posted by: PDP8E Feb 14 2008, 06:42 PM


Breaking: US Military to Shoot Down USA-193 Spy Satellite



http://ap.google.com/article/ALeqM5h7aoM2ii3QVBCAV8m2HtJSuPxPNwD8UQ7CEO0

Posted by: ElkGroveDan Feb 14 2008, 08:21 PM

QUOTE (PDP8E @ Feb 14 2008, 10:42 AM) *
Breaking: US Military to Shoot Down USA-193 Spy Satellite

I just saw that too. I'm dying to know the physics involved; i.e. mass and velocity of the impactor and other critical elements. Probably too classified for that to ever be released.

Posted by: Floyd Feb 14 2008, 09:10 PM

I think they are more interested in destroying secret instruments on board that could fall into the wrong hands than protecting the public. The destruction will create debris left in space, just like destruction of the Chinese Satalite.

Posted by: ugordan Feb 14 2008, 09:16 PM

All that debris will probably end up reentering faster than the original satellite would.

I'm more interested in whether the missile will actually hit the satellite. biggrin.gif

Posted by: edstrick Feb 15 2008, 07:49 AM

"I think they are more interested in destroying secret instruments on board that could fall into the wrong hands than protecting the public. The destruction will create debris left in space, just like destruction of the Chinese Satalite. "

NASA TV carried the press conference this afternoon, 1:30 central time. NASA Admin Griffin was one of the panalists to provide info-backup and support for the 2 military briefers. They spent most of the briefing and Q&A session debunking such double-nonsense as is embedded in this quote.

Point 1: While they may be lying -- some people automatically assume the military will lie about anything as a matter of mere convenience -- they were absolutely categorical about the planned destruction of the satellite being for safety reasons, not for eliminating classified technology information.

Point 2: The debris will not be "left in space". The chinese satellite was at some 450-500 miles altitude. The satellite will be at 130 miles altitude or lower when targeted. You can do about 1 orbit at 85 miles. Mercury early missions orbited at 90 miles where you can do about a day. 130 miles up youi may last a couple weeks or so if you're large and dense.

The debris from the chinese satellite will all (except for stuff that's like dust) be in orbit for decades, up to a century or more for big chunks. It will slowly decay, passing THROUGH the most used low orbit altitudes including where all manned missions fly except lunar missions. Note that if you intercept and fragment (the phrase "shoot down" is so wrong it's "bad astronomy" bad) a sat at exactly 500 miles altitude, essentially all the fragments end up on orbits passing through that 500 mile intercept point. Some will have higher apogees, some will have lower perigees, some end up in elliptical orbits that cross through 500 miles altitude.

When you intercept and fragment a satellite at 130 miles altitude, the fragments end up in orbits passing through 130 miles. Many will have perigees lower than that and re-enter on the next orbit or in a few days. Some will still have a 130 mile perigee but have a higher apogee. They'll still re-enter in a few days, as the drag at perigee is what counts, and their mass-per-surface-area is greatly reduced, so the drag slows them faster. Essentially all the debris will be below altitudes anything normally orbits at and essentially all will re-enter in a month.

What they were extremely specific and emphatic about, including Administrator Griffin, is the hazard involving the hydrazene tank. The tank is big. 40 inches (1 meter) diameter, and full of hydrazine -- frozen hydrazine that was never used up as the satellite failed completely the first day on orbit. There's a lot that IS known about re-entry, particularly after the post Columbia studies. (I've held a small titanium tank from Columbia in my hands -- we were inspecting it for possible internal defects (existing pre-disaster) that other shuttle tanks might have.) Griffin said: The tank WILL survive entry intact. It WILL be full of hydrazine. LITTLE hydrazine will be lost due to heating and boil-off during entry. The tank will not remain sealed during entry and impact: fuel lines will be ripped from other hardware during satellite breakup. (approximate quote) It will cannonball into the ground and sit there, either cracked or intact but leaking as the hydrazine melts and evaporates. With average wind conditions, an area typically the size of 2 football stadiums will be exposed to health-endangering or lethal amounts of hydrazine fumes. They said that if it were not for the specific risk due to the tank, they would not have decided to carry out this operation.

The intercept missile is an Aegis tactical ICBM (really IRBM) interceptor. It had to be modified to carry additional propellant to extend it's range up to the 130 mile (note.. I think they were using nautical miles) altitude. Software had to be specially modified to enable the intercept of this non-warhead like target in this non-warhead like trajectory. As a camoflauged 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.




Posted by: helvick Feb 15 2008, 08:58 AM

Excellent summary Ed - the reporting has certainly been uniformly "Bad Astronomy" bad.

While this is definitely not a useful test of true anti satellite weaponry it is almost certainly a good test of the intercept guidance systems and I would be very surprised if this exercise was not being viewed by a very useful test by the military even though I do believe that the primary reason being given is genuine. Ignoring the pure military angle it is also a useful test of an if-all-else-fails mechanism for "safely" dealing with the de-orbit of potentially hazardous debris.

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 but I would have expected them to have some self destruct capability and even a small charge located on or near the main fuel tank(s) would surely be a much more practical way of safing this thing than trying to hit it with a interceptor at a couple of km/sec.

Posted by: nprev Feb 15 2008, 09:53 AM

QUOTE (helvick @ Feb 15 2008, 12:58 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 -


For all we know, it might; I get the impression that they haven't been able to talk to it for quite some time, though. (Actually, after re-reading Ed's outstanding summary, they might have NEVER made contact with it).

On the other hand, most SVs seem to get boosted into "disposal" orbits at the end of their operational lifetimes or intentionally deorbited if they're low enough, so maybe there is no self-destruct system. Doesn't really seem that you'd want to carry explosives that might accidentally destroy the vehicle, either, and you really don't want to blow it up on-orbit & tick everyone off, esp. if you're trying to keep the entire thing very low-profile in the first place...

However, no idea how the Secret Squirrel crowd handles EOL with their toys.

Posted by: edstrick Feb 15 2008, 10:21 AM

I gather the spooks like to deorbit their birds, rather like the russians dispose of Progress supply barges.

The apparently semi informed discussion that I've seen on this bird is that is was in deep doo-doo when it was deployed from the delta 2 launch vehicle. <note.. this is not one of the big recon sats!.. not on a delta> The computer never booted or went into a locked up mode, safe modes never worked, apparently little or no panels etc deployed. Apparently was unresponsive and running out of power after only a few hours on orbit.

