Calling all space enthusiasts

[guest]

So I'm wondering about the plausibility of a certain scenario.

Employing all of the Earth's industrial capacity at current tech levels, and accepting large scale industrial accidents and mass starvation as acceptable costs of accomplishing this mission, could a small city sized centrifugal space station with about 1-2 thousand people be placed at one of earths Lagrange points within 20 years?

[Peebo-T]

Okay, having absolutely no qualifications or other studies in any fields relating to the question, I have a few questions/sounding boards in response.

1) A lot of the planets industrial capacity is in no way shap or form useful or needed to do such a task.

2) Isn't the term "Centripetal"? Not "Centrifugal"?

3) By "Industrial accidents" are you perhaps talking about launch type failures?



As an answer, I would say that a construction similar to perhaps the station in 2001, scaled 'up' to comfortably house said number of people, could be built in the time specified, with out the starvation etc implied.

Just some thoughts. Much cheer to you and yours.

[guest]

1) A lot of the planets industrial capacity is in no way shap or form useful or needed to do such a task.

well, a lot of the planet's industrial capacity could be converted to contribute, also a lot of the industry needed for such a purpose wouldn't even need to be all that advanced, a space port can be constructed for the most part with early 20th century levels of technology, all the infrastructure needed would be roads, buildings and tons of other things which could be built in 2rd world countries, obviously the more advanced things would need to be built in specially purposed production facilities, but a lot of the stuff wouldn't.

2) Isn't the term "Centripetal"? Not "Centrifugal"?

whatever, more or less I meant a space station which generates artificial gravity by spinning

3) By "Industrial accidents" are you perhaps talking about launch type failures?

well, more or less I was referring to the fact that the drive to get the project done as fast as possible would be so great that even if say a rocket fuel production facility exploded taking out half a city, the rest of the space production pipeline would not be shut down while new safety regulations were worked out. More or less we're talking about a worldwide space travel version of the Maoist "great leap forward" modernization program. I'm not saying that it would be necessary, just that "human costs" wouldn't be too much of an obstacle.

[Broomstick]

I don't think you'd need to use more than a fraction of the current industrial capacity of the planet, and no need for starvation at all. You will risk accidents involving large numbers of people, but if you can get past that I don't think it would take even 20 years.

After all, quite a bit of the needed tech has already been researched and done small scale. We developed very powerful lifting capability for the Moon program. There has been much experience with space stations and supplying them from both the Soviets and their political descendants and the US. It would be a matter of scaling things up and accepting a certain number of launch failures, along with possible construction accidents in space.

We could probably do it in 10, if we went all out. At least as far as getting the first one or two up and running. What is lacking right now is the will, not the technology.

[Batman]

What she said. The current lack in space involvement isn't due to lack of technology leave alone industrial capacity, it's because we can't be arsed to shell out for it because at least for the time being, there's no money in it. Whether or not the permanent moon base and massive orbital stations predicted by enthusiasts to be 'just around the corner' in the wake of the Apollo program (and by quite few SciFi authors before it) were possible back then, both technologically and industrially, they'd be definitely possible now (and likely would have been since the 1990s at the very latest). The problem is they would, for a long time, be net loss projects, no matter how profitable they'll eventually end up to be (scientific, societal, and, eventually, even financial), there's a lot of no incentive for private investors as they most of the time can't think past the next year, nevermind decades, and while governments DO generally actually look at the long range picture, these days they're typically hard strapped to deal with their current ones with finances available so while they might be a lot more inclined to finance that kind of approach, they simply can't, especially with the man on the street being a lot more concerned about having reliable utilities, serviceable roads, and other immediate real world concerns being dealt with now as opposed to some future pie-in-the-skiy space project that benefits them how, exactly?

