Author Topic: If NASA Had An Infinite Budget - Feasible but Ludicrously Expensive Missions  (Read 16879 times)

Offline MarsDude

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Re: If NASA Had An Infinite Budget
« Reply #20 on: 02/16/2017 05:18 PM »
Does anyone have an idea of how to stop the cryogenic tanks from boiling off during the interplanetary cruise?

A cryogenic rocket engine performs both the TSI (Trans-Saturn Injection) and Saturn orbit insertion burns, and I'd like to avoid the fuel being gone upon arrival.
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Offline gospacex

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Offline shooter6947

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Re: If NASA Had An Infinite Budget
« Reply #22 on: 02/16/2017 10:44 PM »
Does anyone have an idea of how to stop the cryogenic tanks from boiling off during the interplanetary cruise?
Active refrigerator system hooked into big-ass radiators

Offline scienceguy

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Does anyone have an idea of how to stop the cryogenic tanks from boiling off during the interplanetary cruise?


Bussard ramjet. Pick up the fuel as you go.
e^(pi*i) = -1

Offline AS_501

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Following up Scienceguy's suggestion, a colony ship along the lines of Arthur C. Clarke's cylindrical vessel "Rama", though maybe not quite as large as Clarke's.  Admittedly this is outside the scope of a NASA-only project.  Same can be said for a 2001-style rotating space station which, by the way, would mitigate the harmful microgravity medical effects being discovered on the ISS.

On a more realistic note, a manned base on Callisto with (obviously) ample radiation shielding for habitats, pressure suits, etc.  Is there any hope for manned missions near Jupiter?

Offline MATTBLAK

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Callisto, Ganymede and Titan would make wonderful destination goals for late in the 21st Century. The subsurface oceans of Callisto and Ganymede might be easier to reach than Europa's and the local surface environment far less flooded by Jupiter's radiation. And of course; Ceres could be an excellent place to explore and drill into. I really hope someone gets a Rover out there one day soonish.
« Last Edit: 02/17/2017 02:05 AM by MATTBLAK »
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Offline brickmack

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Re: If NASA Had An Infinite Budget
« Reply #26 on: 02/17/2017 02:43 AM »
Does anyone have an idea of how to stop the cryogenic tanks from boiling off during the interplanetary cruise?

A cryogenic rocket engine performs both the TSI (Trans-Saturn Injection) and Saturn orbit insertion burns, and I'd like to avoid the fuel being gone upon arrival.

ULA says ACES tech should be scalable to any size (and thermodynamically I'd expect it to be rather more effective with larger fuel volumes). Losses would just be from power generation and attitude control (not seen hard numbers on propellant consumption for these, but its supposed to be very small)

Offline MarsDude

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Re: If NASA Had An Infinite Budget
« Reply #27 on: 02/17/2017 01:03 PM »
Does anyone have an idea of how to stop the cryogenic tanks from boiling off during the interplanetary cruise?

A cryogenic rocket engine performs both the TSI (Trans-Saturn Injection) and Saturn orbit insertion burns, and I'd like to avoid the fuel being gone upon arrival.

ULA says ACES tech should be scalable to any size (and thermodynamically I'd expect it to be rather more effective with larger fuel volumes). Losses would just be from power generation and attitude control (not seen hard numbers on propellant consumption for these, but its supposed to be very small)


I've got power generation figured out: enough RTGs to make a nuclear bomb with their plutonium. Overkill, but it works. As for attitude control: Reaction wheels won't expend any fuel, RCS will.
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Offline MarsDude

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Earth departure, course correction, and gravity assist will take 6.219 km/s of Delta-V. My current plan for this is to have three heavily modified Shuttle External Tanks hold the fuel, and a cluster of three Centaur engines perform the maneuvers.

The tanks will be laid out side-by-side, two side tanks attached to the the middle tank. The side tanks are drained first, and jettisoned when they are empty. The Centaur engines are only on the middle tank.

Each tank is launched separately and empty by an SLS, and are docked together in orbit. Several refueling missions (consisting of an SLS payload that is a control unit, RCS, small solar panels, an antenna, and whatever payload capacity is left holds fuel) will fuel it up. Finally, the payload spacecraft is launched and docked to the front.
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Offline Jim

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I've got power generation figured out: enough RTGs to make a nuclear bomb with their plutonium. Overkill, but it works. As for attitude control: Reaction wheels won't expend any fuel, RCS will.

