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

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.