[PeZook]

The US could probably do it by itself if it comitted major funding to the project. Of course it would require cutting corners, and the Lagrange point requirement is really problematic as it severely cuts down on the weight of useable materials (and number of people) delivered per launch (we're talking an order of magnitude, since the spacecraft would need to use its own propellant to attain the position, not just a short burn to enter orbit)

But technically all it would take would be lots and lots of launches of very heavy rockets, which can be done just fine with current tech levels with no need for mass starvation. Of course we'd need to expand the infrastructure (launch, training and production).

And no, most of the world's industry could not be converted to contribute. The main bottleneck would be rocket production, for which you need precise manufacturing. While technically 1960s tech is enough to make a Saturn V, most of the world's factories can't attain that level of precision. Even if they could, the manufacturing process between most consumer gooda and rocket engines is different enough that you'd probably need to install entire new production lines anyway.

[Sarevok]

So what would be the launcher of choice ? Sea Dragon like megaboosters ? Fully reusable space planes ? Mass drivers ? Or something new altogether ?

[PeZook]

If time is of the essence, then probably classic rockets: you don't want to spend 18 years researching SSTO spaceplanes when you could've done 5000 Ares V launches in the same time. Since we assume the world throws all the necessary resources at the problem, then manufacture of classic rockets would be done simultaneously with research into things like Sea Dragon and other concepts.

We could start mass production of Ares V class rockets easily within the decade given sufficient funding. Of course I wonder if existing transport infrastructure could handle the necessary amount of launches...

[Sarevok]

But Ares V is pricey shuttle derived technology. With every launch you throw away an expensive set of shuttle engines.

If we are going for mass production would not building a cheaper design be feasible ? The Ares design is a product of present spaceflight climate with all the economics and politics that surround NASA.

[PeZook]

Ares V as envisoined would have been equipped with the RS-68, which is a cheaper disposable derivative of the Shuttle engine. And it obviously doesn't have to be exactly an Ares V, just a vehicle in the approximate weight class. We also get a free production facility that's already geared, staffed and working if we go with that one.

[Skgoa]

Yeah, the Hydrogen Core (+ SRB as first stage) with Upper Stage concept is the best we have right now. Engines that can change fuels during flight are being researched right now, but might not come into existence at all.
Rockets have been around so long because they are the most effective way of launching stuff into space. SSTO, Spaceplanes and all those scifi wank pipedreams will most probably either not be around at all during the next 20 years or if they are, they will not be as effective. At launching "dead" cargo.

[PeZook]

One of the main problems is cargo delivered per launch, which quite frankly I can't calculate, just estimate.

SOHO is on a HALO orbit near L1 and it weighs 1850 kilograms. It was launched on an Atlas II with a nominal capacity of 6000ish kilograms to LEO.

If the ratio holds for space station building stuff and larger rockets, then we can estimate a single Ares V launch would bring about 40 tonnes of supplies to L1. Of course a construction effort needs people to actually put all the crap together in an organized fashion...you could use three launches to set up a habitat for them first, another launch per month to supply the crew, and of course they'd need to be rotated. The requirements will raise exponentially as construction proceeds, though, requiring more and more launches.

[Broomstick]

But Ares V is pricey shuttle derived technology. With every launch you throw away an expensive set of shuttle engines.

Fact is travel in space is expensive, period. Make the timeline 20 years to install habitats in every Lagrange point you're going to have to make some sacrifices.

Even if you weren't throwing away engines you'd still be burning a fuckton of fuel. Sure, there are people working on more efficient ways to get into and out of space but the fact remains you need a lot of energy to climb out of the Earth's gravity well. There's a cost to doing that.

If we are going for mass production would not building a cheaper design be feasible ? The Ares design is a product of present spaceflight climate with all the economics and politics that surround NASA.

Well, if we start producing a lot of rockets we'll achieve some savings through some economy of scale. Such a program will still cost shitloads of money but cost per launch will go down. A little.

If you want to go into space, and if you want some reliability (rockets that blow up on the pad not only cost as much as rockets that successfully launch, they impose further costs due to damage to launch infrastructure from their malfunctions and the need to build yet more rockets and make yet more supplies to replace those lost) it's going to cost some money.

