Science a GoGo's Home Page Forums General Discussion General Science Discussion Forum we really do need to clean up the junk in space

this morning the crew on board the ISS were occupying emergency escape pods due to defunct space junk.

http://www.csmonitor.com/USA/2012/0324/A...at-gets-serious





USA X37-B
RUSSIAN MAKS


http://www.youtube.com/watch?v=-snm5HqR2Uc

seems like the un-manned vehicles could maneuver into position , open up a door and scoop up old defunct satellites and debris and bring them back to earth or take the junk further out and jettison the junk or satellites into our sun.
think about the big bucks that could be had retrieving broken satellites and re-deploying them after repairs have been made

Unfortunately it really isn't that simple. The orbits of the junk are very much spread out and trying to match them would take an incredible lot of fuel. Just turning an open bay door to the junk would not work very well, because the approach velocity would probably be too high for safety. There have been a number of suggestions of ways to capture it, but so far nobody has come up with anything that will really work. And the problem just keeps getting worse. Every launch creates more junk. Actually the big pieces are probably not the main problem. The main problem is small stuff, things like bolts. They are hard to track, and if they hit with sufficient velocity they could hole a space craft. I seem to remember that more than once they had to replace windows on the Space Shuttle because they had pits from running into things like flakes of paint.

As far as reusing broken satellites. They tried that with one of the earlier satellite launches from the Space Shuttle. It failed immediately after release and they spent a couple of days and several space walks trying to get it going. They never succeeded. Then they did another mission and recovered the satellite. It was repaired and then relaunched, but it wasn't really economical. And that was a satellite that was designed to be recovered by the Shuttle.


Bill Gill

we were discussing un-manned craft so crew safety is null.
I think that trying to catch up with space junk would require alot of energy , but since the sun shines all the time up there if you want it to then why couldnt it just sit there
in the sun shine charging up batteries waiting for some junk to come along , then speed up to the junks speed and harpoon it or net it , then drag it back into a trash bin.

LOL

ion thrusters use electricity not gasoline and since there arent any gas pumps in space yet , the craft could just use the free energy available from the sun for maneuvering.

things that arent that simple can be made simple using simple thought and imagination.

95,000 ft high toy robot.

http://www.youtube.com/watch?v=ZCAnLxRvNNc&feature=related

just think of the possibilities , note the balloon didnt require a billion dollar rocket strapped to it ass.

Most of the junk is moving way to fast to simply put something in the way it would punch straight thru it.

You need clever engineering to stop that look at the protective shielding on the ISS.

http://en.wikipedia.org/wiki/Whipple_shielding

LOL

I was just thinking about the whipple shielding and the little toy robot.

and the net.

I know it should be much cheaper to build and deploy but even though it would cost ((( WAY ))) less and would not be as technical as a large trash collector would cost to build and deploy.

why not use 4 really small craft and a net !

we know where the junk is and the 4 craft dragging the net behind them could just tow the net around the earth scooping up the space junk.

remote controled or even programatically controled via the data we have on the position and velocities of the junk.

if they get hit by a micrometeor and become unuseable then your out a few thousand dollars.


but if a large multibillion dollar craft is damaged that has a crew onboard then that would surely show that the 4 smaller craft would have been much better.

Paul, the net wouldn't be able to hold the debris when it hit it. It is traveling at much too high a velocity to be stopped by a net. The net would soon be shredded. And there would go the few thousand dollars for the robot, and the millions of dollars for the launch.

Remember that the debris is mostly small stuff and it is not in any standard orbit. It is going around every which way at large relative speeds with respect to any catcher.

Bill Gill

The main problem is that the junk is a vast cloud that surrounds the Earth from the top of the atmosphere to beyond geosynchronous orbit.

Bill Gill

didnt I say that the 4 craft could travel around the earth scooping up the junk?



so , if the junk is traveling at 20kph then the 4 craft towing the net would have to be traveling over 20kph to just catch up with the junk.

also I would think that you wouldnt try to catch the junk traveling in the opposite direction or at any significant velocity other than the velocity of the net itself.

but did you know that if the 4 craft overtake the junk as it is traveling at 20kph and the 4 craft are only traveling at
20,001 meters per hour by the time the junk passes into the net the impact from the collision would be minimal and even that impact can be greatly reduced.

just divide 1 meter per hour by 3600 seconds and you will have the impact speed.

