Author Topic: Kessler on the Kessler Syndrome (March 8, 2009)  (Read 26898 times)

Offline Warren Platts

I found this new paper by Donald J. Kessler himself that he put out on his website less than a week ago that includes his thoughts on the Cosmos 2251 - Iridium 33 collision. Some highlights:


"We are entering a new era of debris control….an era that will be dominated by a slowly increasing number of random catastrophic collisions.   These collisions will continue in the 800 km to 1000 km altitude regions, but will eventually spread to other regions. . . .

Some of the most environmentally dangerous activities in space include large constellations such as those initially proposed by the Strategic Defense Initiative in the mid-1980s, large structures such as those considered in the late-1970s for building solar power stations in Earth orbit, and anti-satellite warfare using systems tested by the USSR, the U.S., and China over the past 30 years.  Such aggressive activities could set up a situation where a single satellite failure could lead to cascading failures of many satellites in a period of time much shorter than years." [my bold]


Think about what this means:

1. The Kessler syndrome is not something abstract that might or might not happen in the future. It's happening now. The early phases of exponential growth always happen so slowly that they're hardly noticeable.

2. Consider the part about large constellations--like GPS constellations. The US built the first, now the Russians and Europeans each have their own. Whose next? Such triple redundancy is not only unnecessary, it endangers the space environment for everybody. One world government, anybody?

3. Consider the part about large structures. The risk of collision for anything in orbit is proportional to its cross-section area. We can start to forget about space solar power for Earth, space elevators, and big O'Neil-style colonies in Earth orbit. Only small, comparatively maneuverable, manned space stations situated in what is basically Earth's upper atmosphere will be practicable. They will never get much bigger than the ISS.

4. Rogue nations and NGO's could wreck a lot of asymmetrical havoc if they wanted.

5. The Moon all of a sudden looks pretty good.
« Last Edit: 03/14/2009 01:44 pm by Warren Platts »
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Offline Jim

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #1 on: 03/14/2009 02:30 pm »
Number 3 is BS.  That is just "chicken little" syndrome.  It just depends on the orbit. 
SPS would be in GSO. 
O'Neil at L2. 
 which are nowhere near 800 km to 1000 km
« Last Edit: 03/14/2009 02:33 pm by Jim »

Offline Warren Platts

Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #2 on: 03/14/2009 03:44 pm »
Number 3 is BS.  That is just "chicken little" syndrome.  It just depends on the orbit. 
SPS would be in GSO. 
O'Neil at L2. 
 which are nowhere near 800 km to 1000 km
Well, 4.33 out of 5 ain't too bad (B+).

I agree that putting an O'Neil at L2--on the other side of the Moon--would probably be the best place for one. Or maybe you're referring to the solar-Earth L2 point, which would be even better.

However, I'm not so sure about your point WRT SPS in GSO, though. For one thing, it's already kind of crowded up there, and there's no deorbiting of defunct satellites from that far up. Granted, the standard policy is to send used up satellites into the graveyard orbit, but there are already those that are defunct, and yet remain at the GSO altitude. Perturbations will cause the figure-8 pattern; eventually, if the figure-8's get big enough, they will cross the ecliptic with enough velocity to do damage. Then of course, there is the case of Express-AM11, the first GSO satellite knocked out of commission due to a collision in 2006.

Quote
A TV and comms satellite, Express-AM11, was sent spinning out of control by a chunk of cosmic crud in March 2006 in a special orbit that is becoming the Piccadilly Circus of the space lanes.

That is because its height of 22,240 miles means satellites will remain above a fixed point on the ground, allowing our TV dishes to stay pointed at them. The satellites that bring us satellite TV all orbit at the same altitude making it a relatively crowded patch of space.
http://www.sciam.com/article.cfm?id=star-wreck-satellites-collide-in-sp-2009-02

Finally, even if you think human debris is not yet a problem in GSO, with gigantic solar panels, ordinary meteors will inevitably strike such giant satellites. These collisions will break off pieces that will add to the problem. You can tell me how many thousands of years it will take for each piece broken off to burn up in the atmosphere.
« Last Edit: 03/14/2009 03:49 pm by Warren Platts »
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Offline mlorrey

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #3 on: 03/15/2009 02:34 am »
I found this new paper by Donald J. Kessler himself that he put out on his website less than a week ago that includes his thoughts on the Cosmos 2251 - Iridium 33 collision. Some highlights:


"We are entering a new era of debris control….an era that will be dominated by a slowly increasing number of random catastrophic collisions.   These collisions will continue in the 800 km to 1000 km altitude regions, but will eventually spread to other regions. . . .

Think about what this means:

1. The Kessler syndrome is not something abstract that might or might not happen in the future. It's happening now. The early phases of exponential growth always happen so slowly that they're hardly noticeable.