Still need RCS with Reaction wheels

Offline Jim

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have three heavily modified Shuttle External Tanks hold the fuel,


No amount of money is going to make that happen.  Also, they are just wrong for the job
« Last Edit: 02/17/2017 01:42 PM by Jim »

Offline MarsDude

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have three heavily modified Shuttle External Tanks hold the fuel,


No amount of money is going to make that happen.  Also, they are just wrong for the job

 
Misspoke, I meant something about that size.
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Offline Hobbes-22

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Re: If NASA Had An Infinite Budget
« Reply #32 on: 02/17/2017 03:35 PM »

I've got power generation figured out: enough RTGs to make a nuclear bomb with their plutonium. Overkill, but it works. As for attitude control: Reaction wheels won't expend any fuel, RCS will.

The Plutonium isotope used in RTGs is useless for nuclear bombs. It won't fission. A GPHS-RTG contains a little under 8 kg of Pu-238, critical mass of Pu-239 is 11 kg. 11 kg of Pu-238 isn't a very large RTG.

Offline MarsDude

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Re: If NASA Had An Infinite Budget
« Reply #33 on: 02/17/2017 03:41 PM »

I've got power generation figured out: enough RTGs to make a nuclear bomb with their plutonium. Overkill, but it works. As for attitude control: Reaction wheels won't expend any fuel, RCS will.

The Plutonium isotope used in RTGs is useless for nuclear bombs. It won't fission. A GPHS-RTG contains a little under 8 kg of Pu-238, critical mass of Pu-239 is 11 kg. 11 kg of Pu-238 isn't a very large RTG.


I meant if it was Pu-239, it would probably be several megatons.
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Offline kch

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Re: If NASA Had An Infinite Budget
« Reply #34 on: 02/17/2017 04:02 PM »

I've got power generation figured out: enough RTGs to make a nuclear bomb with their plutonium. Overkill, but it works. As for attitude control: Reaction wheels won't expend any fuel, RCS will.

The Plutonium isotope used in RTGs is useless for nuclear bombs. It won't fission. A GPHS-RTG contains a little under 8 kg of Pu-238, critical mass of Pu-239 is 11 kg. 11 kg of Pu-238 isn't a very large RTG.


I meant if it was Pu-239, it would probably be several megatons.

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Offline Jim

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I don't think that is asking too much. A bit more funding and I can see these missions coming every 10 years or so.

It is asking for too much.  Those missions would be like JWST and worse.
« Last Edit: 02/17/2017 06:59 PM by Jim »

Offline Jim

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A Europa sub just needs the right fissure--perhaps found by earlier missions. You are right about Webb.
ATLAST is a simpler design.

ATLAST would be worse than JWST.  The folding telescope was not the cost driver for JWST.

Offline MATTBLAK

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have three heavily modified Shuttle External Tanks hold the fuel,


No amount of money is going to make that happen.  Also, they are just wrong for the job
Yes - there aren't 3x External Tanks left in existence and no manufacturing infrastructure to make more. And how would you launch them, anyway? They had a synergy with the Shuttle that would make them nearly impossible to adapt for anything else, other than a Shuttle Derived Sidemount launcher - and that ship has sailed, so to speak. Possibly you could adapt your idea to tooling used to make smaller diameter rocket stages like the 5 meter Deltas - or just clean-sheet design your ideas to the specs you want or need.
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Offline MarsDude

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have three heavily modified Shuttle External Tanks hold the fuel,


No amount of money is going to make that happen.  Also, they are just wrong for the job
Yes - there aren't 3x External Tanks left in existence and no manufacturing infrastructure to make more. And how would you launch them, anyway? They had a synergy with the Shuttle that would make them nearly impossible to adapt for anything else, other than a Shuttle Derived Sidemount launcher - and that ship has sailed, so to speak. Possibly you could adapt your idea to tooling used to make smaller diameter rocket stages like the 5 meter Deltas - or just clean-sheet design your ideas to the specs you want or need.

Sorry, I misspoke. I meant the same size as heavily modified ETs.
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Offline tea monster

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What would probably a more interesting thread would be "What if NASA were funded at relative 1960's levels", or "What if NASA's budget were quadrupled."

Infinite money basically says that anything is possible. You could give Mr. Zubrin a nice birthday present and develop a nuclear salt water rocket and pay off all the hippies to look the other way. You could even set up a dummy corporation in a neutral state and develop an Orion (the Orion that should have flown first) ship to cruise the solar system in style.

With the budget indicated by an 8 on it's side, lunar bases, Mars colonies and all that jazz are just part of the coffee budget.

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