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spaceboy0
2008-Feb-15, 05:30 AM
The concept of this missile shooting down that dead spy satellite falling out of orbit is fascinating. How high is that dead satellite orbiting at? 160 miles? Space Shuttle orbit?

What would be the satellite's orbital velocity at the time of missile impact? Are they trying to hit it while its orbit is decaying or while its still high?

Will the missile go straight up and hit the satellite at the point where the trajectories intersect or would the missile go into a partial orbit and try to chase the satellite by coming in from behind?

amachristian
2008-Feb-15, 05:42 AM
What I'd really like to know is if this satellite is out of control and coming down, how in control will those rockets be once they're up there? Will we then have to worry about them falling on us as well? What if they not only miss but land somewhere blowing up the place? I might not know a lot about all that could or couldn't happen, but most are in my position and quite concerned.
This whole thing just seems crazy to me that any of us are even having to worry about this. It's not the size of whatever comes down, it's the hazardous materials that will kill us. Unless of course it's those rockets adding so much more fun to an already wonderful crash.
ama:lol:

Noclevername
2008-Feb-15, 06:42 AM
What I'd really like to know is if this satellite is out of control and coming down, how in control will those rockets be once they're up there? Will we then have to worry about them falling on us as well? What if they not only miss but land somewhere blowing up the place? I might not know a lot about all that could or couldn't happen, but most are in my position and quite concerned.
This whole thing just seems crazy to me that any of us are even having to worry about this. It's not the size of whatever comes down, it's the hazardous materials that will kill us. Unless of course it's those rockets adding so much more fun to an already wonderful crash.
ama:lol:

Don't fret, the missiles can be exploded remotely.

As for "shooting it down", that's not actually what they're doing. They're just shooting it to pieces, to disperse the hydrazine before it crashes, and to a lesser extent, perhaps to make the pieces smaller and likelier to burn up in reentry.

Van Rijn
2008-Feb-15, 07:06 AM
The concept of this missile shooting down that dead spy satellite falling out of orbit is fascinating. How high is that dead satellite orbiting at? 160 miles? Space Shuttle orbit?


Interesting question. According to http://www.nytimes.com/2008/01/27/us/27spy.html?em

Since it was launched, the experimental satellite has been in a slowly decaying orbit. As of Jan. 22, it was moving in a circular orbit at about 275 kilometers [~171 miles]above the Earth, Mr. McDowell said. In the last month, its orbit has declined by 15 to 20 kilometers.

It has dropped a bit from that by now, so 160 miles probably is close. The shuttle is about 340 km (~211 miles up (currently).



What would be the satellite's orbital velocity at the time of missile impact?


Well, according to:

http://www.chicagotribune.com/news/nationworld/chi-spy_satellite15_webfeb15,1,387878.story

At the time of the launch, officials said the satellite would be about 150 miles above the Earth.

So, circular orbital velocity at 150 miles would be about 27,936 km / 17,359 miles per hour.



Are they trying to hit it while its orbit is decaying or while its still high?


Its orbit is already decaying. Again, according to the Chicago Tribune:

If the satellite is not intercepted, it is expected to enter the atmosphere in late February or early March.

"This has no aerodynamic properties," Cartwright said of the satellite. "Once it hits the atmosphere, it tumbles, it breaks apart. It is very unpredictable and next to impossible to engage. So what we're trying to do here is catch it just prior to the last minute, so it's absolutely low as possible, outside the atmosphere, so that the debris comes down as quickly as possible."



Will the missile go straight up and hit the satellite at the point where the trajectories intersect or would the missile go into a partial orbit and try to chase the satellite by coming in from behind?

It's a suborbital missile. I doubt the trajectory would be quite straight up, but it certainly isn't going to be able to catch up from behind, so it has to hop up and get in the way. I'd guess it would get in position a little ahead of the satellite, make final position adjustments and let the satellite catch up with it.

EndeavorRX7
2008-Feb-15, 07:12 AM
Don't fret, the missiles can be exploded remotely.

As for "shooting it down", that's not actually what they're doing. They're just shooting it to pieces, to disperse the hydrazine before it crashes, and to a lesser extent, perhaps to make the pieces smaller and likelier to burn up in reentry.

Exactly. I was even reading that the missile would be aimed to strike the portion of the satellite where the hydrazine tank is. Pretty remarkable to think at the precision and technology involved in intercepting something at such an altitude and speed. This is supposed to take place anywhere from 3-10 days from now, so let's see how it goes.

RalofTyr
2008-Feb-15, 07:55 AM
SPACE WEAPON QUESTION.

If a shuttle was in reentry, would it be really, really easy to hit with a heat seeking missile fired from the surface?

neilzero
2008-Feb-15, 09:20 AM
20 years ago I splashed perhaps an ounce of hydrozene on my pants leg, but I have seen no symptoms, so the danger of hydrozene is likely exagereated. I'll guess, the satellite will be at an altitude of about 80 miles when it crashes into the missile. Assuming the missle warhead explodes the hydrozine will be scatter widely above Earth's atmosphere. The hydrozine will likely be scattered by the kinetic energy of the collission even if the war head does not explode. Hydrozine is a reducing agent, so it will mostly make oxygen compounds before it reaches Earth's surface. Most of the new chemicals are less hazardous than the hydrozine and are chemicals typically found in trace amounts in Earth's atmosphere, such as water.
The Navy has assured us that they will deliberately avoid the collision at the last second, if there is any reasonable chance of making matters worse. If we do nothing, odds are about a million to one that zero humans will be injured.The Navy hopes to improve the odds to about a billion to one. Most of us are more likely to be injured by something many minutes per day, so our personel hazard is only increased minutely by this re-entry. As the others posted, there is no reason to worry. Neil

Tog
2008-Feb-15, 09:53 AM
SPACE WEAPON QUESTION.

If a shuttle was in reentry, would it be really, really easy to hit with a heat seeking missile fired from the surface?

Most Heat Seekers have far too short of a range to reach the Shuttle. Like under 15, with many even less. Sidewinders are listed in Wiki with an 11.3 mile range at Mach 2.5. Stingers are the little shoulder fired ones, and they are listed with a range of 4800 meters, or about 3 miles.

geonuc
2008-Feb-15, 10:42 AM
What I'd really like to know is if this satellite is out of control and coming down, how in control will those rockets be once they're up there? Will we then have to worry about them falling on us as well? What if they not only miss but land somewhere blowing up the place? I might not know a lot about all that could or couldn't happen, but most are in my position and quite concerned.
This whole thing just seems crazy to me that any of us are even having to worry about this. It's not the size of whatever comes down, it's the hazardous materials that will kill us. Unless of course it's those rockets adding so much more fun to an already wonderful crash.
ama:lol:

You've still got time - best get busy on the bomb shelter.

hody1953
2008-Feb-15, 12:03 PM
amachristian,
The missiles they will use will be in control once they are launched to explode the satellite. The satellite was launched many years ago, and has had very little ability to change its directions since then, so it has been in a constantly decaying orbit ever since it was placed in orbit. The missile(s) (rockets are not guided, missiles are guided) will leave the atmosphere acquire the target, lock-on, run under constant burn (not drift) to the target, and explode both themselves and the target into many very small pieces. If the whole evolution is successful, then all of these small pieces will burn up during re-entry. If the missile(s) should miss, those missile(s) may have the ability to re-acquire and make another attempt. If they do not have that ability, they would drift out into space, once their fuel runs out. The worst thing that could happen with this would be the missile(s) would hit an asteroid, the moon, or another planet some time in the distant future. There would be no chance of those missile(s) returning to Earth, since they would be aimed away from Earth and under thrust on a tangent away from our gravity field.
Having said all of this, the HYDROZINE is liquid rocket fuel, and should burn up in re-entry, or better yet, cause the satellite to explode due to the heat building up in the unit containing the HYDROZINE. I think the only reason they are proposing this whole deal is because they want to test this new missile. Originally, they claimed this satellite would not cause any problems more than Skylab (being that because it was so large a big piece may survive to hit something). Let's face it, the current administration in the US is not capable of telling the truth about anything.