Posted by: nprev Feb 15 2008, 10:53 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, but I get it. In an optimum end-of-mission scenario, what little NH4 would be left would be vented, if not entirely consumed by the deorbit maneuver, and the whole thing goes splash somewhere remote.

Hopefully this will cause some fail-safe redesigns; if that tank was empty (or could confidently be expected to burn up), nobody'd be worried. As is, can't be doing last-minute mods to missiles & scrambling to get Navy ships into position in time to frag errant birds; that must've cost a fortune already, and the meter's stll running!

Posted by: tty Feb 15 2008, 01:36 PM

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.

Posted by: Jim from NSF.com Feb 15 2008, 05:03 PM

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

Posted by: Jim from NSF.com Feb 15 2008, 05:05 PM

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

Posted by: Jim from NSF.com Feb 15 2008, 05:08 PM

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?

Posted by: Tom Tamlyn Feb 15 2008, 07:16 PM

Ed,

Thanks for that thoughtful and knowledgeable http://www.unmannedspaceflight.com/index.php?s=&showtopic=4936&view=findpost&p=109360.

>>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.

http://digbysblog.blogspot.com/2008/02/plot-from-80s-film-by-dday-in-world.html is some amusing commentary on aspects of the story which are off-topic for umsf.com.

TTT


Posted by: nprev Feb 15 2008, 08:55 PM

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

Posted by: djellison Feb 15 2008, 11:25 PM

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

Posted by: nprev Feb 15 2008, 11:57 PM

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 http://www.cnn.com/2008/TECH/02/15/spy.satellite/index.html 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...


Posted by: edstrick Feb 16 2008, 10:02 AM

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.

Posted by: mchan Feb 16 2008, 05:04 PM

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.

Posted by: nprev Feb 16 2008, 05:25 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?

Posted by: mchan Feb 16 2008, 05:55 PM

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.

Posted by: nprev Feb 16 2008, 06:10 PM

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.

Posted by: Jim from NSF.com Feb 16 2008, 10:27 PM

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

Posted by: nprev Feb 16 2008, 11:17 PM

wink.gif ...NRO might see it differently, Jim; bet that they're just loving all this wonderful publicity...

Posted by: Jim from NSF.com Feb 17 2008, 02:24 AM

QUOTE (nprev @ Feb 16 2008, 06:17 PM) *
wink.gif ...NRO might see it differently, Jim; bet that they're just loving all this wonderful publicity...


Doubtful. Adding more penetrations to a tank that could jeopardize a mission would be frowned upon

Posted by: nprev Feb 17 2008, 02:47 AM

I wouldn't advocate adding more penetrations to a tank; understand how difficult it can be to design those things to hold pressure & pass the structural integrity requirements. (The bimetallic valves I was thinking about would be on the main feed line before the pump & shut-off valve, making it effectively one penetration topologically).

I would, however, really like to know if there's some sort of substance out there that's safe to fly to coat the tanks with, something that might promote intense spot-heating during reentry. I don't know; maybe a layer of magnesium coated with plastic to keep the O2 out pre-launch, or even just a few strategically-placed patches of same?

One other thing about such "vent-patches" is that they might blow under some circumstances during a launch failure & dump the crap before it's anywhere close enough to habitable areas to cause problems.

Posted by: Jim from NSF.com Feb 17 2008, 07:08 PM

QUOTE (nprev @ Feb 16 2008, 09:47 PM) *
1. I wouldn't advocate adding more penetrations to a tank; understand how difficult it can be to design those things to hold pressure & pass the structural integrity requirements. (The bimetallic valves I was thinking about would be on the main feed line before the pump & shut-off valve, making it effectively one penetration topologically).

2. I would, however, really like to know if there's some sort of substance out there that's safe to fly to coat the tanks with, something that might promote intense spot-heating during reentry. I don't know; maybe a layer of magnesium coated with plastic to keep the O2 out pre-launch, or even just a few strategically-placed patches of same?

One other thing about such "vent-patches" is that they might blow under some circumstances during a launch failure & dump the crap before it's anywhere close enough to habitable areas to cause problems.


1. It is still a propulsion system penetrations. Also Range safety wouldn't like like them since there is no insight or intentional control of them

2. Since the weight and range safety issues.

Posted by: Sunspot Feb 18 2008, 07:33 PM

Some questions:

The intention is to break the space craft up in to many smaller pieces, increasing the likelihood of most of it disintegrating upon re-entry. Will this debris spread out after the impact producing dozens or possibly hundreds of re-entry "events" spread out over days maybe weeks?

Posted by: PhilCo126 Feb 18 2008, 07:39 PM

I'm a bit amazed that anti-satellite missiles can be fired to such altitudes from the ground (sea) up. I remember that the US Air Force had anti-satellite missiles but these were fired from an F-15 fighter jet flying at maximum altitude...

Posted by: tty Feb 18 2008, 09:34 PM

Firing a missile to 200 km altitude isn't that difficult (after all the Germans did it back in 1942). Launching from an aircraft at 50,000 feet does help, but the reason ASAT was aircraft-borne was mainly for the flexibility and quick-reaction capability. An aircraft can launch almost anywhere in the wrld and in any direction.

Posted by: nprev Feb 18 2008, 10:50 PM

QUOTE (Sunspot @ Feb 18 2008, 11:33 AM) *
Will this debris spread out after the impact producing dozens or possibly hundreds of re-entry "events" spread out over days maybe weeks?


Maybe...but the prime intent per Ed's analysis of the intercept is to rupture that full hydrazine tank on-orbit so that it's not a hazard after impact.

Posted by: jaredGalen Feb 19 2008, 10:37 AM

Do we have any idea what the debris field will be like and how long it will persist in orbit? The satellite is almost out of orbit anyway but the energy of a missile strike will surely boost the orbit of a lot of the debris?

Posted by: Tman Feb 19 2008, 11:10 AM

http://spaceweather.com/ (19. Feb) reports that rumor has it that the US Navy may make its first attempt to hit USA 193 this Wednesday evening as the satellite passes over the Pacific Ocean. Because of Ted Molczan http://www.satobs.org/seesat/Feb-2008/0337.html by the US Government that might point to a possible ASAT attempt on USA 193 on Feb 21, between 2:30 and 5:00 UTC.

If they hit exactly the tank with the hydrazine, at that great combined speed, I would think the missile (without a warhead) penetrates the tank and maybe other parts entirely without larger impact on the orbit of the rest of the satellite.

