Practical propulsion methods for manned interplanetary travel

[mdatspace]

I think this thread is a need. We have had debates on the viability of some propulsion systems(Mostly Orion), but this is about systems that are practical today.

Your constraints are:

Technology:Must be viable today.

Laws:The propulsion system must be viable, politically speaking. Thus, it cannot break any restriction on certain propulsion systems.

Budget:You have 7.5 billion dollar project budget per year.

Schedule:Mars landing by 2025. Large Asteroid landing by 2050. You must have a Mars colony by 2038. The second mission should use non-chemical propulsion.

Safety:Some engines may need to be safely disposed of after use. Nuclear engines must be launched into space before use.

The goal?

-Develop a way to get to said targets on said budget and on said schedule

-Complete the objectives.

Edited January 27, 2014 by mdatspace
Made it harder.Less time to do things, less budget and more objectives.EDIT 2:Removed the payload/Long-term stay issues part.

[G'th]

Considering it wouldn't have taken much more to put men in at least orbit of Mars and then back to Earth back in 1969, and considering that 10 billion budget is more than enough to cover an Apollo launch (taking inflation into account), then this wouldn't be hard just using conventional, already developed propulsion. You'd have the headroom to build the required rocket to get to Mars (Mars is the only realistic interplanetary target for manned mission atm is it not?) plus whatever you'd need to build to get you back, and still with just enough headroom for whatever else.

The real problem is how much of the hardware you'd have to (or decide to) reengineer if not completely reinvent, which is what's going to start eating into your budget the deeper you go with this. Considering the existence of SLS and the fact that no one can seem to decide how humanity should design a manned Mars mission, this is going to be a prevalent problem. Its not just a matter of designing the propulsion method. Its a matter of designing and constructing what you're putting on top of it.

[mdatspace]

snip

The destinations are a challenge. They are just a test

I think I need to make some tweaks to our challenge.

[Skyler4856]

NERVA. The reasonable thrust and insane efficiency allow for a quick and concise arrival date.

[mdatspace]

NERVA. The reasonable thrust and insane efficiency allow for a quick and concise arrival date.

Considering how NERVA is nuclear propulsion, you need to get rid of the engine or put it somewhere where it will not encounter the earth.

[Duxwing]

Considering how NERVA is nuclear propulsion, you need to get rid of the engine or put it somewhere where it will not encounter the earth.

Leaving the NERVA in a graveyard orbit until the nuclear fuel decays and then decorbiting it should be cheap and safe.

-Duxwing

[CalculusWarrior]

Or even do what many KSP players tend to do with their nukes, reuse them. I imagine the engines coming with built-in radiation shielding so an astronaut on EVA could repurpose them for another mission easily.

[mdatspace]

Leaving the NERVA in a graveyard orbit until the nuclear fuel decays and then decorbiting it should be cheap and safe.

-Duxwing

That would work.

[DaveofDefeat]

The propulsion system must be viable, politically speaking.

That would mean no nuclear fission rockets.

[Roastduck]

That would mean no nuclear fission rockets.

Could they potentially be used outside Earth's magnetosphere? Or impose some other limitation, such as lunar orbit and beyond?

[mdatspace]

That would mean no nuclear fission rockets.

Who would use a nuclear rocket in the atmosphere?

I made that limitation so this topic would not become the "Project Orion thread."

Edited January 27, 2014 by mdatspace

[DaveofDefeat]

From a politicians viewpoint, launching a nuclear reactor into space would have a lot of political fallout, so as the op states

The propulsion system must be viable, politically speaking.

the nerva wouldn't be practical.

[mdatspace]

From a politicians viewpoint, launching a nuclear reactor into space would have a lot of political fallout, so as the op states the nerva wouldn't be practical.

You launch the nuclear engine into space, and then you activate it.I will edit my challenge to include this part. Edited January 27, 2014 by mdatspace

[DaveofDefeat]

You launch the nuclear engine into space, and then you activate it.I will edit my challenge to include this part.

Ermagawd NASA is launching one of those things that destroyed fukushima into space? Quick protest, get rid of NASA they are destroying the planet. -the laymans reaction.

Technically viable, reasonably safe, political suicide.

[Pyre]

From a politicians viewpoint, launching a nuclear reactor into space would have a lot of political fallout, so as the op states the nerva wouldn't be practical.

Launch the engine, then launch the fuel on a rocket with a man rated LES.

VASIMR looks promising as a propulsion system.

