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Archive for the ‘Colonization’ Category

Rand Simberg talks about impedance matching. So I’d like to make a post of my comment there (I’ve always wondered why this obvious alternative gets mentioned so little…)

What to do when you arrive at Mars or Earth with your solar electric propelled vessel?

So, the problem with most low fuel demand velocity change schemes is that they only give slow accelerations. Low fuel high velocity change means solar or nuclear electric propulsion and aerocapture mainly.

High delta vee aerobraking is hard to do in one pass – it gets dangerous because of atmospheric variability and potentially other reasons.

Simple: detach a small capsule with the humans that goes directly to the surface (with only days of life support) and leave the untended craft to do multi-pass aerobraking. Hitting van Allen belts a few more times or taking a long time doesn’t matter that much with no humans onboard.

You could also potentially ultimately leave the long distance craft at some Lagrange point instead of LEO. (Cue some clever and complex maneuvers to save fuel – maneuvers that take long.)

Something similar could also be done when a long distance stack is assembled in LEO: send the humans there only after it’s through the belts. They can go with a smallish capsule again. Potentially at some Lagrange point, or in space without any fixed reference, just along the way. It could be dangerous though if the capsule doesn’t have much life support.

Many of these things have potential delta vee penalties as well as timing inflexibilities, but they could have enough other benefits that they should be considered.

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Noticed by Things Break. I’ve only seen Solaris. It had a lot of good in it, although it was quite uneven and somewhat overlong. Certain acting is very intensive and memorable. Having read the book twice, I even experienced it completely differently both times. The American version from 2002 with George Clooney I haven’t seen completely, but from the first quarter, it seems to have some large stylistic jumps from the book which I find odd – the props in the seventies Soviet version actually seemed much more fitting to me! Probably everybody just reads the book differently.

One of the great themes of Stanislaw Lem seems to be dysfunctional organizations. This should ring a bell with my readers… 😉 Though Solaris is very different from all of his other stories. But I don’t want to spoil too much.

I have also read the Strugatski brothers’ Stalker, which was also cinematized by Tarkovski. It was a peculiar book and felt somehow like a weird mishmash with too much familiar and unreal blended to work as a whole. With some changes it might actually work well with modern special effects – or I hear that the computer game of the same name actually is great, though maybe not very plot intensive. Stalker was actually filmed in Tallinn, Estonia I hear and you can see the place somewhere there (if they haven’t torn it down, they’re rebuilding at a pace there).

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He who controls the [Earth-Moon Lagrange points/Phobos/Deimos/Lunar North Pole], controls the solar system.

Why?

Because in space, it is not the tyranny of distance that sets the rules – it’s delta vee instead.

Since there’s no resistance, traveling large distances just takes longer, but doesn’t necessarily require more propellant. Unmanned craft can take this long trip time just fine. This is completely different from the implicit mental models of everyday life or historical exploration, travels and colonization. Even places that are far away in distance can be close in delta vee, and vice versa.

The Earth-Moon Lagrange (EML) points have really low energy trajectories to all the other places, including low Earth orbit (or Earth re-entry). They’re the crossroads. They’re probably not controllable though, like you can’t control low Earth orbit either, it’s just a figure of speech* to stress their significance.

For example, Phobos and Deimos have really low delta vee needs from EML2. And they have really low gravity. This means that it’s cheap to send stuff to them, but perhaps more importantly, it’s cheap to bring stuff from them. Since a lot of space faring is limited by mass that can be brought to locations, a low energy source of material is a real paradigm changer.

The Lunar north pole’s peaks of eternal light are much closer to Earth, but the Moon is so heavy that it takes quite a lot of propellant to descend to and ascend from the surface. The good constant sunlight is an asset though. The area is limited so this is the best incentive so far for a “race”, though I’m skeptical of that.

This post was written partly inspired by Paul Spudis’ and Clark Lindsey’s talking about the importance of the Moon as an enabler for other stuff – I am somewhat less certain. (On VASIMR and JIMO I can refer to Kirk Sorensen who has good reasons for skepticality – the power to mass ratio needed is huge and that’s the really hard part, yet it’s rarely talked about. Space reactors are much harder than Earth ones because of the cooling problem.)

We must dismiss analogies that do not work, since space is a different medium. We must use completely different planning than for exploration on land or the seas, because of the completely different role distance plays. And we must also plan on advancing from exploration ultimately to infrastructure, colonization and self sufficiency.

*: From Frank Herbert’s Dune of course.

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The Man. On Space Review. [EDIT: About a month ago, but I only just read it.] This is just excellent. So many things I agree with, that go against the stupid myths of spaceflight and space policy. If you read one space policy interview this year, this should be it!

“NASA is an organization that is dominated by fixed costs. In business terms everything is in the overhead,” he said. The committee found, with some effort, that the fixed cost of NASA’s human spaceflight program is $6–7 billion a year. “The bottom line is that they can’t afford to keep the doors open with they money they’ve got, let alone do anything with it.”