Argos
2008-Feb-15, 12:10 PM
If they do not have that ability, they would drift out into space, once their fuel runs out. The worst thing that could happen with this would be the missile(s) would hit an asteroid, the moon, or another planet some time in the distant future.

Hmm, are you sure?

EndeavorRX7
2008-Feb-15, 12:16 PM
The worst thing that could happen with this would be the missile(s) would hit an asteroid, the moon, or another planet some time in the distant future. There would be no chance of those missile(s) returning to Earth, since they would be aimed away from Earth and under thrust on a tangent away from our gravity field.

Not correct at all. The missile would eventually reenter earths atmosphere and burn up. It would never run long or fast enough to escape earths gravity.

JohnBStone
2008-Feb-15, 12:40 PM
Surely the missiles are sub-orbital. If we had missiles capable of reaching escape velocity we would be using them now to put micro-payloads in orbit.

Tog
2008-Feb-15, 12:52 PM
If the missile(s) should miss, those missile(s) may have the ability to re-acquire and make another attempt. If they do not have that ability, they would drift out into space, once their fuel runs out. The worst thing that could happen with this would be the missile(s) would hit an asteroid, the moon, or another planet some time in the distant future. There would be no chance of those missile(s) returning to Earth, since they would be aimed away from Earth and under thrust on a tangent away from our gravity field.

The article I read said that although the range of the missile was classified, it could not reach a "normal" satellite orbit. If they can't make it to 250 miles, the odds of hitting another planet are (hopefully) very remote. Nibiru... I'm looking at you there. The missile won't have the speed to get away from the Earth, and probably won't have the shape to survive re-entry.

Jeff Root
2008-Feb-15, 01:36 PM
The missiles they will use will be in control once they are launched to
explode the satellite. ... The missile(s) (rockets are not guided, missiles
are guided)
A rocket is the engine or the entire propulsion system used to propel
the vehicle. A missile is anything which is thrown, such as a spear, a
rock, a hand grenade, or an ICBM. A "guided missile" is a missile with
some kind of guidence after it has been launched. It may be guided
all the way to the target, or only during the first part of the flight.



...will leave the atmosphere acquire the target, lock-on, run under
constant burn (not drift) to the target, and explode both themselves
and the target into many very small pieces. If the whole evolution is
successful, then all of these small pieces will burn up during re-entry.
If the missile(s) should miss, those missile(s) may have the ability to
re-acquire and make another attempt.
No, they don't have that ability. The missile and the target will pass
each other at enormous speed. It would take many times as much fuel
as the missile actually carries to turn around and head in the opposite
direction, and it would take far longer to catch up to the target again
than the time available.



If they do not have that ability, they would drift out into space, once
their fuel runs out. The worst thing that could happen with this would
be the missile(s) would hit an asteroid, the moon, or another planet some
time in the distant future. There would be no chance of those missile(s)
returning to Earth, since they would be aimed away from Earth and under
thrust on a tangent away from our gravity field.
Good grief! Nothing like that. This missile will coast upward perhaps a
few hundred miles, possibly over a thousand miles, then will fall back
down on a parabolic trajectory. The impact point will be known fairly
accurately at the time of launch, and will be known very accurately at
the time the engine stops firing.



Having said all of this, the HYDROZINE is liquid rocket fuel,
Hydrazine, N2H4.

-- Jeff, in Minneapolis

Jeff Root
2008-Feb-15, 01:49 PM
Endeavor, Tog,

If the missile misses its target -- which I think is more likely than not --
it probably will not burn up on re-entry. It will not be moving anywhere
near as fast as a satellite in orbit. It is the orbital speed that gets ya.

-- Jeff, in Minneapolis

ASEI
2008-Feb-15, 01:54 PM
Hydrazine is supposed to be highly poisonous. If it is part of a bipropellant system, then the nitrogen tetroxide would also be very poisonous. I think the idea is to break the tank up, because they expect the tank to survive re-entry fairly well, and don't want trace amounts of fuel everywhere where it lands.

On the other hand, the danger is probably exxagerated in the first place because hydrazine has a very low flash point. (It is a monopropellant after all). It would probably all burn off on re-entry provided the smallest break in the tank.

Still, it would be interesting to see if we could hit the target. Probably not an easy one to get.

PS- side-note - all low earth orbits decay if they aren't maintained by thrusters. The rarified atmosphere drags on the sattelites over time. My understanding is the sattelite lost power after being deployed and hasn't been in communications or under control since. Since it is a low orbit, the space debris from such an engagement would also likely decay within a few weeks and burn up.

Swift
2008-Feb-15, 01:55 PM
20 years ago I splashed perhaps an ounce of hydrozene on my pants leg, but I have seen no symptoms, so the danger of hydrozene is likely exagereated. I'll guess, the satellite will be at an altitude of about 80 miles when it crashes into the missile. Assuming the missle warhead explodes the hydrozine will be scatter widely above Earth's atmosphere. The hydrozine will likely be scattered by the kinetic energy of the collission even if the war head does not explode. Hydrozine is an oxidizing agent, so it will mostly make oxygen compounds before it reaches Earth's surface. Most of the new chemicals are less hazardous than the hydrozine and are chemicals typically found in trace amounts in Earth's atmosphere.

I'm glad you were not hurt, but I do not agree that the hazards of hydrazine have been exaggerated. Here (http://www.sciencelab.com/xMSDS-Hydrazine-9924279) is the MSDS for it.

The National Fire Protection Association, which rates chemicals as to the hazards for emergency personnel, lists it as 3 for health, flammability, and reactivity, on a 0 to 4 scale (0 being safe).

Tog
2008-Feb-15, 01:56 PM
Endeavor, Tog,

If the missile misses its target -- which I think is more likely than not --
it probably will not burn up on re-entry. It will not be moving anywhere
near as fast as a satellite in orbit. It is the orbital speed that gets ya.

-- Jeff, in Minneapolis

:doh:

You mean the atmosphere isn't a blazing wall of death? Bah. Sooo didn't think that through.

NEOWatcher
2008-Feb-15, 02:17 PM
... It would probably all burn off on re-entry provided the smallest break in the tank...
They (the briefing) are saying that is unlikely because the hydrozene is currently frozen solid. If there is a small break in the tank, some will burn off, but most will stay intact.
What they are expecting is that it survives, and the connections will provide the leak points, and will slowly escape as it thaws.