2.7e-4
.00027 mps

not much damage there to the junk or the net , I wouldnt think.

not all of them , sometimes when there is a collision there are hundreds more objects from the collision.

there are currently millions of debris in space these range from small parts to whole defunct satellites , LOL.

before long we will need to clean up our trash dump in space in order to use space for any purpose.

check it out , Lockheed Martin has thought about it too.



http://www.pcworld.com/article/251582/lo...pace_trash.html

according to the article above there are at least 20,000 known debri objects in orbit , these must be the larger ones , just think the 4 craft could be fitted with junk finding instruments that detect unknown debri and radios its telemetry to earth , that debri could then be scheduled for pick up later.

and the nice thing about using nets is that the 4 craft could take the full nets to a drop off point further out in space and then go to the ISS to get fitted with a new empty net...

possibilities.

20kph ?????

Ready look at whipple shielding (http://en.wikipedia.org/wiki/Whipple_shielding)

=> impact shield used to protect manned and unmanned spacecraft from collisions with micrometeoroids and orbital debris whose velocities generally range between 3 and 18 kilometres per second

18 km per second is => 1080 km per min => 64800 Km per hour

You want to try and manouvre and match the speed of a piece of debris moving at that speed have you any understanding of the reaction time your spacecraft is going to have to pull that off.


To put in in perspective mach1 for a jet is between 1100-1200 kmph depending on height.

The particles are doing MACH 54 and you are going to match their speed to scope them up??????

yea , I did write 20kph but I meant 20k kph sry.

and I wasnt trying to catch a micrometeoroid.



so whats the problem?
are you just trying to make a mountain out of a molehill.

are you saying that 3 - 18 km/s is not possible?

earths escape velocity is apx 11.2 km/s

are you saying that people or computers that are piloting the craft remotely would be stupid enough to crash into the debri at a devastating velocity while retrieving the debri traveling at 3 - 18 km/s?

you are traveling around the sun right now at apx 66k/mph
and so is the computer screen in front of you how much damage would you do to the computer screen if you slowly reached out and touched it?



why not , as long as Im not using a gasoline powered piston engine there should be no problem.

and if it takes a few laps around the earth to catch up to it to bag it then theres still no real problem there either.

why do you want to make simple things sound difficult?

dont you already know that using reactionless propulsion you can scoop up all the debri and still have the same amount of energy you started with and plenty more?

It is EXTREMELY difficult the particles have gravitational attraction to every other particle in space and they don't travel in straight lines they are wobbling and moving all the time thats why one can not say with certainty if one is going to hit the ISS.

So you are going to try and manouvre with an object wobbling at MACH 54 and close and capture it.

The only thing remotely like that at the moment is a patriot missle and thats maximum MACH 5 (http://en.wikipedia.org/wiki/MIM-104_Patriot)

The earth speed has nothing to do with anything it is the relative speed of the two objects the earth is spinning under the patriot missle as it tries to knock out the enemy missle as well.

Paul Physics.org has a discussion of such a planned speed matching satelitte and that is targetting to match only large satelites which have relatively modest wobbles the smaller objects would tumble and wobble around more.

Note the thurster and technical challenges listed.

http://www.physorg.com/news/2012-02-swiss-satellite-tackle-space-debris.html

And the Swiss satellite will only take out one relatively large piece of debris. The small stuff will just keep on going and increasing in count.

