Carriers - an idea

soph · 2003-01-13 15:38:14

An idea struck me today. Could we build large fusion or NPP ships that served as carriers? They could contain many smaller mining ships, or exploration ships, bring them out to the asteroid belt, send them out, and park while the ships did their work. they could serve as a mobile collection base. Every few years, a new carrier could relieve an old one.

The carriers could be visited by cargo ships every few months, which could take any goods back to earth or mars. This means that the ship doesnt have to bring the mass back with it, allowing for more ships, infrastructure, etc. Perhaps a hangar could be included, so new ships could be built, and so on.

the rest of the ship could serve as a research center, or whatever.

i was thinking a weight of 500,000 tonnes. This is a lot, yes, but the ship would be reusable, autonomous, etc. The material gain and research gain would probably be worth the cost.

soph · 2003-01-13 17:22:01

Good game, lol.

I think we could do it with orion technology. More would be made possible by fusion though. I can't draw, otherwise I would draw out my idea.

soph · 2003-01-14 22:02:57

did this get lost?

in any case, just a bump so it can be seen

Tyr · 2003-01-22 15:54:50

500,000 tons ships with fusion drives? I like it. Just wait another 100 to 200 years!!! What about going to Saturn with a ship like that. Send out the smaller ships to explore the moons of Saturn and send helium 3 harvesters into the atmosphere of Saturn. Now the question is-do we build these things with lunar materials in Earth orbit or do we build them with materials mined on Phobos and Diemos in Mars orbit and fly to Saturn and the main belt for Mars??? Visiting some of the Kuiper Belt objects beyond Pluto would also be interesting. Pluto is no longer the edge of the solar system.

soph · 2003-01-22 16:41:39

100-200 years? Now thats overly pessimistic. Fine, lets say 100,000 ton ships on ion drives. 100,000 tonnes is the size of an aircraft carrier (give or take), we've built things this big before. the key is to get them up in pieces. This is where the elevator comes in. I cant forsee any other means we can get this much material up...however, with a weekly rate of 100 tonnes, such a ship could be assembled in less than 10 years.

For a large scale mining ship that will probably last that long, id say that this is well worth it. As technology advanced and more elevators were built, this would be sped up. High end mining could be done, with the material used for space construction or sale more than paying for the cost of the ship.

Fusion drive, I would say it will be done in my lifetime, hopefully before 2050. Otherwise, I dont see why such applications cant be done with ion drive. I also think the space elevator will be up by at least 2030.

Tyr · 2003-01-23 13:11:04

Soph, you must realize that I was ten years old when Apollo 11 landed on the Moon. The newspapers carried articles about manned missions to Mars by 1981 with about 50 men going there in nuclear ships launched by the Saturn V and assembled in LEO. The Shuttle was supposed to be a two-stage vehicle with a fly-back fully reusable first stage and there were hopes of sending the president up on the shuttle in 1976!! Then, after Apollo 17 they started hacking away at NASA and the shuttle became the thing it is today. Even so, in the late seventies I read articles indicating they planned 50 to 100 shuttle launches every year for ten years beginning in 1980 for satellite delivery and repair, a space station, a Moon base, a space telescope and a Mars mission. Heck, if we did all that by 1990 we'd be exploring the moons of Saturn and have permanent bases on Mars. Well, the shuttle launched in 1981 and you know what really happened. Do you see why I am such a pessimist????

Tyr · 2003-03-01 20:52:20

Make your carrier ship not much more than a titanium truss with a drive system attached under robotic and radio control. The mass will all be in the form of cargos bolted to the truss. Then when your ship comes back from where ever it went it can drop off all that cargo and go back amassing next to nothing, unless it picks up more cargo. The point is: in the vacuum of space your ship can be 95% cargo. That should be very efficient. Maybe you head out to the asteroid belt with 450,000 tons of refining and smelting equipment, get to work on an asteroid and come back home with 450,000 tons of platinum, irridium, or hydrocarbons, etc. Just leave the refinery out in the belt where it can work until it goes kaput.

soph · 2003-03-01 20:58:36

That's fantastic. We could even design the ship as a hab in itself. For example, it just parks itself, "unfolds," and sits there, with a docking port for expansion/resupply. Maybe even a new reactor can be brought out to replace the first one, and new equipment, etc.

dicktice · 2003-03-02 10:43:22

May I just butt-in here, to suggest reconsidering which asteroids to start with: Those between us and the Sun! Easier to get at than the Moon and, by employing orbital energy exchange tethers from the ISS, do-able "right now."

soph · 2003-03-02 11:42:06

The asteroid belt is a much better target from Mars, which would greatly help Martian infrastructure (which should be developing by the time missions like those I'm talking about happen). Also, the belt has many, many more asteroids, and you can sit in one spot and have an endless supply.