ASEI
2008-Feb-15, 02:39 PM
Oh. In that case, by all means, try to blow it up.

samkent
2008-Feb-15, 02:39 PM
I have it on good authority that the missle uses a secret German guidance system. It has a self adapting neuroptical interface to control the thrust vanes. The delay is due to an O2 supply to the control interface..

In laymans terms it’s a pigeon pecking on different areas of the display screen. Right now they can’t get them to hold their breath above 3 miles. And they are awaiting special high altitude Israeli pigeons.

cmsavage
2008-Feb-15, 02:42 PM
Blowing up the satellite is all about safety. It has nothing to do with the various secretive components of the spy satellite that might survive an uncontrolled entry into an unfriendly country.... :whistle:

NEOWatcher
2008-Feb-15, 02:50 PM
Blowing up the satellite is all about safety. It has nothing to do with the various secretive components of the spy satellite that might survive an uncontrolled entry into an unfriendly country.... :whistle:
Sure, that's what they say...but we're also talking about the gubmt

Seriously though, it does seem entirely plausible that the damage is enough to be useless. Besides, I would assume a lot of the secrecy is in the construction techniques needed, and without those, the other stuff is useless.

ASEI
2008-Feb-15, 02:51 PM
Well, that's not a trivial motive either. I'd be all in favor of blowing it up in that case too, though they said the sensitive electronics wouldn't be likely to survive re-entry into another country in any sort of useable or reverse-engineerable form.

The missile they are trying to shoot it down with isn't a short-range air to air missile. It's an anti-ballistic-missile missile, more than capable of the necessary ranges and speeds.

antoniseb
2008-Feb-15, 03:02 PM
...It's an anti-ballistic-missile missile, more than capable of the necessary ranges and speeds.

And, all it has to do is burst the fuel tank on a target the size of a short school-bus on a very well known path, whereas it is designed to be able to hit a basketball sized object trying to hide its whereabouts. I think the odds of success are pretty good.

Jeff Root
2008-Feb-15, 03:17 PM
With sufficient technical expertise, examining the remains of the
satellite could yield information about its spying capabilities, thus
telling an enemy what it needs to do to avoid being spied on by
other, similar satellites, or to feed them false data. It could also
reveal communications system details that would enable an enemy
to receive data from them or send control messages to them.

-- Jeff, in Minneapolis

NEOWatcher
2008-Feb-15, 03:25 PM
... thus telling an enemy what it needs to do to avoid being spied on by other, similar satellites...
Like what? Duck?
I think these techniques are already well known.

..., or to feed them false data. It could also
reveal communications system details that would enable an enemy
to receive data from them or send control messages to them...
Now, that part, I could see, but I also think that some of that stuff is already known, and that there are safeguards in place to protect from it.

Maybe the enemy can learn something, but I would think the amount of information would be so small in comparison, that the risk factor just fades away.

cmsavage
2008-Feb-15, 03:35 PM
Seriously though, it does seem entirely plausible that the damage is enough to be useless. Besides, I would assume a lot of the secrecy is in the construction techniques needed, and without those, the other stuff is useless.
My comment was tongue in cheek. I think the gubmt was more than willing to let nature take its course until some NASA scientists noted the frozen block of (hazardous) fuel might survive re-entry.

schlaugh
2008-Feb-15, 03:50 PM
...The satellite was launched many years ago...

Not that long ago...from the LA Times:


Administration officials said this instance is different because the satellite failed shortly after its launch in December 2006...

http://www.latimes.com/features/health/medicine/la-na-satellite15feb15,1,1788175.story

Which just goes to show how quickly LEO objects can de-orbit on their own.

NEOWatcher
2008-Feb-15, 04:01 PM
My comment was tongue in cheek...
I kinda thought so... but there are other people listening.


Not that long ago...from the LA Times:
Of course it is...it's one of two ways the media defines "many" to be "more than one".
1) 13 months is more than one year.
2) 2008 - 2006 = 2, therefore more than one year.

:wall:

schlaugh
2008-Feb-15, 05:30 PM
Of course it is...it's one of two ways the media defines "many" to be "more than one".
1) 13 months is more than one year.
2) 2008 - 2006 = 2, therefore more than one year.

Huh? I may be misreading you.

I was replying to hody1953's comment that the bird was launched "many" years ago. Had nothing to do with the media. In casual conversation "many years" would not usually be used to mean "two".

The media content I've read up to now has always referred to the launch date.

NEOWatcher
2008-Feb-15, 05:41 PM
Huh? I may be misreading you.
I was replying to hody1953's comment...
I stand corrected, I thought his comment dealt with a news report.

Although; the media does do things like that... Here's another
NBC Affiliate (http://www.wkyc.com/news/news_article.aspx?storyid=83392)



Officials believe the fuel tank could survive re-entry and create a cloud of toxic gas.

What officials, and what quote?
I watched the press conference and didn't hear anybody use those words (at least not in the same paragraphs).

01101001
2008-Feb-15, 06:26 PM
Officials believe the fuel tank could survive re-entry and create a cloud of toxic gas.
What officials, and what quote?
I watched the press conference and didn't hear anybody use those words (at least not in the same paragraphs).

The US Department of Defense news story: Navy to Shoot Down Malfunctioning Satellite (http://www.defenselink.mil/news/newsarticle.aspx?id=48974) by Jim Garamone, American Forces Press Service, offers:


The satellite belongs to the National Reconnaissance Office and was launched Dec. 14, 2006. It weighs roughly 5,000 pounds, and computer models show that roughly 2,800 pounds would survive reentry. “What is different here is the hydrazine,” [Marine Gen. James E. Cartwright, vice chairman of the Joint Chiefs of Staff] said. “In this case, we have some historical background that we can work against for the tank that contains the hydrazine. We had a similar one on Columbia that survived reentry. We have a pretty reasonable understanding that, if the tank is left intact, it would survive the reentry.”

The possibility of a resulting "toxic cloud" (not with those exact words, but what you referenced wasn't a quotation) was proposed:


“The likelihood of the satellite falling in a populated area is small, and the extent and duration of toxic hydrazine in the atmosphere would be limited,” [Ambassador James F. Jeffrey, assistant to the President and deputy national security advisor] said.

NEOWatcher
2008-Feb-15, 06:32 PM
The possibility of a resulting "toxic cloud" (not with those exaqct words, but what you referenced wasn't a quotation) was proposed:
That's my point...
The phrases "Officials believe" and "toxic cloud" is an unwarrented interpretation of what the officials really are saying. Telling us what they believe may not be the same as a quote, but it is shifting the responsibility of interpretation of what was said away from the reporters interpretations. It's putting words in the official's mouth.

01101001
2008-Feb-15, 07:00 PM
That's my point...
The phrases "Officials believe" and "toxic cloud" is an unwarrented interpretation of what the officials really are saying.

As a summary of events that had transpired, how is what you cited unwarranted? How would you have written the sentence? Needs more weasel words?


Officials believe the fuel tank could survive re-entry and create a cloud of toxic gas.

Jeff Root
2008-Feb-15, 07:05 PM
The NBC/WKYC statement looks good to me. I'd sign it.

