Spaceships: Escape to the asteroids

[DataPacRat]

In my 3e hard-science TL9 'New Attica' setting, a potential plot point involves the main characters deciding to escape the coming MAD-level war between the orbitals and Earth, and scooting off to the asteroids to set up a self-sufficient little colony for themselves. I'm currently fiddling with potential ship designs; and I'm using the boardgame "High Frontier" as part of the background reference material for available technology. Using that system (which has a resolution of 40 tons), the current design is:

Rocket: Salt-water Zubrin and radiators. Thrust 8600 kN (~1-1.3 gravities), Isp 8ksec. 160 tons

Fuel: 160 tons
delta-vee: 16 km/sec (~10 mps)

Active/awake crew and life-support: ~20 people, 120 tons

Main Cargo: Robotic prospectors, smaller vehicles, mining gear, factory gear, generator, reactor, radiator: 200 tons

Second cargo: Colonization gear & frozen colonists: 200 tons

Dry mass: 680 tons
Fueled mass: 840 tons



Trying to convert that to GURPS using Spaceships, the closest approximation I've been able to get is:

TL9, Exposed Radiators
SM+8, unstreamlined: 1000 tons

8 Cargo holds: 400 tons capacity
1 Control room: $2M
1 Engine room: $.3M
4 Fuel tanks: $1.2M
3 Habitats: bunkrooms: $3M
1 Habitat: 6 specialized rooms: $1M
1 Open Space (food production): $.1M
1 Reaction engine, fission, Nuclear saltwater: $5M
Spin Gravity: $.1M

Fuel, 200 tons: $20M

Total cost for 1-way trip: $31.7M (plus cost of colonization gear)


Does that look reasonably sane to you? Do you see any places for obvious improvement?

[Ulzgoroth]

One major deviation between your two designs is the amount of life support. The GURPS Spaceships version has 18 bunkrooms supporting 4 people each, for a total capacity of 72. You only need one habitat full of bunkrooms for your ~20 person crew.

There are some corners you could cut if you're comfortable with using smaller systems. You could use a half-size NSW rocket, or two 1/3 size, to save some space and cost and fit the original specification's acceleration. Also, most civilian designs don't really need a full-size control room.

You probably want to add a hangar for launching your robotic prospectors and smaller vehicles, and for general utility. As written the ship has no way to get anything much more than man-sized in or out without messily depressurizing a third of the ship. A hangar is essentially a giant cargo airlock.

An outside concern would be that that's an unarmored design. That might be what you want, but bear in mind that it's very thin-skinned. A 1/3 system of armor per section goes a long way if the ship is supposed to be sturdy.

[d_ns]

I know it's expensive in terms of weight, but with no armor you're hoping that nothing hits you doing more than 3 damage (that's not decade damage - an unarmored ship's thin hull, unstreamlined, has 3 regular DR against small arms fire and the like).

Other than that, and the fact that the reaction drive you've chosen isn't strictly hard science, I'd not see any real issues - working under the assumption that combat isn't intended.

[Michele]

Originally Posted by d_ns

I know it's expensive in terms of weight, but with no armor you're hoping that nothing hits you doing more than 3 damage (that's not decade damage - an unarmored ship's thin hull, unstreamlined, has 3 regular DR against small arms fire and the like).

Other than that, and the fact that the reaction drive you've chosen isn't strictly hard science, I'd not see any real issues - working under the assumption that combat isn't intended.

I was wondering... if one goes to the asteroid belt, won't he need armor, even if nobody's firing at him intentionally? I mean, won't he meet pinhead- or pebble-sized, hard to detect, fast enough to have plenty of kinetic energy... hull penetrators?

[DataPacRat]

Originally Posted by Ulzgoroth

One major deviation between your two designs is the amount of life support. The GURPS Spaceships version has 18 bunkrooms supporting 4 people each, for a total capacity of 72. You only need one habitat full of bunkrooms for your ~20 person crew.

Whoops. I'd started trying a SM+7 design, and forgot the bunkrooms were larger when I went to SM+8.

Going down to a single bunkroom space, I can also swap out the Open Space for total life support.

There are some corners you could cut if you're comfortable with using smaller systems. You could use a half-size NSW rocket, or two 1/3 size, to save some space and cost and fit the original specification's acceleration.

An outside concern would be that that's an unarmored design. That might be what you want, but bear in mind that it's very thin-skinned. A 1/3 system of armor per section goes a long way if the ship is supposed to be sturdy.

I forgot about half-sizes; knocking the NSW down a half space and adding that amount of armour balance each other out.

Also, most civilian designs don't really need a full-size control room.

Fair 'nuff.

You probably want to add a hangar for launching your robotic prospectors and smaller vehicles, and for general utility. As written the ship has no way to get anything much more than man-sized in or out without messily depressurizing a third of the ship. A hangar is essentially a giant cargo airlock.

Fair 'nuff, again.


Putting it all together, I seem to have 1 and 2/3 spaces currently unused... I suppose I should check the other books in the SS line to see if there's anything appropriate to fill them with. Maybe upgrade the armor to a full space, for a start.

