Satellites and spacecraft face the growing risk of damage and failure thanks to the expanding volume of small pieces of junk hurtling around the Earth's orbit. Scientists have warned the amount of orbital junk has reached a tipping point in volume and size. The National Research Council has said in a report (here) that existing …
"So far the problem has been largely restricted to low Earth orbit (LEO), but geosynchronous Earth orbit (GEO) could suffer the same fate over a longer period of time."
Shurely a piece of junk in geosynchronous orbit is not moving relative to the other pieces of junk there so will not collide with it. Anyway it is all over the Equator so who cares?
Yes the junk might not be moving relating to other bits in geosync orbit BUT what happens when you want to put a $500M Satellite right where said junk is? Boom? then you have thousands if not millions more bits of junk right where you don't want it.
time to send those bin men with the iPads up there to sweep things up....
"Shurely a piece of junk in geosynchronous orbit is not moving relative to the other pieces of junk"
Methinks you need to revisit Newtons laws of motion.
Just because there is a position in the orbit of a planet whereby zero energy input is required to maintain a static overhead position of somewhere on the surface, does not mean that nothing moves in this band.
How do you think the satellites got there in the first place??
To GEO or not to GEO
Ah, what you need to remember is that when they talk about GEO they are talking about satellites which are just the right distance from the earth to orbit at (relatively) the same rate as the surface of the earth. That doesn't mean that a piece of junk couldn't be flung out there, or that a damaged satellite in GEO couldn't send off debris which might cause damage. Being in the GEO orbit doesn't mean that material isn't moving, merely that objects which stop there are more inclined to stay there (relative to the surface).
The moon, varying density of the Earth and other celestial bodies all exert forces on space objects, so as much as satellites need small adjustments to stay in position, objects which don't have station keeping systems can be pulled into inconvenient locations.
Regards, Bob (for whom 5 years of dealing with the foibles of space was a living)
I agree. The GEO problem sounds like FUD.
GEO satellites are only useful to the extent that they sit in equatorial orbits, so they presumably do form an orderly queue around the Earth with small relative velocities. Also, with fewer spacemen dropping hammers and fewer chinese missiles there is a lot less junk being produced to fill that space. Lastly, at a radius of 23500 miles, there's several orders of magnitude more room to play with than in NEO.
NEO satellites move within a smaller volume and generally don't sit in equatorial orbits so they may have relative /transverse/ velocities of many thousands of miles per hour. That will make a real mess of anything (or anyone) it hits. This isn't FUD. This is "just a matter of time".
Probably another reason to "go slow" on that manned space program. Robots don't have wives and children watching on TV back home.
No so, Im afraid.
Just last week the AM4 satellite failed to enter GEO. The craft is now completely lost in a highly inclined geosynchronous transfer orbit.
In plain english, its now out of control, in an orbit varying in height between 1000 and 21000 km, inclined at 51 degrees.
In plainer english between now and the end of time it will cover the entire volume of space between those two heights, approximately between the latitudes of london and Buenos Aires.
It's not the only uncontrolled piece of junk in a similar orbit.
Don't you think it will be more impressive if it _doesn't_ hit anything?
The chinese were infinitely irresponsible with their satellite desctruction test and proved themselves to be an unworthy and immature space nation. If they really wanted to prove the technology they could have shot down a much lower satellite that would have re-entered earths atmosphere, as the Americans did.
Instead they took the first step towards shutting the gates completely on any desires to leave earths atmosphere. Not just for themselves but for all mankind, for a duration that is measured on the geological timescale.
Unless someone starts taking the problem seriously we will see that the Kessler Syndrome is real, and the Chinese have wilfully brought it on.
Disclaimer: my job is at stake if satellites become no longer commercially viable. A surprising amount of the UK GDP is also. In fact, with the support industries, your job is probably at stake.
I'm sticking up for John Arthur on this one
The relative velocities in different bits of junk in LEO are vastly different to GEO. Objects in GEO all have to be in an equatorial orbit, in the same direction as the rotation of the earth and at the same velocity in order to maintain their relative position above the ground.
Objects in LEO are under no such constraint, the can be in polar orbits, equatorial orbits and every inclination between.
I'd say there is a lot more danger of objects colliding destructively when they're flying perpendicular to each other than from objects that are all moving in the same direction at the same speed. Even when launcing new GEO satellites the rocket has to match speed and direction for the same reasons so there's still very little chance of a collsion.
FUD?? actually it's know as FOD
Foreign Object Damage.
