Could a disabled spy satellite crash into Earth and pose a threat to human life?

[Astronuc]

Well part of it.

Disabled spy satellite threatens Earth
http://news.yahoo.com/s/ap/20080127/ap_on_go_ot/dead_satellite

WASHINGTON - A large U.S. spy satellite has lost power and could hit the Earth in late February or early March, government officials said Saturday.

The satellite, which no longer can be controlled, could contain hazardous materials, and it is unknown where on the planet it might come down, they said. The officials spoke on condition of anonymity because the information is classified as secret. It was not clear how long ago the satellite lost power, or under what circumstances.

"Appropriate government agencies are monitoring the situation," said Gordon Johndroe, a spokesman for the National Security Council, when asked about the situation after it was disclosed by other officials. "Numerous satellites over the years have come out of orbit and fallen harmlessly. We are looking at potential options to mitigate any possible damage this satellite may cause."

He would not comment on whether it is possible for the satellite to perhaps be shot down by a missile. He said it would be inappropriate to discuss any specifics at this time.

A senior government official said that lawmakers and other nations are being kept apprised of the situation.

The spacecraft contains hydrazine — which is rocket fuel — according to a government official who was not authorized to speak publicly but spoke on condition of anonymity. Hydrazine, a colorless liquid with an ammonia-like odor, is a toxic chemical and can cause harm to anyone who contacts it.

. . . .

The largest uncontrolled re-entry by a NASA spacecraft was Skylab, the 78-ton abandoned space station that fell from orbit in 1979. Its debris dropped harmlessly into the Indian Ocean and across a remote section of western Australia.

. . . .

BobG, what's up? Or down as the case may be.

Interesting to see if this has any impact on the launch of Atlantis.

 

[BobG]

A deorbiting satellite won't have any impact on a Shuttle launch. This sort of thing happens all the time. The only newsworthy thing is that the satellite is bigger than usual (plus the fact that the satellite never worked properly, but that's newsworthy to a very small crowd).

A few hundred objects a year re-enter the atmosphere (http://www.aero.org/capabilities/cords/chart1.html). The spikes correspond to solar max, which tends to expand the atmosphere and clean up debris in low orbits. You had about 111,000 kg of space debris return to Earth in 2003. http://www.aero.org/capabilities/cords/reentry-stats.html

Large objects that have re-entered the atmosphere: http://www.reentrynews.com/largeobject.html

Hopefully, something like this (http://orbitaldebris.jsc.nasa.gov/reentry/reentry.html ) doesn't land on your house.

Lowering the amount of debris in space is reaching a pretty high priority, hence the latest solar max not producing much of a spike. There's an effort to reduce the amount of debris created by each launch (explosive bolts, springs, bands that are expelled when the satellite unfolds from the launch vehicle, etc), reduce the amount of time rocket bodies stay in orbit, and intentionally deorbit low orbiting satellites at the end of their life.

Since this satellite has never functioned properly, they can't intentionally deorbit it, so it will come down more or less at some random spot (probably in an ocean since oceans cover most of the Earth).

Satellites in extremely high orbits (geosynchronous communication satellites, for example) don't come back down. They're pushed out into a higher orbit to make room for their replacement - at least ideally. The geos that die unexpectedly tend to sweep across the geo belt periodically causing headaches for operators of the functional satellites.

The uncontrolled re-entry of space stations (Salyut 7 and Skylab) were embarrassing for the country that owned them. Skylab re-entered because the Shuttle program fell behind and we had no manned launch program to span the gap. Salyut 7 re-entered because the USSR space program had serious budget problems during the break-up of the Soviet Union.

 

[BobG]

Hmm. This sounds as if the decision came from Bush, himself - Pentagon to shoot down broken spy satellite

You toss something in the air and it suddenly occurs to you it's going to fall back down to the ground? Simple, just shoot it down. Then it will, uh, :uhh:, well ... it will fall back down to the ground.

