boomer

After having a pint or two of apple juice, and reading the Sunday papers (Telegraph cartoon strip) in the pub, i started wondering about the following:

If you wanted to "sweep up" the space junk in the earth's orbit, how would you do so??

A traditional vacuum cleaner would be a no-no because, er, space is a vacuum thus no suction. No even a Dyson would work

Some sort of magnetic device may work for ferrous metals, but not for all the fancy aluminium and titanium alloys out there.

As yet to be invented gravity based aparatus would only work for very big objects.

Maybe some sort of "big net" could be used, or a space feather duster, but that would be cumbersome and liable to major damage.

So, has anyone got any ideas how to sweep up space rubbish?????

mb

BOB.T

I hear the internet is quite big theses days.... has to be usefull for summat

mattstant

this is too muppety for the Muppets

TonyG

Big net/bag made of kevlar. Would need to be very fine mesh though. Would also need some way of making sure that the debris didn't just bounce back out. I saw a design for something like this (some 20-odd years ago) being used to catch material mined on the Moon which was then shot into lunar orbit via a mass-driver, whereupon it was caught by the big bag thingy. The material was then to be used to construct a space colony for 10,000 people. Funnily enough, it was using technology actually available at the time.

boomer

I have been having a few more thoughts...

A "big bag" sounds like it might work, but would it "deploy" in space, as there is no air to blow it into shape (ala windsock)?

As for the vacuum cleaner idea, maybe we need to go back to the original design that actually blew rather than sucked. Jets of gas (or more probably ions) could be directed to push any debris in the chosen direction (which could be a space-net )

I am actually trying to be a bit serious here (not a Muppo). We are talking about very different physical characteristics as to those found on earth (and in gravity). Maybe a bit of lateral thinking is required?

mb

{Edited due to missing /b}

[Edited by boomer - 6/27/2002 12:32:10 AM]

TonyG

The way to deploy the bag is to set it spinning - this will also stabilise it a bit in orbit. However, you've then got the problem of steering it, although if you pick the right orbit, you wouldn't have to worry about that bit.
One problem would be 'how do you empty it?' Never seen an answer to that yet. You could either take it up and crash the bag on the Moon (litterbug!) or let it enter the Earth's atmosphere to burn up. Otherwise you'd have to devise a method of emptying it into a space dustbin of some sort (shuttle cargo bay, or some sort of orbital recycling facility, perhaps attached to the International Space Station).

AndyC_772

iTrader: (2)

Given that each piece of space junk is travelling at huge velocity relative to every other piece of space junk, any net or bag would be shredded to pieces in no time. It'd be like trying to catch bullets in a bin bag.

A.

krankyd

vacuming in space is irrelevant. Since all of the air that you breath is circulated through filters, and since there is no gravity and all the dust is airborne, the air filtration system just filter's it all out of the air..

simple really.

Mufasa

I could Zap them with my Laser...

carl

I suggest you improve your understanding of orbital dynamics before making statements like this [img]images/smilies/mad.gif[/img]

Adjacent pieces of debris will be in similar orbits thus low differential velocity. There is a possibility that you could have two pieces: one in a circular orbit and one in a highly elliptical orbit (which will be travelling like the clappers at perigee) but since the origin of this junk (certainly the big bits) is stuff like satellites that started off in similar orbits, this is unlikely.

AndyC_772

iTrader: (2)

Carl, that's a bit harsh...

I'd still argue that just a few % difference in speed would be plenty fast enough to rip through the bag. Plus, it's not the big bits of junk that are the dangerous ones - they're trackable - but the tiny bits that you can't see on radar but which can nevertheless punch holes in the hull of your spaceship.

Andy.

carl

That's interplanetary dust which is not what we're talking about. There's not a lot you can do about it because it orbits heliocentrically. There was a paper which suggested a lot of it is in resonant lock with the Earth, but there's still a lot which crosses Earth's orbit from further out because it's dragged towards the sun by the Poynting-Robertson effect.

BTW at university we had a hypervelocity impact gun which used to fire small particles at several km/s at targets. The small stuff doesn't do that much damage (punches a little hole which splashes some of the target material outwards towards the direction of the gun). 10 microns at 10km/s isn't nice though. Anyway, the smaller stuff is pretty easy to shield against -- you just have a two-layer shield which vapourizes the incoming particle as it passes through the first layer so it dissipates over a larger area on the second layer.

The big problem in low earth orbit is not interplanetary dust, micrometeorites, etc. but man-made space junk which tends to be bigger. They have to manoeuvre the Shuttle around some of the bigger bits

Edited to add that making holes in the bag wouldn't be disastrous. For a start it would probably be made of something like mylar, but once a hole was made there would be nothing to 'rip it apart'. On the Earth (well in the troposphere really) if you suddenly got a hole in something like a parachute the airflow would rip it apart. But there's nothing like that in space (although there's dust and gas it's really sparse).

[Edited by carl - 6/27/2002 4:17:17 PM]

pwebb

easy -
first decide where you want to collect the debris
next place 'domestic refuse disposal' signposts leading to the site
finally, shut the gates at 6pm and retire...
...all the space debris will be deposited overnight in front of the gates and liberally strewn down any embankments etc nearby.

alternatively, place a half empty skip outside your space station and leave it unattended - it will soon be full of old carpets and mattresses from the last few decades' space missions.

Paul W

TonyG

LOL @ pwebb.
I still think kevlar would be a better material - isn't that what's used in bullet proof vests? Presumably a conical shape would be best, then most of the debris would tend to end up in the narrow end. But which way would the open end be pointing? Would it be traveling slower or faster than the debris it's trying to scoop up.
Still got the problem of disposing of the 'waste' though. You could build an orbiting recycling facility - no shortage of energy to power it, you've got solar energy guaranteed for at least 50% of the time, more if you have a higher orbit.