GEO isn't stable
Due to the Earth not being a sphere and having the moon going round it and both going round the sun geostationary orbits aren't stable. The lifetime of a satellite up there is largely determined by the amount of station keeping fuel it can carry.
Left to their own devices the satellites start drifting up and down so that from the ground they don't stay in one place but appear to loop round a figure of eight over the course of the day. Over time the inclination of the orbit gets higher and higher, so the figure of eight looks larger and larger. From the point of view of another satellite in GEO the drifting satellite is moving in a circle, crossing GEO twice a day at right angles, the bigger the circle, the faster it's moving relative to GEO so the worse any collision will be. Debris from a collision at any altitude spreads into different orbits very quickly so eventually you have bits coming at you from all directions.
Just send metal theives into orbit, they can scrounge for the scrap metals.
... all we need to do is develop a spacefaring Transit dropside van...
Rockets for scrap metal thieves?
I'm not sure what type of rocket would be best. Strap the thief to a chair with a pile of gun-powder underneath and douse in petrol, stand well back and throw a match?
Re: Space tatters
There's one for sale down the road.
Well, it's got spaceship milage on it.........
Given what they're doing up there, that should obviously read "fly tipping point".
Sorry the yanks have just scraped it.
Scraped it you say?
Don't worry that'll polish out.
Genius! I think you've just solved the Dale Farm problem!
Let's build a rocket
I say let's build a rocket! Let's see, we can make the capsule of of that cement mixer, use those old tanker trailers as the fuselage. I have some old explosives as fuel. We need a name...
How about "The Vulture"? That would be apropos.
Mine's the "Broderick Salvage" one...
I wonder how long
...it would take for all the crap to become captured by Earths gravity and burn up in the atmosphere.
Assuming nothing new was launched of course. 100 years, 1000 years???
I see NASA are helping to keep space clear.
Captured by Earth's gravity?
An orbit is a gravitationally curved path of an object (e.g. "crap") around a point in space (e.g. Earth). Ergo all of the "crap" is already "captured". In fact it never really escaped.
I think you mean slowed sufficiently through atmospheric drag to cause re-entry.
looks like we can now say...
mankind has truly arrived in space, and true to form is filling the place up with his shit.
well done us!
LEO yes, GEO, don't think so
I can understand the problem in LEO; there are lots of different orbits in different planes, different altitudes, different amounts of circularisation, different inclinations, etc. This all means that things that com into contact can be travelling at very different velocities (leading to spectacular events).
However in GEO, everything runs in a flat plane level with the equator, and at a fixed altitude, so they all go around together. Old things get pushed out to a higher altitude. Anything left un-powered at the normal GEO altitude will gently drift to one of a few dead-spots. I don't think that there is much chance of things coming together up there.
GEO usually isn't
If all the satellites in "GEO" actually were in GEO, there wouldn't be much opportunity for high-speed collisions. Many of them orbit at a slight angle to the equator, however, and that gives you the opportunity for collision at several kilometers per second.
The slight angle is the reason you see figure-8 curves when the position of the satellite is plotted on a map of the Earth. If the orbit was truly equatorial, the position would be a single point.
See my earlier post. If everything works well then its all on the same plane (nominally, but in reality +/- 3 ish degrees). However it doesn't all work well. See AM4 reports for that.
The old things getting pushed to a higher altitude is a convention that has been brought in amongst satellite operators for exactly this reason. It doesnt apply to old satellites and ones over which you have no control.
Finally the unpowered ones will as you say slowly drift to a stable orbit. Those stable points are approximately 75deg east and 105deg west. Over the indian ocean and in prime position to broadcast to the whole of the americas. To call them 'dead spots' is complete nonesense. The unpowered satellites don't just drift there either. Their orbital position slowly oscillates around the dead spot whilst decaying. As it does so the eccentricity of their orbit increases.
Commercial satellite operators routinely move their satellites out of the way of these rogue wondering junk satellites. Eventually 2 will collide, not at LEO velocities but still enough to make a mess up there.
Really, the notion that GEO satellites just stay put and don't move realtive to each other is just not true.
That's one of the jobs that RAF Fylingdales does, keep an eye on whats going on up there. Even when the space shuttle was launvhed it became an entry in the database for tracking.
Anyone remember that (short lived) series?
Venture Capital opportunity me thinks.
