Bus sized UARS satellite crashing back to Earth Friday

[matrixshaman]

The UARS weather satellite will be crashing back to Earth sometime around Friday this week. They say there is a 1 in 3200 chance it will hit someone. Does this seem to you rather irresponsible? Oh and if you find a chunk of it don't touch it. It belongs to the U.S. Government. They say it will create a 500 mile debris field and it will not all burn up on re-entry. It is expected to land somewhere between Northern Canada and southern South America. For any geographically challenged members that puts the U.S. right in the target zone. WTF? Is anyone else feeling a little like your government doesn't give a shift? IMO this should be blown to bits before it has a chance to re-enter so that any debris will be small enough to burn up on re-entry. Or they could attach a small rocket and just give it a push out into space so it will never re-enter.
Nah, better make that a titanium helmet

[matrixshaman]

One other thing I find very odd about this is that they say even at 2 hours before it crashes down that they claim they will not be able to pinpoint where it will crash down at. Sounds to me like they don't want any scavengers waiting around to grab up pieces. They did mention this will NOT end up on eBay. That leads one to believe that is their bigger concern rather than who it falls on.

[JacobJones]

Money isn't it, why spend billions sending a rocket with explosives up to it and deal with it in a way that doesn't risk harming the citizens of your own country when you can let it plumet back to earth with a few prayers. it'll probably be too broken up by the time it lands to do much damage anyway, few broken windows perhaps

[Colorblinded]

Maybe they're making it all up and they do have a pretty good idea of where the main chunk will land.

[matrixshaman]

Oh I agree money to make this a non-threat is an issue. But they put it up there and they need to be responsible for keeping people safe from their space junk. We pay their salaries and personally I'm not okay with their current plan. I also find it hard to believe they are saying they can't pinpoint any closer than plus or minus 12000 kilometers (that's over an 8000 mile radius) even 2 hours before it crashes down. But in the past space capsules have Navy ships waiting for them within a few miles when they re-enter.

[matrixshaman]

Maybe they're making it all up and they do have a pretty good idea of where the main chunk will land.

I'm leaning toward that idea and that they even may have planned for it to land on U.S. soil for easier recovery. There is fairly solid evidence that these satellites contain nuclear material and they don't want that getting into the wrong hands. There was something that crashed a while back in South America (I might be wrong on that but I believe it was somewhere around there) which left a small crater. Shortly after all the villagers were getting very sick and I think those who visited the crater were in bad shape. I am fuzzy on the details but it sounded very much like radiation sickness from a crashed satellite.

This is a very interesting document from NASA on this and the risk assessment : http://www.nasa.gov/pdf/585584main_UARS_Status.pdf

[RBR]

U(-)ARS ????

What a name for a sattelite.



At least you know what to eff and blind when it comes down in your yard.

Sorry fot the OT.

Cheers

RBR

[LukeA]

Money isn't it, why spend billions sending a rocket with explosives up to it and deal with it in a way that doesn't risk harming the citizens of your own country...

And scatter literally tons of hypersonic orbital debris around at the same altitude as the ISS? Yeah...

[Colorblinded]

And scatter literally tons of hypersonic orbital debris around at the same altitude as the ISS? Yeah...

The last thing we need is more orbiting debris. Deorbiting would still seem to be the best choice if we want to have any future to continue putting stuff up in orbit without it getting clobbered by spacejunk.

[JacobJones]

And scatter literally tons of hypersonic orbital debris around at the same altitude as the ISS? Yeah...

I didn't think of that

[matrixshaman]

I was thinking more along the lines of one of our top fighter jets hitting it with a high power non nuclear rocket during it's descent into the top of the jet's altitude capabilities thus exploding it into small pieces that would likely all burn up or at least be a lot smaller pieces than what they currently predict. Although like I said before IF these have nuclear power that will be one reason they won't attempt it. I think the best solution would have been to have an on board small rocket that could be deployed at the end of it's useful life to simply give it a push out into space before it's orbit degrades much so it wouldn't take much power and once given a push it would just keep going or until it ran into the gravity pull of some celestial object.