2. Consider the part about large constellations--like GPS constellations. The US built the first, now the Russians and Europeans each have their own. Whose next? Such triple redundancy is not only unnecessary, it endangers the space environment for everybody. One world government, anybody?

3. Consider the part about large structures. The risk of collision for anything in orbit is proportional to its cross-section area. We can start to forget about space solar power for Earth, space elevators, and big O'Neil-style colonies in Earth orbit. Only small, comparatively maneuverable, manned space stations situated in what is basically Earth's upper atmosphere will be practicable. They will never get much bigger than the ISS.

4. Rogue nations and NGO's could wreck a lot of asymmetrical havoc if they wanted.

5. The Moon all of a sudden looks pretty good.

This seems to be a bit of bloviation by Kessler, plus there is a lack of logic here.

a) a few large orbiting structures is less risky than a lot of small ones. space structures will be modular. SPS' have never been considered for use in LEO, btw, so chicken littling about them is unsupported. One incident does not a trend make.

b) It is unfortunate that some folks want their own navigation constellations, logically everybody using the same one puts everybody on the same tactical level playing field. Using separate ones implies that those developing new systems are intent on jamming the US' GPS system and they consider the US a threat to their own military expeditions in the future. Thats a much bigger problem than whether more satellites collide, it implies an intentional stance for war.

c) Rogue nations and NGO's will need their own space programs to put anything in orbit, and would need to do so illicitly, or somehow hijack existing satellites.

d) the moon can only be seen from half the Earth at once.
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Offline Vacuum.Head

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #4 on: 03/15/2009 02:57 am »

2. Consider the part about large constellations--like GPS constellations. The US built the first, now the Russians and Europeans each have their own. Whose next? Such triple redundancy is not only unnecessary, it endangers the space environment for everybody. One world government, anybody?
Whilst American's regard their GPS as a military asset and denied at will ...it is wise to have your own backup. Galileo constellation not in place yet apart from the legal minimum.

Echo Jim re: O'Neill Except to *cough* note in passing that the Mass Catcher was to be at EML2. http://www.nss.org/settlement/ColoniesInSpace/colonies_chap08.html with colonies initially at L5. Hence the <a href="http://en.wikipedia.org/wiki/L5_Society>Society[/url].

One of the nice things about the SPS program of yesteryear was the bonus of really large communication platforms with the various hardware all attached to a singular power and service structure thus avoiding the current GSO 'clutter'.
And the Moon has always looked good!
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Offline LegendCJS

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #5 on: 03/15/2009 03:27 am »

2. Consider the part about large constellations--like GPS constellations. The US built the first, now the Russians and Europeans each have their own. Whose next? Such triple redundancy is not only unnecessary, it endangers the space environment for everybody. One world government, anybody?
Whilst American's regard their GPS as a military asset and denied at will ...it is wise to have your own backup. Galileo constellation not in place yet apart from the legal minimum.

Echo Jim re: O'Neill Except to *cough* note in passing that the Mass Catcher was to be at EML2. http://www.nss.org/settlement/ColoniesInSpace/colonies_chap08.html with colonies initially at L5. Hence the <a href="http://en.wikipedia.org/wiki/L5_Society>Society[/url].

One of the nice things about the SPS program of yesteryear was the bonus of really large communication platforms with the various hardware all attached to a singular power and service structure thus avoiding the current GSO 'clutter'.
And the Moon has always looked good!

One of the other nice things about SPS is that once you have the ability to harvest the sunlight's power, convert it to electricity, and beam it precisely to receiving stations on earth, you also have the ability to aim the beams at the space junk.  This would impart momentum in the space junk by vaporizing the illuminated sides of the junk in short bursts.  From then on its just a matter of timing the pulses correctly and you can easily de-orbit all the crap up there in almost any orbit.  SPS stations would be able to protect themselves.

But guess what: studies show you don't have to wait on SPS to clean out space.  For the price of one shuttle launch we could build an aiming turret for some of the national ignition source lasers that already exist and start de-orbiting space junk today.  The invested money would also yield advances in power beaming technologies and open up really effective space weapon/ satellite killer opportunities.  So while it would mean "open season" on space weapons and destroying working satellites up there, the space junk laser could clean up after it self just as easily.
Remember: if we want this whole space thing to work out we have to optimize for cost!

Offline rklaehn

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #6 on: 03/15/2009 03:45 am »
Space debris will only be a large problem for objects in LEO. In higher orbits there is much more room for the debris to spread out. And the maximum relative velocities are much lower. Both effects combine to make the probability of a collision much lower. And a small piece of debris  will not create much debris at the lower collision velocities.

The critical zone will remain between 300km and maybe 2000km. Unfortunately this zone is very valuable for earth observation and low latency communication. But even with a worst case kessler syndrome, GSO and above would not become unusable.

Navigation sats use an altitude range that is relatively empty, so debris is not a big problem.