-- Jeff, in Minneapolis

spaceboy0
2008-Feb-15, 07:13 PM
It will be an SM-3 missile with a max altitude of 100 miles. Will hit satellite when it's at 150 miles

http://en.wikipedia.org/wiki/SM-3

RalofTyr
2008-Feb-15, 07:48 PM
Most Heat Seekers have far too short of a range to reach the Shuttle. Like under 15, with many even less. Sidewinders are listed in Wiki with an 11.3 mile range at Mach 2.5. Stingers are the little shoulder fired ones, and they are listed with a range of 4800 meters, or about 3 miles.


What if you had one that could reach it?

Terran Overlord Government?

NEOWatcher
2008-Feb-15, 08:11 PM
As a summary of events that had transpired, how is what you cited unwarranted? How would you have written the sentence? Needs more weasel words?
I only have trouble with this "cloud"... I never heard that, and discussions I heard talked about discharges that wouldn't be large enough for a "cloud". Especially if it is a frozen hunk.
No, not weasel words, just some quotes, or explanations, or something other than an image of a killer cloud.

geonuc
2008-Feb-15, 08:19 PM
It will be an SM-3 missile with a max altitude of 100 miles. Will hit satellite when it's at 150 miles:confused:

Hornblower
2008-Feb-15, 08:50 PM
After reading the Washington Post article, my educated guess is that the missile will release a large load of something resembling shrapnel for a head-on impact with the satellite. At an impact velocity of 5 miles per second, plus whatever the missile is contributing in the opposite direction, that should demolish the satellite. If all goes well, it will rupture the hydrazine tank. My guess is that it would be like using a shotgun to kill a moth. Anything that misses should come down not far from the cruiser.

The experts quoted in the body of the article were not envisioning a quick drop of the wreckage immediately downrange. They said it could take several days for all of it to come down, which would scatter it all over the world.

If the tank is successfully ruptured, the hydrazine will be dispersed harmlessly before it gets anywhere near the ground.

Noclevername
2008-Feb-15, 08:55 PM
I only have trouble with this "cloud"... I never heard that, and discussions I heard talked about discharges that wouldn't be large enough for a "cloud".

Cloud is not a description of size, just of state.


Especially if it is a frozen hunk.

An evaporating frozen hunk.

spaceboy0
2008-Feb-15, 09:08 PM
If the satellite should survive, will the missile have enough fuel for a rocket burn of another 90 minutes to wait for another pass around of the satellite?

What is the maximum speed of this type of missile?

Van Rijn
2008-Feb-15, 09:21 PM
If the satellite should survive, will the missile have enough fuel for a rocket burn of another 90 minutes to wait for another pass around of the satellite?


No, it's a suborbital missile. But, they might try to hit it with another missile.



What is the maximum speed of this type of missile?

I'm sure that's classified information, but the range information that they do provide (while certainly not matching what it can really do) is a few hundred miles.

Van Rijn
2008-Feb-15, 09:23 PM
It will be an SM-3 missile with a max altitude of 100 miles. Will hit satellite when it's at 150 miles

http://en.wikipedia.org/wiki/SM-3

That page says max altitude for the SM-3 is greater than 100 miles and obviously it is! :)

spaceboy0
2008-Feb-15, 09:29 PM
When they say a satellite is moving at 17,500 m.p.h., is that measured relative to a fixed reference point or to the Earth which itself spins around at 1000 m.p.h.?

George
2008-Feb-15, 09:32 PM
Why don't they simply use Bravo Battery ( http://www.thespoof.com/news/spoof.cfm?headline=s2i7414) again? [I haven't stopped laughing since the time ToSeek used this on us during the Hubble troubles. :)]

Van Rijn
2008-Feb-15, 09:44 PM
When they say a satellite is moving at 17,500 m.p.h., is that measured relative to a fixed reference point or to the Earth which itself spins around at 1000 m.p.h.?

Usually, they're just counting the orbital velocity. I was, when I calculated a velocity of about 17,400 mph.

cmsavage
2008-Feb-15, 10:07 PM
If the satellite should survive, will the missile have enough fuel for a rocket burn of another 90 minutes to wait for another pass around of the satellite?
They have three rockets, so they can try multiple times. I've seen it stated that, if a large chunk of hydrazine survives the first impact, they might target that chunk and try again within 24 hours.


What is the maximum speed of this type of missile?
Essentially zero compared to the satellite. It is the huge kinetic energy of the satellite that is going to do pretty much all of the damage. Even any explosive on the missile is going to be negligible.

Hornblower
2008-Feb-15, 10:09 PM
Usually, they're just counting the orbital velocity. I was, when I calculated a velocity of about 17,400 mph.
The rotation of the Earth reduces the launch vehicle's delta V by up to 1,000 mph, making heavier payloads possible with a given amount of propellant. It's analogous to using a catapult to launch a plane from an aircraft carrier.

Van Rijn
2008-Feb-15, 10:27 PM
The rotation of the Earth reduces the launch vehicle's delta V by up to 1,000 mph, making heavier payloads possible with a given amount of propellant. It's analogous to using a catapult to launch a plane from an aircraft carrier.

Yes it does, but the orbital velocity that he was asking about wasn't measured against that.

spaceboy0
2008-Feb-16, 01:08 AM
These missiles will explode shrapnel and create a cloud of fine metallic debris which, when the satellite rams into even the smallest bits at 17,000 m.p.h., should wipe out the satellite.

joema
2008-Feb-16, 01:08 AM
...my educated guess is that the missile will release a large load of something resembling shrapnel for a head-on impact with the satellite...
No the SM-3 does not use a fragmenting warhead. There is no shrapnel released prior to impact. Rather the missile seeker (or kinetic kill vehicle) collides with the target. In effect, it simply rams it. At extreme hypervelocity (maybe over 9,000 meters per second closing speed) this is about equal to 300 kg (661 lbs) of high explosives.

The accuracy of the SM-3 missile can be seen in this video take from an instrumented kinetic warhead right before impact. The picture is what it's about to hit: http://en.wikipedia.org/wiki/Image:Fm3_kw_ir.jpg

joema
2008-Feb-16, 01:27 AM
...The missiles...are launched to explode the satellite.
They do not explode the satellite, they ram it.



...The satellite was launched many years ago
It was launched in December 2006, not many years ago.



...missile(s) (rockets are not guided, missiles are guided)
Also wrong, e.g, the Saturn V rocket is definitely guided.


...lock-on, run under constant burn (not drift) to the target
Again incorrect -- flight to target is unpowered except for attitude/divert control. In essence, it simply coasts, but at very high speed.


...those missile(s) may have the ability to re-acquire and make another attempt.
The SM-3 cannot re-acquire the target. The kinetic warhead has no propulsion and if it misses, will simply fly past the target.


...they would drift out into space, once their fuel runs out.
The SM-3 kinetic warhead will not drift into space after a miss. It's simply a suborbital missile and will reenter within a few minutes.


...the missile(s) would hit an asteroid, the moon, or another planet some time in the distant future.
The SM-3 warhead cannot possibly reach any other celestial body, it cannot ever achieve orbit.


