Author Topic: Cleaning up near earth space  (Read 34766 times)

Online A_M_Swallow

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Re: Cleaning up near earth space
« Reply #80 on: 03/09/2009 10:32 AM »
{snip}

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.

The solar panels on the ISS generate 131 kW of power so 100kW(e) is possible.  At that sort of power the satellite could be equipped with Hall Effect or VASIMR thrusters, allowing the laser satellite to change its orbit.

Offline rklaehn

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Re: Cleaning up near earth space
« Reply #81 on: 03/09/2009 10:47 AM »
{snip}

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.

The solar panels on the ISS generate 131 kW of power so 100kW(e) is possible.  At that sort of power the satellite could be equipped with Hall Effect or VASIMR thrusters, allowing the laser satellite to change its orbit.

Possible, yes. But not cheap. Nowadays you could do much better than the ISS solar arrays mass wise, but it would still be a huge satellite. You would need a heavy EELV to launch that beast.

Of course you could power an electric propulsion system with that kind of power. But I think you would not have to change orbit to get close to most space debris. Just launch into a 28 degree inclination, 500km altitude circular orbit from the cape. That would put you right in the middle of the high LEO space debris cloud, and every piece of debris will come sufficiently close (~400km) to you in time.
« Last Edit: 03/09/2009 01:00 PM by rklaehn »
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Offline nooneofconsequence

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Re: Cleaning up near earth space
« Reply #82 on: 03/09/2009 06:11 PM »
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.

You are correct, but try to think like a businessman (which is how we get into this problem - no self respecting engineer would abandon a conflict monitoring process). If they get the idea that its just odds, a form of gambling that replaces a budget item with $0 and they can not book the contingency liability because they can just lie, they'll do it in a heartbeat. The only way you can fight this is put a gun to their head and cock the trigger.

They don't see it as an active cost to the business - so they don't believe it exists for them. Until they do, you can't get traction.

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Best answer is don't dirty it.

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

Not really - people talk themselves into working around the problem by avoiding the trash zones. Then they think they'll just not have another  accident. That's exactly what will happen here.
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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.

Lasers are very efficient at converting energy, not efficient at converting energy to metal vapor/explosions - look at the end to end process here. Particle beams heat metal/glass/electronics/composites much more efficiently.
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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.

Correct. Even better, you can create the lasing cavity in interesting ways that can take advantage of the hard vacuum of space to get greater efficiencies than on earth.

It's harder for particle beams, and they are heavier as well. But you get more effect of what you want per watt.
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By the way: The russians will blame you whenever you do anything in space. And if you don't do something for that.
I know - that's how they make life more interesting. But I guarantee that a particle beam weapon in orbit will get their attention.
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Offline nooneofconsequence

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Re: Cleaning up near earth space
« Reply #83 on: 03/09/2009 06:17 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.

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.
You need a bulk switched semiconductor laser with high duty cycle feeding an optically coupled array of YAG crystals with a very large radiator to cold soak the bulk switching and crystals. Very severe thermal issues here.
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Offline nooneofconsequence

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Re: Cleaning up near earth space
« Reply #84 on: 03/09/2009 06:24 PM »
{snip}

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.

The solar panels on the ISS generate 131 kW of power so 100kW(e) is possible.  At that sort of power the satellite could be equipped with Hall Effect or VASIMR thrusters, allowing the laser satellite to change its orbit.

Possible, yes. But not cheap. Nowadays you could do much better than the ISS solar arrays mass wise, but it would still be a huge satellite. You would need a heavy EELV to launch that beast.

Of course you could power an electric propulsion system with that kind of power. But I think you would not have to change orbit to get close to most space debris. Just launch into a 28 degree inclination, 500km altitude circular orbit from the cape. That would put you right in the middle of the high LEO space debris cloud, and every piece of debris will come sufficiently close (~400km) to you in time.
You charge a bank of capacitors, so the size of the array is set more by the firing rate / discharge. You don't use continuous current.

As an aside, VASIMIR and/or other plasma engines are basically unfocused particle beams - you could use the same equipment to change orbit that you use to generate a particle beam weapon. Also, considering the MHD properties, you can generate plasmas from nuclear sources as well very "weight/size" efficiently, so current limits don't necessarily require 4 Shuttle equivalent launches of PV arrays.
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Online A_M_Swallow

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Re: Cleaning up near earth space
« Reply #85 on: 03/09/2009 07:52 PM »
Solar panel technology has moved on since the ISS was designed so only a single pair of panels may be needed.