Offline khallow

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #7 on: 03/15/2009 07:26 am »

Think about what this means:

1. The Kessler syndrome is not something abstract that might or might not happen in the future. It's happening now. The early phases of exponential growth always happen so slowly that they're hardly noticeable.

2. Consider the part about large constellations--like GPS constellations. The US built the first, now the Russians and Europeans each have their own. Whose next? Such triple redundancy is not only unnecessary, it endangers the space environment for everybody. One world government, anybody?

3. Consider the part about large structures. The risk of collision for anything in orbit is proportional to its cross-section area. We can start to forget about space solar power for Earth, space elevators, and big O'Neil-style colonies in Earth orbit. Only small, comparatively maneuverable, manned space stations situated in what is basically Earth's upper atmosphere will be practicable. They will never get much bigger than the ISS.

4. Rogue nations and NGO's could wreck a lot of asymmetrical havoc if they wanted.

5. The Moon all of a sudden looks pretty good.

1. Exponential growth cannot happen in the absence of exponentially growing resources.

2. The constellations aren't all at the same altitude. There's no likelihood of a collision between satellites of different constellations. And remember a second copy of a service isn't redundant, if you can't count on the original service to be there when you need it.

4. They need to be able to launch something into orbit. That means launch infrastructure which is something that can be bombed. I think that will be sufficient incentive to keep most from doing it.

5. The Moon looks good for what? It's no good for most of the things you mention in points 2 and 3.

As I see it, this all points to eventual deployment of technology for cleaning orbits of debris. No matter how careful you are, you can't eliminate accidental collisions unless you stop launching things into space. Simply put, a space-faring civilization will have garbagemen in orbit.
Karl Hallowell

Offline mlorrey

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #8 on: 03/15/2009 10:27 am »

2. Consider the part about large constellations--like GPS constellations. The US built the first, now the Russians and Europeans each have their own. Whose next? Such triple redundancy is not only unnecessary, it endangers the space environment for everybody. One world government, anybody?
Whilst American's regard their GPS as a military asset and denied at will ...it is wise to have your own backup. Galileo constellation not in place yet apart from the legal minimum.


Actually they can't deny GPS at will, the best they can do is detune the accuracy for anybody who doesnt have a military chipset to about 35 meters, which is still good enough for most military applications, and that detuning also impacts civillian uses globally, not just in a specific theater.
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Offline Jim

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #9 on: 03/15/2009 11:24 am »

But guess what: studies show you don't have to wait on SPS to clean out space.  For the price of one shuttle launch we could build an aiming turret for some of the national ignition source lasers that already exist and start de-orbiting space junk today.  The invested money would also yield advances in power beaming technologies and open up really effective space weapon/ satellite killer opportunities.  So while it would mean "open season" on space weapons and destroying working satellites up there, the space junk laser could clean up after it self just as easily.

There is a whole lot of bunk in that statement

1.  Cost is based on what
2.    ignition source lasers have limited number of firings.  Less than the number of human digits
3.  It can't deorbit HEO junk

Offline Warren Platts

Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #10 on: 03/15/2009 01:25 pm »
1. Exponential growth cannot happen in the absence of exponentially growing resources.
It's true that the number of space launches worldwide has been declining for some time now.

http://www.geocities.com/launchreport/blog010.html

However, the population of space objects grows not so much by the addition of new hardware, but by the fissioning of old hardware. In a biological ecology, as Darwin and Malthus pointed out long ago, there is always something that will reign in exponential growth: predators, disease, bad weather, or simply eating up the available food supply. In space, however, the "organisms" are virtually immortal. There are no predators to speak of as of yet, and there are no corrosive diseases that can cause them to disintegrate from the inside out. There has been some bad weather lately: increased solar wind activity has puffed up the Earth's atmosphere somewhat, and so that definitely helps within the lower levels of LEO--but the solar-induced "drought" seems to be abating. Moreover, space "organisms" don't have to worry about food because they don't eat. Like biological organisms, however, (with the exception of parthenogentic hydrazine tanks), space organisms must seek out a "mate" in order to reproduce. Finding a mate has proved difficult in the past, but it's becoming less and less of a problem because the probability that two organisms will find each other and reproduce is proportional to the square of the total population N. Like biological organisms, space reproduction typically involves a smaller male "seed" that is implanted into the larger female "egg". However, as we have just seen, space organisms reproduce best of all when two "females" get together. So the space ecology violates just about every rule of biology. Unfortunately, the laws of physics are no help either.
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Offline Warren Platts

Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #11 on: 03/15/2009 02:07 pm »
This seems to be a bit of bloviation by Kessler, plus there is a lack of logic here.

a) a few large orbiting structures is less risky than a lot of small ones. space structures will be modular. SPS' have never been considered for use in LEO, btw, so chicken littling about them is unsupported. One incident does not a trend make.
It's too bad you weren't around 50 years ago to make this point! It's too late for that now. . . . (And Iridium 33/Cosmos 2251 were not first collision; it was just the first "accidental" collision between two fully intact satellites.)

