Could a Disabled Spy Satellite Pose a Threat to Earth?

[belliott4488]

I don't think they've cordoned off the area for falling debris (though maybe some fragments will be propelled by the impact into a more rapid fall), but rather to keep planes from flying into the path of the missile, or perhaps to keep ships from spying on their missile test, or otherwise getting in the way.

Those patterns are for both Notices to Airmen and Notices to Mariners (see Wash. Post, for e.g.), so it's not just aircraft safety that is being considered. Also, if you look at the predictions for the path of the satellite at intercept, you'll that it's headed the other direction.

It's not debris from the target object that is being considered here.

 

[Ivan Seeking]

... Questions about hydrazine
MARGARET WARNER: Now, Professor Postol, I gather you don't think this is a good idea.

THEODORE POSTOL, Massachusetts Institute of Technology: Well, I don't think the idea has any technical merit. What you have is a vehicle that's in space. It's built as light as it possibly can be, because it's a satellite designed to just be in space.

When this thing hits the upper atmosphere, large pieces of it are going to burn up. Now, there will be big pieces that survive to the ground, but the idea that this hydrazine tank will survive to the ground really makes no sense.

Let me just give you an example. This hydrazine tank is going to decelerate at a rate of -- let me just use the numbers -- 50 Gs. I just did the calculations before the program.

What that means is I take this spherical hydrazine tank and I accelerate it from rest to 1,000 miles per hour in one second. Now, this gossamer tank, this spherical tank is going to squash up and break open.

And it's going to be -- the hydrazine is going to behave like a snowball fired out of a cannon. It's just going to spray all over the place, stop in the upper atmosphere probably at an altitude of 60 or 70 miles, and it's never going to reach the ground.

There will be pieces of the satellite that reach the ground, but the hydrazine is never going to come close to the ground.

MARGARET WARNER: Now, General Cartwright, who we had in the little tape there, said, well, you know, if it were to hit the ground, the dispersal would be about the size of two football fields and anyone who breathed it would have real lung damage and that prolonged exposure could lead to death. Are you saying that's absolutely impossible to happen or that it's a risk worth taking?

THEODORE POSTOL: Well, I wouldn't say it's absolutely impossible, nor would I say it's a risk worth taking. I'm saying that it's extremely improbable that this stuff will reach the ground.

And if you want to argue that you're shooting at this satellite, the argument for shooting at the satellite is not justified based on the argument that the hydrazine presents a threat to people on the ground.

You don't know where the big pieces from this satellite are going to fall in either case. And although there's a low chance of there being damage on the ground or individuals being injured or killed, the piece of it that's associated with this solid hydrazine container is a near-zero probability to play a significant role. It's just...

Theodore Postol: This is a bus-sized object. And the kill vehicle is maybe a 50-pound kill vehicle that's fairly compact. So it's sort of like shooting an empty soda can with a bullet.

Political considerations a factor?
MARGARET WARNER: Let me just play devil's advocate with you here. What is the risk of doing this? Why not do it?

THEODORE POSTOL: Well, I think the risk is really -- if you want to call it a risk -- I think the international repercussions are quite serious.

I think people who look at this from a political point of view will see this, as I believe it probably is, an attempt by the United States government to show the world that it's got a large-scale, operating, low-altitude, anti-satellite capability.[continued]

http://www.pbs.org/newshour/bb/military/jan-june08/satelliteshoot_02-20.html

 

[lisab]

MSNBC is reporting the satellite has been hit:

http://www.msnbc.msn.com/id/23265613/

 

[belliott4488]

** kablooie! **

 

[CaptainQuasar]

Oh well. There goes an arms race with China.

Although, since it's antimissile technology, this reminds me of some comedy sketch show I saw where they had an advertisement for a telemarketing call blocker, then an advertisement to the telemarketers for a call blocker blocker, then an advertisement for a call blocker blocker blocker…

⚛​

 

[nesp]

I'm waiting to hear of any debris cloud that may have been generated. During events like this, one of the first things to do is to survey the orbital path for fragments and establish which of them will decay right away and which may stay for a while. Hopefully they will all reenter quickly, but there's a lot of delta-v being imparted to many pieces, probably with lots of secondary collisions and explosions so I don't think anyone will know the results for a few days.

 

[mgb_phys]

Can you patent conspiracy theories as a business practice in the USA?
I would like to patent the theory that this was done to hide the arrival of an alien mothership (possibly carryying the lizard people). Then when anybody claims this they have to pay me a license fee!

 

[tribdog]

The lizard people do not pay license fees.

 

[belliott4488]

Can you patent conspiracy theories as a business practice in the USA?
I would like to patent the theory that this was done to hide the arrival of an alien mothership (possibly carryying the lizard people). Then when anybody claims this they have to pay me a license fee!

Shhh ... you don't want people connecting this event with the "meteor" that fell in the Pacific NW yesterday morning (http://ap.google.com/article/ALeqM5j57Ij_Mq1BPLN6ijp4odgjyP-7WAD8UUCUP81" ), nor with the Lunar eclipse that was happening at the same time!