...HYDROZINE is liquid rocket fuel, and should burn up in re-entry, or better yet, cause the satellite to explode due to the heat building up in the unit containing the HYDROZINE.
It will NOT burn up on reentry, which is why the intercept is being attempted. It's 1,000 lbs of toxic hydrazine, which is frozen solid and inside a titanium tank. In effect it's an armored toxic iceberg. It will certainly survive reentry.

A tiny amount of hydrazine almost killed the crew of Apollo-Soyuz during reentry.

ASEI
2008-Feb-16, 02:02 AM
Hmm, you guys should see some of the youtube videos posted about it. It's got that thrust vectoring scheme that we went over in solid propulsion class. Pretty good at intercepting things like this.

http://www.youtube.com/watch?v=cA-Ahd2vgx4

Now that's rocket science!

amachristian
2008-Feb-16, 03:06 AM
You know, sometimes I wonder if I've miss-understood myself. So this missile is supposed to zero in on the satellite and blow it into tiny pieces seconds before reentry? Has the U.S. ever done anything like this before or is this our first test to see if we'll also be able to avert enemy missiles? Is this what China did with their satellite when they shot theirs down? If I remember correctly, they did hit it. I still find it hard to believe that any amount of the fuel won't be left, that it will all burn up. I suppose what's hardest for me is to believe anything about this until it's over. If our government is correct in their choice and the missile hits as it should and all turns out well, then I'll think about believing them the next time around. We all know there WILL be a next time.

ASEI
2008-Feb-16, 03:28 AM
We've had plenty of SM-3 tests to see if we could avert enemy missiles. We can, 80-something percent of the time.

Leaving the fuel frozen in a titanium tank will leave a heck of a lot more of it, than if it's been scattered in tiny shards across the atmosphere - in that case, enough of it will be exposed that it will all ignite and burn off.

Ara Pacis
2008-Feb-16, 03:50 AM
They have three rockets, so they can try multiple times. I've seen it stated that, if a large chunk of hydrazine survives the first impact, they might target that chunk and try again within 24 hours.

I would have to be about 24 hours later for the setup to occur again as the next orbit would move the track about 1000 miles. Or they could use more than one ship to launch the missiles.

spaceboy0
2008-Feb-16, 04:22 AM
Is the spy satellite in a Molniya orbit or in a precession orbit?

spaceboy0
2008-Feb-16, 04:43 AM
Just noticed something: on GoogleEarth the images are from the European Space Agency. Are U.S. satellites no longer supplying images of the Earth for non-military uses?

ASEI
2008-Feb-16, 05:36 AM
Is the spy satellite in a Molniya orbit or in a precession orbit? Why would a spy sattelite be in a Molinya orbit? Molinya orbits are high lattitude substitutes for geostationary orbits - they hang far above the earth at a given point for a long period of time, before swinging back in close for a very fast perigree. A circular orbit at any given inclination would keep it close to the earth over the target area for much longer than a high eccentricity orbit (twice as long at the limit) and cover the entire surface.

spaceboy0
2008-Feb-16, 05:54 AM
This exercise is worth $ 60 million? Glad my country's government isn't footing that bill.

In 1979 the Russian Cosmos 954 crashed over the Northwest Territories here in Canada and spilled radioactivity over a large area. We billed Russia $ 6 million in clean up costs and they only paid up half.

What would happen if the satellite broke up over Iran?

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

spaceboy0
2008-Feb-16, 06:04 AM
It's orbit is inclined 58 degrees after all...

Today through Feb. 22, USA 193 will make a number of evening passes over North America and western Europe. It's orbit is inclined 58.5-degrees to the equator, a setup that makes it readily observable from most of the Northern Hemisphere.

During this period, USA 193 will move along a general southwest-to-northeast trajectory and pass over a number of cities in the United States, southern Canada and western Europe.

Predictions for the times and locations of USA 193 are available at the Heavens Above website (www.heavens-above.com). Based on this website's sighting information, USA 193 will be very favorably placed for observation over a number of large cities, assuming it is still in orbit around the Earth and weather conditions permit.

From Chicago, as an example, the spy satellite is predicted to reach as high as 38-degrees above the horizon (nearly four fists) on Feb. 17. That same date, as seen from Orlando, Florida, an evening pass as high as 65-degrees is predicted.

From Boston and Seattle, nearly overhead passes are forecast for (respectively) Feb.18 and Feb. 22. And on the latter date, London, England should have a fine pass, with USA 193 arcing as high as 77-degrees above the horizon.

Those who have seen the International Space Station (ISS) flying across their local skies should be aware that USA 193 will appear noticeably fainter, since it's quite a bit smaller than the ISS. Yet, at its brightest, the spy satellite still should rank as bright as the brightest stars, at roughly first magnitude in astronomers parlance.

Also, since the spy satellite is in a lower orbit than the ISS, expect USA 193 to move much more rapidly across your line of sight.

Spysat Downing: Sci-Fi Turns

ASEI
2008-Feb-16, 06:27 AM
What would happen if the satellite broke up over Iran?

Oh no! It smashed directly into your uranium centrifuge plant? What a terrible terrrrible accident. Our condolences. (snicker).

Ah, I wish we had the gall to plan something like that.

astromark
2008-Feb-16, 08:49 AM
The question was.... How?
The simple answer is... Due to the auspice's of modern electronics and other technologies not widely understood a missile will be lunched to the location very near if not at the offending inbound object of concern. There will be a controlled explosion at which time the object will be effected in the manner conducant with the planed inception of this event....:) Whew! Lol
Keep an ear on the news and an eye on the teli... If pictures are possible we will see them. It could be interesting.... ;)

neilzero
2008-Feb-16, 01:48 PM
A Molniya orbit would be useful for a spy satellite as it concentrates on a small area of Earth rather than spying on the entire surface of Earth. If this was supposed to be Molniya, it likely did not make it higher than LEO, nor to a precision orbit. It is possible our government is deliberately releacing disinformation as there seems to be a wide varity of opinions in this thread.
The SM-3 may have a maximum altitude of 100 miles, but a slant range exceeding 150 miles if a max height of 80 miles is chosen.
The USA has successfully demonstrated the dumb rock kill and the fragment method, but another test often yeilds useful data, so it is likey the Navy reguards this as both a public service and a training exersize for the crew.
I hope Joema is not blabbing classified information. Loose lips sink ships. Neil

3488
2008-Feb-16, 02:15 PM
This is reminiscent of the hit & miss (literally) THAAD tests (http://uk.wrs.yahoo.com/_ylt=A1f4cfR477ZHgUkAkCZLBQx.;_ylu=X3oDMTExcXNkdHF hBHNlYwNzcgRwb3MDMQRjb2xvA2lyZAR2dGlkAwRsA1dTMQ--/SIG=122rbvqog/EXP=1203257592/**http%3A//www.army-technology.com/projects/thaad/).:whistle:

Andrew Brown.

cmsavage
2008-Feb-16, 03:12 PM
I would have to be about 24 hours later for the setup to occur again as the next orbit would move the track about 1000 miles. Or they could use more than one ship to launch the missiles.
They put one of the modified missiles on each of three different ships. But I don't think it would be attempted on the next orbit since they need some time to observe for any large fragments first. Somewhere on a 24 hour time frame, like you said.

spaceboy0
2008-Feb-16, 05:21 PM
Can a spy satellite operate efficiently at Geosync distance of 23,000 miles? Or do spies generally orbit closer to the Earth ?

