orion project question

[kunkmiester]

What was the high end size limit the engineers were looking at? One paper was showing 4,000 tons, but I was also looking at volume and dimensions.

I can't remember what exactly I was googling but I came across this:
http://www.nss.org/settlement/space/ber ... detail.htm

Which is one of the smaller colony ideas. Looking at it, it puts it at about 840 feet in diameter. I'm thinking that's too big, especially if it's two or three times that in length.

However, I was looking at how big you could make it for monolithic ground launch. Obviously, Orion is the only thing that could hope to put it in orbit economically. I'm sure that 500 feet is reasonable, but I'm not sure how many people you could fit in there--Bernal intended 10,000, cutting it down like that might make 2-3000 max, I don't know. I do know it'd be much bigger than anything we've put up there, and monolithic launch means that it might actually be reasonable to put in orbit. Even Jupiter isn't going to make orbital assembly practical at this point.

[Skipjack]

Hmm, I would rather tie 100s of Sundancers together to form a wheel. Intuitively a wheel shaped structure seems to be more reasonable than a sphere to me.
Plus that thing can be easily transported into orbit in pieces and assembled there. Sure the wheel would not be quite as big as the sphere, but you could connect multiple wheels to get a pretty roomy station. And that would be doable with todays tech.

[csgt428]

Hmmm... It seems pretty obvious when you think about our long term best case "survival" as a race. By that I mean a continuing expansion of our horizons ....something inherently human and a part of our species. We are natural expanders and explorers...The negative among us liken it to a "cancer" on the face of the planet though that seems a bit extreme. Nevertheless, we do have limited resources here in our "cradle" and we are fast approaching some nasty reality checks as our reproductive success overwhelms our common sense. The sooner we get out there (off planet) and start bringing new resources to the table the better.

[93143]

The biggest design above is the "super" Orion design; at 8 million tons, it could easily be a city. In interviews, the designers contemplated the large ship as a possible interstellar ark. This extreme design could be built with materials and techniques that could be obtained in 1958 or were anticipated to be available shortly after. The practical upper limit is likely to be higher with modern materials.

The expense of the fissionable materials required was thought high, until the physicist Ted Taylor showed that with the right designs for explosives, the amount of fissionables used on launch was close to constant for every size of Orion from 2,000 tons to 8,000,000 tons. The larger bombs used more explosives to super-compress the fissionables, reducing fallout. The extra debris from the explosives also serves as additional propulsion mass.

...

Hmm, I would rather tie 100s of Sundancers together to form a wheel.

I would rather tie 100s of Sundancers together

100s of Sundancers

That's because you're absolutely barking mad. That is no way to do space colonization...

[csgt428]

It would certainly help if a fusion drive were available to get us out there..... yes, without a far more cost effective way to boost ourselves off planet the realities of the situation are daunting. Still... think of earth as an Island in the greater scheme of things. Eventually we are going to want to leave when food, shelter, space and freedom become less and less available. Better do it while we still have trees left to build the boat heh? Besides, with robotics, software, AI, remote viewing/control and the raw materials and energy available on the moon and asteroid belt, a few techs keeping everything going could create new habitats with minimal support from Earth. The robots replicate themselves as needed and just keep on building....

[djolds1]

What was the high end size limit the engineers were looking at? One paper was showing 4,000 tons, but I was also looking at volume and dimensions.

The HIGH end? The ablative starship was one million metric tonnes+. Second generation concepts were 10,000 metric tonnes. The NASA design was ~200 metric tonnes.

I can't remember what exactly I was googling but I came across this:
http://www.nss.org/settlement/space/ber ... detail.htm

Which is one of the smaller colony ideas. Looking at it, it puts it at about 840 feet in diameter. I'm thinking that's too big, especially if it's two or three times that in length.

The Bernal Sphere is a SPHERE, not a cylinder. Diameter is uniform.

However, I was looking at how big you could make it for monolithic ground launch. Obviously, Orion is the only thing that could hope to put it in orbit economically. I'm sure that 500 feet is reasonable, but I'm not sure how many people you could fit in there--Bernal intended 10,000, cutting it down like that might make 2-3000 max, I don't know. I do know it'd be much bigger than anything we've put up there, and monolithic launch means that it might actually be reasonable to put in orbit. Even Jupiter isn't going to make orbital assembly practical at this point.

A Wang Gun would be useful for getting large quantities of raw mass to orbit.

http://www.centauri-dreams.org/?p=11598

That's because you're absolutely barking mad. That is no way to do space colonization...