Bill Gill

the wobbling of a tiny object is null.

unless your trying to capture the object with a three pronged
fork.

unless the tiny wobbling objects are orbiting each other at a significant distance as they orbit the earth.

just how much of a wobble are you talking about?

say for a 1/2 inch cubed object , would its wobble show physical impossibilities?

a object cannot have a wobble more than its own size
and that wobble can only be due to its center of gravity
or its wobble can be due to its gravity and the combination of other objects gravities as the objects orbit each other.

speaking of three pronged forks.



why not attach a net to the four prongs in the above fork !!

huh...to simple and cost effective?

have you ever tried to use one of these in a game room to grab anything?

you only get a couple of tries then you have to put another quarter in and start over again.

finally

why not use reactionless propulsion such as described in the below video , I think , anyway it looks similar to something me and kalog was discussing in this forum before he left.

http://www.youtube.com/watch?v=y77MUuP0gUk

in the above video you see a mass being accelerated inside a tube or on a rail in one direction and decelerated in the opposite direction , both the acceleration and deceleration would cause motion of the overall system in a single direction.

!!! the sun could shine light on solar pannels and the thing could stay in space and pick up all the trash because
the deceleration = energy generated , additional energy if ever needed could be had from solar panels.

BTW --- such a propulsion system would have no real speed limitations.

Paul please read the wiki discussion of space debris in LOW EARTH ORBITAL (LEO)

=> http://en.wikipedia.org/wiki/Space_debris <=



What they are saying is they wobble because the earth, sun and moon wobble ... its called chandler wobble. You then add in slight atmospheric drag and its a reciepe for alot of movement especially on small objects.


The situation you are talking about is much higher up




I have no doubt if you chase the debris for long enough you can get enough perturbation data to match it but that doesn't make it a speedy process.

I am with Mike you are much more likely to zap the small stuff rather than get anywhere near it.

just how much perturbation are you talking about there
1 inch 1 ft 1 mile?

you still havent said just how much of a wobble you are talking about.

and I suppose that the current projects would be speedy , LOL
capturing 1 single object then burning up the craft and object durring the process.

just how long would it take to remove the 20,000 known and tracked objects?

I think that there would be no problem catching up to any orbiting object , nor would there be any problem capturing any orbiting object its wobble or speed would present no serious problems.

if the 4 craft were controlled by a computer and the computer "sees" an object that is not recognised as a valid operating satellite or platform then the 4 craft could be guided to the object then the 4 craft can detach from each other moving outward and away from their previous position and expand the net , then slowly capture the object in the net.

then the 4 craft could manuver towards the earth and apply a braking to release the object and let the object burn up all alone durring re-entry or simply point the object towards our sun and apply braking to send it into the sun to burn up.

and other than a object that has been set into a wobbling orbit due to a collision or some other force wouldnt a craft following behind a wobbling junk object also wobble?

and the 4 craft could just stay up in orbit around the earth doing this trash cleanup until they are replaced by newer versions of space trash trucks that scoop them up and send them into the earth to burn up.

you guys need a little imagination to go along with your negative thinking towards everything.

its a good thing there werent many of you doubters around when we first used the nazi war weapon ideas and turned them into a space program.

You can't quantify the wobble it's not like it's regular or really predictable in most cases.

Look conceptually it's like chasing a rock thats being thrown a few inches over the top of the pond.

At some points you will get periods where it's flying nice and constant a bit like you describe and is true at higher space orbits.

But randomly either because the atmosphere is slightly bulged because of terrain below or position of moon or sun or because the orbit of what you are chasing it will touch the atmosphere.

So in our rock example the rock just hit a wave on the pond.

What happens well anything .... our rock can bounce up, stop dead, sink into the water.

If it stops violently for example you will slam into it at extremely high speed.

This is why the tracking of the objects by SOCRATES updates twice a day (http://celestrak.com/SOCRATES/) and 200 odd very dangerous pieces are continually tracked.

You are sort of describing a stable space flight scenario and what you are describing would probably be true for recovering high orbit junk but not the 70% of junk that is a problem in LEO.

Ours is not negative thinking it's more understanding the problem correctly. If the scenario was as you picture SOCRATES could put out data like for a year ahead because all the orbits would be slow and predictable.

so , if its not a good idea then how is the following trash truck going to have a slight chance of a sucessfull mission?



should they reconsider that because of all the air resistance their craft would encounter their concept has a fatal flaw and could never accomplish its intended goal?

or are you over emphasizing the amount of air resistance.

seems to me that a larger craft would be affected by air resistance more than tiny space craft would.

and a net should see less air resistance than a big box with a big grappling hook on the front of it.

