Re^10: "Practices and Principles" to death

[grinder]

I think you are seriously underestimating the complexity of this endeavour. I suspect it would be easier to clean the North Pacific Gyre with a tea strainer.

Try catching a leaf falling of a tree in autumn some time. Thousands of leaves falling, everywhere, all the time. And yet, you are never in the right place at the right time.

One could probably sail to the middle of the Gyre, toss a bucket over the side and haul it back up, and find nothing but... water. You might see lots of trash float by, lots and lots and lots, but never grab a single piece.

And it is the same with space. Sure, we are led to believe that near space is full of all sorts of shrapnel ready to drill holes through delicate equipment like space shuttles or, heaven forfend, people. Go up there for a week, and you'll wind up shredded like character in a Tex Avery cartoon.

I think people forget how utterly vast space is, even low earth orbit. You are simply not going to rendez-vous with so much as a 2 inch bolt.

I also think you underestimate the mass the reflector would need to be of any use. Unless it was solid metal several centimetres thick, anything colliding with it would just drill right through. If you have sufficient mass to make it useful, you won't have the energy available to move it around. Make it light enough to move around, and you won't be able to do anything, it will just be shredded like a hand going through a rice-paper screen.

God, I sound like a hippy but still, I say we should avail ourselves to cleaning up the oceans. The heavens can wait.

[BrowserUk]

Try catching a leaf falling... toss a bucket over the side and haul it back up...

Leaves are subject to winds which are chaotic. Sea borne litter is subject to currents and winds and is even more chaotic.

Space debris moves according to well-known and relatively simple mathematics. They can even account for atmospheric drag. Their paths are very predictible, barring collisions which do occur, but relatively infrequently due as you pointed out, the vastness of the volumes of space involved. And they are predicted, for every space mission. Launches and returns.

An example of the predictability of space debris trajectories.

I also think you underestimate the mass the reflector would need to be of any use.... If you have sufficient mass to make it useful, you won't have the energy available to move it around. Make it light enough to move around, and you won't be able to do anything,

A 1.25" x 15ft x 30ft (3cm x 4.5m x 9m) titanium ellipse: Mass 4 tonnes. You could double the thickness for 8 tonnes and the shuttle could still easily get it up there. And the arm could deploy it. The Columbus science module taken up last month was 15ft x 30ft and 12.75 tonnes. It was manipulated from the cargo bay into position for attachment using a robotic arm. Albeit ISS' arm, not the shuttle's.

The reason debris is such a risk to ISS modules is because their walls are made of two skins of thin aluminium (3mm or 4mm?). Some of the debris are bits of titanium which is nearly twice as strong and 60% denser. Soft, thin collides with harder denser, and the latter wins.

If you fire a bullet at brick wall face on, it penetrates. Fire it at an angle and it bounces off. I seem to recall an incident of a gunman firing at the driver of a car through the side window at an angle, when the glass crazed but the bullet bounced off rather than penetrating. But it might have been a movie rather than a real life incident?

I'm quite expecting for the idea to be shown to be bunkum, but most of your points don't do that. Your point about the vastness of the territory is valid, but remember the idea is send the shuttle up at the end of it's useful life never to return. Remote controlled, with vastly increased manouvering fuel and no rush to get any particular place fast.

So you aim it at the point you want it to be to intercept one or more pieces of debris in a few days or weeks time and give it a gentle nudge in that direction. In a vacuum, it'll get there eventually. And you concentrate your efforts on clearing specific important orbits, like the frequently used equatorial launch paths used by things like the European ATV and Russian Progress supply vehicles to and from the ISS.

[dragonchild]

It would be exceedingly unlikely that any concept thrown together in the 20minutes BrowserUk took to think through his reply (I normally take about 3, at best!) would be workable in its first incarnation. Heck, it's unlikely that any code I write is going to be workable in the first incarnation.

The key here is that there are solutions and, frankly, it's not that hard to get them going. And, it's not a matter that you're going to rendezvous with a 2" bolt this year. The question as posed 6 replies back was how to effectively make space something that private enterprise can colonize. tilly brought up the tragedy of the commons and cleaning space. I replied with one possible way that private enterprise can solve that specific problem. BrowserUk then replied (several replies later) with one possible way to solve the technical problem of cleaning space. I didn't care what the solution was, only that if there was enough potential revenue, a solution would be found. Just like the problem of clearing minefields post-conflict. Right now, it's expensive. But, imho, that's just because the value of clearing the mines is too low. If several US states were heavily mined, the cost of de-mining them would go down significantly because there would be competition to clear the land because there would be significant value in having that land cleared. Right now, there are mines in places where the land has little value. Increase the value of the land to be cleared and you increase the number of companies willing to invest in mine-clearing technology, thus driving down the cost of removing a single mine.