Author Topic: Cleaning up near earth space  (Read 49184 times)

Offline mmeijeri

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Re: Cleaning up near earth space
« Reply #60 on: 03/04/2009 01:52 pm »
MMOD risk is one subject I don't read about being covered nearly enough from space elevator proponents. An elevator is a sitting duck, unable to avoid anything (a thin sitting duck, but one nonetheless).

See http://www.tethers.com/Hoytether.html. Robert Hoyt is Mr Space Tether.
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Offline MKremer

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Re: Cleaning up near earth space
« Reply #61 on: 03/04/2009 06:57 pm »

Anyway, my totally pie-in-the-sky idea uses a very thick, massive Orion-class baseplate disk (the nuclear bomb-type Orion design), but much larger.

I don't see why it should be *that* thick. I bet a ~1mm thick metallic plate will do a lot of damage to any "small" debris (say under 5 cm). A 1mm thick plate is much more feasible.

1mm is just a ballpark figure. Optimal thickness, layering and composition need to be optimized for maximum energy transfer to the impacting debris.

It needs to be thick and massive - it's meant to 'sweep up' *all* debris, from micron-sized paint flecks on up to spent rocket stages, dead sats, and other larger remains and various orbital debris.

(which is why I mentioned it would be a risk to *anything* not able to move out of the way by itself)
« Last Edit: 03/04/2009 06:58 pm by MKremer »

Offline rklaehn

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Re: Cleaning up near earth space
« Reply #62 on: 03/05/2009 09:35 pm »
Nope. Because when you incident explode/vaporize/shatter the parts, they emerge at a 180 degree distribution, so in order to gaurantee that  you reduce orbital velocity to all components, you have to hit edge on.

If the vapors emerge with a 180 degree distribution, there will still be an impulse in the direction opposite to the side where the particle was hit. And as long as this impulse is partly in the right direction, you will get deceleration.

If the vapors would emerge with a 360 degree distribution, then you would not get any net impulse. But that is not the case since half the particle is "in the shade".
« Last Edit: 03/07/2009 08:47 am by rklaehn »

Offline gospacex

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Re: Cleaning up near earth space
« Reply #63 on: 03/05/2009 10:36 pm »
It needs to be thick and massive - it's meant to 'sweep up' *all* debris, from micron-sized paint flecks on up to spent rocket stages, dead sats, and other larger remains and various orbital debris.

(which is why I mentioned it would be a risk to *anything* not able to move out of the way by itself)

You want to simplify sweeping up of largest debris items by making "flyswatter" x100 times more massive and expensive? That's extremely inefficient use of $$$. I'd rather make 100 thin flyswatters instead.

Big debris is less numerous, can be easily tracked by radar and thus avoided. A modest upgrade of USAF computers (perhaps only software upgrade will suffice) will get you automatic warning of any collision danger from these.

If you definitely absolutely have to take out some particular dead sat, talk to the Navy. They need to train crews operating AEGIS and Standard. :D

Offline Jim

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Re: Cleaning up near earth space
« Reply #64 on: 03/05/2009 11:07 pm »
A modest upgrade of USAF computers (perhaps only software upgrade will suffice) will get you automatic warning of any collision danger from these.


Incorrect.  You have no comprehsion of the issues.  It has nothing to do with software or computing power.  It is tracking assets and and frequency and visibility to those assets

Offline gospacex

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Re: Cleaning up near earth space
« Reply #65 on: 03/06/2009 04:08 pm »
A modest upgrade of USAF computers (perhaps only software upgrade will suffice) will get you automatic warning of any collision danger from these.

Incorrect.  You have no comprehsion of the issues.  It has nothing to do with software or computing power.  It is tracking assets and and frequency and visibility to those assets

Correct me if I am wrong, but Cosmos/Iridium smashup was predictable based on USAF data, just no one actually checked the data. Neither USAF (because it wasn't their bird) nor Iridium (because then just hoped this won't happen).

A software upgrade at USAF (calculate _all_ possible collisions + send emails to respective sat owners) could have saved Iridium.

If I am wrong and current radar data is not precise enough to predict collisions without too many false positives, upgrading radars is still cheaper than flying the monster plate described. Upgrading radars is also useful for other purposes.

Offline Jim

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Re: Cleaning up near earth space
« Reply #66 on: 03/06/2009 04:37 pm »
No, because the software already predicts over 400 conjunctions per week for Iridium.   

Doesn't do any good if Iridium ignores them

Again, it isn't the software, it already does it.