@ John Arthur
GSO does not mean "not moving" it means moving forward at the same rate as falling towards the ground. (Remember Douglas Adams explanation of flying " falling towards the ground and missing")
Things are still whizing about at a few hundred meters per second.
Also it's not all in a nice circle around the equator, they tend to pass overhead as well...
it (geostationary) means just that - the satellites are not moving relative to the ground and therefore each other.
From Wikipedia :
"Satellites in geostationary orbit must all occupy a single ring above the equator."
No, you've just defined "orbit" not "geosynchronous orbit". ALL orbits are "falling towards the ground and missing".
There are two special features of a GSO:
1. The period of the orbit is the same as the rotational period of the Earth (~24 hours).
2. The orbit is aligned with the Earth's equatorial plane.
As a result, from the point of view of an observer on earth, the satellite does not move.
From the point of view of a bit of space junk ejected from an exploding satellite, it's no different to any other orbit. But luckily, everything we try to put into the GSO belt tends to go in the same direction, which should help.
I remember an old Scrooge McDuck story where he went up in space to collect all that junk... And sell it to collectors back on earth.
how much it would cost to put together an LEO dustpan and brush with re-entry capability. Could you get enough back on the scrap to self-finance?
Just to correct you. Relative speeds of up to 7km/s are possible in GEO. At those speeds, objects impacting eachother pack several times more kinetic energy than exploding TNT.
Also, the anime PlanetES.
"Asteroids" has become reality. Don't they disappear after three hits?
What we need is...
...Toybox and the Debris section.
All the Americans need do is get up there in the shuttle, fill the cargo bay and then return to earth. Oh, wait a minute ...
Surely an iPad is needed?
If Bury Council think that an iPad is required to ensure the smooth running of garbage collection in Bury then surely an iPad is a fundamental part of any space junk solution? But, strangely, I could find no mention of one in the article.
Why NASA only?
Surely the Chinese, Indians and Russians can chip in too?
...when two pieces of orbiting junk cross orbits and collide, the resulting debris ends up in a number of different orbits, most of which will intersect with the Earth's atmosphere? I would have thought that the orbits of most pieces of junk would be decaying anyway, given that space isn't a perfect vacuum in the first place, and most would not be in perfect circular orbits to start with? As mentioned above, does anyone know the lifetime of these orbits? Does the claim of a tipping point really stand up to scrutiny?
Yes, little bits coming off won't all share the same orbit as the thing from which they detached, either because they were expelled with force, collided with parts of the craft, picked up some drag, etc.
The orbital decay starts immediately precisely because of what you said - space isn't a perfect vacuum and there are faint forces like sunlight, solar wind, dust, & cetera. The instant it arrives in GEO it is starting its reentry. All of the stuff up there eventually comes down or goes away, depending on what happens to it.
None stays GEO forever.
The time for that decay to result in contact with the atmosphere or the planet can be measured appropriately in seconds, minutes, ... or many hundreds of years.
Yes, tipping point is very apt, and speaks to a probability curve regarding collisions based on population, distribution, and trajectories.
At a certain point the likelihood of a serviceable satellite getting dinged and itself shedding bits becomes high enough to create a chain reaction in exactly the same fashion as that of nuclear fission reactions.
It won't be a domino or arithmetic reaction, but a geometric progression because each collision has a high likelihood of resulting in several more bits of debris.
We need sticky satellites to introduce some negative feedback so that collisions result in a decrease in junk pieces rather than an increase.
Sticky satellite.... I like it!
For the small "paint fleck" debris then perhaps something like this could be made to work? Perhaps a giant cylinder or ball with a penetrable outer surface but filled with kinetic absoarbing "kevlar foam". The thing could sweep (literally) across the heavens collecting debris then be directed back into the atmosphere.
Or, how about lazers (with a Zed) to atomise the small bits??
Obviously one for your old game series - Asteroids. I seem to remember in that, shooting an asteroid resulted in it breaking into lots of smaller ones.
Does anyone remember the Tomorrows World on this?
During the 80's? They were talking about sending up a large multilayered disk to try and catch some of it.
This is why the vacuum cleaner guy invented the Dyson Sphere, so we would have an enormous vacuum cleaner to suck all the space debris back up without even having to change the bag.
Oh, wait. That's a Dyson Ball.
Megamaid.... simple solution!!
Calling Ben Gunn
and his "space vaccum"!
I don't believe one word they say.
I bet its all a secret conspiracy to create a "spacejunk shield" in order to keep the invading aliens out of our atmosphere!
Not to mention
That the Earth is flat.