Debris Policy on other worlds/bodies

[G'th]

So, lately I've been poring over material about the Constellation program (among others) and something that occurred to me was the rather high amount of debris that would be ejected somewhat randomly onto the Martian surface. Much of it would come in the form of the aeroshells and the ascent vehicle (I didn't see what they would do with it, but I would imagine deorbit), but even so. It seems strange that for what would likely be several landings you'd end up with over 3x that in debris crashed into the surface.

Obviously I can understand that the debris is more or less unavoidable as Constellation was designed, but I'm curious as to what NASA's policy actually is in regards to debris when it comes to places like the Moon, Mars, etc. Do they actively minimize it? Do they try to control where it actually ends up so that potential science! isn't destroyed or otherwise inaccessible?

I know during Apollo they initially ejected the S-IVB's out of the system and then moved towards turning them into impactors for seismic readings, so in that case I can see why the debris was acceptable. But for something like Constellation, I'm curious as to the thought process behind why the debris would have been acceptable beyond the simple "not wanting to redesign the entire mission" bit.

[Kryten]

NASA would avoid creating enough debris to hinder scientific exploration, in line with the outer side treaty, but there's pretty much no way they could actually do that with foreseeable technology other than introducing life to Mars or some other potentially habitable environment.

[PB666]

I think they are more worried about bugs than debris. Provided the equipment is sterile, don't see a problem.

Of course if you are colonizing, you are going to have many landings at the same site. Possibly a landing platform.

So best to move the debris away

But also if you are colonizing that debris also represents precious metal resources, best to recycle, smelting ore on mars without a nuclear reactor is very, very expensive.

With a nuclear reactor still very expensive.

[Mazon Del]

The primary debris concern is to ensure a lack of orbital debris, so even though deorbiting various satellites from Mars orbit will probably toss chunks down at the ground, it's better to do that then to risk a collision in an environment where they have no ability to predict it. On Earth the US Space Command is pretty good about informing various people that their satellites are on a collision course (even, technically, our enemies) as nobody wants to Kessler.

[Finox]

If the debris is aluminum then it might end up being more useful than nuisance. Aluminum would be hard to manufacture on a Mars or Moon base due to the large amounts of electrical power required. It's not likely that future astronauts will have much spare power for making raw aluminum, but recycling it is far cheaper in terms of power. Thus the debris problem could be self correcting due to the value a future base would place on debris as useful scrap.

[Wild Cobra]

If the debris is aluminum then it might end up being more useful than nuisance. Aluminum would be hard to manufacture on a Mars or Moon base due to the large amounts of electrical power required. It's not likely that future astronauts will have much spare power for making raw aluminum, but recycling it is far cheaper in terms of power. Thus the debris problem could be self correcting due to the value a future base would place on debris as useful scrap.

Actually, aluminum would be rather easy to manufacture on the moon. A large array of solar cells would generate enough electricity to smelt aluminum from the moon ore.

https://en.wikipedia.org/wiki/Smelting

Out of high School years back, I worked at an aluminum reduction plant. We had two cell lines, each consisting of 150 series cells at 4.3 volts each and 170,000 amps. This produces something like 225 tons a day, per cell line. This can be done at a much smaller scale.

This calculates to about 5.85 kWh per pound of aluminum.

Just in case I'm wrong...

Someone check my math please.

If we ever do start building on the Moon, one of our first goals should be to build a smelter and foundry. We would then need to bring so little earth resources to keep building.

Edited October 22, 2015 by Wild Cobra

[NuclearNut]

Actually, aluminum would be rather easy to manufacture on the moon. A large array of solar cells would generate enough electricity to smelt aluminum from the moon ore.

https://en.wikipedia.org/wiki/Smelting

Out of high School years back, I worked at an aluminum reduction plant. We had two cell lines, each consisting of 150 series cells at 4.3 volts each and 170,000 amps. This produces something like 225 tons a day, per cell line. This can be done at a much smaller scale.

This calculates to about 5.85 kWh per pound of aluminum.

Just in case I'm wrong...

Someone check my math please.

If we ever do start building on the Moon, one of our first goals should be to build a smelter and foundry. We would then need to bring so little earth resources to keep building.

Hmmm. But you would also have the problem of those panels working for a few weeks and then suddenly not working for a few more weeks, also that stuff is quite flammable with oxygen, so you might have a minor combustion problem, not to mention gamma radiation produced from high speed impacts by cosmic wind. Though it would be just fine as an exterior frame for structures.