Quote
b) It is unfortunate that some folks want their own navigation constellations, logically everybody using the same one puts everybody on the same tactical level playing field. Using separate ones implies that those developing new systems are intent on jamming the US' GPS system and they consider the US a threat to their own military expeditions in the future. Thats a much bigger problem than whether more satellites collide, it implies an intentional stance for war.
That's a good point. Some things are more important that space exploration--that's for sure.

Quote
c) Rogue nations and NGO's will need their own space programs to put anything in orbit, and would need to do so illicitly, or somehow hijack existing satellites.
There are lots of good hackers out there. Really, a hacker would need to get a hold of two things: (1) the "SP" high-accuracy elsets that USSTRATCOM have--presumably these can predict the position of satellites to ~10 m or better, and hence be useful for targeting, or else they wouldn't be a secret; and (2) the access codes to a private company's communication satellite maneuvering system--and how hard can that be to hack? So for $2,000 worth of computer equipment and the right skill set, it might be possible to destroy some satellites.

Quote from: Vacuum.Head
5. The Moon looks good for what?
Local opportunities for manned space travel. Ironically, because of the Kessler syndrome, the Moon is probably a safer place for humans than LEO. Don't be surprised when the service mission to Hubble gets permanently scrubbed.
« Last Edit: 03/15/2009 02:22 pm by Warren Platts »
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline LegendCJS

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #12 on: 03/15/2009 02:26 pm »

But guess what: studies show you don't have to wait on SPS to clean out space.  For the price of one shuttle launch we could build an aiming turret for some of the national ignition source lasers that already exist and start de-orbiting space junk today.  The invested money would also yield advances in power beaming technologies and open up really effective space weapon/ satellite killer opportunities.  So while it would mean "open season" on space weapons and destroying working satellites up there, the space junk laser could clean up after it self just as easily.

There is a whole lot of bunk in that statement

1.  Cost is based on what
2.    ignition source lasers have limited number of firings.  Less than the number of human digits
3.  It can't deorbit HEO junk

If you wouldn't be so quick to jump on ideas that haven't been proven and take a moment to think about it...

1. For one cost is based on this and other scientific or Air-Force studys: 
http://www.au.af.mil/au/awc/awcgate/cst/csat20.pdf
http://sciencelinks.jp/j-east/article/199923/000019992399A0814545.php
http://sciencelinks.jp/j-east/article/199911/000019991199A0322295.php

Also if you don't trust the studies, realize that the technology behind building laser targeting turrets already exists in a highly developed form ala the ABL project.  And I can't imagine that the ground station they need to build for this idea would cost more or be more complicated than something like the Keck Observatory.

2.  Ignition source lasers do have a limited number of firings, but that limit is probably more to do with funding than physics.  In any case you would modify the source laser for less power and more firings in this application.  I was pointing out that building a large enough and powerful enough laser to do the job is something that we already know how to do and have been doing for decades.

3.  Anywhere that the laser beam can see, LEO, HEO, ... junk there can be given a change in momentum.  It might take repeated firings on repeated passes, but the junk's orbit can be perturbed.  Its just a technical problem of tracking and targeting.  As others have pointed out, the higher the orbit, the less necessary the debris removal anyway.  The only area that can't be "swept up" is the regions of the Geostationary orbits that are permanently below the horizon of the ground station.
Remember: if we want this whole space thing to work out we have to optimize for cost!

Offline Jim

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #13 on: 03/15/2009 09:13 pm »
  For the price of one shuttle launch we could build an

When using the shuttle as comparison, it insinuates a orbital vehicle.  Additionally you reference the ABL, a flight experiment

A ground based laser is discussed on other threads
« Last Edit: 03/15/2009 09:15 pm by Jim »

Offline LegendCJS

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #14 on: 03/15/2009 09:27 pm »
  For the price of one shuttle launch we could build an

When using the shuttle as comparison, it insinuates a orbital vehicle.  Additionally you reference the ABL, a flight experiment

A ground based laser is discussed on other threads


If your comments are meant to tell me that I am posting in the wrong thread, then I apologize.  Look at my post count: I'm new around here, and any unspoken rules about what can be discussed where that I may have broken were not broken intentionally.

I thought that since this thread was about space debris, then talking about proposals to counteract space debris was a valid line of conversation.   Especially since the OP seems to imply that space travel is doomed to because of increasing space junk.  I was trying to say that the OP's fears are unfounded, and provided the space debris laser example as justification.

By the way when referencing the "cost" of (insert noun or action here), I "insinuates" a monetary amount.  I don't know what your talking about otherwise. 

The ABL reference was meant to show that the technology to track complicated moving targets from other moving platforms already exists.  The ground station space debris laser will have a similarly difficult task.