Posted by: ElkGroveDan Feb 19 2008, 04:28 PM

QUOTE (Tman @ Feb 19 2008, 03:10 AM) *
If they hit exactly the tank with the hydrazine, at that great combined speed, I would think the missile (without a warhead) penetrates the tank and maybe other parts entirely without larger impact on the orbit of the rest of the satellite.

As we all know it's all about mass and velocity. If that impactor arcs up and strikes the satellite at a high velocity opposite to the direction of travel then it will indeed impact the orbit of the doomed satellite. I suspect that this is part of the plan, or if not it has been calculated for. Not knowing the impactor mass and it's expected impact velocity it would be difficult for us to even pencil it out here, but the orbital effect will be significant (with a small number on the mass side of the equation, but a very large multiplier on the velocity side.)

Posted by: NGC3314 Feb 19 2008, 05:54 PM

QUOTE (nprev @ Feb 16 2008, 05:17 PM) *
wink.gif ...NRO might see it differently, Jim; bet that they're just loving all this wonderful publicity...


Wondering why Michael Griffin is so prominent in all these public statements. Hey - I have an idea. Maybe he's thinking this offers a way to avoid HST's eventual reentry violating NASA debris footprint rules, and a lot cheaper than developing a (probably still one-off at that point) robotic module for controlled deorbit.

Posted by: Jim from NSF.com Feb 19 2008, 06:45 PM

QUOTE (ElkGroveDan @ Feb 19 2008, 11:28 AM) *
As we all know it's all about mass and velocity. If that impactor arcs up and strikes the satellite at a high velocity opposite to the direction of travel then it will indeed impact the orbit of the doomed satellite. I suspect that this is part of the plan, or if not it has been calculated for. Not knowing the impactor mass and it's expected impact velocity it would be difficult for us to even pencil it out here, but the orbital effect will be significant (with a small number on the mass side of the equation, but a very large multiplier on the velocity side.)



The impactor's velocity is not really part of the "equation", it could be zero. The bulk of the energy is from the satellite. The velocity differences are on the order of several km/sec.
The impactor just has to get in the path of the satellite at the right time. Sort of like throwing up a baseball glove to knock down a fly ball.

Posted by: ElkGroveDan Feb 19 2008, 08:42 PM

I get your point, but come on now there is no such thing as a zero velocity except with respect to another body. If the velocity is zero with respect to the satellite then there will be no damage (and no impact for that matter). Even if the impactor is moving in the same direction of travel, albeit slower, its momentum must be factored in to the final momentum of the system after the impact. And in every instance I can imagine, the result will be greater decay in the orbit of the satellite and it's fragments.

Posted by: Jim from NSF.com Feb 20 2008, 12:49 AM

QUOTE (ElkGroveDan @ Feb 19 2008, 03:42 PM) *
I get your point, but come on now there is no such thing as a zero velocity except with respect to another body. If the velocity is zero with respect to the satellite then there will be no damage (and no impact for that matter).


Didn't say with respect to the satellite , I was referring with respect to the earth (basically hovering)

Posted by: ElkGroveDan Feb 20 2008, 03:09 AM

http://www.space.com/news/080219-satellite-shootdown.html

The collision between the fired missile and the satellite would not only break the massive hunk of metal into pieces but would also speed up its tumble through Earth's atmosphere.

"If you want to bring something down, you slow it down. You apply a force on it which results in it being slowed down and decrease in its orbit," Carrico told SPACE.com. "Right at that point where they want to engage [the satellite] is at the edge of the atmosphere, so you're bringing it down faster."



I believe that was the point I was trying to make above.

Posted by: Tman Feb 20 2008, 05:43 PM

Time and location of this first shot down attempt is well chosen. There's a graphic http://news.astronomie.info/ai.php/200802035 (text in German) that show roughly the orbit(s) (in orange) after the possible hit. The most part of the following two orbits are over the sea and the rest good enough for military secrets. The large green colored circle shows the area where the satellite (or debris) can be seen from the ground.

Posted by: Jim from NSF.com Feb 20 2008, 06:05 PM

QUOTE (ElkGroveDan @ Feb 19 2008, 10:09 PM) *
http://www.space.com/news/080219-satellite-shootdown.html

[i]The collision between the fired missile and the satellite would not only break the massive hunk of metal into pieces but would also speed up its tumble through Earth's atmosphere.


I believe that was the point I was trying to make above.


The force that is going to bring down the fragments is drag, not the impact. The fragments have a lower ballistic coefficent

Posted by: ugordan Feb 20 2008, 06:09 PM

QUOTE (Jim from NSF.com @ Feb 20 2008, 07:05 PM) *
The force that is going to bring down the fragments is drag, not the impact. The fragments have a lower ballistic coefficent

I believe the space.com story doesn't mean the impact will bring down the fragments, it will lower the perigee so it runs into the denser atmosphere much sooner. Hence the "speed up its tumble through Earth's atmosphere". It's inevitable the fragments will be robbed of some energy by the impact in addition to increased drag due to fragmentation you mention.

Posted by: helvick Feb 20 2008, 06:55 PM

I know this is a stupid question and I'm sure I should know the answer myself but I'm having trouble getting my head around it. Lower orbits have a higher orbital velocity than higher orbits so if this exercise is (as seems likely) going to be a head on collision then it will slow down the whole satellite and probably seriously slow down quite a lot of the debris. Ignoring drag which I fully accept will act much more effectively on the resulting impact compromised debris why doesn't this deceleration cause the whole thing to end up in a higher orbit?

Posted by: ugordan Feb 20 2008, 06:59 PM

QUOTE (helvick @ Feb 20 2008, 07:55 PM) *
why doesn't this deceleration cause the whole thing to end up in a higher orbit?

Because this event will take away from the total energy of the satellite. Higher orbits have higher total angular momentum, but a lower kinetic energy. If you very gradually take away energy from an orbiting satellite (say in a circular orbit via air drag), it will actually be speeding up a bit because the orbit will effectively remain circular and just the radius will decrease. Overall, it still loses energy because the gravitational potential energy drops off more rapidly than the kinetic energy is increasing.

It's a bit counterintuitive, but true. A lower orbit is a higher speed one, yet one with a lower angular momentum. In our solar system, the majority of the energy is carried by the outer planets, not inner ones.