Now, you could cut back on some of the procedures and safety backups used by NASA. You will also experience catastrophic failure more often if you do so. NASA has lost two shuttles in 132 flights, or 1 in every 61 flights. What's your tolerance for loss of vehicles?

[General Trelane (Retired)]

That [PeZook's comment re: Earth-Sun L1] raises the question, which Lagrange point? How about Earth-Moon L4 or L5?

-Edited to add [ ].

[eion]

Each of the Earth/Moon Lagrangian points has their benefits.

• L4 and L5’s biggest advantage is their stability, and were a proposed site for the O'Neill cylinders.
• L1 makes for a great location for a midpoint between the Earth and Moon and could house a nice supply base.
• L2 is the perfect place in the solar system to locate a radio observatory since the Moon blocks out all radio transmissions from Earth, but one could just as easily build a dish in Daedalus crater (100km diameter, Arecibo is only 300m), which is quite near the center of the far-side of the Moon and has a nice 3km bowl that should block any radio transmissions from lunar satellites.
• And L3 would be a great place to locate solar power stations since it has direct line-of-sight to the Sun. It would also be a good place to locate a sunshade should the Earth need cooling down.

So the real question isn't whether we could build a city-sized rotating artificial gravity station using current tech, we most certainly could, but why we would do so. Solar power stations probably don't need that many personnel, nor do radio telescopes, but as a midway port between the Earth & Moon it might work.

[Broomstick]

Well, then L1 might be the logical one to "colonize" first, being a convenient stepping stone between Earth and Moon, which might one day translate not only into utilitarian purposes such as a supply base but also a tourist destination (never underestimate that - it can always provide valuable supplemental income). I expect you'll also have initial space industries, research facilities, and some sort of means of growing supplemental food.

Next, L3 as a power source. You'll need a small "town" to build and maintain the solar arrays and any peripheral equipment, but setting one up shouldn't be too hard after putting something up in L1. You can then add on a research base to study various manufacturing concepts, what with access to power so close by.

L2 could be used for a radio telescope, sure - you might not want this one inhabited full time, just a largely automated research station with a small docking facility for anyone out there performing construction, repairs, or maintenance.

I figure by that time you'll know what, if any, industries belong in space. Use L4 and L5 for that, whether it's manufacturing or growing food for those living in orbit or both. I figure both will start small and grow from there, ideally (if it all works out) evolving into small towns that not only have manufacturing businesses but possibly room for entertainment venues, a small number of accommodations for space tourists, and so on. The larger they become the more like actual towns they'll become, with commercial as well as industrial businesses.

Needless to say, that's an evolving picture - the initial habitats will be all business all the time. The key thing is you need a reason to be in space to launch each habitat. Once you have a stable reason for being there and it starts growing you'll get long term habitats. You won't have asteroid mining or trips to Mars to start with but these could be viable points from which to start those endeavors for the long term. 20 years out L1 might be a thriving orbital habitat, L3 and L2 might have skeleton crews and be largely automated, and construction just starting on L4 an L5. So what? You have to start somewhere and some time. On the other hand, L1 might come up with some use for space or reason to be in space we haven't thought of yet and suddenly L4 and L5 get built quickly and turn into boom towns.

Very idealistic of course - I'd love to see humanity get started on those sorts of projects but realistically there just isn't the will in the world today to make it a priority.

[Eternal_Freedom]

^! I would say that Earth-Sun L1 would be a better sight for a power station than Earth-Moon L3. If I remember my celestial mechanics correctly, the L3 point will remain on the line crossing through Earth, the Moon and the L1 point, so anything positioned there will effectively orbit Earth as well, just a long way out. Whilst it would still face the sun for all but a fraction of it's orbit, the Earth-Sun L1 station will remain in place between Earth an the Sun constantly.

Whilst it is further from Earth (two or three million km IIRC), it does have the bonus of being closer to the Sun, so the energy per square metre of solar panel will be higher than at the Earth-Moon L3. It probably works out as only a few percent, but a few percent on a massive solar panel array can be a lot of power.