EDIT:  Sorry Jim I just realized where you were coming form, I forgot that you posted the original doubts about the laser concept that I posted.  My original post did not make it clear that the laser "aiming turret" was a ground based installation.  I see the source of confusion now.  I would not believe my price numbers either if it was for an orbiting laser aiming turret.
« Last Edit: 03/15/2009 09:50 pm by LegendCJS »
Remember: if we want this whole space thing to work out we have to optimize for cost!

Offline madscientist197

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #15 on: 03/16/2009 07:23 am »
Actually they can't deny GPS at will, the best they can do is detune the accuracy for anybody who doesnt have a military chipset to about 35 meters, which is still good enough for most military applications, and that detuning also impacts civillian uses globally, not just in a specific theater.

A bit OT but: I had a talk to a guy from Trimble Navigation a year or so ago and he said that they could get 2cm precision by using the civilian GPS data and the carrier wave of the millitary signal (the phase offset is proportional to the distance modulo the wavelength). This would break down if they deliberately reduce the accuracy -- but if you could also incorporate the same information from Glonass and Galileo, I bet you could massively reduce the effect of any additional offset or random error.

Incidentally, India has recently been working with Russia to restore global coverage. Unfortunately it uses a different modulation technique from GPS (FDMA instead of CDMA), however it is in negotiations to change to the same technique.
« Last Edit: 03/16/2009 07:26 am by madscientist197 »
John

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #16 on: 03/16/2009 11:23 am »
Actually they can't deny GPS at will, the best they can do is detune the accuracy for anybody who doesnt have a military chipset to about 35 meters, which is still good enough for most military applications, and that detuning also impacts civillian uses globally, not just in a specific theater.

Also a bit OT, but the below better explains why other countries would want their own satellite navigation systems.

The US military can turn off the civilian component of the GPS signal completely in whatever conflict zone they choose. After that they just jam all other navigation signals in that theater, as long as the other signal's frequencies don't overlap too closely with the military GPS signal.  This is the reason for all the frequency overlap discussions and drama between the USA and Europe concerning their Galileo system, and now between the Europeans and the Chinese over the frequency for the proposed Chinese system.  No accuracy "de-tuning" of the civilian signal required- they just turn it off. (Of course they can also de-tune it too if they want.)  Only the encrypted signal for military use would remain. 

I can't imagine that they built these million dollar GPS satellites without the simple ability to just not broadcast a certain subset of the signals it normally broadcasts for a fraction of every orbit...
Remember: if we want this whole space thing to work out we have to optimize for cost!

Offline Warren Platts

Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #17 on: 03/16/2009 11:41 am »
You all raise some good points. Are you prepared, however, to accept limits on the total number of active satellites? Most towns limit the number of liquor licenses they will issue, the idea being that one bar on each corner is enough. How many active satellites are enough?
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Jim

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #18 on: 03/16/2009 12:07 pm »

The US military can turn off the civilian component of the GPS signal completely in whatever conflict zone they choose.

That is not true.  It is always on.
« Last Edit: 03/16/2009 12:09 pm by Jim »

Offline LegendCJS

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #19 on: 03/16/2009 12:17 pm »

The US military can turn off the civilian component of the GPS signal completely in whatever conflict zone they choose.

That is not true.  It is always on.


I'll take your word for it.  It seems strange to me tho, but maybe the de-tuning to +- 35m accuracy leaves other methods (old fashion map and compass based) more accurate, so its pointless to turn the civilian signal off completely?
Remember: if we want this whole space thing to work out we have to optimize for cost!

Offline Jim

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #20 on: 03/16/2009 12:24 pm »

The US military can turn off the civilian component of the GPS signal completely in whatever conflict zone they choose.

That is not true.  It is always on.


I'll take your word for it.  It seems strange to me tho, but maybe the de-tuning to +- 35m accuracy leaves other methods (old fashion map and compass based) more accurate, so its pointless to turn the civilian signal off completely?


Just think of mechanics of trying "turning it off" one region.  30 or more spacecraft, in different positions, with only 6 (ground stations),etc.  The region would be huge.  Also turning on and off a signal that has be calibrated and validated.  What insures it is good when it comes back on?

And also I believe the military signal is not standalone, it still needs the basic signal.
« Last Edit: 03/16/2009 12:26 pm by Jim »

Offline Warren Platts

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Offline mlorrey

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #22 on: 03/17/2009 02:33 pm »
THis makes for some interesting reading:

http://books.google.com/books?id=q0qVc8dQrpgC&pg=PA48&dq=%22kessler+syndrome%22&ei=8FuxSaLGN6OOyQS7x_nNDQ#PPA51,M1

"If we had 10 platforms in orbit each 100 meters across, one would get hit each year."