Posted by: ElkGroveDan Feb 20 2008, 07:07 PM

QUOTE (Jim from NSF.com @ Feb 20 2008, 10:05 AM) *
The force that is going to bring down the fragments is drag, not the impact. The fragments have a lower ballistic coefficent


You left out this part:

"If you want to bring something down, you slow it down. You apply a force on it which results in it being slowed down and decrease in its orbit,"

This is what I have been saying, and they weren't referring to atmospheric drag. The impactor will slow it down and it will begin to drop.

Posted by: helvick Feb 20 2008, 08:22 PM

If I'm understanding ugordan's explanation of the dynamics correctly what will actually happen is that the ASAT will slow it all down a little. That situation is unstable so the debris cloud will fall lower into the atmosphere and speed up in the process as it swaps gravitational potential energy for kinetic energy.

The satellite is (believed to be) about 2600kg and is currently orbiting at around 7.8km/sec. I've no idea how the ASAT intercept is supposed to work but lets assume that they put it into a similar orbit moving in the opposite direction. The impact head of the ASAT is not likely to mass much more than 100kg and probably will mass less than 25kg if it's similar to the earlier US ASAT tests. For a perfect collision where a 100kg ASAT warhead transferred all it's momentum into the satellite the resulting object would be moving at 7.22km/sec. That's now unstable at that altitude and so it will fall until its rising velocity matches the orbital velocity at the altitude it finds itself. My [highly unreliable and full of gross simplifications] back of the envelope calculations put that at about 18 km lower down.

That alone will significantly increase the drag but the really important factor is that the end result of a successfull intercept will be a debris cloud that has a massively increased effective cross section compared to the original satellite and that is what will really bring it down fast.

Posted by: stevesliva Feb 20 2008, 09:13 PM

I heard somewhere that the KV was only 10kg... can't find the discussion now. Some more info here:
http://blog.wired.com/defense/2008/02/the-weapon-that.html

Ahh, here it is, in the FAS anti-ASAT take:
http://www.fas.org/blog/ssp/2008/02/us_plans_test_of_anti-satellit.php

Says the interceptor is 20lb.

Posted by: ugordan Feb 20 2008, 09:31 PM

QUOTE (helvick @ Feb 20 2008, 09:22 PM) *
My [highly unreliable and full of gross simplifications] back of the envelope calculations put that at about 18 km lower down.

According to my fooling around with Orbiter, a 7.22 km horizontal velocity at 250 km altitude brings you 700 km below the surface at perigee.

Lithobraking is the word.

My back of the envelope calculation says a head-on collision with a static 100 kg impactor should give a resulting velocity of 7.5 km/s, not 7.22 km/s. If the impactor is 10 kg, that comes down to 7.77 km/s (a perfect inelastic collision). I haven't done a check for 7.77, but my gut feeling say that, too, guarantees reentry in less than half an orbit. Depending on how solid the impactor and the satellite are, the impactor might partially rip-through the satellite implying an even smaller deceleration.

Posted by: rlorenz Feb 20 2008, 11:31 PM

A couple of things crack me up about this whole business

1. the hydrazine cover story..... as if stuff like this doesnt re-enter all the time. If anything gets decomposed
or dispersed during the entry, it'll be the hydrazine. This has to be a total non-issue that the spin doctors have
figured would be a good angle for public consumption (NB hypergolics are a problem for launch failures
where their toxicity etc sticks around, but for hypervelocity entry, I think not....)
2. the way all the TV coverage seems to use Magellan and Cassini footage or models.... I guess to a lot of
people a spaceship is a spaceship...
3. And now they are talking about delaying the shot because of weather... let's hope the Iranians/Koreans/whoever
don't play nasty and try to attack us on a cloudy day........ :-)

(I know, I know, it's for the observations to see how it all went, not for the intercept itself...)

Posted by: Jim from NSF.com Feb 20 2008, 11:34 PM

QUOTE (rlorenz @ Feb 20 2008, 06:31 PM) *
A couple of things crack me up about this whole business

1. the hydrazine cover story..... as if stuff like this doesnt re-enter all the time. If anything gets decomposed
or dispersed during the entry, it'll be the hydrazine. This has to be a total non-issue that the spin doctors have
figured would be a good angle for public consumption (NB hypergolics are a problem for launch failures
where their toxicity etc sticks around, but for hypervelocity entry, I think not....)


You haven't been keeping up with things, it is solid hydrazine. Many propellant tanks (Delta II, Columbia, etc) have survived hypervelocity entry

Posted by: helvick Feb 21 2008, 02:22 AM

ugordan - yeah I got a better quality envelope and it looks like the orbiter perigee is probably correct. It surprises me that even a small 10kg impactor could actually bring down a 2600kg satellite from a low earth orbit, even if there was no atmosphere involved. But it does appear to be true. Quite cool actually. Now let's see if it actually works. smile.gif

Posted by: Jim from NSF.com Feb 21 2008, 02:59 AM

QUOTE (ugordan @ Feb 20 2008, 04:31 PM) *
According to my fooling around with Orbiter, a 7.22 km horizontal velocity at 250 km altitude brings you 700 km below the surface at perigee.

Lithobraking is the word.

My back of the envelope calculation says a head-on collision with a static 100 kg impactor should give a resulting velocity of 7.5 km/s, not 7.22 km/s. If the impactor is 10 kg, that comes down to 7.77 km/s (a perfect inelastic collision). I haven't done a check for 7.77, but my gut feeling say that, too, guarantees reentry in less than half an orbit. Depending on how solid the impactor and the satellite are, the impactor might partially rip-through the satellite implying an even smaller deceleration.




But the hit isn't head on. It is around 90 degrees. the missile and warhead fly straight up into the path of the satellite. Both vehicle are destroyed by the kinetic energy into small fragments.

Posted by: Pavel Feb 21 2008, 03:04 AM

http://www.spaceref.com/news/viewpr.html?pid=24802

QUOTE
So we're pretty comfortable right now that we'll have windows available to us through about the 29th or 30th.

I'm not sure they'll have a good chance to hit it on February 30. rolleyes.gif

Posted by: centsworth_II Feb 21 2008, 03:53 AM

http://www.msnbc.msn.com/id/23265613/#storyContinued and http://www.cnn.com/ reporting a hit.
No story, just the headline.

edit:
AP story now out: "The operation is so extraordinary that Defense Secretary
Robert Gates, not a military commander, made the final decision to pull the trigger."

