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Predicting When Space Junk Will Come Home To Earth

Soulskill posted more than 2 years ago | from the not-in-my-back-yard-unfortunately dept.

Space 43

Following up on recent news of a NASA satellite falling from the sky and a German satellite that did the same, new submitter blais writes "NPR has an interesting interview about space junk falling back to Earth — and the odds of it possibly hitting someone. I thought it might be of interest to the other space nerds out there. Quoting: '... it's very difficult to know exactly when a satellite's going to come down. The Earth's atmosphere is hard to model. It's very thin up there, 100 miles or more up, but it exists. And sometimes it's a little bit denser, sometimes not, and the satellite might be tumbling, and so it makes it very difficult to know exactly when it's ... going to come down."

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Zat's not my department (2)

Mantrid42 (972953) | more than 2 years ago | (#37820680)

Vunce ze rockets are up, who cares vhere zey come down?

Re:Zat's not my department (3, Informative)

perpenso (1613749) | more than 2 years ago | (#37820838)

Vunce ze rockets are up, who cares vhere zey come down?

My understanding of history is that the famous rockets scientists implied by your accent were very much concerned with where the rockets came down.

Re:Zat's not my department (0)

Anonymous Coward | more than 2 years ago | (#37820890)

Dr. Strangelove? No, he just wanted to mate. and mate. and mate. With many women of superior physical attributes.

Re:Zat's not my department (0)

sconeu (64226) | more than 2 years ago | (#37820914)

Whoosh. Google for "Tom Lehrer".

Don't say that he's hypocritical.
Say rather, that he's apolitical.
"Vunce ze rockets are up, who cares vhere zey come down?
Zat's not my department!", says Werner von Braun.

Re:Zat's not my department (2)

perpenso (1613749) | more than 2 years ago | (#37821170)

You might reconsider who is having the woosh moment. That satirist who penned the original was essentially making the same point as I. :-) Out of context the original intent is easily missed.

Re:Zat's not my department (0)

sconeu (64226) | more than 2 years ago | (#37822858)

And you might want to reconsider as well. Lehrer wrote that when Von Braun was NASA's chief designer. It was a joke about how VB used to do the V2, and now he was working for NASA designing moon rockets.

Re:Zat's not my department (2)

perpenso (1613749) | more than 2 years ago | (#37823226)

And you might want to reconsider as well. Lehrer wrote that when Von Braun was NASA's chief designer. It was a joke about how VB used to do the V2, and now he was working for NASA designing moon rockets.

Yes, I was aware of all that. :-)

Re:Zat's not my department (0)

Anonymous Coward | more than 2 years ago | (#37827966)

So sick of the anti-german attitude, read some history (WITH SOURCES, NOT EYEWITNESS BULLSHIT ARTIST ACCOUNTS) and educate yourself, you have them to thank for many of the things you cherish.

Re:Zat's not my department (3, Funny)

Spy Handler (822350) | more than 2 years ago | (#37820992)

WVB: "it vill go up like a cannonball, und come down like a... cannonball, vid a parachute to spare ze life of the speceeman inside"

LBJ: "Spaceman?"

WVB: "Spe-ci-men!"

LBJ: "Well what kind of a spe-ci-men?"

WVB: "A tough one. Responsive to orders... I had in mind a jimp."

LBJ: "A Jimp? What in the hell is a jimp??"

WVB: "Jimp... a jimpanzee, senator!"

There is a reason... (1)

tyldis (712367) | more than 2 years ago | (#37820712)

There is a reason that the international norm when decommissioning a satellite you put it in an orbit which makes it reenter and disintegrate within 25 years. It's hard to get it to reenter controlled and switch it off at the same time.

Re:There is a reason... (2)

jd (1658) | more than 2 years ago | (#37821370)

Never quite understood the idea of remotely switching a satellite off when de-orbiting it. You'd want to switch off any non-command channel transmitter, sure, as that could interfere with other satellites, but there's no obvious reason to switch off any command channel stuff and this isn't the sort of crash you want to be able to reboot from. Now, I'll throw in one proviso in there - you DO want the computer system switching off once the thermal conditions go out of range, as you don't want a partially-functioning system sending random messages that could mess with the trajectory. But you absolutely want to have the satellite on a controlled descent for as long as possible (ideally via a mix of ground control and on-board computer, since you don't want control lost if the link is lost).