[matrixshaman]

BTW if anyone sees a whole lot of unexpected military vehicles or activity in their area around Thursday or early Friday you may be in the expected target zone. Report here so I'll know which helmet to wear that day.

[nbp]

Humans really are their own worst enemy. We can't do anything without screwing something else up.

A 1 in 3200 chance that I get hit by some satellite crap??? I was a bio major not a stats major, but that's a really high probability if you think about it. If you look at a chart like this, it's staggeringly likely that I am hit by this thing. I am an outdoorsman, and I live in Wisconsin, where we have very cold winters. Getting lost or injured outside and freezing to death is a *reasonably* likely way to die for me, and yet I am twice as likely to get hit by these satellite chunks than die that way? That's absurd. I am not truly concerned that I will be killed by UARS, but the numbers would certainly make a person think they should be. Seriously, how do they not plan for these kinds of events when they go launching all this junk up there in the first place???

[Empath]

The "Estimated human casualty risk (updated to 2011): ~ 1 in 3200" isn't indicating a 1 in 3200 chance of a particular individual casualty. It's indicating the chance of any individual casualty. That extends chances in your favor by a few billion.

The fear-mongering and unsubstantiated blaming of the mysterious and unidentfiable THEY being blamed for this so called great threat is being presented like a tabloid article at the grocery store check out.

Direct your concern at the sky full of planes overhead that can, and often does, come crashing down with heart breaking casualties. The chances there of disaster is so much more.

[Colorblinded]

Direct your concern at the sky full of planes overhead that can, and often does, come crashing down with heart breaking casualties. The chances there of disaster is so much more.

I'm more worried about other vehicles on the ground than I am planes.

[TedTheLed]

you can track it here

http://spaceweather.com/flybys/

[nbp]

The "Estimated human casualty risk (updated to 2011): ~ 1 in 3200" isn't indicating a 1 in 3200 chance of a particular individual casualty. It's indicating the chance of any individual casualty. That extends chances in your favor by a few billion.

Ah, ok, that makes more sense, it seemed I was misunderstanding something.

Either way, it doesn't change my feelings that humans do an awful lot of stupid things to wreck the earth, the stuff on it, and apparently now the space around it.

Currently, there are more than 20,000 pieces of debris larger than a softball orbiting Earth.

[beerwax]

lets investigate this 1 in 3200 statistic. if that number has been calculated by a competent person it includes allowance for populated vs unpopulated areas. the vast majority of area is relatively unpopulated or lightly populated.

so if by bad luck it hits a densely populated area you would expect the 'chance ' of fatality to be far greater than 1 in 3200.

it would more informing if they quoted the chance of hitting a populated area, and then the damage they expect if it does. for example do they expect peices that could penetrate a house.

i think, correct me if i am wrong, a lot of insurance policies specifically exclude 'space junk' ?
cheers

[Steve K]

... There is fairly solid evidence that these satellites contain nuclear material and they don't want that getting into the wrong hands. There was something that crashed a while back in South America (I might be wrong on that but I believe it was somewhere around there) which left a small crater. Shortly after all the villagers were getting very sick and I think those who visited the crater were in bad shape. I am fuzzy on the details but it sounded very much like radiation sickness from a crashed satellite.

This is a very interesting document from NASA on this and the risk assessment : http://www.nasa.gov/pdf/585584main_UARS_Status.pdf

"fairly solid evidence that these satellites contain nuclear material"???

Please, would you share that with us?

For what it's worth, I was part of the group at McDonnell Douglas that provided the Modular Power Subsystem, which takes power from the solar panel, charged up the nicad batteries in our module, and provided the battery power to the rest of the satellite. The three batteries, which each weigh about 100 pounds, are on the list of the 26 chunks that are expected to make it back to the surface of the earth.