Posted by: dvandorn Feb 21 2008, 04:01 AM

CNN just ran the story about 20 minutes ago, reporting a hit. No details, and no information whatsoever about how direct the hit was. The only "information" given was that the satellite was traveling at orbital velocity (first cosmic velocity to our Russian friends), roughly 17,500 mph, and the impactor was going about 5,000 mph in the opposite direction. (Yeah, I know, it's olde English imperial units -- but it's CNN, after all.)

-the other Doug

Posted by: ElkGroveDan Feb 21 2008, 05:14 AM

Space/AP

Navy Hits Satellite With Heat-Seeking Missile

http://www.space.com/news/080220-satellite-hit.html

Posted by: rlorenz Feb 21 2008, 06:31 AM

QUOTE (Jim from NSF.com @ Feb 20 2008, 06:34 PM) *
You haven't been keeping up with things, it is solid hydrazine. Many propellant tanks (Delta II, Columbia, etc) have survived hypervelocity entry



I know *empty* propellant tanks can survive entry because of their low ballistic coefficient e.g.
http://www.lpl.arizona.edu/~rlorenz/spaceball.pdf

Have any full tanks ever done so? They would surely experience much higher loads.
I wonder, can solid hydrazine detonate?

(Columbia doesnt count as it started the entry with thermal protection)


Posted by: volcanopele Feb 21 2008, 07:42 AM

I am still waiting for the video from the missile. Don't tell me they didn't put one on it...

Hey my tax dollars paid for this, I don't think it is too much to ask for a video of said impact laugh.gif

Posted by: ugordan Feb 21 2008, 07:49 AM

They need time to clean out the aliens from the footage.

Posted by: mchan Feb 21 2008, 08:07 AM

QUOTE (nprev @ Feb 16 2008, 06:47 PM) *
I would, however, really like to know if there's some sort of substance out there that's safe to fly to coat the tanks with, something that might promote intense spot-heating during reentry. I don't know; maybe a layer of magnesium coated with plastic to keep the O2 out pre-launch, or even just a few strategically-placed patches of same?

One other thing about such "vent-patches" is that they might blow under some circumstances during a launch failure & dump the crap before it's anywhere close enough to habitable areas to cause problems.

Well, Nick, looks like there have been some studies along the lines of your thoughts. I was looking at one of the sci.space.* groups and pulled this signal out of the noise --

http://ntrs.nasa.gov/search.jsp?R=623231&id=1&qs=Ntt%3D20070023407%26Ntk%3Dall%26Ntx%3Dmode%2520matchall%26N%3D0%26Ns%3DHarvestDate%257c1

Posted by: mchan Feb 21 2008, 08:19 AM

QUOTE (ugordan @ Feb 20 2008, 11:49 PM) *
They need time to clean out the aliens from the footage.

You don't know half of it. You think it was a coincidence that the missile was launched exactly at the midpoint of the total lunar eclipse when the lowest level of solar radiation was reaching the moon?

Posted by: CAP-Team Feb 21 2008, 09:00 AM

How much more space debree is now orbiting Earth? blink.gif

Posted by: ugordan Feb 21 2008, 09:44 AM

And, more importantly, anyone know if there's a possibility for updated orbital elements of the bulk of the debris cloud so we skygazers could go out and hope for reentry fireballs at certain times?

Posted by: djellison Feb 21 2008, 09:54 AM

QUOTE (CAP-Team @ Feb 21 2008, 09:00 AM) *
How much more space debree is now orbiting Earth? blink.gif


Quite a lot, but below an altitude of any active vehicle and it'll be gone within a few weeks. China's ASAT test debris, however, continues to endanger LEO vehicles (including ISS, Hubble etc) , and will do so for many years to come.

There's a Press conf. at 1200UT today I think ( http://www.defenselink.mil/news/newsarticle.aspx?id=49024 )
Doug

Posted by: helvick Feb 21 2008, 09:58 AM

Immediately after the impact there was quite a lot but by now there is likely to be very little and by this time next week virtually none. The dynamics of the situation have stacked the odds very much in favour of this being a very clean strike.

Timing it to coincide with a full lunar eclpise may entirely coincidental or even have been useful for some aspects of the exercise but I can't help thinking that at some point in the planning there were a bunch of military types hovering over some Cassini (and New Horizons) Kodak Moments thinking - "Guys these are cool and all but I know how we can get an even better shot". I'm waiting for that tracking shot that shows the moment of impact against a backdrop of a red-brown lunar disc.

Posted by: jaredGalen Feb 21 2008, 11:12 AM

Apparent FEMA document outlining the satellite reentry and potential response etc.

One statement says that ninety-nine percent of the debris will renter the atmosphere within one week. The same as the original reentry timeline of the intact satellite I think.

http://88.80.13.160/wiki/US_spy_satallite_shootdown_briefing

Posted by: Sunspot Feb 21 2008, 11:12 AM

As expected some of the British press are using the event to take some not so subtle digs at the United States....drawing attention to their criticism of the Chinese test, without realising much of the criticism of that event came from the scientific community highlighting how insanely stupid it was.

Posted by: djellison Feb 21 2008, 11:23 AM

Which bits of the British Media? I've got some letter writing to do it seems

What I simply can't believe I'm reading is Chinese criticism of this. That defies belief.

Doug

Posted by: Sunspot Feb 21 2008, 11:29 AM

It was the lead story on Newsnight last night....and the first thing the presenter asked. Sadly the press are unable to see past the politics of these events... and see how totally different they are.

LOL.. you've got to laugh at this quote from China:

QUOTE
Spokesman Liu Jianchao said: "China is continuously following closely the possible harm caused by the US action to outer space security and relevant countries.

"China requests the US to fulfil its international obligations in real earnest and provide to the international community necessary information and relevant data in a timely and prompt way so that relevant countries can take precautions."

Posted by: jaredGalen Feb 21 2008, 11:38 AM

QUOTE (djellison @ Feb 21 2008, 11:23 AM) *
What I simply can't believe I'm reading is Chinese criticism of this. That defies belief.


The Chinese were never going to let the opportunity pass by without getting a dig or two into the US.

The 'we must protect our citizens from falling, toxic fuel soaked, shrapnel from the sky' angle seems to be part of it too.

They are going to milk it though.