 

[turbo]

Shhh ... you don't want people connecting this event with the "meteor" that fell in the Pacific NW yesterday morning (http://ap.google.com/article/ALeqM5j57Ij_Mq1BPLN6ijp4odgjyP-7WAD8UUCUP81" ), nor with the Lunar eclipse that was happening at the same time!

Not to mention the M 6.3 earthquakes in Nevada and Norway... You didn't hear it here, shhh...

 

[mgb_phys]

MSNBC is reporting the satellite has been hit:

A triumph for British technology ..
( It must have been British, it didn't work when it was launched and then was hit with amazing accuracy by the US military )

 

[edward]

Here is the story from the Pentagon with video clips.

http://machinist.salon.com/blog/2008/02/21/satellite_shoot_down/

Hydrazine even the UDMH derivative needs to combine with another chemical in order to oxidize (burn). Did they also rupture an oxidizer tank? I presume the oxidizer would also have been frozen.

The old Titan II series missiles used hydrazine 50/50 mix with UDMH. Nitrogen tetroxide was used as the oxidizer. Both the fuel and the oxidizer were very hazardous.

 

[mgb_phys]

Hydrazine even the UDMH derivative needs to combine with another chemical in order to oxidize (burn). Did they also rupture an oxidizer tank? I presume the oxidizer would also have been frozen.

Hydrazine in thrusters is generally used as a monopropellant. N2H2 -> H2 + N2 via NH3
Although you don't get as much power as using an oxidiser it's better thrust / weight because you aren't carrying the extra oxidiser load.

 

[edward]

Hydrazine in thrusters is generally used as a monopropellant. N2H2 -> H2 + N2 via NH3
Although you don't get as much power as using an oxidiser it's better thrust / weight because you aren't carrying the extra oxidiser load.

Thanks I was just reading up on that. I've gotten a bit behind the times.

I understand that there are several versions of electro-thermal hydrazine thrusters using various catalysts to increase thrust.

 

[nesp]

Impressive, not often we get to see $100 billion being blown up. Note the different velocities of the fragments coming off. It's the ones that get injected into slightly higher orbits that may hang around a while.

 

[belliott4488]

Impressive, not often we get to see $100 billion being blown up. Note the different velocities of the fragments coming off. It's the ones that get injected into slightly higher orbits that may hang around a while.

That's true, if by "higher orbits" you mean "higher apogees". The maximum perigee height of any debris particle will be given by the altitude of the intercept, neglecting secondary collisions or maybe explosions of little hydrazine snowballs.

 

[nesp]

That's true, if by "higher orbits" you mean "higher apogees". The maximum perigee height of any debris particle will be given by the altitude of the intercept, neglecting secondary collisions or maybe explosions of little hydrazine snowballs.

Yes, that's what I meant. Any positive delta-v's imparted would result in higher apogees. Even though the perigee would remain at approximately the original altitude, the apogee would have less atmospheric drag, thus lengthening the debris lifetime -- perhaps significantly so. Sort of an unintentional Hohmann burn. My guess is that some of the pieces may remain in orbit for a year or longer, though those would likely be the smaller pieces that got ejected at higher delta v's. Of course, at orbital velocities of around 8 km/s, the effect of a collision with a "small" piece can still be serious, even for a small m the m*v^2 gets pretty large.

 

[rewebster]

the bad thing is that even if you find (or get hit by) a small piece of this thing, I don't think you can legally keep it

 

[joema]

not often we get to see $100 billion being blown up...

Did you mean $100 million? The expended SM-3 missile cost about $10 million, the overall effort inc'l software, relocation of ships and other assets, etc about $40-$60 million.

The satellite itself probably cost around $1 billion.

 

[belliott4488]

the bad thing is that even if you find (or get hit by) a small piece of this thing, I don't think you can legally keep it

Man, a piece of this thing comes through my roof - I'm framing it and hanging it on the wall!

 

[rewebster]

It's going to hard to frame a four foot diameter steel hollow ball and hang it

 

[chemisttree]

I understand that the debris field will pass over Canada first. It should make for an interesting light show for the next couple of days.

 

[belliott4488]

Yes, that's what I meant. Any positive delta-v's imparted would result in higher apogees. Even though the perigee would remain at approximately the original altitude, the apogee would have less atmospheric drag, thus lengthening the debris lifetime -- perhaps significantly so. Sort of an unintentional Hohmann burn. My guess is that some of the pieces may remain in orbit for a year or longer, though those would likely be the smaller pieces that got ejected at higher delta v's. Of course, at orbital velocities of around 8 km/s, the effect of a collision with a "small" piece can still be serious, even for a small m the m*v^2 gets pretty large.

Yeah - what you said. I was actually surprised when I started thinking about it, since initially I kind of guessed that for a given delta-v, the ones with higher flight path angles would go higher, and thus live longer, but it ain't so. A FPA of positive theta is the same as one of negative theta, in terms of apogee and perigee heights. It's the ones that produce a zero FPA that last the longest - i.e. the Hohmann Part 1, as you described it.