You really don't have to manuver much to get to the asteroids, and you also have a docking port for deep solar system missions.

It could even have a hangar to build new facilities and ships on site. Which means, once again, better launch conditions to Mars and the deep solar system. You also have a self-sufficient material base (except for food and other supplies, which could be acquired through a ships/material->supplies trade), which could be used to continue a chain of building ships, acquiring resources, and so on.

dicktice · 2003-03-02 12:38:47

Doggone it, Soph. You've got the cart in front of the horse (nice, phrase, I may use that again). We're nowhere near the Mars Expedition stage, which I probably won't live to see, even--get my point?
The asteroids I'm referring to are inside Earth's orbit--the "Atens." Easier to get at than the Moon's surface: Dead comets (dirty water-ice, mineral salts, etc.) in addition to the general run of regular sizes and shapes. They're almost impossible to observe and count from here, because of the glare from the Sun. But once prioritized, a quite small orbiting telescope will be able to pick them out.
Gee, Soph, I wish you'd apply some of your obvious brainpower towards feasible private launching methods, to get us started. (Any comments regarding maglev launching ramps up the western slopes of the Andes--an old suggestion I seem to remember reading about somewhere?)

soph · 2003-03-02 12:42:59

I see what you're saying. My initial purpose of this thread was for longer-term ideas, though.

The asteroids I'm referring to are inside Earth's orbit--the "Atens." Easier to get at than the Moon's surface: Dead comets (dirty water-ice, mineral salts, etc.) in addition to the general run of regular sizes and shapes. They're almost impossible to observe and count from here, because of the glare from the Sun. But once prioritized, a quite small orbiting telescope will be able to pick them out.

Sure, I see what you're saying. My general idea was for a large carrier, or more appropriately, I guess, an outpost in the belt, where a huge fleet could be built, and research can be done, and so on. An Earth orbit base isn't really suited for this goal. It also wouldn't have the deep space capability. A belt-base telescope would have much more range. Also, you could build them in your outpost, with no launch costs.

Tyr · 2003-03-02 14:00:13

Let's stick with carriers instead of an argument about NEOs vs. the Main Belt. The Nuclear Propulsion thread is nothing but a debate about plasma sails these days. The titanium truss would be the "keel" of the ship. You could bolt different habitat modules to it depending on crew size and even bolt different drives on it depending on mission, to get as many customized configurations as you want. A truss about 100 feet long of 12 inch wide titanium tubes one inch thick would amass about 100 metric tons. Since your in microgravity and you won't be accelerating very fast you could bot massive modules to it. You could go out into the main belt, leave the hab mods out there for a mining base along with other equipment and send the skeleton of the ship to some other asteroid to pick up cargo and go back, etc. Since fusion has not been perfected yet, and it may turn out that fusion reactors are too massive for efficient drives ( look up the ITER-its about 10,000 tons for just 500 MWe), I like the vapor core fission reactor system with a VASIMR or ion drive. If the ship is going to accelerate out of LEO it will pass thru the belts over the course of weeks or months, so it would be unmanned until it got out of the belts then the crew would fly up to it in a small rocket "taxi." If leaving Mars orbit, no problem, Mars doesn't have radiation belts.

For information on vapor core reactors see: http://www.inspi.ufl.edu/index.html and http://www.highway2space.com/ast/presen … _knigh.pdf

soph · 2003-03-02 14:07:30

A Tokamak based thrust may be able to be the size of a tabletop.

Also, fusion pulse propulsion could be very fast, and done in a small space.

But I like the truss idea. We could use it as the basis of an ever-expanding outpost. Pehraps in time, a community of outposts could grow around the original outpost.

I was thinking, you have a hangar or docking point on your large ship, which is in the belt. So, you have a bunch of smaller (maybe shuttle sized) ships that do the actual mining. They pick up their cargo, bring it to the large outpost, and go back. You can mine many asteroids at a time this way, and you have manuverable ships to do it.

Based on this principle, you could have a shipyard on your outpost churning out dozens of these mining ships.

An Orion drive may be a good idea to get it out there, lots of thrust for the mass, so it allows a bigger vehicle. This would require orbital construction (I dont want an Orion-based launch, bombs in the atomosphere doesnt suit me), or a space elevator to send the pieces of our ship up piecemeal, to be assembled in space.

Or, a hybrid NEP/NPP (the same could go for fusion) might be best. Good isp for cruising, good thrust for initial thrusting.