At least most of it. If I blow it up, then at least portions of it will become space debris that will orbit the Earth until ... well, :uhh:, until they fall down to the ground. Unless we get lucky and a piece or two hit another satellite - surely that will keep at least one or two pieces up for quite a while, right?

 

[mgb_phys]

The fuel tank in the above link isn't so bad, it's relatively light so reaches a low velocity.
The problem with a deorbiting keyhole/hubble type satelite is that the mirror is likely to reach the ground intact - so you get hit by a 1ton block of glass at high speed rather than a shower of smaller debris.

Where it hits depends on the orbit - you normally put photo-recon sats in a polar orbit so they get lots of passes across the width of a certain large country that covers quite a lot of the northern hemisphere - in which case it is likely to hit the pacific.
This is also let's you keep the solar panels constantly in sunlight and let's you take pictures at dawn/dusk when shadows give you good height information.

But since it didn't make orbit it could still be in an east-west orbit which means it is most likely to land in the certain large country. Hence the sudden concern to destroy it.

Because the orbit of any satelite is quite easy to work out from the launch site a couple of sightings they are quite easy to spot http://mysite.wanadoo-members.co.uk/satcom_transits/193bw.jpg

If you want to spot it yourself the USAF provides this useful identification chart
https://freeinternetpress.com/mirrors/usaf/airforce-id-chart.jpg

 

[BobG]

If you want to spot it yourself the USAF provides this useful identification chart
https://freeinternetpress.com/mirrors/usaf/airforce-id-chart.jpg

:rofl::rofl::rofl:

Actually, the entire spacecraft will break up as it enters the atmosphere. The likelihood of pieces surviving re-entry depend on their shape and the material they're made out of. I don't know the construction of this satellite, but spherical titanium fuel tanks are a popular option for satellites and the most likely part to survive re-entry. A large mirror would be unlikely to survive.

Blowing the satellite up with a missile will break up the satellite almost as effectively as the atmosphere will. Any objects likely to survive re-entry would also the be the pieces most likely to be propelled away from the explosion intact. The pieces might be propelled into a new orbit that take longer to decay. The pieces might be propelled into a new orbit that intersects the Earth's atmosphere, resulting in the pieces reentering sooner. I don't think there's any net gain.

At best, you spread the debris shower over a longer period of time. At worst, you create more space debris for at least a short period of time, increasing the chances of colliding with an operational satellite.

And, of course, all of the pieces from the missile will also re-enter the atmosphere.

If the satellite's a low altitude, polar orbiting satellite, then it was launched directly into its final orbit, so it would be in a polar orbit no matter what. High altitude satellites are launched into a parking orbit and later maneuvered into their final inclination.

 

[D H]

It's a bit of a misnomer to call the planned activity "shooting it down", since (a) the satellite is already on the way down, and (b) the explosion won't make it magically deorbit. The explosion won't change the momentum of the pieces by much. So ... I'll simply call the planned activity "blowing it up".

Blowing this satellite up accomplishes at least four ends:

• It will nearly eliminate the likelihood of hazardous chemicals (i.e. hydrazine) from reaching the ground.
• It will most likely render sensitive avionics and sensors useless if the pieces fall into the wrong hands.
• It will drastically reduce the likelihood of anything reaching the ground. Debris from a satellite is most likely to hit the ground if the satellite remains intact through at least part of the entry. If the satellite finally breaks up in the dense lower atmosphere the fragments will quickly slow down and fall. An upper atmosphere breakup means the fragments are subject to very intense heating as air drag is roughly inversely proportional to fragment size.
• Last but certainly not least, it gives the military a chance to play with their ASAT toys.

 

[mgb_phys]

The likelihood of pieces surviving re-entry depend on their shape and the material they're made out of. ... A large mirror would be unlikely to survive.

I think lots of sensitive circuitry in very heavily sheilded boxes is the surving bit they worried about.
One of the major concerns about Hubble was the damage the mirror would do on re-entry. It was predicted to survive rather well since all the instrumentation around the back of it would make a good heat shield. Obviously it wouldn't be in good shape when it hit the ground but it might be in one piece.

