Could a Disabled Spy Satellite Pose a Threat to Earth?

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A large U.S. spy satellite has lost power and is expected to re-enter Earth's atmosphere in late February or early March, posing potential hazards due to its hydrazine fuel. Government officials are monitoring the situation and considering options to mitigate risks, including the possibility of shooting it down, although specifics remain classified. The satellite's uncontrolled descent raises concerns about where debris might land, with historical precedents indicating that most re-entries occur harmlessly over oceans or uninhabited areas. There are debates about the implications of using a missile to destroy the satellite, as this could create additional debris and alter the trajectories of remaining pieces. The decision to act is partly influenced by the satellite's sensitive technology and the potential dangers posed by its hazardous materials.
  • #31
They have cordoned off a 1400 x 700 mile section of the pacific for the alien mothership/dangerous fuel tank to land in.
 
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  • #32
Astronuc said:
This close to earth, satellites use solar power. RTG's are typically used on satellites going out to Mars and beyond where the sunlight intensity drops considerably.

Right, solar power would be the primary source, charging batteries that provided regulated power to the various systems. For LEO polar orbits, which I assume this satellite is in, the solar panels would be in darkness roughly half the time, so they would be used to keep the batteries charged while in sunlight.

If they've lost contact with the satellite and have no control over it, it could be that the power system has continued to maintain the hydrazine liquid, or perhaps it's shut itself down and the hydrazine is frozen. Without knowledge of the state of the fuel, the safest approach is to assume it's frozen and may come down in an iceball unless it's first broken up.

I have some doubts about the effects of impacting a hydrazine fuel tank. If the hydrazine explodes into small chunks, they may outgas when exposed to the sun and vaporize on re-entry. On the other hand, they may cause secondary explosions that would scatter debris along higher orbits that may stay there for a long time. Guess we'll soon find out -- this is a bit like guessing on the Shoemaker-Levy collision with Jupiter.
 
  • #33
The news is now saying the most likely time for this to happen is 10:30 PM EST tonight (should I add a big "ish" to that time?). http://www.reuters.com/article/domesticNews/idUSN1930844420080221

I couldn't help but wonder if this is really a chance to test whether the missiles can track a cooler target.

If one assumed there was a chance of the satellite fuel tanks re-entering the atmosphere intact, with the amount of fuel contained in them (1000 lbs according to media reports), what is the actual risk? Would it explode? If not, how far would it spread at toxic levels? If it did explode, how large of an area would be impacted?
 
  • #34
mgb_phys said:
They have cordoned off a 1400 x 700 mile section of the pacific for the alien mothership/dangerous fuel tank to land in.
There's a bit of a logical disconnect here. If you fragment a satellite, does gravitational attraction get negated, causing all the pieces to plummet to earth? Wrong on a lot of levels.
 
  • #35
turbo-1 said:
There's a bit of a logical disconnect here. If you fragment a satellite, does gravitational attraction get negated, causing all the pieces to plummet to earth? Wrong on a lot of levels.

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.
 
  • #36
Moonbear said:
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.
 
  • #37
... 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
 
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  • #39
** kablooie! **
 
  • #40
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…
⚛​
 
  • #41
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.
 
  • #42
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!
 
  • #43
The lizard people do not pay license fees.
 
  • #44
mgb_phys said:
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!
 
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  • #45
belliott4488 said:
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...:rolleyes:
 
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  • #46
lisab said:
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:-p )
 
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  • #47
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.
 
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  • #48
edward said:
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.
 
  • #49
mgb_phys said:
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.:smile:

I understand that there are several versions of electro-thermal hydrazine thrusters using various catalysts to increase thrust.
 
  • #50
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.
 
  • #51
nesp said:
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.
 
  • #52
belliott4488 said:
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.
 
  • #53
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
 
  • #54
nesp said:
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.
 
  • #55
rewebster said:
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!
 
  • #56
It's going to hard to frame a four foot diameter steel hollow ball and hang it
 
  • #57
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.
 
  • #58
nesp said:
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.
 
  • #59
we need photos of anything you find
 
  • #60
rewebster said:
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". ;-)
 

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