I would think the cameras work better at 160 miles than 23,000 miles but mabey it doesn't make much difference?

ASEI
2008-Feb-16, 06:58 PM
It does. Remember the diffraction limited resolution of an optical system is 1.22*lamda/D. Longer distances need larger apertures to acheive the same resolution.

Spy sattelites and other surface imagers are usually in low earth orbits. Communications sattelites are in high earth orbits.

spaceboy0
2008-Feb-16, 07:48 PM
When China fired a missile to shoot down their satellite, was it a successful hit? How does that situation differ from this one in terms of complexity (not political, scientific)

boom stick
2008-Feb-16, 11:07 PM
When China fired a missile to shoot down their satellite, was it a successful hit? How does that situation differ from this one in terms of complexity (not political, scientific)

1) The Chinese satellite was in a polar orbit at an altitude of about 865 km. USA 193 is at an altitude of about 240 km, where the atmospheric drag is much larger and has to be compensated for, which makes this attempt technically more challenging.

2) USA 193 is totally dead and has to be tracked by radar. The chinese sat was still functioning and able to do course corrections (which they actually did to place it in an easier to hit orbit after three unsuccessful tests)

3) like mentioned, the chinese succeeded on their fourth time. Yep: according to Jane's and NYT China had attempted shooting their sat down three times before. The United States has prepared three missiles for the test and if one of them misses another will be launched right away without months of analyzing what went wrong.

4) The launch window to hit USA193 is estimated to be about a week compared to up to decades for the chinese sat.

5) China used a specially designed test vehicle to shoot down whereas the SM-3 is in active duty. According to an expert interviewed on new scientist, the modifications made are trivial, but the military doesn't want to advertise that it has an asat capability.

So IMHO what the DOD is doing now is several orders of magnitude more impressive than China's asat test.

spaceboy0
2008-Feb-16, 11:25 PM
At what altitude does friction with the air start to warm up the front end of an object reentering?

ASEI
2008-Feb-16, 11:31 PM
Hmm. Interesting question.

The temperature of a gas impinging on the front of an object can be taken to be (1+(gamma-1)/2*M^2) * T_freestream, where T_freestream is the temperature of the gas unperturbed by interaction with the object.

For extremely rarified gasses though, I wouldn't expect normal heat transfer and convection to hold exactly. In addition, when you use mach numbers like 25 or so, there is chemistry involved in what goes on at the leading edge which prevents the full effective temperature from blowing up to something like 36000 K.

3488
2008-Feb-16, 11:37 PM
Can a spy satellite operate efficiently at Geosync distance of 23,000 miles? Or do spies generally orbit closer to the Earth ?

I would think the cameras work better at 160 miles than 23,000 miles but mabey it doesn't make much difference?

Its a huge difference.

143.75 x the difference. 143.75 x 143.75 = 20,664.

So a spy satellite in Geosynchronous Orbit wil have only 1/20,664th the resolution as one in LEO @ 160 miles.

Andrew Brown.

boom stick
2008-Feb-16, 11:42 PM
The atmosphere thinnens roughly exponentially, so even at higher low earth orbits you have some heating. So the altitude also depends on how much warming you want.


Its a huge difference.

143.75 x the difference. 143.75 x 143.75 = 20,664.

So a spy satellite in Geosynchronous Orbit wil have only 1/20,664th the resolution as one in LEO @ 160 miles.

Andrew Brown.
For a sigint satellite a Geosynchronous Orbit is an advantage. You can collect signals from a very large area with just one satellite

joema
2008-Feb-17, 12:59 AM
At what altitude does friction with the air start to warm up the front end of an object reentering?
Reentry heating only begins after "entry interface", generally defined as about 400,000 ft (122 km, or 76 mi.) altitude. For the first few minutes after entry interface, heating is very slight, then it ramps up.

I seriously doubt there's any measurable heating at the discussed interception altitude of about 140 mi (225 km). However it doesn't matter -- an ice cube is over 400 degrees hotter than the near-absolute-zero backdrop of space, and would show up brightly on IR sensors.

spaceboy0
2008-Feb-17, 02:42 AM
If a satellite is inserted into a 160 mile high orbit and no thruster adjustments are ever made to maintain it's orbit, how long will it take for the satellite's orbit to decay and cause it to reenter?

Is there a table somewhere that shows orbit altitude and expected length of time before reentry?

EndeavorRX7
2008-Feb-17, 02:52 AM
If a satellite is inserted into a 160 mile high orbit and no thruster adjustments are ever made to maintain it's orbit, how long will it take for the satellite's orbit to decay and cause it to reenter?

Is there a table somewhere that shows orbit altitude and expected length of time before reentry?

Nobody knows for sure. Sometime in late February/early March. They plan to shoot it down before reentry. The reason they have been unable to narrow it down to a specific day or time of day is that the interaction between the upper atmosphere and the satellite is unpredictable. There's no way of knowing the exact moment of when it begins to heat up/slow down. Nor what rate it will slow down at.

EndeavorRX7
2008-Feb-17, 02:54 AM
If a satellite is inserted into a 160 mile high orbit and no thruster adjustments are ever made to maintain it's orbit, how long will it take for the satellite's orbit to decay and cause it to reenter?

Is there a table somewhere that shows orbit altitude and expected length of time before reentry?

Oops. I didn't quite read your question lol. I guess the thread topic is why I got confused. i thought you were talking about USA 193. For any other satellite put in a 160 mi. orbit - I have no idea.

ASEI
2008-Feb-17, 04:17 AM
Is there a table somewhere that shows orbit altitude and expected length of time before reentry?

Figuring out how this thing is going to decay is a pretty complicated problem when you think about it. You have to take into account miniscule amounts of drag building up over time. The drag is dependent on the orientation of the sattelite. It also acts on the orientation of the sattelite. The orientation of the sattelite is also acted on by gravity perturbations and the stability of it's attitude dynamics.

And the drag is probably something that you have some pretty good error bars on as far as modeling it goes, leading any model of the orbital decay to begin propogating uncertainty.

When it finally does start to decay, the forces begin piling up quickly. Anywhere within a long timespan, things could begin happening much faster. It's sort of chaotic. That's probably why they don't know for sure where it is going to come down.

joema
2008-Feb-17, 01:48 PM
...Is there a table somewhere that shows orbit altitude and expected length of time before reentry?
There's no fixed table, since it depends on solar activity, which affects earth's atmosphere, orbit type, also the mass-to-surface area ratio of the satellite.

However below are two charts of orbital altitude vs lifetime.

djellison
2008-Feb-17, 02:59 PM
20 years ago I splashed perhaps an ounce of hydrozene on my pants leg, but I have seen no symptoms, so the danger of hydrozene is likely exagereated

Sorry. I don't believe you. An ounce of Hydrazine would produce fumes that would cause some serious respiratory distress very rapidly. Furthermore, human body temperature isn't far off the flash point for Hydrazine. You would have been lucky for the whole lot to not go up in smoke.

Hydrazine is handled on the ground, by men who are essentially in space suits - carefull plumbing work, to pump this very nasty stuff into spacecraft ready for launch. It's HIGHLY toxic, very dangerous to handle and is not the stuff you just 'splash' around.