BTW , wouldnt that grappling hook tend to flip the box around as it encounters the massive amounts of air resistance
at 20 km/s

Read what they are recovering ... a satellite.

The satellite is still in stable orbit and would not be bouncing off the atmosphere.

This is very different to recovering space debris which is bouncing off the atmosphere.

It's really only space junk in that the satellite has probably stopped working etc not that it has started bouncing off the atmosphere. So it would be space junk not space debris that they are recovering and there is a difference between those two things.

Well, it is debris, because debris is anything that has been "discarded". The satellite hasn't be discarded, but it is just hanging there and is useless. Essentially it has been "abandoned in place".

That of course doesn't have much to do with the problem. This satellite may be able to bring down one satellite, but the cost of doing it for all the abandoned satellites is going to get really large. And that doesn't even start to address the millions of small items that may be even more of a hazard, because it is almost impossible to track them. NASA is tracking around 18,000 items from 10 cm in diameter and up. That's about 4 inches for those of us in the USA. Items smaller than that are almost impossible to detect. And they may be even more dangerous because of that. And trying to catch them with some sort of scoop is a really tricky enterprise, because the orbits are so wildly variable. Most of them will be traveling with such high velocity with respect to a scoop that they would just punch right on through it like a rifle bullet through a metal road sign.

Bill Gill

well I guess I'll say it again.
if the "scoop" is traveling close to the same velocity as the
debri it would just slip into the scoop or net with no collision at all , just like a controlled landing.

nets are really strong , Im not talking about using rope fishing nets, metal nets with holes in them apx 1/2 inch square or more or less would be best.

the more we discuss this the more I think it is the best way to catch debri in space.

I think my idea is the best I've heard so far.

Paul, I guess I will try this one more time. The debris does not all have the same velocity. Some of it is traveling E-W, some N-S, some at all orientations in between. Plus a lot of it will have a vertical component to its velocity. So at any one location there is no way to match the velocity of the debris field, since it doesn't have any one velocity. Every piece of debris has its own velocity.

I wonder if we could come up with something like silly putty that would hold anything that hit it. It would probably have to be something pretty special. First it would have to be able to keep its consistency in a vacuum. That is a pretty good trick in itself. Then it would have to be able to absorb the energy of anything that hit it without volatilizing. In fact it is beginning sound like a good science fiction material. But if we could do that we could throw up balls of the stuff and then when they get saturated we could deorbit them and let them burn up in the atmosphere.

Bill Gill

bill , I dont think that silly putty would hold its size in the vacuum.

it would probably expand.

of course if the debri would punch through a net or a scoop then wouldnt the debri also punch right through silly putty if it expanded or not?



you guys keep saying that , possibly thinking that there would be a complete idiot designing the craft I suppose.

or maybe its not that at all.

yes its pretty clear that the debri would travel in all directions and also that the debri would not all have the same exact speed
so why do you guys have to keep repeating the same old borring stuff?


is it that that is your only argument , and you like it so your sticking to it.

when I wrote the following...



doesnt close to the same velocity (speed + direction) seem to you to cover the below that you wrote.



given that people who design these types of things actually think about the above situations
wouldnt you think that they would automatically know that?

and program a interception course to capture the debri even if the capturing craft is not folling the exact
course that the debri is on...

have you ever shot a rifle at a moving target or a bird.

if you have then you should know that your bullet does not have to be following in the exact
course that the bird or target is on in order to intercept the target.

heres a thought helper video that might help yo to understand somewhat how a craft might capture a debri
that is not on the same exact course or traveling at the exact speed as the debri target.

http://www.youtube.com/watch?v=UrlSqDe-_-Q

and heres another thought assist via video that shows an moving target being trapped in a net fired from a gun.