Thats nice, what SIZE of object are we talking about here is going to strike? The article talks about objects down to 1 mm in size, which is something even the shuttle has previously dealt with and which even spacewalking astronauts are trained to handle. http://www.newscientist.com/article/dn10235

Furthermore, his comment is as if a 100x100x100 meter cubic volume is all pressurized modules and critical systems. Even the ISS doesnt approach a tiny fraction of one such platform.

That said as most here understand, LEO isnt one specific altitude, it is a wide range of altitudes from 100 miles up to a few thousand miles.

Now, how hard would it be to put up a few 'scrubbers'? I can imagine orbiting a satellite that would inflate a hugh Echo type baloon with aerogel, and use electric propulsion to slowly maneuver through a range of orbital planes before deorbiting. A 100 meter sphere of aerogel should be sticky enough to catch most anything.
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Offline Warren Platts

Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #23 on: 03/18/2009 01:01 pm »
Now, how hard would it be to put up a few 'scrubbers'? I can imagine orbiting a satellite that would inflate a hugh Echo type baloon with aerogel, and use electric propulsion to slowly maneuver through a range of orbital planes before deorbiting. A 100 meter sphere of aerogel should be sticky enough to catch most anything.

K.E. = 1/2 mv2

Defunct satellite 1,000 kg
Relative velocity 10,000 m/s

Total energy = 5 x 1010 J = 10 tons of TNT

A direct hit by a Cosmos 2251-like satellite might wind up blowing your gel ball to smithereens. And what goes up must come down. The Aussies might not appreciate flaming gel-balls crashing into the outback.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline gospacex

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #24 on: 03/18/2009 05:12 pm »
Now, how hard would it be to put up a few 'scrubbers'? I can imagine orbiting a satellite that would inflate a hugh Echo type baloon with aerogel, and use electric propulsion to slowly maneuver through a range of orbital planes before deorbiting. A 100 meter sphere of aerogel should be sticky enough to catch most anything.

K.E. = 1/2 mv2

Defunct satellite 1,000 kg
Relative velocity 10,000 m/s

Total energy = 5 x 1010 J = 10 tons of TNT

A direct hit by a Cosmos 2251-like satellite might wind up blowing your gel ball to smithereens. And what goes up must come down. The Aussies might not appreciate flaming gel-balls crashing into the outback.

That's why I prefer flat plate style scrubbers. They can't be blown up, only holed. Imagine how cool Cosmos-2251 shaped hole in the plate would look like :)  Not that it is intended to clean up whole sats, but it at least can survive one impacting it.

Offline MKremer

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #25 on: 03/18/2009 05:31 pm »
That's why I prefer flat plate style scrubbers. They can't be blown up, only holed. Imagine how cool Cosmos-2251 shaped hole in the plate would look like :)  Not that it is intended to clean up whole sats, but it at least can survive one impacting it.

You'd end up with a bunch of satellite debris, too, with too thin a 'plate'. Much of the larger pieces with hardly any change in energy, either, but now spreading into different orbits making the 'junk' situation even worse.

If you're going to use an impact plate, make it thick and massive enough to survive even larger impacts, so any debris left over is robbed of much of its kinetic energy.
« Last Edit: 03/18/2009 05:37 pm by MKremer »

Offline khallow

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #26 on: 03/18/2009 05:31 pm »
Now, how hard would it be to put up a few 'scrubbers'? I can imagine orbiting a satellite that would inflate a hugh Echo type baloon with aerogel, and use electric propulsion to slowly maneuver through a range of orbital planes before deorbiting. A 100 meter sphere of aerogel should be sticky enough to catch most anything.

K.E. = 1/2 mv2

Defunct satellite 1,000 kg
Relative velocity 10,000 m/s

Total energy = 5 x 1010 J = 10 tons of TNT

A direct hit by a Cosmos 2251-like satellite might wind up blowing your gel ball to smithereens. And what goes up must come down. The Aussies might not appreciate flaming gel-balls crashing into the outback.

I guess it wouldn't be a good idea to run into such a satellite then. If you can get the density of the gel-ball low enough, then it won't heat up to burning temperatures when it reenters.
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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #27 on: 03/18/2009 06:00 pm »
Now, how hard would it be to put up a few 'scrubbers'? I can imagine orbiting a satellite that would inflate a hugh Echo type baloon with aerogel, and use electric propulsion to slowly maneuver through a range of orbital planes before deorbiting. A 100 meter sphere of aerogel should be sticky enough to catch most anything.

Aerogel?  You can't treat aerogel like you treat a can of shaving cream or spray foam insulator.  To make aerojel you need a mass of liquid water or CO2 jelled with the jelling agent and the whole mass needs to be in the final desired shape.  Then you pressurize the relatively incompressible liquid and bring it on a path around and over the liquid's critical point on the PV plane, then lower the pressure but keep the temperature and bleed it off as a vapor without ever having made the liquid go through a phase transition to vapor.  That is how the structure and shape of the jelling agent is preserved with all the voids intact- no evaporation happens.  This can't be done in space like you think in an 'inflationary" manner like blowing up a balloon.