Edit: How prompt was China's notice of their weapons test? smile.gif

Posted by: djellison Feb 21 2008, 11:41 AM

But fuel soaked shrapnel from their own failed LV's crashing into nearby villages is fine. mad.gif

Posted by: jaredGalen Feb 21 2008, 11:42 AM

QUOTE (djellison @ Feb 21 2008, 11:41 AM) *
But fuel soaked shrapnel from their own failed LV's crashing into nearby villages is fine. mad.gif


That's my point smile.gif

Posted by: ugordan Feb 21 2008, 11:46 AM

Politics... I don't know whether to laugh or cry when I hear things like these... That's just insulting our intelligence on China's part.

Posted by: Tman Feb 21 2008, 01:57 PM

There's a video from the military that shows the missile launch and the hit, represented in http://www.pentagonchannel.mil/pcindex.aspx

Posted by: stevesliva Feb 21 2008, 02:42 PM

The BBC radio I heard in my car this morning included good info from the press conference...
http://news.bbc.co.uk/2/hi/americas/7256741.stm

Although I must say that in the recorded press conference, it sounded like they had targeted the tank specifically with the KV. *That* may have been a sort of look-what-our-ABM can do demo.

Posted by: Jim from NSF.com Feb 21 2008, 02:50 PM

QUOTE (stevesliva @ Feb 21 2008, 09:42 AM) *
The BBC radio I heard in my car this morning included good info from the press conference...
http://news.bbc.co.uk/2/hi/americas/7256741.stm

Although I must say that in the recorded press conference, it sounded like they had targeted the tank specifically with the KV. *That* may have been a sort of look-what-our-ABM can do demo.



The sensor on the warhead wouldn't be able to discriminate the tank from the rest of the spacecraft. I is hard enough to just to target the spacecraft

Posted by: Tman Feb 21 2008, 02:52 PM

There's more from the debris cloud right after the hit http://www.youtube.com/watch?v=vvrP1ZQrk10

Posted by: djellison Feb 21 2008, 02:58 PM

I presume the tank was fairly central in the spacecraft bus. They had mentioned reprogramming the head - I presume to identify the bus, and aim for the middle of it.

Doug

Posted by: stevesliva Feb 21 2008, 03:40 PM

I was definitely ready to believe the implication that a specific area of the satellite was targeted because of the mention in this article:
http://blog.wired.com/defense/2008/02/the-weapon-that.html
... that the kinetic warhead targets the "leathal payload area." In other words, the RV rather than the booster. Or, hopefully, decoys, clouds of chaff, etc. wink.gif I can't recall the exact words used, so it may have been jumping to conclusions on my part, but the ability to discriminate the warhead from the booster and other junk *is* a key part of ABM technology, no? (well, at least post-boost-phase ABM)

Posted by: centsworth_II Feb 21 2008, 04:03 PM

If the fuel tank is one meter in diameter, and they see nothing remaining
larger than a football, wouldn't that be proof of destruction? Where would
the tank be hiding?

Posted by: Jim from NSF.com Feb 21 2008, 05:50 PM

QUOTE (stevesliva @ Feb 21 2008, 10:40 AM) *
I was definitely ready to believe the implication that a specific area of the satellite was targeted because of the mention in this article:


Where would you target the spacecraft in my avatar to hit its 1000lb propellant tank?

Posted by: stevesliva Feb 21 2008, 09:32 PM

QUOTE (Jim from NSF.com @ Feb 21 2008, 12:50 PM) *
Where would you target the spacecraft in my avatar to hit its 1000lb propellant tank?

Definitely that bowl-shaped thigamabob on top.

Posted by: tedstryk Feb 21 2008, 11:57 PM

QUOTE (Jim from NSF.com @ Feb 20 2008, 12:49 AM) *
Didn't say with respect to the satellite , I was referring with respect to the earth (basically hovering)


Not really...you were saying that the impactor's speed was irrelevant. With such a narrow margin (in other words, such a small, fast-moving target), nothing is irrelevant. Curt little defenses are your prerogative, but you were still wrong nonetheless.

Posted by: Jim from NSF.com Feb 22 2008, 01:53 AM

QUOTE (tedstryk @ Feb 21 2008, 06:57 PM) *
Not really...you were saying that the impactor's speed was irrelevant. With such a narrow margin (in other words, such a small, fast-moving target), nothing is irrelevant. Curt little defenses are your prerogative, but you were still wrong nonetheless.



Huh? I disagree and rightly so. The destruct mechanism is the satellites velocity. The warhead only has to be fast enough to get in the way at the right time. The warhead's velocity (magnitude and direct) contribution to the destruction IS irrelevant

Posted by: tedstryk Feb 22 2008, 02:28 PM

That's fine. rolleyes.gif The conversation was not only about velocity relative to earth. Your making the a posteriori claim that it was after ElkGroveDan's post doesn't make it so.

Posted by: PhilHorzempa Feb 26 2008, 11:02 PM

Now that we see that we are able to successfully de-construct a satellite with a Star
Wars projectile, I would like to suggest that this method could be a cost-effective procedure to
de-orbit other satellites when their missions have ended. The principal satellite that I have in
mind is the Hubble Space Telescope.
You may recall that NASA has planned to launch a mission, manned or unmanned, to dock
with the HST (after a docking ring is attached during STS-125) and effect a de-orbit maneuver.
This is likely to drain anywhere from $100 million to $500 million from NASA's Space Science budget.
Why not spend $25 million on a Star Wars projectile to do the job?


Another Phil





Posted by: ugordan Feb 26 2008, 11:10 PM

QUOTE (PhilHorzempa @ Feb 27 2008, 12:02 AM) *
Why not spend $25 million on a Star Wars projectile to do the job?

Because at Hubble's height of 600 km you would be basically doing what the Chinese did - creating a load of dangerous space junk.

Posted by: nprev Feb 26 2008, 11:14 PM

Not a bad idea! It'll take a few more years then planned for HST to get low enough for a hit (and favorable debris reentry), but certainly doing so would be more cost-effective then a dedicated Shuttle mission.

Kind of a bummer to think about, though... sad.gif

Posted by: Stu Feb 26 2008, 11:37 PM

Might be more "cost effective", but after all the wonders she's shown us I think Hubble deserves a better end than being shot out of the sky and blown to bits by a stupid missile. Over-romantic, I know, but I'd much rather she ended her mission burning up like Enterprise did in the 3rd ST movie than being used as an orbital clay pigeon for some trainee A-SAT gunner's target practice. mad.gif

Posted by: nprev Feb 27 2008, 12:24 AM

Yeah...<sigh>...I feel ya, Stu, but this actually might be the best solution.