However, he said, if you’re trying to minimize costs, it makes more sense to use a smaller launch vehicle that flies more frequently and has other users and applications. The key to making that work for exploration architectures that require large amounts of propellant—and hence have driven the planning for heavy-lift vehicles like the Ares 5—is the use of propellant depots and in-space propellant transfer. “If you use in-space propellant transfer, it’s no longer true that you have to have a really big piece,” he said.

He said that while he had his own opinions on the right selection of launch vehicles, he didn’t have any insights on what direction the White House and Congress would go. “It’s really up to policymakers whether we have a space program or a jobs program.”

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Concept art of lunar bases tends to show spherical or cylindrical structures, but they suffer from one problem: radiation. (Both of the gamma / particle and heat kinds). The lunar environment has lots of solar and cosmic radiation. Nights also last for two weeks, during which a badly insulated thing will freeze.

If you bury your moon base under a layer of regolith, you can avoid both of these problems. You don’t have to bring heavy shielded modules from earth, or heat during the night with nuclear batteries. Regolith is thermally well insulating.

NASA seems to catch onto this a little in some clearly low budget “alternative configuration” posted at Nasawatch, but it only goes halfway, putting some shallow “berms” around cylindrical structures, for shielding.

In reality, lunar bases (if crews are to spend many lunar nights there) would probably be completely buried.

Burying might actually be easy: a small automated/remotely controlled snow blower style rover vehicle might be able to do it slowly with the help of just solar power. Since there is no air, tiny amounts of regolith can be thrown large distances. A thin wheel with whiskers spinning rapidly would throw the sand to the wanted direction. A lunar day is 336 Earth hours. Even if the “regolith lobber” robot can not survive the night and is expendable, it could manage to move significant amounts of regolith. A sub-MER size rover with large solar cells could throw perhaps 20 grams of regolith per second, or 72 kg in an hour. That’s 7 tons if there is 100 hours of efficient sand throwing time.

Say, landing at 50 hours from dawn, setting up 50 hours (survey area, lower rover from lander, unfold solar cells etc), operating for 150 hours (which includes maneuvering 50 hours and sand lobbing 100 hours), and finally stopping at a low sun angle 50 hours before dusk.

Such concepts are probably unlikely to work in an atmosphere, though I would be happy if proved wrong. The 2009 lunar regolith excavation challenge is coming up, after all…

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Testing Quickpress (EDIT: it didn’t really work.)
Stuff like this happens when using a common resource not owned by anyone. In this case, fisheries.

Via Michael Tobis. Go read the post.

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FAO published some numbers on fishing today:

Global marine catches have been stagnant for over a decade, hovering at around 85 million tons per year. Meanwhile fisheries productivity — measured in terms of catch per fisher, or per fishing vessel — has declined, even though fishing technology has advanced and fishing effort increased.

Naturally, with a global resource that nobody owns or regulates, everybody is trying to exploit it before others can, leading to its decline and reduced benefit for all. Actually, it’s even worse than a grab free for all – governments subsidize vast overfishing fleets.

This is a game theoretical problem. If people can’t do agreements or there can’t be any agreed regulation, the situation leads, perhaps not to the last fish being caught, but at least to the state of fisheries being kept so low that fishing is very barely profitable.

A local optimum (everybody fishes for themselves as much as they can) is very far from the global optimum (total fish catch is increased and it is easier to fish since there are more fish when everybody limits the amount they fish), but the lack of coordination prevents from reaching the global optimum.

This nicely and sadly illustrates how things like contracts, agreements, treaties or regulations could improve the situation for everyone involved.

Of course from one fisherman’s viewpoint, it’s not his fault that everyone is fishing, and any regulations would only hurt him (in the short term they would).

In the past many such things were not a matter of much attention. Technology was so primitive that one could not overfish the seas. Or in other, smaller places where the limits of exploitation could be reached, nations controlled their resources wholly, meaning they could enforce regulation by themselves. It is mostly in the twentieth century that the effects of human action have been so vast that there have been needs for international regulation.

It would be interesting to hear how a libertarian takes these things into account. In my view “everybody for themselves” is a good strategy for many problems, but too simplistic to be used for everything. We see now where it has lead with global fishing.

Central control has also resulted in vast environmental damages, and hurting people as well. The Aral sea is one example.

Hence one would need some kind of negotiations between all the effecting and effected parties, and science and justness based decision making to manage the global fisheries. It is a very hard problem, not technically (you just fish less, nothing could be easier!), but politically.

At the same time, it is a test for humanity. Can this 6 billion bunch of apes engage in decision making that results in the medium term in positive results for all, even though it can be bad for some persons in the short time (though they can be compensated). On this finite size planet, as our capabilities grow, more and more actions are having longer term effects on the whole system. That means the future of both the actor as well as others.

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