[Ulzgoroth]

Originally Posted by DataPacRat

Putting it all together, I seem to have 1 and 2/3 spaces currently unused... I suppose I should check the other books in the SS line to see if there's anything appropriate to fill them with. Maybe upgrade the armor to a full space, for a start.

A factory system might be interesting, though those draw power so you'd also need some kind of power plant, which is rather excessive.

I don't think you've got enough systems to spare for a full armor system on each section.

[Fred Brackin]

Originally Posted by DataPacRat

Does that look reasonably sane to you? Do you see any places for obvious improvement?

No, the use of NSW does not look sane to me. The fuel is ridiculously dangerous. Fortuately, it's also not efficient and there's no reason to ever try and use one if you don't need the raw Accel.

Go to the TL9 Fusion Pulse or Advanced Fusion Pulse. Those give you Delta-v of 5mps or 20 mps comapred to te 2.5 of NSW. Never mind the lower accels. It's all about the Delta-V. The Fusion Pulse Drives will actually give you shorter trip times because yoou have more Dalta-V to spend.

You also have no radiation protection and with conventional Gurps TL9 the only radiation treatment is an expensive genetic therapy that you would have to repeat frequently.

If this were my project I would design a thick-walled long-term habitat of much greater size that just happened to have an engine. It wouldn't matter how long the trip took. You were already home when you started and will still be home when you finish. Home will just be farther away from those neighbors you don't like (or who don't like you).

This starter hab would have the full industrial plant you'd need to exapnd into the asteroids. Something lie a full-sized factory module and a Mining one too.

Does this mean you probably can't do thsi on the cheap? Yes, that's what it measn and it's probably true, There's a reason that the outer system in TS is ellted moslty by wealthy ideologues rather than businessmen. You have to be both willing and able to spend money on intengibles like elbow room..

[Ulzgoroth]

Originally Posted by Fred Brackin

No, the use of NSW does not look sane to me. The fuel is ridiculously dangerous. Fortuately, it's also not efficient and there's no reason to ever try and use one if you don't need the raw Accel.

It's dangerous, but no more so than a magazine full of missiles, for instance. That said, if you've got free choice of TL9 technologies I certainly wouldn't pick that for my interplanetary drive.

Originally Posted by Fred Brackin

You also have no radiation protection and with conventional Gurps TL9 the only radiation treatment is an expensive genetic therapy that you would have to repeat frequently.

This just isn't true. The fuel tanks and drive system can be arranged to provide a fairly substantial PF to 2 sections of the ship, and you can manage some mass shielding everywhere. It's enough to make solar flares negligible, at least. It won't do much against cosmic rays, but it's very hard to do anything about that.

Originally Posted by Fred Brackin

If this were my project I would design a thick-walled long-term habitat of much greater size that just happened to have an engine. It wouldn't matter how long the trip took. You were already home when you started and will still be home when you finish. Home will just be farther away from those neighbors you don't like (or who don't like you).

This starter hab would have the full industrial plant you'd need to exapnd into the asteroids. Something lie a full-sized factory module and a Mining one too.

Does this mean you probably can't do thsi on the cheap? Yes, that's what it measn and it's probably true, There's a reason that the outer system in TS is ellted moslty by wealthy ideologues rather than businessmen. You have to be both willing and able to spend money on intengibles like elbow room..

I'm pretty sure that's totally missing the point. This is a colony ship, not a mobile colony. The eventual habitat is supposed to be built on site.

[Fred Brackin]

Originally Posted by Ulzgoroth

It's dangerous, but no more so than a magazine full of missiles, for instance. That said, if you've got free choice of TL9 technologies I certainly wouldn't pick that for my interplanetary drive.

This just isn't true. The fuel tanks and drive system can be arranged to provide a fairly substantial PF to 2 sections of the ship, and you can manage some mass shielding everywhere. It's enough to make solar flares negligible, at least. It won't do much against cosmic rays, but it's very hard to do anything about that.

I'm pretty sure that's totally missing the point. This is a colony ship, not a mobile colony. The eventual habitat is supposed to be built on site.

No, a tank of NSW fuel can go critical if accidentaqlly compressed. Missile warheads won't do that.

It _is_ cosmics that you have worry about on a long term basis (like living in space beyond Earth's magnetosphere). A thick enough hull will shield from them though. This is what deep space habs have to have if the people in the hab don't have TL11 nano or TL10 Regeneration (radiation only) genes.

I'm only trying to suggest something that might work. I don't think the OP's orignal plan would.

[Ulzgoroth]

Originally Posted by Fred Brackin

No, a tank of NSW fuel can go critical if accidentaqlly compressed. Missile warheads won't do that.

How do you accidentally compress a fuel tank?

Originally Posted by Fred Brackin

It _is_ cosmics that you have worry about on a long term basis (like living in space beyond Earth's magnetosphere). A thick enough hull will shield from them though. This is what deep space habs have to have if the people in the hab don't have TL11 nano or TL10 Regeneration (radiation only) genes.

I'm only trying to suggest something that might work. I don't think the OP's orignal plan would.

It's a colony ship, not a flying colony. It's presumably not intended for indefinite habitation, though I don't know how long the mission schedule is.

Also, unless I'm confused about the PF system, there's really nothing you can do to negate cosmic rays. With an insanely thick hull you might divide them by, say, 10.