Given an unlimited budget & a choice, I'd have the Shuttle catch HST & bring it back home for permanent display in the US National Air & Space Museum. However, I don't think that the Shuttle is actually capable of returning a large payload like that (might be wrong, but IIRC there are some very stringent mass restrictions for the landing envelope), nor do I think that the cost vs. benefit vs. risk profile for such a mission would be favorable, even if it did turn out to be feasible.

Like I said: a bummer. At least we seem to have a relatively safe deorbit option available for large SVs now.

Posted by: Jim from NSF.com Feb 27 2008, 12:29 AM

QUOTE (nprev @ Feb 26 2008, 07:24 PM) *
Yeah...<sigh>...I feel ya, Stu, but this actually might be the best solution.

Given an unlimited budget & a choice, I'd have the Shuttle catch HST & bring it back home for permanent display in the US National Air & Space Museum. However, I don't think that the Shuttle is actually capable of returning a large payload like that (might be wrong, but IIRC there are some very stringent mass restrictions for the landing envelope),



The shuttle could since HST is relatively light. The issue is that some of the servicing "mods" would have to be undone to allow it to fit in the bay

Posted by: dvandorn Feb 27 2008, 03:39 AM

QUOTE (nprev @ Feb 26 2008, 06:24 PM) *
I don't think that the Shuttle is actually capable of returning a large payload like that (might be wrong, but IIRC there are some very stringent mass restrictions for the landing envelope...

As Jim said, some mods would have to be removed, and an orbiter would have to be *significantly* modified in order for HST to fit in its payload bay (for a variety of reasons, Columbia was the only orbiter whose bay was suitable for returning HST, and plans said that it was going to be used for that task prior to its destruction).

But while landing with a significant payload in the bay can make things a little dicey under some circumstances, it's just plain impossible that a Shuttle would be allowed to lift off with a payload it can't land with. Otherwise, most all of the ascent abort modes would be worthless -- you can't take time in an RTLS abort, for example, to open the payload bay doors and dump the contents... huh.gif

-the other Doug

Posted by: nprev Feb 27 2008, 04:10 AM

Thanks for the clarification/feedback, guys. Bottom line: Not an insignificant effort to return Hubble, funding to do so is unlikely to say the least (and could certainly be better spent).

Argh. I hate playing the heavy, esp. in this case, 'cause I philosophically agree with Stu: by all rights, Hubble should be preserved & honored for what it really is, a revolutionary leap in our understanding of the Universe. Pragmatically, though, all things in LEO must come to an end, and with minimal damage to both the orbital environment & anything along the reentry ground track. HST has many years left, of course, but when the time comes we must accept it, and prepare for it.

Posted by: mchan Feb 27 2008, 07:48 AM

HST does not have a big tank of frozen hydrazine like USA 193, so there is even less of a reason for an ASAT mission against it.

Posted by: djellison Feb 27 2008, 07:59 AM

To be honest, if you look at some of the really good pics o Hubble - she's a bit of a mess. The insulation is cracking all over the place. I think a return to 1G would do a lot of damage and make he look like something of a sorry bird aestheticaly. Far better to have a 1:1 model, and then photos of the real thing where she belongs.

Doug

Posted by: Stu Feb 27 2008, 08:17 AM

That's a great shame Doug, I hadn't realised she was so worn, but if that's true then fair enough.

Like many, I always imagined going on some sort of pilgrimage to see Hubble in the Smithsonian - the original plan was to return her to Earth and put her on display there, I think I'm right in saying? - and walking beneath that huge barrel tube and marvelling at all she gave us, but I guess that just won't happen. But swatting her out of the sky like an annoying bug seems just wrong to me, a quick and dirty fix that's typical of the way we so quickly look for the easiest way out of problems today. I actually think there'd be a lot of resistance to the idea of blowing Hubble up, and rightly so. Apart from anything else, it wouldn't teach us a thing; de-orbiting Hubble in a controlled way would be expensive, yes, but it would teach us a lot about how to do that with other payloads in the future. Blasting her to a cloud of tumbling, twinkling debris would just be a gung-ho, macho display of firepower.

IMO.

Posted by: djellison Feb 27 2008, 08:49 AM

Here's one example : http://www.nasa.gov/centers/glenn/images/content/84596main_99_96i1.jpg - big crack down the MLI.

You can see more cracks and gaps on the left here, near the ESA logo : http://spaceflight.nasa.gov/gallery/images/shuttle/sts-109/hires/sts109-328-026.jpg

You can see an MLI patch they mounted with string one servicing mission : http://spaceflight.nasa.gov/gallery/images/shuttle/sts-103/hires/sts103_731_051.jpg : there are cracks in the panels on the left as well I think.

The thermal cycling has made it very very brittle. It wouldn't surprise me if they ended up taking a fairly 'bare' Hubble out of the payload bay, and then a dozen bin-liners of broken MLI from under it on the payload bay floor. Lots of long words like embrttlement etc are here - http://www.grc.nasa.gov/WWW/RT2001/5000/5480dever1.html


Posted by: AndyG Feb 27 2008, 10:19 AM

Interesting - so it might be worth returning bits of it as an "LDEF" type-experiment? It'll have been in orbit for eighteen years this April, last servicing in August this year...

Andy

Posted by: djellison Feb 27 2008, 10:35 AM

They already have - indeed, I've seen Hubble solar cells at the National Space Centre (complete with micro meteor impacts )

Doug

 

Posted by: edstrick Feb 27 2008, 12:01 PM

A better intermediate term disposal solution for hubble would be to boost it into a higher "disposal" type orbit, one of those orbits above the masses of low orbit constellations of sats, where almost nothing will have any chance of intersecting it before a future vehicle can retrieve it for an orbital museum.

Posted by: Jim from NSF.com Feb 27 2008, 12:26 PM

QUOTE (dvandorn @ Feb 26 2008, 10:39 PM) *
As Jim said, some mods would have to be removed, and an orbiter would have to be *significantly* modified in order for HST to fit in its payload bay (for a variety of reasons, Columbia was the only orbiter whose bay was suitable for returning HST, and plans said that it was going to be used for that task prior to its destruction).