Re:There is a reason... (1)

tyldis (712367) | more than 2 years ago | (#37821716)

You are required to (a)deplete the fuel tanks and (b)disconnect the batteries.

I think
(a) is to reduce the potential damage in case of a collision
(b) is to stop the satellite from reactivating itself due to solar storms and the like

Re:There is a reason... (1)

dgatwood (11270) | more than 2 years ago | (#37825286)

Only on older satellites that don't need that power/fuel for a controlled deorbit. For most satellites, you'd ideally fire those thrusters at the right time to plant it in the ocean like they did with Mir, Skylab, etc.

AFAIK, current launch rules (at least in the U.S.) require that a satellite be designed to support a controlled deorbit unless the satellite is small enough to completely burn up on reentry. So eventually, this should cease to be a significant problem. It's just a shame that those rules weren't in place when these birds went up.

Put me in Orbit (0)

Anonymous Coward | more than 2 years ago | (#37820780)

With a baseball bat and the Office Space soundtrack, I'll fix your satellite problems...

I don't see the problem (1)

jd (1658) | more than 2 years ago | (#37820806)

You run the simulation through a CFD package, compare the prediction with reality, and tweak the parameters for the upper atmosphere accordingly. Keep crashing satellites until you consistently get good results. Problem solved.

The problem is weather, solar and atmospheric (2)

perpenso (1613749) | more than 2 years ago | (#37820910)

You run the simulation through a CFD package, compare the prediction with reality, and tweak the parameters for the upper atmosphere accordingly. Keep crashing satellites until you consistently get good results. Problem solved.

There is solar "weather" in space that can affect an orbit. There is weather and turbulence in the upper atmosphere. It is not a static environment where we can refine our parameters for greater accuracy.

Re:The problem is weather, solar and atmospheric (2)

jd (1658) | more than 2 years ago | (#37821226)

The whooshing sound you hear is the incredibly large number of theoretical satellites you'd need to be able to model the upper atmosphere (plus the fact that you can't treat the extreme upper atmosphere as a fluid).

Yes, the space weather affects things, but we monitor that increasingly. It can be modeled. Not in fine detail, but in aggregate, as indeed can the weather. You may not be able to compute the exact trajectory (you can actually prove you can't, since it's a chaotic system) but you can improve your estimation of the probability of any individual trajectory.

Re:I don't see the problem (1)

Frenzied Apathy (2473340) | more than 2 years ago | (#37821110)

Gee! Hey, that's a great idea!

How come NASA and the rest of the international space industry didn't think of that!?!?!

obviously (4, Insightful)

Hatta (162192) | more than 2 years ago | (#37820828)

It's a non-linear dynamic system. Of course it's going to be chaotic.

Re:obviously (1)

poofmeisterp (650750) | more than 2 years ago | (#37822762)

It's a non-linear dynamic system. Of course it's going to be chaotic.

Chaotic. + or - 1%.

Was anybody ever killed by space junk? (4, Informative)

mapkinase (958129) | more than 2 years ago | (#37820834)

According to NPR, Lottie Williams of Tulsa, Oklahoma, is the only person to have ever actually been hit by space junk. In 1997, she was hit on the shoulder by a piece of what was thought to be the Delta II rocket.

Re:Was anybody ever killed by space junk? (1)

Oswald McWeany (2428506) | more than 2 years ago | (#37820868)

I think some of the rednecks that get probed in UFOs have been "hit" by "space junk".

Re:Was anybody ever killed by space junk? (1)

edxwelch (600979) | more than 2 years ago | (#37821328)

> she was hit on the shoulder by a piece of what was thought to be the Delta II rocket.

That must have hurt

Re:Was anybody ever killed by space junk? (1)

Deadstick (535032) | more than 2 years ago | (#37822074)

I think it was a leather or fabric material, some kind of strap.

rj

Re:Was anybody ever killed by space junk? (0)

Anonymous Coward | more than 2 years ago | (#37822518)

Ooh baby, hit me again!

Re:Was anybody ever killed by space junk? (1)

mapkinase (958129) | more than 2 years ago | (#37829814)

Also, it could have been slowed down by trees or structures before hitting the victim.