[mdatspace]

Ermagawd NASA is launching one of those things that destroyed fukushima into space? Quick protest, get rid of NASA they are destroying the planet. -the laymans reaction.

Technically viable, reasonably safe, political suicide.

I know people will react that way. The engine poses no threat once it is in space.

Launch the engine, then launch the fuel on a rocket with a man rated LES.

VASIMR looks promising as a propulsion system.

Could work. Or doesn't work at all. http://www.spacenews.com/article/vasimr-hoax

VASIMR needs an enormous amount of electricity. You should bet on other forms of propulsion.

Edited January 27, 2014 by mdatspace

[SargeRho]

I'd say Fusion engines. The Fusion Driven Rocket looks rather promising, and partially solves the issue of neutron emissions from the fusion reaction.

Other than that, NERVA. Or a laser-beamed thermal rocket. Laser- or microwave-beamed power could also make a VASIMR powered ship easier to build.

[mdatspace]

I'd say Fusion engines. The Fusion Driven Rocket looks rather promising, and partially solves the issue of neutron emissions from the fusion reaction.

Other than that, NERVA. Or a laser-beamed thermal rocket. Laser- or microwave-beamed power could also make a VASIMR powered ship easier to build.

A part of my design criteria:

"Technology:Must be viable today."

Is fusion viable today?

[SargeRho]

Not quite, but if the Fusion Driven Rocket works, it soon will be. Using fusion to create large pulses isn't a new thing. The FDR doesn't use the fusion engine to produce power, purely for propulsion, which makes it a lot simpler. A small nuclear reactor or large solar pannels are enough to power it as far as I know. A prototype is currently in development to see if it's viable at all, after that a space-based test engine would/should be built.

NERVA in turn would require *a lot* of work to make politically viable, as you'd have to get people to realise that nuclear reactors aren't doomsday devices.

[mdatspace]

Not quite, but if the Fusion Driven Rocket works, it soon will be. Using fusion to create large pulses isn't a new thing. The FDR doesn't use the fusion engine to produce power, purely for propulsion, which makes it a lot simpler. A small nuclear reactor or large solar pannels are enough to power it as far as I know. A prototype is currently in development to see if it's viable at all, after that a space-based test engine would/should be built.

NERVA in turn would require *a lot* of work to make politically viable, as you'd have to get people to realise that nuclear reactors aren't doomsday devices.

It still needs to be validated. It has to be ready by 2050, according to my post.

[Aghanim]

Yes, the only thing viable today is NERVA. Period.

What is our eco friendly alternatives?

1. Solar sail: No way, the crew will die long before it reaches its destination

2. Ion drive / VASMIR = Still needs nuclear reactor for its power

3. Good old chemical hydrolox drive: Why not? Probably if its optimized for space environment the ISP isn't too terrible

[Brotoro]

When you launch a fresh NERVA engine, its core need not contain any radioactive elements other than enriched Uranium 235 (and some daughter nuclei from its decay chain). No Plutonium. No short-lived fission products. No Highly radioactive isotopes at all. Just Uranium 235. Naturally harvested and purified. Organic. Just like Mother Nature made. Chock full of natural energy recycled from old supernovas.

[Nuke]

i wouldnt go as far as calling vasimr a hoax but it is certainly not the right engine to fly men to mars. face it the problem with high isp, high thrust electrical propulsion is you need a lot of freaking power (tens of megawatts to gigawatts). maybe in the future when we got a lightweight fission, fusion or even possibly an antimater reactor to provide the gigawatts neccisary for vasmir (and there are better options available as far as electric thrusters go), then we will see electric propulsion really emerge.

we could just go on chemical engines. or skip mars entirely until we have a moon base and some infrastructure. we can completely circumvent the political aspects of nuclear if can do lunar uranium mining and processing. we can launch an un-fueled reactor or nerva, fuel it at the moon base and then go to mars. of course none of these options would fit the rules layed out in the op (frankly its a little ambitious).

[SargeRho]

If you have the capability to produce enough antimatter to power vasimr, you don't need vasimr anymore

[Winter Man]

When you launch a fresh NERVA engine, its core need not contain any radioactive elements other than enriched Uranium 235 (and some daughter nuclei from its decay chain). No Plutonium. No short-lived fission products. No Highly radioactive isotopes at all. Just Uranium 235. Naturally harvested and purified. Organic. Just like Mother Nature made. Chock full of natural energy recycled from old supernovas.

Was the NERVA capable of using 235 though? I thought it was just hot plutonium like an RTG.