 

[rewebster]

we need photos of anything you find

 

[belliott4488]

It's going to hard to frame a four foot diameter steel hollow ball and hang it

Ha ha - luckily, they're now saying that the biggest chunk is no larger than a football - although they didn't specify if that was a US or Euro "football". ;-)

 

[nesp]

Did you mean $100 million? The expended SM-3 missile cost about $10 million, the overall effort inc'l software, relocation of ships and other assets, etc about $40-$60 million.

The satellite itself probably cost around $1 billion.

No, I meant Billion with a "B." To start with, $1B would hardly cover the overruns on this satellite. If the following report is true, this satellite was part of a $10B program, including $4-5B in overruns.

http://blog.wired.com/defense/2008/02/that-satellite.html

That's the cheap part. Now, let's count the cost of the missile defense program, of which the SM-3 is just a part. That individual $10M missile would not be there if not for the program that brought it into existence, and $100B is probably a lowball estimate.

 

[belliott4488]

I understand that the debris field will pass over Canada first. It should make for an interesting light show for the next couple of days.

I think that was for the first orbit after the intercept. By now it's had time to do many revs, and has probably passed over most of the planet's surface, either on ascent or descent.

 

[rewebster]

I bet:

they don't hit that tank with the hydrazine

and most of the spy satellite will end up falling on land someplace

 

[belliott4488]

I bet:

they don't hit that tank with the hydrazine

and most of the spy satellite will end up falling on land someplace

So you think their claims of nothing larger than a football surviving are just plain lies? I guess it wouldn't be the first time, but there are a lot of people with insight into this who could catch them out if they were lying.

 

[D H]

Yes, that's what I meant. Any positive delta-v's imparted would result in higher apogees. Even though the perigee would remain at approximately the original altitude, the apogee would have less atmospheric drag, thus lengthening the debris lifetime -- perhaps significantly so. Sort of an unintentional Hohmann burn. My guess is that some of the pieces may remain in orbit for a year or longer, though those would likely be the smaller pieces that got ejected at higher delta v's.

The missile hit the satellite at an altitude of 130 miles, so the perigee of any chunks sent into a higher orbit will still be 130 miles. 130 miles is quite deep in the atmosphere. Vehicles with circular orbits at 130 miles fall within a day or so. Elliptical orbits take a bit longer, but not years. The Pentagon quotes a max of 40 days for all of the debris to re-enter.

 

[belliott4488]

The missile hit the satellite at an altitude of 130 miles, so the perigee of any chunks sent into a higher orbit will still be 130 miles. 130 miles is quite deep in the atmosphere. Vehicles with circular orbits at 130 miles fall within a day or so. Elliptical orbits take a bit longer, but not years. The Pentagon quotes a max of 40 days for all of the debris to re-enter.

No, that's true only for debris ejected with a vertical flight path angle of 90 deg. (i.e. horizontally). Any other angle and perigee will be lower; I think that's the reason for the claims. I believe the imparted delta-v is distributed approximately evenly in direction about the incoming velocity vector.

 

[rewebster]

I think they should wait until it actually starts entering the atmosphere to shoot at it---it would show a lot better on the news

 

[nesp]

No, that's true only for debris ejected with a vertical flight path angle of 90 deg. (i.e. horizontally). Any other angle and perigee will be lower; I think that's the reason for the claims. I believe the imparted delta-v is distributed approximately evenly in direction about the incoming velocity vector.

I agree that's the reason for the claims, but I was referring to those pieces ejected with additional velocity along the parth of the original orbit. There probably are not many such pieces, in comparison with the total, but some will obtain additional velocity for the same reason that someone shooting a bullet at, say, a piece of concrete, will have some concrete fragments fly back into their face. The movie shows what appears to be a pressure sphere exploding, probably the outgassing hydrazine. That pressure will itself impart positive delta v to any pieces in front of it.

DH, I don't have the chart in front of me, but if you find a chart for decay of elliptical orbit debris, you will find that even at 130 mile perigee there are orbits that won't decay for over a year, those with apogees in the hundred of miles. Doesn't take more than a couple of km/s extra to get those apogees.

 

[edward]

Oh well. There goes an arms race with China.

Not necessarily, they pay for their weapons development by selling us consumer goods.

We pay for ours by borrowing money from China.

 

[BobG]

DH, I don't have the chart in front of me, but if you find a chart for decay of elliptical orbit debris, you will find that even at 130 mile perigee there are orbits that won't decay for over a year, those with apogees in the hundred of miles. Doesn't take more than a couple of km/s extra to get those apogees.

That's correct. The perigee altitude will barely change until the orbit becomes circular. Then the orbit will start to decay.

Any maneuver, including maneuvers performed by the atmosphere, primarily affect the opposite side of the orbit.

Assuming an even distribution of material, there will be very few pieces of debris with a perigee of 130 miles. The overwhelming majority will have lower perigees and higher apogees.