Tyr · 2003-03-02 14:14:03

a table top tokamak? You're dreamin' IF such a device was possible it would only crank out out a few hundred watts at most, and that's a flea's sneeze when you're talking about the energies required for space travel. As for nuclear pulse, it is terrible inefficient and hogs alot of uranium as well as releasing enough radiation to kill the crew and damage the payload. And what do you do about those intense square wave thrust pulsations? Shock absorbers? Not good enough. Stick with NEP (vapor core is best), gravity assists, hi-thrust chemical, gas core fission (not to be confused with vapor core reactors) and solid core fission. That's stuff is or will soon be real.

soph · 2003-03-02 14:25:03

Why not liquid or gas core fission? In space, dirty thrust doesn't matter?

Sorry, not table-top Tokamak, table-top dense focus thruster:

http://www.islandone.org/APC/Nuclear/12.html

DENSE PLASMA FOCUS (DPF)

An alternative to large fusion or antimatter-catalyzed micro-fission/fusion systems is the dense plasma focus (DPF) thruster under evaluation at Lawrenceville Plasma Physics (LPP) and the University of Illinois. The DPF thruster has the potential of being a compact (table-top sized) magnetic confinement fusion (MCF) device that operates in a magnetic "pinch" mode to compress the fusioning plasma. This device could also operate on a number of fusion fuels including aneutronic fuels like p-B11. However, unlike most ICF or MCF devices, it is not designed to operate at a high "gain", where gain is defined as the fusion energy output divided by the energy input to make the fusion reaction occur. In fact, the gain of the DPF thruster is estimated to be around one, corresponding to "break-even". Thus, from a spacecraft point of view, the DPF thruster has the potential of acting like an electric propulsion engine with an efficiency of 100% and with the Isp of a fusion engine (e.g., 106 lbf-s/lbm when directly using the fusion products, down to 4000 lbf-s/lbm with hydrogen added to the fusion products).
This concept, previously supported by the Air Force Phillips Laboratory (Edwards AFB) and now by JPL, is still in its early stages of development. To date, theoretical modeling and some limited testing have shown the preliminary feasibility of the concept.

As for nuclear pulse, it is terrible inefficient and hogs alot of uranium as well as releasing enough radiation to kill the crew and damage the payload. And what do you do about those intense square wave thrust pulsations? Shock absorbers? Not good enough. Stick with NEP (vapor core is best),

Fusion pulse could alleviate the radiation and inefficiencies, including the fuel hogging. Fission pulse is brute force only, though.

Tyr · 2003-03-03 16:41:16

here's a pulse unit for you Orion drive:
W48 155-millimeter Nuclear Artillery Shell

During the 1950s and 1960s, nuclear weapons were developed for every conceivable military mission. An estimated 1,000 W48 nuclear artillery shells (designed by Lawrence Livermore National Laboratory) were produced and deployed with Army and Marine Corps forces between 1963 and 1991. The W48 had a yield of 0.02-0.04 kilotons (equal to 2-4 tons of TNT).

AS for the tokamak thrusters, you could cluster a few hundred together to make a space drive system, but that's only possible if these things ever work. Although you will get a high Isp, at 100% efficiency you will only get as much power out as you put in, which is good when you condsider that ion drives are about 50% eff. and VASIMR about 70%. Your typical steam turbine 30-40%. I recommend the vapor core fission reactor to power the tokamak thrusters. However, they still have to get these things to work, and you will need deuterium and tritium. Those don't come cheap.

soph · 2003-03-03 16:42:41

Why would you use a fission reactor to power a fusion spaceship?

Tyr · 2003-03-07 14:10:05

think about it, at 100% efficiency you will only get as much power out as you put in, so if you use the power from the tokamak to run the tokamak you get nowhere. If you run the fusion reactor, which is hopefully a linear reactor because there's no way a tokamak can make a decent thruster despite what you may have read-and I can't prove that to you without drawing a picture in 3D-with a fission reactor that generates many, many times more power than is put into it, you get better efficiency from the drive than is typical with ion drives or VASIMR that are 50-70% efficient. Get it?

soph · 2003-03-08 08:57:22

The DPF thruster is a different thruster than the Tokamak. And what if you used a linear magnetic confinement thruster? I certainly expect that in the next few decades, we will be able to generate a net gain of power out of fusion reactions.

And adding a fission reactor is a serious complication politically. Fusion is perceived in a much less harsh light than fission. If you could keep a straight fusion drive, without fission power, that would be a benefit.

soph · 2003-03-17 19:47:03

What if you had a small fusion reactor dedicated only to producing power for the ship and engines? For the purposes of the outpost, this would make sense anyway, as we would need a lot of power for our facilities, factories, etc.

It would release less radiation to the crew, wouldn't be an explosion risk, and would use more abudant (and thus, potentially cheaper) fuel.

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