I had the pleasure of transporting one of the MPS electronics modules (I think it was the Power Regulator Unit) to Kennedy Space Center and helped swap it out for the one in the MPS (don't recall why). Pretty neat, and was in the clean room with the UARS satellite itself.
You can get some tech details on the MPS module from our simple sales literature here and here.

I'm not sure why the gov't doesn't want people to keep any debris... maybe just to discourage people from traveling into the impact area prior to the event and getting injured? Besides, some of the stuff in the satellite is toxic. Certainly the cadmium in our nicads is toxic. The beryllium used in some of the satellite structure is toxic too, if it has oxidized. BeO is not uncommon in power semiconductors, and the packaging often contains warnings.

Anyway, don't listen to the conspiracy theories or other craziness out there. Just stay indoors, and put on a hard hat... just in case you win the 1 in a trillion lottery.

Steve K.

[Samy]

It's ok everyone! I'm on the other side of the world so i'll possibly maybe slightly be ok!

cheers

[LEDAdd1ct]

The "Estimated human casualty risk (updated to 2011): ~ 1 in 3200" isn't indicating a 1 in 3200 chance of a particular individual casualty. It's indicating the chance of any individual casualty. That extends chances in your favor by a few billion.

Empath, could you please explain the statistic to me in simpler terms? I'm not an idiot, but I am having trouble grasping the distinction.

[LEDninja]

... It belongs to the U.S. Government. ... For any geographically challenged members that puts the U.S. right in the target zone.

A U.S. satellite should return to the U.S.A. On its own if possible.

No fun looking for another country's satellite. I still remember the search for a Russian satellite powered by a nuclear reactor instead of solar panels. Never found the reactor BTW.

This satellite was decommissioned back in 2005-2006. Then brought to a lower orbit to avoid hitting other satellites. They should have brought it down all the way then. A powered reentry would have a much better chance of coming down where they wanted rather then somewhere on earth.

[DM51]

... could you please explain the [1 in 3200] statistic to me in simpler terms? I'm not an idiot, but I am having trouble grasping the distinction.

It means the chance of a fragment hitting someone are 1 in 3200. As there are ~6,000,000,000 people in the world, the chance of it hitting you are about 1 in 20,000,000,000,000.

[Colorblinded]

This satellite was decommissioned back in 2005-2006. Then brought to a lower orbit to avoid hitting other satellites. They should have brought it down all the way then. A powered reentry would have a much better chance of coming down where they wanted rather then somewhere on earth.

It's possible they set it on a course to have it land in the US back then... maybe. I don't know how well they can predict the exact path of a powerless orbiting satellite that many years in to the future.

[DM51]

I don't know how well they can predict the exact path of a powerless orbiting satellite that many years in to the future.

They can't predict it with any accuracy, really - it's basically out of control. They'll get a better idea of where it's likely to fall as the time gets nearer. As almost 70% of the earth's surface is sea rather than land, the likelihood is it will fall into the sea.

[AnAppleSnail]

Knowing what little I do about satellite de-orbiting, I'll try to shed a bit of light here.

An orbit: Imagine a big cannon. If you shoot a cannonball fast, it will travel rather far. If you shoot it far enough, it will hit the ground over the horizon, since the ground will curve down below the shot's path. If you shoot fast enough, the cannonball's trajectory will not touch the ground for quite some time - possibly never.

The International space station is in orbit. If the Space Shuttle links up and pushes it along its orbit, its altitude will slowly increase as it speeds up. Slowing down an orbiting object will decrease its altitude, and slowing it enough will (crash)-land it on the Earth.

Most methods of de-orbiting require a lot of fuel. A satellite goes quite fast in its orbit, and to slow down enough to come down quickly uses more fuel than it has - so a quick de-orbit is out.