[Wild Cobra]

Hmmm. But you would also have the problem of those panels working for a few weeks and then suddenly not working for a few more weeks, also that stuff is quite flammable with oxygen, so you might have a minor combustion problem, not to mention gamma radiation produced from high speed impacts by cosmic wind. Though it would be just fine as an exterior frame for structures.

Yes, power cycles do pose another challenge... Big batteries... Looks like the biggest problem may be supplying power when the surface is on it's dark cycle. Batteries would be too massive to bring from earth. Probably need to use fuel cells, and using 2/3rds of the electricity from the solar cells to break down the water into hydrogen and oxygen and stored to use in a fuel cells while there is no solar power.

We could just suspend operation when there is no solar energy, leave the minimal amount of aluminum and molten ore to solidify, and let focused solar energy heat it back to temperature and resume smelting.

One good thing about smelting aluminum is it produces oxygen too. This would be practical for a moon base.

Aluminum does not readily burn with oxygen.

Spaceships use about a 3mm thickness of aluminum. If we are going to have larger spaces, that thickness would have to be much greater to contain the pressurized interior. Radiation inside should be greatly diminished.

Edited October 23, 2015 by Wild Cobra

[Nibb31]

Space organizations haven't had a problem with crashing stuff in deserts, steppes, or various bodies of water. They also haven't had any problem with leaving chutes and aeroshells on Mars or crasher stages on the Moon.

At this stage, as long as everything is sterilized, there shouldn't be any concern for science. As soon as we start landing humans on Mars, of course, the sterilization concern goes out the window.

[Kobymaru]

Quite frankly, what's the point of worrying about debris? Humans have been launching stuff into space for over 6 decades, and only now it has become a problem in orbit.

Space is big! To quote the quote inNibb31's signature right above me:

Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.

Probability of collisions with debris on solar orbit are so low that we can assume them to be zero.

Even collisions from a few dozen, even a few hundred pieces in Martian orbit is still incredibly unlikely.

About the surface... So what if things crash down on the surface! It's not like it can fall on peoples heads. The only thing to consider is a) it's waste material that should be recycled and maybe to not drop debris on peoples heads when approaching a landing site. Other than that - we're fine.

We might have to come back to the question in 100, maybe 200 years. But there's really no point in worrying about it now.

ps.: I don't really share peoples (and NASA's) carefulness when it comes to not microbially contaminate solar system surfaces. I'm pretty sure there never was life in our system apart from earth.

Edited October 23, 2015 by Kobymaru

[Mazon Del]

Generally speaking NASA doesn't really care about junk in solar orbit, they agree that it is hideously unlikely for there to be a collision. However, at locations of interest, such as the orbits of Mars, they want to try to minimize the junk they just leave floating in orbit there. We used to think that because space was so big, collisions in orbit around Earth were so unlikely as to basically be thought of as impossible. And then we learned otherwise. These days it is a bit easier because we have these giant radars keeping track of anything bigger than a couple centimeters, but we don't have any of that at Mars. So we might as well try to put some limits on it now, while there's still a point to doing it.

As far as your views on life. Even you just said "pretty sure" which means you yourself are not 100% certain. Until such a time as we can BE 99%+ certain that a given environment doesn't have life on it, we should make some effort to ensuring we don't accidentally drop down bacteria and such. In short, we should try to only drop life on planets that we intended to. For example, I am all for the idea of colonizing/terraforming Mars, even though there is the possibility we might kill some previously undiscovered Martian bacteria hiding out in some briny sludge. That said, until we get to the point of actually TRYING that, we should try to not mess things up too badly, just in case we do find something.

[Nibb31]

ps.: I don't really share peoples (and NASA's) carefulness when it comes to not microbially contaminate solar system surfaces. I'm pretty sure there never was life in our system apart from earth.

You being pretty sure isn't good enough. The problem is that we can't yet be 100% sure, and if we contaminate a landing site, we also contaminate any samples, so we can't be sure whether any bacteria we find is indigenous or something that we brought along.

[Finox]

Actually, aluminum would be rather easy to manufacture on the moon. A large array of solar cells would generate enough electricity to smelt aluminum from the moon ore.

Yeah, but any newly founded base is not going to have much power to spare for quite sometime after its establishment. Even if you landed with a small nuclear reactor you're still only going to have at most a few MW of power available. Even with all the power in the world available it would still be much cheaper to recycle scrap aluminum. Your right that any base would want a foundry early on though, a small foundry and a machine shop are on my list of things to bring to Mars!

Edited October 23, 2015 by Finox