The problem is not "upgrading", it is numbers and locations of the radars
« Last Edit: 03/06/2009 04:39 pm by Jim »

Offline kevin-rf

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Re: Cleaning up near earth space
« Reply #67 on: 03/06/2009 05:29 pm »
Excellent article on the collision in last weeks theSpaceReview : http://www.thespacereview.com/article/1314/1

Goes into how it is really analyst limited and not as much computer limited.
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Offline nooneofconsequence

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Re: Cleaning up near earth space
« Reply #68 on: 03/06/2009 07:07 pm »
The root problem with the current collision is that Iridium isn't / hasn't worked the problem ... and before the bankruptcy they did.

Don't make it bigger than it is - they just are/were gambling. And lost.

The Russians are just being russian. End of story.

You are left with two scenarios currently not dealt with - 1)removing dead sats with long decay orbits before they hit - like the Cosmos, and 2) eliminating collision debris to prevent collateral damage. Fair debate as to cost/benefits for dealing with either.

As to creating an "orbital police", that's silly. Part of the cost of maintaining an orbital asset is a process to cope with the potential for collision. There will always be gamblers (iridium), bad luck/consequential (russians) and willful negligent(russians).
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Offline khallow

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Re: Cleaning up near earth space
« Reply #69 on: 03/07/2009 08:18 am »

Perhaps you might want to do a little work on your own, in particular look at the effectiveness of YAG lasers used in manufacturing, to get some idea of what is required at 10mm distance to vaporize metal, then apply this to meters or kilometers, to get an idea of the issues involved.

Thank you for clarifying that there are "issues" involved. Now what makes it "nonsense"? For example, I can increase the aperture size considerably. For example, the cutting laser example above has an effective aperture of a few millimeters in diameter. What happens if my system has an effective aperture of hundreds of kilometers? And I can increase the power level considerably before issues like atmospheric ionization becomes a problem. And frankly, just hitting the object with intense light pulses every few hours changes its momentum over time.
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Offline KelvinZero

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Re: Cleaning up near earth space
« Reply #70 on: 03/07/2009 01:24 pm »
What about putting tons of fine dust or station-keeping propellent into a reversed orbit?

If space junk sits up there for a long time, then wouldnt these do the same? Because they are very fine they would only be a minor nuisance to large objects, however they would apply a significant drag to small objects, especially paint flecks etc.

We wouldnt even need to send up mass specifically for this purpose. We have to expend propellent to keep things in orbit anyway. If this propellent was ejected at about 16km/s we could encourage it to build up in an orbit roughly opposite the satellites orbit.

Offline DrCoffee

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Re: Cleaning up near earth space
« Reply #71 on: 03/07/2009 05:54 pm »
I do not think adding debris is the way to go. Unless an object is under our direct control that we can change direction and orbit manually our selves then we would in effect only be adding to the problem we are trying to eliminate. Much is being said of lasers, however at the speeds we are talking of many of these object would only be exposed to the laser for short periods, the sun itself has the debris under its exposure for a lot longer and has not made much difference in its orbital characteristics.


Is there any study being done to find some way to attract the debris to a certain point or orbit?

Apart from altering its speed and orbit, what else could be used to bring the debris under our control?

A lot of debris is being monitored, what is the estimate on debris not being monitored?

Is there any small area or areas that can be said "x amount of debris will pass this area in x amount of time" ?

What other questions need to be addressed to start someone thinking of a solution?


Offline Jim

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Re: Cleaning up near earth space
« Reply #72 on: 03/07/2009 06:21 pm »

1.  Is there any study being done to find some way to attract the debris to a certain point or orbit?

2.  Apart from altering its speed and orbit, what else could be used to bring the debris under our control?

3.  Is there any small area or areas that can be said "x amount of debris will pass this area in x amount of time" ?

4.  What other questions need to be addressed to start someone thinking of a solution?


1.  No

2.  capture

3.  no

4.  None, because the solution for now is not to generate debris and if it is followed then nothing else is needed

Offline rklaehn

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Re: Cleaning up near earth space
« Reply #73 on: 03/07/2009 06:43 pm »
What happens if my system has an effective aperture of hundreds of kilometers?

An aperture of hundreds of kilometers might be a little technically challenging... I think the biggest aperture you can realistically build is about 10m, like the biggest optical telescopes existing today.

But anyway, the boeing YAL-1 (if it works) is an existence proof that it is possible to focus laser light over several 100km even if the sender is in the atmosphere.