Offline rklaehn

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Re: Cleaning up near earth space
« Reply #86 on: 03/09/2009 08:55 PM »
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.

You are correct, but try to think like a businessman (which is how we get into this problem - no self respecting engineer would abandon a conflict monitoring process). If they get the idea that its just odds, a form of gambling that replaces a budget item with $0 and they can not book the contingency liability because they can just lie, they'll do it in a heartbeat. The only way you can fight this is put a gun to their head and cock the trigger.

They don't see it as an active cost to the business - so they don't believe it exists for them. Until they do, you can't get traction.

The problem is that everybody has gotten used to treating LEO as an infinite resource. And it turns out that it is finite.

This is an old economic problem: the global utility function would be optimized by action A, but the individual utility function is optimized by action B. Guess what people will do...

Statists would call this a market failure. Libertarians would say that the problem is that a resource that has no owner will be used as if it was free. In any case, it is difficult to get the actors to choose action A if action B is more profitable for them in the short term.

In the long term, the major space faring nations will have to define some code of conduct for using LEO, and enforce it by sanctioning everybody that violates that code of conduct. There are beginnings of such a code of conduct: for example you are supposed to at least vent your upper stage to prevent upper stage explosions. You are supposed to deorbit your satellite at the end of its life if possible. And if it is a GEO bird you are supposed to use the last drops of propellant to send it to a graveyard orbit. But as far as I know there are no real sanctions if you fail to do any of this. Kind of like the united nations  ;)

I know that at least the europeans take this code of conduct very seriously. For example they usually won't allow small sats without propulsion system as secondary payloads for high LEO missions. The russians and the chinese probably just don't care.

It would still be very reassuring to have the capability to do something about the problem if something goes wrong. On the oceans you have the law of the sea, but to give people an incentive to actually obey this law you also have the US navy...

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Not really - people talk themselves into working around the problem by avoiding the trash zones. Then they think they'll just not have another  accident. That's exactly what will happen here.

Avoiding the trash zones is not always possible. For example a project I am involved with requires a sun-synchronous orbit with the exact same parameters as an existing satellite. It is absolutely impossible to change the orbital parameters even a bit to avoid debris. And flying a collision avoidance maneuver is a major PITA if you are flying two satellites in close formation.

Especially the people doing earth observations are very worried about the situation. Most of them use relatively high altitude, high inclination orbits that are right in the middle of the zone polluted by that stupid chinese ASAT demo and the recent collision.

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Lasers are very efficient at converting energy, not efficient at converting energy to metal vapor/explosions - look at the end to end process here. Particle beams heat metal/glass/electronics/composites much more efficiently.

One nice thing about particle beams is that most materials are affected by them in almost the same way, whereas with a laser you have large variation between e.g. a piece of mirror and a piece of black plastic. But a laser is much easier to focus over large distances, so I think it will still be the better choice.

The total amount of energy you need to deorbit all small space debris is not that high, so you can probably live with inefficient coupling.

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Correct. Even better, you can create the lasing cavity in interesting ways that can take advantage of the hard vacuum of space to get greater efficiencies than on earth.

It's harder for particle beams, and they are heavier as well. But you get more effect of what you want per watt.

Wouldn't a particle beam also have problems because of the earth magnetic field? Or are you talking about a neutral beam? In any case, my gut feeling is that the laser still wins.

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I know - that's how they make life more interesting. But I guarantee that a particle beam weapon in orbit will get their attention.

If the russians had a) the money and b) the need to put such a thing in orbit, they would not hesitate for a second just because the USA might be irritated. Russians being irritated is just something you will have to live with if you do anything significant in space...

Quote
You need a bulk switched semiconductor laser with high duty cycle feeding an optically coupled array of YAG crystals with a very large radiator to cold soak the bulk switching and crystals. Very severe thermal issues here.

I completely forgot about that. Getting rid of heat in space is almost as difficult as collecting energy. So in addition to the huge solar array, this orbital brush (laser battle station sounds so militaristic) will have some huge radiators.

Quote
As an aside, VASIMIR and/or other plasma engines are basically unfocused particle beams - you could use the same equipment to change orbit that you use to generate a particle beam weapon.

Now that's an interesting concept: an electric engine that also doubles as a particle beam emitter. Which of the existing electric propulsion systems would have the most coherent beam? Hall effect, VASIMIR or ion engines? I still think it would be difficult to get a significant effect on a target a useful distance (>100km) away.