Not sexy, but it is doable. Use them as cyclers...

[kunkmiester]

The Bernal Sphere is a SPHERE, not a cylinder. Diameter is uniform.

Actually, the living area is a sphere. The entire thing is quite a bit more than that, so you do have a cylindrical load, everything included.

A million tons should be plenty. Thing is, I think you could launch either the sphere, or a small version of the O'Neil cylinder into orbit. Stay inside the earth's magnetic field, and much less shielding is needed, making things even easier.

Any nuclear capable country can put a space colony in orbit. It sounds like they thought it'd be manrated easily, so you could probably put the colonists up at the same time.

India might be interested.

[93143]

That's because you're absolutely barking mad. That is no way to do space colonization...

Not sexy, but it is doable. Use them as cyclers...

Sundancer modules are less than 9 mT, with an outside diameter of 6.3 m fully inflated. And he wants to launch HUNDREDS of them to build a ring station.

Doable? Sure. Optimal? ...no.

And what do you mean, cyclers? Why would we want a cycler that big? Made out of pieces that tiny?

Stay inside the earth's magnetic field, and much less shielding is needed, making things even easier.

With the structural strength required of this thing, and the large available lift capacity (eight million tons using '50s materials, not one million, at least according to Wikipedia), I don't think it's at all unreasonable to pack it with enough radiation shielding to get the exposure down to Earth normal.

Besides, if you park it an an L point, you don't have to worry about accidentally pulling a Skylab... there'd be quite a bit of drag on a Bernal sphere in LEO...

[MirariNefas]

The Kalpana One is one of the smallest (but still large) space habitats that I've seen proposed. It would only house 5,000 people. Yet... it still would weigh 15 million tons. From: http://alglobus.net/NASAwork/papers/NSS ... anaOne.pdf

Passive radiation protection may be provided by approximately ten tons of imported lunar regolith per square meter on the inside of the hull. This implies a total mass for Kalpana One of perhaps 15 million tons.

--*edit: the above design has apparantly been revised. See: http://www.nss.org/settlement/space/2007KalpanaOne.pdf

--They now estimate 3000 people and 7 million tons, kept below the Van Allen radiation belts. It would be more if you wanted it further out.

There are differing opinions. From http://space.mike-combs.com/spacsetl.htm

a Stanford Torus would mass 10 million tons, a Bernal Sphere would come in at under 4 million tons, and a simple Space Manufacturing Facility would mass much less still

I don't really know which one to beleive, but I expect that a massive space settlement built to stand under its own weight here on earth and hold up during launch would not be the most mass efficient structure by far. I don't think that 8 million ton launches would cut it for something the size of a Bernal Sphere (even a smaller one). You could get something up there, but I don't think it would even hold 3,000 people with enough sheilding for Earth normal radiation.

So one way or another, you're going to need some orbital assembly if you want cities.

[MirariNefas]

Any nuclear capable country can put a space colony in orbit. It sounds like they thought it'd be manrated easily, so you could probably put the colonists up at the same time.

...that might be a bad idea. The structure is designed for the floors to be what would amount to walls down here. You could design some special compartments to make that work, but doing so for 10,000 people sounds like a nightmare.

[MSimon]

Any nuclear capable country can put a space colony in orbit. It sounds like they thought it'd be manrated easily, so you could probably put the colonists up at the same time.

...that might be a bad idea. The structure is designed for the floors to be what would amount to walls down here. You could design some special compartments to make that work, but doing so for 10,000 people sounds like a nightmare.

The proper terms are overheads, bulkheads, and decks.

[TallDave]

The estimates topped out at 8 million tons (40M for interstellar travel), which is a small city.

http://en.wikipedia.org/wiki/Project_Or ... ropulsion)

And that was with 1950s materials.

The bigger you make it, the better it works.

[MirariNefas]

8 million tons is more like a village. I don't buy the small city stuff.

[MirariNefas]

The proper terms are overheads, bulkheads, and decks.

Fair enough, then what I'm saying is that the decks of the craft would be perpendicular to the earth's surface prior to launch. Not so bad for a small craft with professional astronauts strapped in. It's a bit of an issue if you're trying to make an earth-like open air environment big enough to house a small city. It's even worse if you try building the interior structures prior to launch and then stick thousands of colonists inside.

[TallDave]

8 million tons is more like a village. I don't buy the small city stuff.

Depends what you consider a city, I suppose. Dyson was talking about sending thousands of people to Alpha Centauri to start a colony there.

With half a kilometer diameter, you could fit a lot of stuff inside.