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
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.
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.
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?
Quote from: Warren Platts on 03/14/2009 01:38 pm2. 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!
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.
Quote from: Warren Platts on 03/14/2009 01:38 pm2. 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.
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.
1. Exponential growth cannot happen in the absence of exponentially growing resources.
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.
5. The Moon looks good for what?
Quote from: LegendCJS on 03/15/2009 03:27 amBut 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 statement1. Cost is based on what2. ignition source lasers have limited number of firings. Less than the number of human digits3. It can't deorbit HEO junk
For the price of one shuttle launch we could build an
Quote from: LegendCJS on 03/15/2009 02:26 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
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.
The US military can turn off the civilian component of the GPS signal completely in whatever conflict zone they choose.
Quote from: LegendCJS on 03/16/2009 11:23 amThe 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.
Quote from: Jim on 03/16/2009 12:07 pmQuote from: LegendCJS on 03/16/2009 11:23 amThe 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?
THis makes for some interesting reading:http://books.google.com/books?id=q0qVc8dQrpgC&pg=PA48&dq=%22kessler+syndrome%22&ei=8FuxSaLGN6OOyQS7x_nNDQ#PPA51,M1
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.
Quote from: mlorrey on 03/17/2009 02:33 pmNow, 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 mv2Defunct satellite 1,000 kgRelative velocity 10,000 m/sTotal energy = 5 x 1010 J = 10 tons of TNTA 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.
Quote from: gospacex on 03/18/2009 05:12 pmThat'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.
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.
Quote from: mlorrey on 03/17/2009 02:33 pmNow, 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.
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.
Quote from: khallow on 03/19/2009 05:48 amHowever, 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.