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Also, considering the MHD properties, you can generate plasmas from nuclear sources as well very "weight/size" efficiently, so current limits don't necessarily require 4 Shuttle equivalent launches of PV arrays.

I think nuclear power is unrealistic. But solar power is not as bad as the ISS suggests. The dawn spacecraft has a weight of 1250kg and a solar array producing 10kW at 1AU. And that is a complete spacecraft.

So a 100kW solar array should be possible for significantly less than 10 tons.
« Last Edit: 03/09/2009 09:04 PM by rklaehn »
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Offline nooneofconsequence

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Re: Cleaning up near earth space
« Reply #87 on: 03/09/2009 10:16 PM »

The problem is that everybody has gotten used to treating LEO as an infinite resource. And it turns out that it is finite.

It's called "the rape of the commons". Quite a bit of experience with it.

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This is an old economic problem: the global utility function would be optimized by action A, but the individual utility function is optimized by action B. Guess what people will do...

Statists would call this a market failure. Libertarians would say that the problem is that a resource that has no owner will be used as if it was free. In any case, it is difficult to get the actors to choose action A if action B is more profitable for them in the short term.

In the long term, the major space faring nations will have to define some code of conduct for using LEO, and enforce it by sanctioning everybody that violates that code of conduct. There are beginnings of such a code of conduct: for example you are supposed to at least vent your upper stage to prevent upper stage explosions. You are supposed to deorbit your satellite at the end of its life if possible. And if it is a GEO bird you are supposed to use the last drops of propellant to send it to a graveyard orbit. But as far as I know there are no real sanctions if you fail to do any of this. Kind of like the united nations  ;)

Note the current fun and games with Chinese ships happening right now. Violates international law. Only matters when they wish to. Sanctions are a joke.

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I know that at least the europeans take this code of conduct very seriously. For example they usually won't allow small sats without propulsion system as secondary payloads for high LEO missions. The russians and the chinese probably just don't care.

It would still be very reassuring to have the capability to do something about the problem if something goes wrong. On the oceans you have the law of the sea, but to give people an incentive to actually obey this law you also have the US navy...

Note the Chinese are playing hardball with the US Navy.
Quote

Quote
Not really - people talk themselves into working around the problem by avoiding the trash zones. Then they think they'll just not have another  accident. That's exactly what will happen here.

Avoiding the trash zones is not always possible. For example a project I am involved with requires a sun-synchronous orbit with the exact same parameters as an existing satellite. It is absolutely impossible to change the orbital parameters even a bit to avoid debris. And flying a collision avoidance maneuver is a major PITA if you are flying two satellites in close formation.

Same issue with halo orbits. But at least you don't have high differential speed in these cases, so even if they "bump", the debris isn't like bullets.

Speaking of which, it would be a royal PITA to clean up L1/L2 points.
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Especially the people doing earth observations are very worried about the situation. Most of them use relatively high altitude, high inclination orbits that are right in the middle of the zone polluted by that stupid chinese ASAT demo and the recent collision.

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Lasers are very efficient at converting energy, not efficient at converting energy to metal vapor/explosions - look at the end to end process here. Particle beams heat metal/glass/electronics/composites much more efficiently.

One nice thing about particle beams is that most materials are affected by them in almost the same way, whereas with a laser you have large variation between e.g. a piece of mirror and a piece of black plastic. But a laser is much easier to focus over large distances, so I think it will still be the better choice.

Actually you can get beam coherence of particles just like photons - the technique is used in accelerators/particle storage rings. While you can't use a cavity (the particles stick/erode mirrors) like a laser, you use microwaves to cascade/phase particle groups.

You can focus lasers in the "near field" (where the geometry of the "lens" is significant in size to the source/sink foci) , in the "far field" case you are left with the size of the beam determined by the diameter needed to keep from being diffracted (e.g. parallel and not pinhole). That vacuum isotropy allows you to reach diffraction limits (actually slightly better for a weird effect with certain optical cavities - takes some quantum mechanics to describe) means you can just barely do this.
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The total amount of energy you need to deorbit all small space debris is not that high, so you can probably live with inefficient coupling.

Not so sure of this given coupling effects we previously described. But I guarantee with a particle beam you can vaporize/explode at tens of miles with current(hah!) techniques - you will have sufficient, measurable dV.
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Correct. Even better, you can create the lasing cavity in interesting ways that can take advantage of the hard vacuum of space to get greater efficiencies than on earth.

It's harder for particle beams, and they are heavier as well. But you get more effect of what you want per watt.