Are you perhaps confusing Hydrazine with Hydrogen Peroxide or something else, because I don't believe anyone would be in a situation where they could be handling the stuff in such a way as to spill it on their legs - nor that if such a situation were to occur, you would have 'no symptoms'

Doug

spaceboy0
2008-Feb-17, 10:27 PM
The two tables show vastly different results. One table shows expected decay time in days (vertical axis), the other table shows values measured in years, each table showing similar orbital altitudes on the horizontal axis. (?)

hhEb09'1
2008-Feb-17, 11:21 PM
Spy sattelites and other surface imagers are usually in low earth orbits. Communications sattelites are in high earth orbits.This one is now in a low orbit, surely. But some "spy" satellites (http://en.wikipedia.org/wiki/Satellite_Data_System) are relays for other spy satellites, and then there are others (http://en.wikipedia.org/wiki/Trumpet_%28satellite%29).

Are you perhaps confusing Hydrazine with Hydrogen Peroxide or something else, because I don't believe anyone would be in a situation where they could be handling the stuff in such a way as to spill it on their legs - nor that if such a situation were to occur, you would have 'no symptoms'This wiki article about hydrazine (http://en.wikipedia.org/wiki/Hydrazine) talks about different mixtures of hydrazine. It says that it is toxic and unstable "especially in the anhydrous form," but the rocket fuels seem to be hydrated forms.

Jerry
2008-Feb-18, 12:24 AM
Hydrozine is a monopropellant, meaning that under the right conditions it is self-oxidizing: HHN-NHH > HN=NH, NH3, and so on. It is useful in space because all it takes to work as a fuel is a simple valve and a catylist. It is extremely corrosive, toxic and difficult to work with - If you spilled it on your leg and did not suffer a severe burn, you were very lucky. Pour liquid hydrozine on a rusty surface and it may explode.

I have worked with it, but never been directly exposed. It is a somewhat oily liquid and they say it smells like ammonia.

Blowing up a satellite with a missile is not trivial; it is a capability China demonstrated a couple of years ago. If the hydrozine tanks are breached, virtually all of the liquid will vaporize during reentry - whether or not it reacts will not really matter, it will be highly dispersed.

With or without the missile attack, it is unlikely the hydrozine tanks would survive reentry; but as others have said, there are other reasons for not wanting a nearly intact spy satellite to land who knows where.

Fascinating.

mugaliens
2008-Feb-18, 01:12 PM
20 years ago I splashed perhaps an ounce of hydrozene on my pants leg, but I have seen no symptoms, so the danger of hydrozene is likely exagereated. I'll guess, the satellite will be at an altitude of about 80 miles when it crashes into the missile. Assuming the missle warhead explodes the hydrozine will be scatter widely above Earth's atmosphere. The hydrozine will likely be scattered by the kinetic energy of the collission even if the war head does not explode. Hydrozine is a reducing agent, so it will mostly make oxygen compounds before it reaches Earth's surface. Most of the new chemicals are less hazardous than the hydrozine and are chemicals typically found in trace amounts in Earth's atmosphere, such as water.
The Navy has assured us that they will deliberately avoid the collision at the last second, if there is any reasonable chance of making matters worse. If we do nothing, odds are about a million to one that zero humans will be injured.The Navy hopes to improve the odds to about a billion to one. Most of us are more likely to be injured by something many minutes per day, so our personel hazard is only increased minutely by this re-entry. As the others posted, there is no reason to worry. Neil

Ok, so it's a CYA manuver.

Regardless, hydrazine (http://en.wikipedia.org/wiki/Hydrazine)(despite your encounter) remains a very toxic chemical. Fortunately, via a kinetic "kill" we can allow it to harmlessly burn up in the atmosphere rather than descend en masse to the surface.

joema
2008-Feb-18, 01:38 PM
With or without the missile attack, it is unlikely the hydrozine tanks would survive reentry...
The 1,000 lb of hydrazine is apparently frozen solid inside a titanium tank. NASA thinks it will survive reentry unless intercepted: http://www.msnbc.msn.com/id/23172469/

hhEb09'1
2008-Feb-18, 02:29 PM
The 1,000 lb of hydrazine is apparently frozen solid inside a titanium tank. NASA thinks it will survive reentry unless intercepted: http://www.msnbc.msn.com/id/23172469/And just to make sure, they're going to target the debris! :)

NEOWatcher
2008-Feb-18, 02:41 PM
And just to make sure, they're going to target the debris! :)
Only IF there is no indication of a hydrozene rupture.

DyerWolf
2008-Feb-18, 03:27 PM
Seriously, this is just something fun for our Navy to do. That and a little saber rattling.

I hope they pull it off.

Also, there will be a serious game of "finder's keepers" should it fall on certain landmasses accessible only to the 'competition.'

Remember when China forced one of our EP-3's down? They had a field day with the electronics package. They've also been quite successful at acquiring US technology - often through our corporate partners.

Should this thing land in the Gobi...

Besides, when else are we going to have such a good chance to test our missile tech under (somewhat) realistic conditions?

John Jones
2008-Feb-18, 07:45 PM
Sorry. I don't believe you. An ounce of Hydrazine would produce fumes that would cause some serious respiratory distress very rapidly. Furthermore, human body temperature isn't far off the flash point for Hydrazine. You would have been lucky for the whole lot to not go up in smoke.

Hydrazine is handled on the ground, by men who are essentially in space suits - carefull plumbing work, to pump this very nasty stuff into spacecraft ready for launch. It's HIGHLY toxic, very dangerous to handle and is not the stuff you just 'splash' around.

Are you perhaps confusing Hydrazine with Hydrogen Peroxide or something else, because I don't believe anyone would be in a situation where they could be handling the stuff in such a way as to spill it on their legs - nor that if such a situation were to occur, you would have 'no symptoms'

Doug


We used to use hydrazine hydrate in the lab. You could spill a solution of it on you and live to tell about it. Maybe it was something like this the OP was recollecting.

Jerry
2008-Feb-18, 08:24 PM
We used to use hydrazine hydrate in the lab. You could spill a solution of it on you and live to tell about it. Maybe it was something like this the OP was recollecting.
What molarity? A weak solution is just that - very weak.

I cannot fathom how a 1000 lb tank of hydrazine could survive reentry: Satellites are not aerodynamic, and we all saw what non-aerodynamic descent through Mach +6 did to the shuttle engine, tanks and cargo.

NEOWatcher
2008-Feb-18, 08:36 PM
...and we all saw what non-aerodynamic descent through Mach +6 did to the shuttle engine, tanks and cargo.
That's exactly what they are basing it on. The shuttle's tanks survived intact, and they weren't filled with a supercold solid block of ice to cool them.

spaceboy0
2008-Feb-19, 05:37 AM
when this thing reenters will there be a spectacular light show like when that Russian booster reeneted and filled the sky with red lines?

pghnative
2008-Feb-19, 11:28 AM
Sorry. I don't believe you. An ounce of Hydrazine would produce fumes that would cause some serious respiratory distress very rapidly. Furthermore, human body temperature isn't far off the flash point for Hydrazine. You would have been lucky for the whole lot to not go up in smoke. <snip> It's HIGHLY toxic, very dangerous to handle and is not the stuff you just 'splash' around.