A slow de-orbit is harder to predict. The atmosphere attenuates to lower and lower densities, but temperature and solar fluctuations make it more or less dense at a satellite's orbital height. This increases or decreases the braking that will bring the satellite down. If you have a low orbit, it might circle the Earth once an hour. Uncertainty of as much as 15 minutes means that it would hit a quarter of the Earth from where you thought. Given +/-, that's half the Earth under fire.

Satellite wreckage is dangerous. The fuel (often hydrazine) is very toxic, and leaks from wreckage. Often that burned up on the way down. Other chemicals can be dangerous, and of course there are heavy pieces of metal falling out of the sky. Some solid-rocket motors weigh about 1 metric ton on impact.

There is a possible non-fuel-using de-orbit method that is faster and slightly more predictable than un-controlled de-orbiting. Paying out a conductive wire from an orbiting satellite low enough in the ionosphere will slow the satellite. The conductive wire travels through the Earth's magnetic field, producing a braking force. This only works in the ionosphere, because the return path for electrons is the ionosphere. It's rather like a bicycle dynamo. There have been attempts to mount a de-orbit tether reel on every satellite.


Summary: Satellite landings are hard to predict. Satellites do not make good hats, and wreckage should not be licked. De-orbiting satellites in a way that is easy to predict (that is, quickly) costs hundreds of thousands or millions of dollars worth of fuel in orbit. For slower methods (tether or uncontrolled) it is harder to estimate landing zones.

[Colorblinded]

They can't predict it with any accuracy, really - it's basically out of control. They'll get a better idea of where it's likely to fall as the time gets nearer. As almost 70% of the earth's surface is sea rather than land, the likelihood is it will fall into the sea.

Kind of my suspicion. Up to an extent you can make a prediction (not 5-6 years) but with so many variables it's basically just a guess that ultimately states: "well, it should probably land on our heads in late 2011."

[Steve K]

Knowing what little I do about satellite de-orbiting, I'll try to shed a bit of light here.
<..... a big snip.... >

Summary: Satellite landings are hard to predict. Satellites do not make good hats, and wreckage should not be licked. De-orbiting satellites in a way that is easy to predict (that is, quickly) costs hundreds of thousands or millions of dollars worth of fuel in orbit. For slower methods (tether or uncontrolled) it is harder to estimate landing zones.

that's an excellent summary! Any satellite in low earth orbit (which is most satellites) experiences a little bit of drag from the atmosphere that will eventually cause it to return to earth. The UARS was slowed down by a controlled burn in 2005 which put it in a lower orbit with thicker air, which caused it to return sooner than it would have otherwise. Still... it's taken 6 years to finally make it back home. With the odd shape and lousy aerodynamics that it has, it's anyone's guess where it'll eventually end up.

Steve K.

[Mattb]

Just googled and found this:

http://www.foxnews.com/scitech/2011/...-in-real-time/

Quoting a portion of the article:

"The 20-year-old research satellite is expected to break into more than 100 pieces as it enters the atmosphere, most of it burning up. Twenty-six of the heaviest metal parts are expected to reach Earth, the biggest chunk weighing about 300 pounds (136 kilograms). The debris could be scattered over an area about 500 miles (800 kilometers) long."

300 pounds!!!

[Steve K]

The NASA site for the satellite is here.

The report describing the 26 items that are expected to impact the earth is here.

The report has the info on the size, weight, material, etc. of each of the parts (see page 8). Oddly, it lists the batteries as being made of stainless steel, which only describes the shell of each cell. Each battery is about 100 pounds and rather dense, so if you see one coming your way, try to jump out of the way.

To me, the most interesting bit of data on page 8 is the "debris casualty area" for each of the chunks. Each of the batteries has a debris casualty area of 0.91 square meters, so they really have to hit you directly to hurt you (and it *will* hurt!). A big piece of the structure has a debris casualty area of 2.44 square meters, so it's going to be harder to jump out of the way. It's the 300 pound chunk, but it's just made out of aluminum, so it's not going to hurt quite as much as the batteries.
Good news, eh??

Steve K.