Given the StarWars/ASAT technology tests upto now the safest thing to do would probably be to paint a big red target on your roof - it pretty much guarantees it will miss you!

 

[waht]

US plans to shoot down a spy satellite

President Bush decided to make a first-of-its-kind attempt to use a missile to bring down a broken U.S. spy satellite because of the potential danger to people from its rocket fuel, officials said Thursday.

Deputy National Security Adviser James Jeffries, briefing reporters at the Pentagon, did not say when the attempted intercept would be conducted, but the satellite is expected to hit Earth during the first week of March.

http://news.yahoo.com/s/ap/20080214/ap_on_go_ca_st_pe/dead_satellite


Is this a response to last year's Chinese weather satellite shoot down? We had this capability since the '80s. Why now? I thought we had a treaty with the Russians outlawing just that.

 

[turbo]

Right now, that object is just one big inanimate piece of hardware, and its trajectory is known. If they manage to break it up into lots of little pieces, that's one thing, but if they don't get a clean hit and it breaks up into just a few massive pieces, those pieces will have brand-new trajectories that could very well endanger other satellites. Most of the Earth is uninhabited and/or covered with ocean, so why not let it come down in one piece?

 

[mgb_phys]

Most of the Earth in uninhabited and/or covered with ocean, so why not let it come down in one piece?

Because of what that one piece might contain.
The satelite's small size and odd orbit suggest that it wasn't a standard photo-recon, the rumours are that it was a test bed for a range of radar and imaging systems - so it might have some very interesting technology on board.
Most of the uninhabited Earth is in Russia / China (and Canada!) and it isn't impossible to recover stuff from the ocean if you watched where it landed.

The tricky bit of shooting it down is that if you shoot it down while it is still in orbit with an ICBM like the Chinese did you create lots of debris. If you wait until it starts deorbiting you have to shoot from near where it is landing, which means a ship.
The trouble is that if it looks like it is coming in over Russia/China and you shoot a medium range interceptor at it, from just off their coastline - where does space stop and their restricted air space start ?

The we are doing it because we are concerend about the rocket fuel is pure spin. Hydrazine isn't terribly nice but it's not going to have much left after it burns up in the atmosphere.

 

[Ivan Seeking]

Me thinks this is a show for China.

 

[russ_watters]

We had this capability since the '80s. Why now? I thought we had a treaty with the Russians outlawing just that.

Perhaps it is about China, but also we now have new capabilities that we want to test: A test of this sort would be more a demonstration for North Korea than China.

 

[drankin]

I wouldn't be surprised if that satellite is more than just observation equipment. It would explain the need to blow it up before it gets down here.

 

[Ivan Seeking]

Perhaps it is about China, but also we now have new capabilities that we want to test: A test of this sort would be more a demonstration for North Korea than China.

Considering that China just shot down a satellite and Korea can't get a missile off the ground, I don't see where Korea comes into this.

 

[russ_watters]

Considering that China just shot down a satellite and Korea can't get a missile off the ground, I don't see where Korea comes into this.

It is to be shot down by our new Navy-based ABM system. "Hey Kim - look what we can do!"

 

[RonL]

Where's Captain Kirk when you need him?

 

[devil-fire]

[*]Last but certainly not least, it gives the military a chance to play with their ASAT toys.[/list]

i was thinking this too, its a great opportunity for that type thing anyway. imo blowing the satellite up with a nuke would be by far the coolest option. why go small when you can go big when it comes to explosions in space is all I am saying.

 

[edward]

The Raetheon standard missile 3 will be used. They are manufactured here in Tucson so we have a lot of local interest. The satellite was launced in 06 and never maintained proper orbit. The local buzz is that there may be some high tech equipment that may survive the trip through the atmosphere if all 5000 lbs came down in one piece.