Wouldn't a particle beam also have problems because of the earth magnetic field? Or are you talking about a neutral beam? In any case, my gut feeling is that the laser still wins.

It has to be compensated for given tracking (right hand rule), and shooting down polar orbit debris would have interesting issues. You don't want a neutral beam because a) they don't couple to metals/glasses as well and b) they are more inefficient to generate (unless you want to play with nuclear items).
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I know - that's how they make life more interesting. But I guarantee that a particle beam weapon in orbit will get their attention.

If the russians had a) the money and b) the need to put such a thing in orbit, they would not hesitate for a second just because the USA might be irritated. Russians being irritated is just something you will have to live with if you do anything significant in space...

The main reason they'd complain is because of the budget/work/time they'd need to duplicate/better such work - throws them off plan.  :)
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You need a bulk switched semiconductor laser with high duty cycle feeding an optically coupled array of YAG crystals with a very large radiator to cold soak the bulk switching and crystals. Very severe thermal issues here.

I completely forgot about that. Getting rid of heat in space is almost as difficult as collecting energy. So in addition to the huge solar array, this orbital brush (laser battle station sounds so militaristic) will have some huge radiators.

Yes - and even worse is the thermal runaway - you need more than just a large passive radiator.
Quote

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As an aside, VASIMIR and/or other plasma engines are basically unfocused particle beams - you could use the same equipment to change orbit that you use to generate a particle beam weapon.

Now that's an interesting concept: an electric engine that also doubles as a particle beam emitter. Which of the existing electric propulsion systems would have the most coherent beam? Hall effect, VASIMIR or ion engines? I still think it would be difficult to get a significant effect on a target a useful distance (>100km) away.

Anything that generates plasmas - the same technique you use for propulsion is to increase current flow. The main difference is in what is referred to as "beam control". Electron accelerators, like the famous SLAC LINAC have refined beam control to a fine art.

Do some research on the topic - you're just not familiar with it. Just as you might also be presuming that high energy laser vaporization is easy - its not as easy as it seems. Details, details...
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Also, considering the MHD properties, you can generate plasmas from nuclear sources as well very "weight/size" efficiently, so current limits don't necessarily require 4 Shuttle equivalent launches of PV arrays.

I think nuclear power is unrealistic. But solar power is not as bad as the ISS suggests. The dawn spacecraft has a weight of 1250kg and a solar array producing 10kW at 1AU. And that is a complete spacecraft.

So a 100kW solar array should be possible for significantly less than 10 tons.

Dunno. Not my department. Just notice that for the ISS, those array's push Shuttle limits - probably for good reason.
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Offline rklaehn

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Re: Cleaning up near earth space
« Reply #88 on: 03/09/2009 10:59 PM »
It would still be very reassuring to have the capability to do something about the problem if something goes wrong. On the oceans you have the law of the sea, but to give people an incentive to actually obey this law you also have the US navy...
Note the Chinese are playing hardball with the US Navy.

Makes sense. Whenever there is a new president, somebody tests his resolve. Maybe they get lucky and obama will stop surveillance of the south china sea to avoid "provoking" the chinese.

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Same issue with halo orbits. But at least you don't have high differential speed in these cases, so even if they "bump", the debris isn't like bullets.

Speaking of which, it would be a royal PITA to clean up L1/L2 points.

At least the relative velocities are small, so you could collect all the big bits with a space tug.

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Actually you can get beam coherence of particles just like photons - the technique is used in accelerators/particle storage rings. While you can't use a cavity (the particles stick/erode mirrors) like a laser, you use microwaves to cascade/phase particle groups.

You can focus lasers in the "near field" (where the geometry of the "lens" is significant in size to the source/sink foci) , in the "far field" case you are left with the size of the beam determined by the diameter needed to keep from being diffracted (e.g. parallel and not pinhole). That vacuum isotropy allows you to reach diffraction limits (actually slightly better for a weird effect with certain optical cavities - takes some quantum mechanics to describe) means you can just barely do this.

There is no strict boundary between near field and far field. At least theoretically you can focus on arbitrary large distances. Of course the light in the focus will not be a point, but a disk with a diameter determined by the diffraction limit.

I guess you could say that the far field begins when the disk created by the diffraction limit when focusing on a point is as large as the aperture. But for a large (>1m) aperture, that distance is >200km away.

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Not so sure of this given coupling effects we previously described. But I guarantee with a particle beam you can vaporize/explode at tens of miles with current(hah!) techniques - you will have sufficient, measurable dV.