A note to all the people championing ideas that involve collisions in space- why do we want more things smacking into each other at orbital velocities up there?  Common sense and experience shows that at those energies it just ends up making more debris.
Remember: if we want this whole space thing to work out we have to optimize for cost!

Offline gospacex

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #28 on: 03/18/2009 06:02 pm »
That's why I prefer flat plate style scrubbers. They can't be blown up, only holed. Imagine how cool Cosmos-2251 shaped hole in the plate would look like :)  Not that it is intended to clean up whole sats, but it at least can survive one impacting it.

You'd end up with a bunch of satellite debris, too, with too thin a 'plate'. Much of the larger pieces with hardly any change in energy, either, but now spreading into different orbits making the 'junk' situation even worse.

Define "larger".

For every foot-sized chunk there are ten 1/3 foot sized chunks, so there are more small chinks to clean up than big ones. Also, untrackably small chunks are more dangerous, ISS et al. can't dodge those => again, cleaning up those is more important.

Quote
If you're going to use an impact plate, make it thick and massive enough to survive even larger impacts, so any debris left over is robbed of much of its kinetic energy.

Plate made with the same technology as ISS protection will stop dead 1 cm sized impactors, and I'll hazard to guess will shatter and deorbit impactors up to ~10 cm. These bigger ones will hole the plate, but it is sacrificial anyway.

This is already not so bad. The real problem is "who is willing to foot a bill for such a thing?"

Offline gospacex

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #29 on: 03/18/2009 06:09 pm »
A note to all the people championing ideas that involve collisions in space- why do we want more things smacking into each other at orbital velocities up there?  Common sense and experience shows that at those energies it just ends up making more debris.

What about a scrubber on retrograde orbit? It will have mean collision speeds of about 12 km/s, and impacts debris in the best direction for deorbiting it - roughly opposite to debris' velocity vector.

Offline khallow

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #30 on: 03/19/2009 05:48 am »
Now, how hard would it be to put up a few 'scrubbers'? I can imagine orbiting a satellite that would inflate a hugh Echo type baloon with aerogel, and use electric propulsion to slowly maneuver through a range of orbital planes before deorbiting. A 100 meter sphere of aerogel should be sticky enough to catch most anything.

Aerogel?  You can't treat aerogel like you treat a can of shaving cream or spray foam insulator.  To make aerojel you need a mass of liquid water or CO2 jelled with the jelling agent and the whole mass needs to be in the final desired shape.  Then you pressurize the relatively incompressible liquid and bring it on a path around and over the liquid's critical point on the PV plane, then lower the pressure but keep the temperature and bleed it off as a vapor without ever having made the liquid go through a phase transition to vapor.  That is how the structure and shape of the jelling agent is preserved with all the voids intact- no evaporation happens.  This can't be done in space like you think in an 'inflationary" manner like blowing up a balloon.

I guess we'll just have to settle for a stiff foam then.

Quote
A note to all the people championing ideas that involve collisions in space- why do we want more things smacking into each other at orbital velocities up there?  Common sense and experience shows that at those energies it just ends up making more debris.

We want less things smacking into each other. Hence, the proposals to remove or slow down orbital debris. Common sense and experience shows that you are incorrect in your last sentence. Sure slamming large dense objects into each other has been shown to create a lot of debris.

However, we have plenty of cases where a orbiting object is "sticky" enough to absorb the impact of another, much smaller object. For example, things collide with the ISS all the time. They're microscopic and get embedded in the ISS's skin. mlorrey's proposed aerogel ball is intended to catch or slow down small objects not one ton satellites.
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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #31 on: 03/19/2009 01:35 pm »
However, we have plenty of cases where a orbiting object is "sticky" enough to absorb the impact of another, much smaller object. For example, things collide with the ISS all the time. They're microscopic and get embedded in the ISS's skin. mlorrey's proposed aerogel ball is intended to catch or slow down small objects not one ton satellites.


Have you seen the videos of the debris impact tests during ISS shield material development?  It sure looks like a lot of crap is flying away form the points of impact to me.  Maybe its just gasses and plasmas and it dissipates harmlessly, but I'd like to know for sure what those "splashes" of material are at the impact sites before saying that the impact is completely or even usefully sticky.

I'm going to outline my initial thoughts about the foam scrubber concept.  Don't get me wrong, I relish challenging engineering design projects, and I'm not saying that these issues are insurmountable.  Every worthwhile project is challenging.

Any maneuverable foam ball will have to have thrusters, sensors, power sources (solar panels), antenna, and everything else that goes with a standard spacecraft.  All this hardware will need to be attached to a structural skeleton of some sort.  Especially the thrusters, so they don't punch right through the foam when you turn them on to do orbit changes.  At minimum all the thrusters and other components that depend on precise orientation will need to be rigidly connected to each other. 