Re:Was anybody ever killed by space junk? (1)

jzancanaro (2183416) | more than 2 years ago | (#37823446)

To Point out the Obvious fact that People are Missing. The SpaceShuttle Columbia Distingrated and Fell over The Southern US and nobody was hit by anything and the only near miss was when one of the Main Engines fell in a lake Missing some fisherman by a Few Hundred yards.

Re:Was anybody ever killed by space junk? (1)

mjr167 (2477430) | more than 2 years ago | (#37824144)

Sure... you drop one thing out of the sky without hitting anyone, therefor nothing falling out of the sky will ever hit anyone.

No one could have predicted (1)

Fr05t (69968) | more than 2 years ago | (#37820996)

No one could have predicted when Duke Nukem Forever would arrive.

When E.T. phones home (0)

Anonymous Coward | more than 2 years ago | (#37821048)

The junk comes back when E.T. phones home and tells it to come back.

I don't understand (0)

Anonymous Coward | more than 2 years ago | (#37821208)

I thought space was a kind of very large Wal Mart filled with resources just waiting to be plundered by us. How can there be "junk" up there? Can't someone make lots of money going up there to harvest all the gold on the space-rated PCBs? You know, maybe one of the thousands, no, millions, of private space tourists can just roll down his window, reach out and grab a random piece of treasure and bring it back and clear Earth customs?

Re:I don't understand (1)

scharkalvin (72228) | more than 2 years ago | (#37821254)

Oh like Salvage - One?

Re:I don't understand (1)

Anonymous Coward | more than 2 years ago | (#37821606)

Yes, like that. I think that was a documentary show from the late 1970s, I believe? I wonder what happened? Was there a crash in the price of space gold so the market disappeared? The other documentaries I've seen show how easy it is to get into space, you don't even need special clothes, and there is artificial gravity. Although I'm not sure why you'd go into space to get a few grams of gold if you have the money and resources to build the Enterprise in the first place. But space has its own logic.

There's nothing to worry about (1)

Anonymous Coward | more than 2 years ago | (#37821562)

With extensive simulation, I've found that there is about a 71% probability any falling object will land in the ocean.

Re:There's nothing to worry about (1)

Anonymous Coward | more than 2 years ago | (#37822844)

Actually your simulation doesn't account for the trajectories that most sattelites follow...

Re:There's nothing to worry about (0)

Anonymous Coward | more than 2 years ago | (#37823998)

It's 50/50 isn't it? Either it falls in the ocean, or it doesn't. 50%

Watch out for toilet seats (1)

Quila (201335) | more than 2 years ago | (#37821902)

I can't believe all these posts and no Dead Like Me reference yet.

I am a trained volunteer (1)

Chapter80 (926879) | more than 2 years ago | (#37822892)

When I was much younger, I underwent extensive training in destroying falling near-earth objects. I would love to use that training to secure a high paying job protecting our civilian and military population.

The training that I received is discussed here [softpedia.com] , with screen shots.

Design for it (0)

Anonymous Coward | more than 2 years ago | (#37823614)

Any reason satellites can't be designed with rockets to ditch themselves on demand when they've exceeded their operating life. Once a satellite's orbit starts to deteriorate, its owners plot out a reentry plan, and fire the rocket at the right time to drop it safely in the ocean.

Re:Design for it (2)

mjr167 (2477430) | more than 2 years ago | (#37824198)

I think the problem is that all the space junk is ALREADY in space. There is far more crap orbiting the planet than operational satellites. AGI has a nice plugin for Google Earth that plots all the space junk and it looks like a swarm of bees attacking the planet.

What's the contingency plan for a space junk kill? (0)

Anonymous Coward | more than 2 years ago | (#37825900)

I'm interested to know if anyone knows (preferably with a verifiable source) what the space agencies plan to do should their space junk cause one or more deaths - even more so if the space junk kill is in a foreign country???

hey, I know that guy! (1)

The Bad Astronomer (563217) | more than 2 years ago | (#37827950)

So I'm reading that quotation about modeling the atmosphere, thinking, "That sounds familiar". When I get halfway through I realize, hey! I said that! That's when I finally look at the source and realize it's NPR, the interview I did on Science Friday. That made me LOL.

Lay-Offs (0)

Anonymous Coward | more than 2 years ago | (#37832466)

This "problem" of predicting when and where space junk falls is proportional to the lay-offs of scientists. I guess when the "junk" strikes the white house unannounced some of those unneeded workers will be called back.

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