If you can really get sufficient energy on target over large distances then a particle beam might indeed be the better choice. But the laser will also work. Even a "worst case" object such as a piece of a broken mirrors will have some spots where it is not completely reflective (the back side and/or the edges).

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Wouldn't a particle beam also have problems because of the earth magnetic field? Or are you talking about a neutral beam? In any case, my gut feeling is that the laser still wins.

It has to be compensated for given tracking (right hand rule), and shooting down polar orbit debris would have interesting issues. You don't want a neutral beam because a) they don't couple to metals/glasses as well and b) they are more inefficient to generate (unless you want to play with nuclear items).

Then you need an accurate model of the earth magnetic field and/or a way to observe the beam and walk it into the target.

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You need a bulk switched semiconductor laser with high duty cycle feeding an optically coupled array of YAG crystals with a very large radiator to cold soak the bulk switching and crystals. Very severe thermal issues here.

I completely forgot about that. Getting rid of heat in space is almost as difficult as collecting energy. So in addition to the huge solar array, this orbital brush (laser battle station sounds so militaristic) will have some huge radiators.

Yes - and even worse is the thermal runaway - you need more than just a large passive radiator.

But the radiator to get rid of the low temperature waste heat is probably the biggest mass item. The cooling system (pumped liquid) can be designed similar to what you do on earth.

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As an aside, VASIMIR and/or other plasma engines are basically unfocused particle beams - you could use the same equipment to change orbit that you use to generate a particle beam weapon.

Now that's an interesting concept: an electric engine that also doubles as a particle beam emitter. Which of the existing electric propulsion systems would have the most coherent beam? Hall effect, VASIMIR or ion engines? I still think it would be difficult to get a significant effect on a target a useful distance (>100km) away.

Anything that generates plasmas - the same technique you use for propulsion is to increase current flow. The main difference is in what is referred to as "beam control". Electron accelerators, like the famous SLAC LINAC have refined beam control to a fine art.

But a particle accelerator that creates coherent particle bunches would look completely different than an ion engine where you mainly care about high currents and don't really care about coherence as long as the ions are going roughly in the right direction.

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Do some research on the topic - you're just not familiar with it. Just as you might also be presuming that high energy laser vaporization is easy - its not as easy as it seems. Details, details...

I don't claim to be an expert in this field. I have some physics knowledge, but nowadays I work as a software engineer in space operations. And I am not saying that it is easy, just that it is possible.

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I think nuclear power is unrealistic. But solar power is not as bad as the ISS suggests. The dawn spacecraft has a weight of 1250kg and a solar array producing 10kW at 1AU. And that is a complete spacecraft.

So a 100kW solar array should be possible for significantly less than 10 tons.

Dunno. Not my department. Just notice that for the ISS, those array's push Shuttle limits - probably for good reason.

First of all, the shuttle has surprisingly little payload to that stupid orbit the ISS is in because of the russians. And second, the ISS solar arrays are a 20 year old design, and 20 years are a long time when it comes to semiconductors.

The dawn solar array is an example of a state of the art solar array. Obviously it has a specific power of significantly more than 10kW/t or 10W/kg. So it follows that you can get 100kW in 10 tons if you are willing to pay for the ridiculously expensive triple junction cells.
« Last Edit: 03/09/2009 11:06 PM by rklaehn »
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Offline DrCoffee

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Re: Cleaning up near earth space
« Reply #89 on: 03/15/2009 09:30 AM »
It seems most ideas tend to favour some laser or particle beam.
My fear of this is what happens to the part of the beam that does not connect the target but continues to whatever is in its path. If pointed to earth it will connect earth’s atmosphere. If it continues through space,  mmm....  would that not cause some unknown signal to be sent out or damage some asteroid or comet that could wander into its path?

Oh, well, maybe it also means nothing.

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Re: Cleaning up near earth space
« Reply #90 on: 03/15/2009 09:55 AM »
It seems most ideas tend to favour some laser or particle beam.
My fear of this is what happens to the part of the beam that does not connect the target but continues to whatever is in its path. If pointed to earth it will connect earth’s atmosphere. If it continues through space,  mmm....  would that not cause some unknown signal to be sent out or damage some asteroid or comet that could wander into its path?

Oh, well, maybe it also means nothing.

The problem with both laser beams and particle beams is to keep the beam diameter small enough so that sufficient energy arrives at the target. Over larger distances, the divergence of the beam will make it completely harmless.