To justify the need for a rigid skeleton structure for the foam read the following:  I've got images of a wobbling and gyrating mass of foam after a large impact in my head.  If the thrusters are only sunk in to local unconnected anchor sites around its periphery, its going to be a very hard thing to control or move while the relative orientation of the thrusters is changing randomly with time due to the heaving waves of foam underneath it.  If you try to make the foam stiff, it will have trouble being as stiff as required (remember its a big ball we are talking about here) without also loosing its ability to capture the debris in sticky collisions.  In addition every collision changes the structural characteristics of the foam mass in an un-predictable way.   So you can't rely exclusively on the foam for long term structural support or for short time stability, especially when you might need it most- to regain control after a particularly large impact.

There will need to be some kind of radiative heat rejection and thermal management of the foam mass to keep it in a stable and narrow temperature range in order to extend the foams life,  Otherwise the solar heating and cooling thermal expansion cycle will wreck the foam's integrity in no time.  The thermal management equipment will also be called on to cool the foam mass down especially after absorbing some significant impacts.  All that will require equipment distributed throughout the foam and large space viewing radiators that should also not be hit by the debris. 

Then there will need to be a trade off between how much help the foam gets in finding its debris to absorb from the ground vs from its own sensors.  The trade off needs to factor in the sensor mass and power requirements, the lead time the sensors give for different types and sizes of debris, and the reaction time and capabilities of the scrubber's thrusters.  It is a question of the needed positional accuracy to absorb the target piece of debris.  I don't know to what accuracy the orbit of the debris to be cleaned is known.  I do know that the smaller the debris the less accurate their orbits are known, so the best debris to absorb might have to be found with short notice by the scrubber itself, thus requiring powerful chemical thrusters.

Given that the scrubber is being repeatedly and purposely directed into harms way on a frequent basis, the chances that a part of the 'scrubber' getting hit that you don't want getting hit increases dramatically.  The chemical rocket thrusters might also be needed to quickly change the projected point of impact of the particular piece of debris if its found to have been a risk to a critical hardware component of the scrubber.   So the best fuel sipping thrusters for the job- hall effect or ion thrusters, might be inadequate.

Don't say you can put the foam in front and the hardware in back and then try to take all your hits form the same 'front side' direction.  Doing that will cause the scrubbers orbit to degrade or change much faster than it needs to in comparison with taking hits from all directions (assuming you can model the debris momentum flux as evenly distributed form every direction).  And you can't do all the maneuvers you might need to do if you mount all your thrusters so they thrust in the same hemisphere i.e in the 'back.'

So there are some challenging design issues here, not to say they can't be solved, but challenging none the less.  But every worthwhile project is challenging.  Maybe people can propose more specifics about the foam scrubber concepts and get some of these details worked out.
Remember: if we want this whole space thing to work out we have to optimize for cost!

Offline gospacex

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Re: Kessler on the Kessler Syndrome (March 8, 2009)
« Reply #32 on: 03/19/2009 02:19 pm »
However, we have plenty of cases where a orbiting object is "sticky" enough to absorb the impact of another, much smaller object. For example, things collide with the ISS all the time. They're microscopic and get embedded in the ISS's skin. mlorrey's proposed aerogel ball is intended to catch or slow down small objects not one ton satellites.

Have you seen the videos of the debris impact tests during ISS shield material development?  It sure looks like a lot of crap is flying away form the points of impact to me.  Maybe its just gasses and plasmas and it dissipates harmlessly, but I'd like to know for sure what those "splashes" of material are at the impact sites before saying that the impact is completely or even usefully sticky.

I didn't see videos, do you have URLs?

I saw some photos. Basically, when projectile impacts first layer, it gets shattered to pieces, or vaporizes completely if it is small enough. Then these pieces and vapors fly further through standoff gap, and impact the second layer. Impact area is bigger, but the force of the impact is smaller.

The ideas here (I guess) are (1) to produce many smaller impacts over the wider area instead of one, nearly pointlike impact which delivers all enrgy and impulse to a small area, and (2) let some part of energy to be released as light while vapors travel through the gap, and expend some of the energy for melt and vaporization.

This works best when the gap is wide, and first layer is dense. Not necessarily heavier - we want to drive as strong shock through the projectile as we can, and for that we need denser material. For example, at the same mass aluminum wall will perform worse than steel one.

If this design is to be adapted into a dedicated debris scrubber, the gap can be made really big (a few feet) to increase the diameter of debris cone, third wall can be added to repeat the same process when debris cone impacts second wall, and so on.

This can be refined further by folks who know this stuff better. I've seen advanced models with more than two walls, with two closely-spaced walls instead of one wall in the front etc. I don't know why is that better, guess there are some subtler effects at play.

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