Offline dunderwood

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Re: Cleaning up near earth space
« Reply #74 on: 03/07/2009 08:15 pm »

An aperture of hundreds of kilometers might be a little technically challenging... I think the biggest aperture you can realistically build is about 10m, like the biggest optical telescopes existing today.


You could build a sparse aperture array, and get an effective aperture much larger than what you can actually build using a monolithic lens.

Offline kevin-rf

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Re: Cleaning up near earth space
« Reply #75 on: 03/08/2009 08:02 pm »

But anyway, the boeing YAL-1 (if it works) is an existence proof that it is possible to focus laser light over several 100km even if the sender is in the atmosphere.

It is also a chemical laser that only has enough chemicals to fire twenty times before it has to land and be loaded up again.


« Last Edit: 03/08/2009 08:02 pm by kevin-rf »
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Offline nooneofconsequence

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Re: Cleaning up near earth space
« Reply #76 on: 03/08/2009 11:14 pm »
There is no reasonable cost way of sweeping space clean  :)

Best answer is don't dirty it.

If you must play with ray guns, an on orbit particle beam weapon might get you enough vapor pressure to matter, the troubles are: beam coherence (e.g. distance), beam current (accelerator weight/power), wiggler/buncher - to avoid charge dissipation/impedance issues(size).

Also superpowers would blame it every time their satellite would die - witness Russians blaming Orbital Express (obviously it sabotaged things ...).
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Offline KelvinZero

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Re: Cleaning up near earth space
« Reply #77 on: 03/09/2009 07:54 am »
I do not think adding debris is the way to go. Unless an object is under our direct control that we can change direction and orbit manually our selves then we would in effect only be adding to the problem we are trying to eliminate.

Not really. You are adding a material that is at worst a nuisance to remove objects that could be catastrophic. You could say it is under our direct control because its effects and decay are predictable and it is targeted very accurately to only significantly affect very small manmade objects (those orbiting in the direction of the earths rotation with a very high surface area to mass ratio).

The way I see it, barring natural removal, every ton of this safe material you put up would neutralise itself against a ton of dangerous space junk, even and especially if that junk is distributed in millons of fragments.

Also perhaps it is possible to design a material that removes itself, eg eventually ionises and interacts with the magnetic field or solar wind.

Offline rklaehn

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Re: Cleaning up near earth space
« Reply #78 on: 03/09/2009 09:48 am »
There is no reasonable cost way of sweeping space clean  :)

Depends on what you define as reasonable.

A single large earth observation satellite like MetOp-A costs close to a billion euros. If you add the value of all satellites that are using high LEO (polar and sun-synchronous earth observation satellites and communications constellations), you get significantly more than ten billion USD. So the high LEO environment is worth a lot. It would make sense to invest 10% of that value so that the high LEO environment remains usable.

Quote
Best answer is don't dirty it.

Of course that would have been best. But it is a bit too late for that.

Quote
If you must play with ray guns, an on orbit particle beam weapon might get you enough vapor pressure to matter, the troubles are: beam coherence (e.g. distance), beam current (accelerator weight/power), wiggler/buncher - to avoid charge dissipation/impedance issues(size).

Also superpowers would blame it every time their satellite would die - witness Russians blaming Orbital Express (obviously it sabotaged things ...).

Why particle beams? Lasers have made tremendous improvements in the last 20 years. There are infrared semiconductor lasers with 50% efficiency. And if you use those to pump a Nd:YAG pulsed laser, you get an overall system efficiency of >20%. That is extremely impressive.

If your laser is in orbit, you have no problems whatsoever with atmospheric turbulence. You are only limited by diffraction. So you don't need adaptive optics for your targeting system. The only tiny problem is where you get the 100kW(e) to power such a laser. On earth that is a trivial amount of power, in space not so much.

By the way: The russians will blame you whenever you do anything in space. And if you don't do something for that.

Offline rklaehn

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Re: Cleaning up near earth space
« Reply #79 on: 03/09/2009 09:52 am »

But anyway, the boeing YAL-1 (if it works) is an existence proof that it is possible to focus laser light over several 100km even if the sender is in the atmosphere.

It is also a chemical laser that only has enough chemicals to fire twenty times before it has to land and be loaded up again.

You would have to replace the laser (probably by a diode-pumped Nd:YAG laser) since for space debris removal you want a relatively small pulsed laser instead of an extremely powerful continuous laser. But the targeting system could be reused.

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