A ground-based installation would obviously never fire towards earth. And a space-based weapon would fire almost horizontally for maximum effect, so it would not fire towards earth either.

You should probably avoid firing the beam if there is an active satellite in view though.
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Re: Cleaning up near earth space
« Reply #91 on: 03/15/2009 10:15 AM »
Right in the beginning Blackstar said “The only realistic policy is to try and reduce the amount of junk that is produced from each launch.”

I know this is a major change in direction within this thread, it might even warrant opening a new thread.

If a totally clean launch were possible, the growth in space debris would be limited to a large extent.

Some time back I saw some investigation in using electromagnets to launch object…. I did not see or notice if they had actually been able to place an object into orbit and was wondering if anyone knows of these experiments and what has come of them..

Offline Jim

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Re: Cleaning up near earth space
« Reply #92 on: 03/15/2009 11:18 AM »
It is not just launch that causes the debris, spacecraft are part of the problem.

As for electromagnets, not really viable for spacecraft, only bulk material.  Nothing has yet to be orbited. Also it doesn't solve the debris problem

Offline kevin-rf

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Re: Cleaning up near earth space
« Reply #93 on: 04/02/2009 06:50 PM »


Interesting article on the wires, calling for active removal...

http://news.yahoo.com/s/ap/20090402/ap_on_re_eu/eu_sci_europe_space_junk
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Offline gospacex

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Re: Cleaning up near earth space
« Reply #94 on: 04/02/2009 08:21 PM »
If it [laser] continues through space,  mmm....  would that not cause some unknown signal to be sent out or damage some asteroid or comet that could wander into its path?

Yeah right, poor two-mile wide asteroid can be badly hurt. Gotta be careful...

Offline khallow

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Re: Cleaning up near earth space
« Reply #95 on: 04/02/2009 09:34 PM »
Right in the beginning Blackstar said “The only realistic policy is to try and reduce the amount of junk that is produced from each launch.”

I know this is a major change in direction within this thread, it might even warrant opening a new thread.

If a totally clean launch were possible, the growth in space debris would be limited to a large extent.

This would just delay the need for orbital cleanup. Bottom line is human activity in orbit creates debris. We can reduce the rate at that debris is created, and for low orbits where air resistance deorbits debris on the order of decades or shorter, that may be enough to keep those regions viable. But for orbits where debris can loiter for centuries or longer, that isn't good enough.
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Offline nooneofconsequence

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Re: Cleaning up near earth space
« Reply #96 on: 04/08/2009 06:26 PM »
"Wise men talk because they have something to say; fools, because they have to say something" - Plato

Offline Patchouli

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Re: Cleaning up near earth space
« Reply #97 on: 04/08/2009 07:11 PM »
I completely forgot about that. Getting rid of heat in space is almost as difficult as collecting energy. So in addition to the huge solar array, this orbital brush (laser battle station sounds so militaristic) will have some huge radiators.
Depends if you need to deal with high thermo loads continuously or for just a short peak period.
If it's just for a short duty cycle vs continuously then dealing with the heat is no longer as big an issue.
Many high power laser can't fire continuously anyway they'll melt down or they are pulsed lasers anyway.

If you only need to deal with a 100KW or more thermo load for only a few minutes at a time which is all you'll have with any given piece of space debris then you can make use of a flash evaporator or even thermo mass to deal with the peak thermo load.

A few tons of water and a modest radiator no larger then those on ISS or even the shuttle might be all you'll need cooling wise.
« Last Edit: 04/08/2009 07:12 PM by Patchouli »

Offline Cbased

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Re: Cleaning up near earth space
« Reply #98 on: 04/10/2009 07:53 AM »
I have to say I don't like the idea of having lasers and/or particle guns/cannons in space even for a good cause - still looks too similar to weapons to me.

I agree with the "no new debris" agenda - it is the best we can do at t he moment.

And I've got 2 questions:
1. Low altitude debris pieces deorbit in a matter of days. Higher altitude - months/year and so on. Is there a table that will demonstrate the approximate time it takes debris to reenter as a function of an altitude?

2. The new planned Russian spacecraft in the list of requirements has got a task of capturing and deorbiting objects in space/debris. Does anyone know more about it? Are they planning to remove non-funtional satellites or real debris pieces???


Offline Vacuum.Head

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Re: Cleaning up near earth space
« Reply #99 on: 04/10/2009 09:05 AM »
http://news.bbc.co.uk/1/hi/sci/tech/7916582.stm
Comprehensive report by the BEEB including ESA's proposed Space Situational Awareness capability.
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