http://www.youtube.com/watch?v=AJnVR_aGDeA&feature=related

15k lb truck stopped by a net

http://www.youtube.com/watch?v=FYLxgKbjP64

a system that calculates the moment of impact and then fires rockets or other systems to counteract the impact force from the debri collision prevents the collision from changing the velocity of the retrieving craft.

or how about this.
F14 trap on a carrier.

http://www.youtube.com/watch?v=EoZm_bFDJDE

this pilot probably is estatic that you guys arent the people who do the engineering
of emergency aircraft landing equipment onboard aircraft carriers.

http://www.youtube.com/watch?v=ct17otlE58k

and another that is more visible , so that you dont get confussed.

http://www.youtube.com/watch?v=QHGp5wEuRAE&feature=related

and guess what , theres no energy consumed in the system that stops the aircraft on a carrier.

its all just pressurized air on top of hydraulic fluid in large pistons with cables attached to them.


and guess what else , there has never been any two landings on aircraft carriers
where the aircrafts exact course and velocities were exactly the same.

but the arresting system on aircraft carriers works very well.

theres no ( REAL ) reason this type of system couldnt be deployed to capture
the tiny debri or even the biggest defunct sattelites in space.

Let's assume your scoop is in an orbit approximately the same as the ISS. The orbital speed of the Iss is 17,227 mph (27,724 kph). If your scoop meets a piece of debris that is traveling in the opposite direction at the same speed the meeting speed will be twice that or 34,454 mph (55,448 kph). I just checked on the web and the M16 rifle fires a 5.56 mm bullet at a muzzle velocity of 3,110 ft/s (948 m/s) = 2,120 mph (3,412 kph). This bullet will penetrate a 3/8 inch mild steel door. If it was traveling at 16 times that speed how far would it penetrate? And that is the problem with your scoop.

Bill Gill

the same 3/8 inch...



not really, but that is the reason for the scoop / net.

wouldnt you think , unless we can expect to do this for the rest of time.



its spooky but it is catching



oh my !!!



http://www.futuretimeline.net/21stcentury/2030-2039.htm

Kessler Syndrome. This scenario is where space junk reaches a critical mass, triggering a chain reaction of collisions until virtually every satellite and man-made object in an orbital band has been reduced to debris. Such an event could destroy the global economy and render future space travel almost impossible.

So, here is another idea for a way to clean up the junk.

Physorg.com has an article about a possible way that has been suggested. Use a plasma beam from another satellite to change the velocity enough to let it decay into the atmosphere and burn up.

Bill Gill

I dont see why that wouldnt work either.

or a sound wave cannon directed inside the plasma beam.

Having thought about this over night it seems like it might work. The biggest problem would be all the small stuff. Getting things like nuts and bolts, or even smaller stuff, down might be tricky. And in some ways the small stuff could be worse than the larger stuff. It is too small to detect reliably, and there is more small stuff than big stuff. I'm talking about things like paint flakes. But just taking care of the things that you could hit with the plasma beam would be a big help.

If I recall correctly NASA is tracking things larger than 10 cm. That's about 4 inches. There is a huge amount of stuff smaller than that up there.

Bill Gill

and that amount increases and increases.



you would think that they would be more careful wouldn't you.

well , Im not sure if it would help , and it might even make things worst but putting magnets in orbit should attract the ferrous objects.

and any collisions of an object such as a bolt with the magnet would result in an overall reduction of the speed of the object because of momentum transfer (magnet + object)
especially if the object sticks to the magnet.

could even result in a slow enough orbit to allow for decay.
if not it would have to wait until more object's stick to it.

might make it even more messy up there though for awhile until the small ferrous stuff is cleaned up by the magnets.

and of course if the magnets get too close to a working satellite or platform it could attach itself to the satellite or platform and change its velocity.

which would require a velocity adjustment by that satellite or platform.

if you had a vehicle that fired several hundred of the heavy neo magnets at a satellite this would change the overall mass of the satellite and cause its orbit to decay if the magnets stuck to it.




you could even adjust a falling satellites impact point this way.

if a satellites path is determined to be over a densely populated area you could use the magnets to cause the satellites point of impact to occur over a ocean or
unpopulated area.