Personally I don't think that the hydrazine would survive the heat of re-entry.

http://www.azstarnet.com/news/225242.php

 

[BobG]

Here's James Oberg's take on it: Heading off a toxic iceberg from space
The fuel tanks aren't completely hollow. Since the fuel is 'weightless' and can slosh around during satellite maneuvers, fuel tanks have a series of vanes and baffles inside. I don't know how much structural integrity they give the tanks, but frozen hydrazine will give it a lot more, at least until the heat of reentry melts it.

The fuel tanks (or similar spherical tanks) are the most likely part of the spacecraft to survive reentry by far - http://www.reentrynews.com/recovered.html . In 1997, a piece of debris struck a woman in Oklahoma. Once in a while, the pieces land in a city. Pieces of Salyut 7, a very large Soviet space station, pelted the town of Capitan Bermudez, Argentina in 1991 (a relative term since debris fields are large and only a few pieces actually landed in the city).

It's not that the idea is unfeasible. It's that it's a lot of money and effort to reduce a snowball's chance in hell to a snowball's chance in an even hotter place in hell. On it's own merits, it's like declaring war on the environment because lightning kills people.

Obviously, there's ulterior motives. Shooting the missile is more important than reducing the risk of hydrazine.

 

[Ivan Seeking]

So remember kids: We were given a very technical and logical explanation for this by the Government, but in all likelihood it is complete nonsense.

I think this is the second shot in the new cold war with China.

 

[BobG]

For those interested enough to get out of the city, tonight would give quite a few a chance to see the falling satellite, the International Space Station, plus the comet 17P Holmes, all within a half hour period.

Heavens above can give you the info for all three (although the elset for the spy satellite is 6 days old, so the actual start time could vary by a couple minutes).

I also think it's a sorry state of affairs when even NBC News can't resist showing the shoot down ending with a huge fireball in space in their simulation.

 

[edward]

Here's James Oberg's take on it: Heading off a toxic iceberg from space
The fuel tanks aren't completely hollow. Since the fuel is 'weightless' and can slosh around during satellite maneuvers, fuel tanks have a series of vanes and baffles inside. I don't know how much structural integrity they give the tanks, but frozen hydrazine will give it a lot more, at least until the heat of reentry melts it.

OOPS I didn't stop to think that without power that the hydrazine would be frozen. Now I wonder what the power source was. They aren't using nuclear RTG anymore are they?Apparently no solar backup was used.

This should be interesting. The Raytheon standard missile 3 uses a kinetic kill vehicle deployed form the missile's third stage. The original standard guidance system was a heat seeking device which would have a hard time finding an iceball.

In early 06 sensors built by Raytheon were sold to Northrup to assist with the Northrup STSS tracking system. The sensors were to be deployed in low orbit satellites. ? Could this errant little turkey be one of them?

http://www.spacewar.com/reports/Ray...nd_Tracking_Sensors_For_US_Space_Program.html

 

[edward]

According to a senior official there is no RTG power generator.

A senior official with insight into the planning says that a rumor that the satellite carried a small, nuclear generator is "absolutely and totally incorrect." However, government agencies including MDA and NRO "are studying options that include" hitting the satellite with a weapon so that it breaks up in space - and ruptures the hydrazine tank -- before beginning its descent.

http://www.aviationweek.com/aw/generic/story.jsp?id=news/NRO02128.xml&headline=U.S.%20Considering%20Shooting%20Down%20Satellite&channel=defense

 

[Astronuc]

OOPS I didn't stop to think that without power that the hydrazine would be frozen. Now I wonder what the power source was. They aren't using nuclear RTG anymore are they?Apparently no solar backup was used.

This should be interesting. The Raytheon standard missile 3 uses a kinetic kill vehicle deployed form the missile's third stage. The original standard guidance system was a heat seeking device which would have a hard time finding an iceball.

In early 06 sensors built by Raytheon were sold to Northrup to assist with the Northrup STSS tracking system. The sensors were to be deployed in low orbit satellites. ? Could this errant little turkey be one of them?