Putting the solar power station there would mean it has to be automated. And it poses a problem of how to transfer that power to Earth. But you'd have that problem at the Earth-Moon L3 point anyway.

[Broomstick]

Well, it's possible I got a bit confused about which L point is where - if different positions make more sense by all means rearranged things to be more sensible.

[Eternal_Freedom]

They can get a bit muddled, especially when you're talking about different sets. Earth-Moon or Earth-Sun for instance.

[Broomstick]

I was poking around a bit on the internet and apparently we already have a couple objects at the Sun-Earth L1 point, the Solar and Heliospheric Observatory, and Global Geospace Science WIND and Advanced Composition Explorer. The Sun-Earth L2 already has the Wilkinson Microwave Anisotropy Probe, ESA Planck Surveyor, and ESA Herschel Space Observatory.

The Earth-Moon Lagrange points seem to have far less stuff in them.

Might want to take those items into account when planing space habitats. Obviously, we're already finding the Lagrange points useful.

[Eternal_Freedom]

We covered this stuff in our astrophysics lecture this morning. The Lagrange points are great of things that are low maintenence, or are only expected to have short life spans. We can't exactly run a repair mission to Herschel the way we did with Hubble. So putting stuff there means quality control ha to be even more strict than it usually is for satellites.

NB when I say short life-spans, I mean stuff like Herschel and other IR telescopes, which need to be cooled to about 50 or so Kelvin. And that burns coolant quickly.

On another thought. If we had a station at Earth-Moon L1, would we even need propellant to get stuff from the station to the moon/Earth? would we just give it a nudge, perhaps with a launcher on the station, and let gravity do the rest?

[Broomstick]

In theory, yes, but practice would probably require a little bit more than someone giving it a push with their hand.

During the Apollo 13 emergency they used the Moon's gravity to pull the spaceship towards a lunar orbit then slingshot it around the rock and back to Earth, a maneuver that used less fuel than simply turning around. It's pretty routine to use the gravity of what's out there in space to either change course or give a velocity boost to various spacecraft. There's even a thing call the interplanetary transport network for space travel that makes use of Lagrange points as a means of saving energy.

The thing to remember, though, is that efficient isn't the same thing as fast. If you're transporting humans you need to balance the cost of fuel against the cost of life support, whereas if you're talking about an automated probe or just a lump of raw materials then it might make a lot more sense to wait as it travels slowly and saves fuel.

[Eternal_Freedom]

Oh I know it wouldn't simply be pushing with your hands, that's why I said "perhaps with a launcher on the station."

Good point on the fuel/life support tradeoff though. And I'd heard of the Interplanetary Transport Network, it's a fascinating idea, and a brilliant one.

[Broomstick]

Part of the problem with selling space to the general public is they don't understand it. They don't comprehend how it works on an intuitive level. You may say, well, space isn't intuitive. Neither is driving a car or flying an airplane but a person can achieve that level of fluency with driving or flying via education and experience. Well, the average human being just hasn't any space experience, so concepts like going farther away from Earth and around the Moon gets you home faster and safer than simply turning around (like Apollo 13) just doesn't make sense.

Once we get people who really do spend time in space, when people get more exposure and experience to how things work out there, such things will become obvious to them. Planning travel will become much more second-nature, allowing travelers to pick a general strategy based on "intuition" (really, it would be informed experience) and balance out the trade-offs based on fuel vs. time vs. life support vs. feasibility of using the ITN or Lagrange points or gravitational effects, then refine it with detailed calculations rather than approaching the whole thing with brute-force computations and lots of arguing over alternatives.

[PeZook]

Broomie, I feel that i need to clarify somthing: The reason they chose a free-return option for 13 wasn't becaue it wa faster (quite the oppoite, in fact) but becaue they couldn't be sure the SMME wouldn't fail catatrophically when fired. same reason why they did all course corrections with the lunar module.

A direct abort would, in fact, have been the best option.Of course, it wouldn't look anywhere like "turning around" either