Off topic, but I'd disagree. First, hydrazine doesn't seem all that toxic by inhalation*. Compare this (for toluene (http://ptcl.chem.ox.ac.uk/MSDS/TO/toluene.html)) to this (for hydrazine (http://ptcl.chem.ox.ac.uk/MSDS/HY/hydrazine.html)). Toluene, which is very common and which many chemists "splash around" in the lab, is "toxic by inhalation" compared to hydrazine which is only "harmful". (By the way, anyone who's played with "airplane glue" in modeling has smelled toluene.)

Also, you shouldn't confuse "flash point" with "auto-ignition temperature". The hydrazine won't burst into flame at it's flash point (~38C or ~ body temp as you note), it will only burst into flame at that temp if exposed to a spark.

*The biggest hazard would seem to be skin absorption -- if he/she dropped trou and washed off, it'd be no big deal at all...

John Jones
2008-Feb-19, 12:19 PM
What molarity? A weak solution is just that - very weak.



I don't recall. Too many years ago.

joema
2008-Feb-19, 01:31 PM
Off topic, but I'd disagree. First, hydrazine doesn't seem all that toxic by inhalation
"Caustic burns to the skin are the immediate result of contact with the liquid. Hydrazine dissolves hair, and causes caustic-like burns on skin...The vapour is extremely irritating to the eyes and temporary blindness can result, and eye contact with the liquid causes burns and possibly permanent damage"

http://www.asi.org/adb/04/03/09/hydrazine-info.html

The Apollo-Soyuz astronauts were nearly killed from breathing a small amount of hydrazine and nitrogen tetroxide (N204) fumes during reentry. They were hospitalized for two weeks: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760023153_1976023153.pdf

That raises the question, is the satellite a hydrazine monopropellant system, or bipropellant using hydrazine fuel and nitrogen tetroxide oxidizer (N204)? If the latter, N204 is as dangerous as hydrazine.

pghnative
2008-Feb-19, 04:02 PM
"Caustic burns to the skin are the immediate result of contact with the liquid. Hydrazine dissolves hair, and causes caustic-like burns on skin...The vapour is extremely irritating to the eyes and temporary blindness can result, and eye contact with the liquid causes burns and possibly permanent damage"Hey, I'm not saying it's as safe as candy --- I'm just saying that based on the information I linked to, that neilzero's story is entirely plausible.

Jerry
2008-Feb-21, 01:29 AM
That raises the question, is the satellite a hydrazine monopropellant system, or bipropellant using hydrazine fuel and nitrogen tetroxide oxidizer (N204)? If the latter, N204 is as dangerous as hydrazine.
Monopropellant.

A solid block of hydrazine in a tank is much less likely to survive reentry than the space shuttle propellant tanks.

One, there was the insulating tiles on the main body of the shuttle, which survived well into the reentry phase; two, the shuttle tanks had plenty of expansion volume and relief valves; three you can't expand a solid through a relief system. Whenever a body that is not designed to enter the atmosphere does so, it burns - hot and fast.

Noclevername
2008-Feb-21, 01:55 AM
Whenever a body that is not designed to enter the atmosphere does so, it burns - hot and fast.

If the tank walls are thick enough, the ablating outer material can keep the interior cool; some meteors are cold enough to gather frost after impact. So the propellant might still be intact on impact.

neilzero
2008-Feb-21, 04:29 AM
Someone posted on the eclipse tread (astronomy equipment) that the spy satellite has been hit. Will we see shooting stars from bits of satellite entering the atmospere the rest of tonight at scattered locations around the Earth? Neil

Bearded One
2008-Feb-21, 04:33 AM
CNN reports they shot it down. Gee, I thought it was coming down just fine before they shot it :lol:

ASEI
2008-Feb-22, 04:40 AM
A great shot. You should check it out on Youtube if you missed the explosion on the news!

Cylinder
2008-Feb-22, 06:31 AM
A rocket is the engine or the entire propulsion system used to propel
the vehicle. A missile is anything which is thrown, such as a spear, a
rock, a hand grenade, or an ICBM. A "guided missile" is a missile with
some kind of guidence after it has been launched. It may be guided
all the way to the target, or only during the first part of the flight.

In US military nomenclature, rockets are weapons systems powered by rocket motors and lacking active guidance (e.g. FROG = free rocket over ground.) Missiles are weapons systems powered by rocket motors and possessing active guidance (e.g. SM-3.)

To further complicate matters "guided missile" (sans modifier such as "radar") is a legacy term that remains in unofficial usage and officially as a sanitized term but violates regulation when used in intelligence reports in most cases except when describing naval vessels. The term missile can also still be encountered informally to describe any projectile in flight.

mugaliens
2008-Feb-22, 02:27 PM
We used to use hydrazine hydrate in the lab. You could spill a solution of it on you and live to tell about it. Maybe it was something like this the OP was recollecting.

The hydrate is different from the form that's contained in the satellite.

mugaliens
2008-Feb-22, 02:34 PM
Please do not discount the lethal effects of hydrazine. I know people who have died (1992) to it's exposure.

I'm glad they shot it down.

schlaugh
2008-Feb-22, 02:54 PM
Clearly it's a dangerous substance. For details, download the PDF in this link
http://www.atsdr.cdc.gov/tfacts100.html


This fact sheet answers the most frequently asked health questions (FAQs) about hydrazine, 1,1-dimethylhydrazine, and 1,2-dimethylhydrazine. Hydrazines are colorless liquids that are used in rocket fuels,
chemical manufacturing, and as boiler water treatments. Exposure to hydrazines may cause nervous system effects, as well as liver and kidney damage. Hydrazines have been found in at least 8 of the 1,416 National Priorities List sites identified by the Environmental Protection Agency (EPA).And from NASA:
http://www-pao.ksc.nasa.gov/nasafact/count2.htm

Hypergolic propellants are fuels and oxidizers which ignite on contact with each other and need no ignition source. This easy start and restart capability makes them attractive for both manned and unmanned spacecraft maneuvering systems.
Another plus is their storability — they do not have the extreme temperature requirements of cryogenics . The fuel is monomethyl hydrazine (MMH) and the oxidizer is nitrogen tetroxide (N2O4).

Hydrazine is a clear, nitrogen/hydrogen compound with a "fishy" smell. It is similar to ammonia. Nitrogen tetroxide is a reddish fluid. It has a pungent, sweetish smell. Both fluids are highly toxic, and are handled under the most stringent safety conditions. Hypergolic propellants are used in the core liquid propellant stages of the Titan family of launch vehicles, and on the second stage of the Delta.

The Space Shuttle orbiter uses hypergols in its Orbital Maneuvering Subsystem (OMS) for orbital insertion, major orbital maneuvers and deorbit. The Reaction Control System (RCS) uses hypergols for attitude control.

The efficiency of the MMH/N2O4 combination in the Space Shuttle orbiter ranges from 260 to 280 seconds in the RCS, to 313 seconds in the OMS. The higher efficiency of the OMS system is attributed to higher expansion ratios in the nozzles and higher pressures in the combustion chambers.