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.

 

[edward]

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.

Thanks Astronuc.

We will probably never know what really failed. They claim it was a total power failure, and that they lost all contact with the satellite, but we will probably never know.

Raytheon needs a direct hit on this one. They were just awarded a $1.1 billion contract to produce 70 more standard 3 missiles. That is a lot of money. It looks like the cold war has restarted without a defined enemy.

 

[joema]

...The original standard guidance system was a heat seeking device which would have a hard time finding an iceball...

The space backdrop is nearly absolute zero (3 degrees K). An iceball is over 400 degrees warmer. In the IR spectrum it would stand out like a search light. Plus the satellite is much larger than the normal missile target.

Here's an IR image taken from the SM-3 kill vehicle moments before impact. Imagine something much larger than that. http://en.wikipedia.org/wiki/Image:Fm3_kw_ir.jpg

The problem is likely not detecting the target, but the intercept geometry is different from the normal mission. The satellite is moving much faster and is much higher.

But unlike a normal missile target, they know ahead of time the exact satellite orbital parameters and ground track. This allows optimal pre-positioning of the launch ship, so no cross-range maneuvering is required.

 

[edward]

The space backdrop is nearly absolute zero (3 degrees K). An iceball is over 400 degrees warmer. In the IR spectrum it would stand out like a search light. Plus the satellite is much larger than the normal missile target.

Here's an IR image taken from the SM-3 kill vehicle moments before impact. Imagine something much larger than that. http://en.wikipedia.org/wiki/Image:Fm3_kw_ir.jpg

Thanks for the info and the great wiki link.

 

[belliott4488]

The space backdrop is nearly absolute zero (3 degrees K). An iceball is over 400 degrees warmer. In the IR spectrum it would stand out like a search light. Plus the satellite is much larger than the normal missile target.

Here's an IR image taken from the SM-3 kill vehicle moments before impact. Imagine something much larger than that. http://en.wikipedia.org/wiki/Image:Fm3_kw_ir.jpg

The problem is likely not detecting the target, but the intercept geometry is different from the normal mission. The satellite is moving much faster and is much higher.

But unlike a normal missile target, they know ahead of time the exact satellite orbital parameters and ground track. This allows optimal pre-positioning of the launch ship, so no cross-range maneuvering is required.

Well, keep in mind that the SM-3 is designed to seek targets that have just risen through the atmosphere at hypersonic speeds, not ones that have been chilling in space for many months. You're talking about a pretty big difference in temperatures. Also, that target in the image you linked is not all that small, compared to a satellite. These claims of a "schoolbus-sized" satellite are kind of vague, but even one that size would not be "much larger" than the target in that image.

 

[edward]

Well, keep in mind that the SM-3 is designed to seek targets that have just risen through the atmosphere at hypersonic speeds, not ones that have been chilling in space for many months. You're talking about a pretty big difference in temperatures. Also, that target in the image you linked is not all that small, compared to a satellite. These claims of a "schoolbus-sized" satellite are kind of vague, but even one that size would not be "much larger" than the target in that image.

I have also read that the satellite was compared in size to a small school bus and I would imagine that would be with the solar panels extended. Something the size of a school bus on top of the delta II launch vehicle would certainly have had some aerodynamic problems.

http://www.spaceandtech.com/spacedata/elvs/elv-images/BA_Delta_II_Rocket_Pict.gif

 

[Astronuc]

http://www.nytimes.com/2008/02/19/world/asia/19china.html

China warned against threats to security in outer space, without mentioning its own successful anti-satellite missile test last year.

Well - all I can say is "I hope they don't miss". :uhh:

 

[mgb_phys]

They have cordoned off a 1400 x 700 mile section of the pacific for the alien mothership/dangerous fuel tank to land in.

 

[nesp]

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.

 

[Moonbear]

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?

 

[turbo]

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.

 

[Moonbear]

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.