But while landing with a significant payload in the bay can make things a little dicey under some circumstances, it's just plain impossible that a Shuttle would be allowed to lift off with a payload it can't land with. Otherwise, most all of the ascent abort modes would be worthless -- you can't take time in an RTLS abort, for example, to open the payload bay doors and dump the contents... huh.gif

-the other Doug


They are moving the docking system from Atlantis to make room for the "servicing" hardware. Another "issue" for the retrieval mission, is that the payload bay would have to be empty at launch. This would make the mission really cost prohibitive.

The ASAT idea also has holes in it. HST is large enough that a hit isn't going to obliterate it. Large pieces of the mirror and CMG's from the hit could still survive entry

Posted by: nprev Feb 27 2008, 12:39 PM

Jim, what's a CMG?

Posted by: tasp Feb 27 2008, 01:07 PM

{Psst: Control moment gyro}




Posted by: tty Feb 27 2008, 02:42 PM

QUOTE (Jim from NSF.com @ Feb 27 2008, 01:26 PM) *
The ASAT idea also has holes in it. HST is large enough that a hit isn't going to obliterate it. Large pieces of the mirror and CMG's from the hit could still survive entry


Still, they would be a lot smaller and perhaps fewer after an ASAT hit. I doubt if any very large pieces of mirror would survive a hit at 8+ kms-1 for example.

Posted by: ilbasso Feb 27 2008, 04:01 PM

And besides, it's bad luck to break a mirror.

Posted by: Jim from NSF.com Feb 27 2008, 06:11 PM

QUOTE (tty @ Feb 27 2008, 09:42 AM) *
Still, they would be a lot smaller and perhaps fewer after an ASAT hit. I doubt if any very large pieces of mirror would survive a hit at 8+ kms-1 for example.



Not if the hit was the forward part of the spacecraft

Posted by: nprev Feb 27 2008, 07:42 PM

QUOTE (tasp @ Feb 27 2008, 05:07 AM) *
{Psst: Control moment gyro}

(Thanks! smile.gif Yeah, I imagine that those are a bit hefty.)

Posted by: ElkGroveDan Feb 28 2008, 03:03 AM

Does anyone have a link to a map of the debris orbit(s)?

I just saw the most amazing little fireball to the Northeast of me around 6:15 local time. It was unusual in so many ways, that it made me think it might be some kind of debris reentering.

Posted by: nprev Feb 28 2008, 03:26 AM

Was it kind of slow compared to normal meteors? That's usually the big observational difference; real meteors are fast!

Posted by: ElkGroveDan Feb 28 2008, 03:43 AM

Slow, and quite bluish in color with a much longer tail than any I have ever observed. It also seemed to be traveling in a discernible arc downward. 60 degrees or so above the NNE horizon traveling from North to East.

Posted by: mchan Feb 28 2008, 04:47 AM

I saw this too from South Bay. I had just finished an ATM transaction and the timestamp on the receipt says 6:15. It was also to the Northeast about 20-30 deg up from horizon. Bright fireball, bluish, with faint trail, slight angle down. Speed was slower than most meteors in showers, maybe 3 times slower than a Leonid.

Posted by: nprev Feb 28 2008, 05:15 AM

Boy howdy, and I can't say for certain, but this sure sounds like a debris reentry event. I saw a Molynia booster come in about 30 years ago in dark skies, and it was painfully slow compared to a meteor (albeit spectacular nonetheless). You guys might have gotten lucky indeed!

Posted by: mchan Feb 28 2008, 06:06 AM

Looking on a map, the direction to the fireball from my location was also NNE. If EGD was in Elk Grove, he is also NNE of my location by about 130 km. Given my elevation of 25 deg and EGD's elevation of 60 deg would place the object about 83 km over a location about 48 km NNE of EGD.

Posted by: ElkGroveDan Feb 28 2008, 07:17 AM

I agree. That would have put the ground track between Auburn and Grass Valley heading along a path South of Lake Tahoe. Probably nothing left of it, but if something did survive as far as the lithosphere, it would have impacted in a very remote section of the High Sierras or Eastern Nevada.

Posted by: Bill Harris Mar 1 2008, 02:27 PM

Wouldn't it be ironic of a large piece of debris made it to Edwards AFB, where (IIRC) many of the mil-sats are launched?

--Bill

Posted by: djellison Mar 1 2008, 03:17 PM

I'm not aware of any launches actually FROM EAFB. I may be wrong though.

Doug

Posted by: nprev Mar 1 2008, 03:26 PM

Unless you count Pegasus or perhaps the X-15 program...no, no launches from EAFB.

Vandenberg AFB is around 130 miles west of there as the crow flies, which is what Bill probably meant, and I believe that was in fact where US-193 was launched given its (former) orbital inclination.

Posted by: rlorenz Mar 2 2008, 11:34 AM

QUOTE (Bill Harris @ Mar 1 2008, 09:27 AM) *
Wouldn't it be ironic of a large piece of debris made it to Edwards AFB, where (IIRC) many of the mil-sats are launched?



Maybe they got the tractor beams at Groom Lake working now..... THAT's what this test was really
all about...

Posted by: Bill Harris Mar 2 2008, 02:29 PM

QUOTE
Vandenberg AFB is around 130 miles west of there as the crow flies, which is what Bill probably meant...

Yep, I was thinking Vandenburg but my fingers typed Edwards.

--Bill

Posted by: PhilHorzempa Mar 31 2008, 03:43 AM

One aspect of the USA-193 episode that has not been discussed is the need for
secrecy regarding its demise. As some of you know, stamping a program with
the "CLASSIFIED" label can hide a multitude of sins. Of course, I am not in favor of
revealing details of USA-193's payload.
However, the details of what caused USA-193 to arrive DOA in orbit (according to
the Space rumor mill) should be discussed. When MPL or MCO disappear at Mars, the media
is all over the story, as well they should be. However, when USA-193 becomes the latest
space recon SNAFU, barely a peep is heard.
Billions are invested in NRO's satellites, but the Military "good-ole-boys" network have the
perfect rip-off scheme. They get ALL aspects of an NRO recon satellite classified, so that they
get their billions of dollars regardless of whether the satellite works or not. All that they have
to say when the media come calling with questions is one word - "Classified."
Now whether USA-193's demise was caused by the malfunction of its radio, guidance system,
power system, or propulsion system, an Anomaly Review Board could be appointed with
the directive to release its findings publicly. This could be done without compromising national
security and without revealing the nature of the payload.
As with ITAR, I am against ALL unnecessary government secrecy. It costs us money and
enables contractors to pad their fees and build shoddy satellites. Oversight is the only means
to keep this business honest.

Another Phil



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