What propulsion system should we use for Mars exploration?

[tater]

11 minutes ago, Ackoli said:

the spun habs would have to be inflatable.

Bigelow would be happy to comply. Heck, they'll probably get chucked onto the Senate Launch System manifest just so they can fill out the schedule, anyway.

[Spaceception]

8 minutes ago, Kaos said:

Then we should test it.

Aside from the proposed gravity ring that 's going to the ISS, (Which has since been cancelled) we don't have any plans, so unless we test Artificial gravity between now and 2030 (Which I guess is likely) I don't want to put chem propulsion on a manned Mars mission, and about the radiation thing, the Sun can still be a jackass, and bombard the spacecraft with deadly amount of radiation from solar flares.

6 minutes ago, Kaos said:

That is your opinion. Not my opinion. So you do not want to have my vote in the poll? I can live with that, but then the poll is not complete and perhaps that is not what you want.

Alright.

Edited January 21, 2016 by Spaceception

[Kaos]

Solar flares are also handled in Mars Direct. You can construct a safety tube in the middle of your craft that is shielded by the supplied you bring with you. If you use a faster flight plan, you still have to do that, as you still can be hit by solar flares. So this again is an argument for chemical propulsion.

[Spaceception]

1 minute ago, Kaos said:

Solar flares are also handled in Mars Direct. You can construct a safety tube in the middle of your craft that is shielded by the supplied you bring with you. If you use a faster flight plan, you still have to do that, as you still can be hit by solar flares. So this again is an argument for chemical propulsion.

Okay, I guess Chem propulsion would be on the first few manned Mars missions (For the only reason being we have experience with it), but I think we should switch to one of the other propulsion systems as soon as we make a working reliable system.

[Mitchz95]

We'll probably start with chemical, then switch to NERVA once it's perfected.

[Spaceception]

1 minute ago, Mitchz95 said:

We'll probably start with chemical, then switch to NERVA once it's perfected.

Or SEP, whichever comes first.

[Kaos]

I am sure we will switch to some other method eventually. But I do not know to which one. And I am quite sure that it will take a while until we use a flight plan with no free return trajectory (aka shorter or faster flight).

Thank you for adding chemical to the poll.

[Spaceception]

2 minutes ago, Kaos said:

I am sure we will switch to some other method eventually. But I do not know to which one. And I am quite sure that it will take a while until we use a flight plan with no free return trajectory (aka shorter or faster flight).

Thank you for adding chemical to the poll.

Your welcome

[batman78781]

Actually, assuming that we end up using or at least considering NERVA, it looks like it is powered by liquid hydrogen. Storing this is already a problem, even the Centaur can only retain fuel (LH2 at least) for about five hours with the best insulation. So, what would be the plan for the braking burn at mars, or the return? I doubt they will risk aerobraking, and even so the fuel will have boiled off for the return. Actually under normal circumstances, it would be gone before you left earths soi. I think the NERVA is a good idea for the transfer (earth to mars), but the fuel evaporates way too fast.

 

[Spaceception]

Just now, batman78781 said:

Actually, assuming that we end up using or at least considering NERVA, it looks like it is powered by liquid hydrogen. Storing this is already a problem, even the Centaur can only retain fuel (LH2 at least) for about five hours with the best insulation. So, what would be the plan for the braking burn at mars, or the return? I doubt they will risk aerobraking, and even so the fuel will have boiled off for the return. Actually under normal circumstances, it would be gone before you left earths soi. I think the NERVA is a good idea for the transfer (earth to mars), but the fuel evaporates way too fast.

 

Use a different fuel, if you do a solid core NTR, you can use Ammonia at the expanse of reduced power. https://en.wikipedia.org/wiki/Nuclear_thermal_rocket

[tater]

Recent DRAs for Mars have crew transit times about 6 months (bimodal NTR). A Hohmann transfer orbit is ~8.5 months. 2.5 months makes no difference, particularly if you spin the crew compartment.

[fredinno]

5 hours ago, Kaos said:

I do not consider chemical propulsion too inefficient. Some month can be waited and the technology exists. The other methods are only a bit faster, if at all. But rely on stuff that does not exists.

Ever read Voyage? In that novel, they needed to use 8 Saturn VB rockets to launch just the fuel for the Mars Mission (carried by another Saturn VB). Keep in mind each Saturn VB had double the capacity of a Saturn V. And they only used chemical propulsion.

Edited January 21, 2016 by fredinno

[fredinno]

4 hours ago, Mitchz95 said:

We'll probably start with chemical, then switch to NERVA once it's perfected.

SEP is better- it doen't use politically unacceptable Nuclear, and it can be repurposed for as a much more efficient space tug than any cryogenic fuel, which could become a business in and of itself.

[Spaceception]

4 minutes ago, fredinno said:

SEP is better- it doen't use politically unacceptable Nuclear, and it can be repurposed for as a much more efficient space tug than any cryogenic fuel, which could become a business in and of itself.

Exactly, although, we will have to scrap that "No Nuclear in space" thing sometime this century, or our space efforts are going to be hard.

[fredinno]

4 minutes ago, Spaceception said:

Exactly, although, we will have to scrap that "No Nuclear in space" thing sometime this century, or our space efforts are going to be hard.

That is, if we ever launch a manned mission beyond the Moon or Mars this century... 

[Spaceception]

1 minute ago, fredinno said:

That is, if we ever launch a manned mission beyond the Moon or Mars this century... 

We better, or I'm going to flip my excrements.

[fredinno]

8 minutes ago, Spaceception said:

We better, or I'm going to flip my excrements.

I guess we might still be able to go to Venus or Ceres, though- the latter would need a pretty big set of solar panels, but hopefully they've advanced enough by then.

[Spaceception]

Just now, fredinno said:

I guess we might still be able to go to Venus or Ceres, though- the latter would need a pretty big set of solar panels, but hopefully they've advanced enough by then.

I don't think we'll go to Ceres (Or should go) until we begin putting Nuclear reactors in space, because the amount of solar panels we'll need for a mining colony will be ridiculous, Also, I hope we at least do a Venusian flyby by 2040.

[fredinno]

22 minutes ago, Spaceception said:

I don't think we'll go to Ceres (Or should go) until we begin putting Nuclear reactors in space, because the amount of solar panels we'll need for a mining colony will be ridiculous, Also, I hope we at least do a Venusian flyby by 2040.

But efficencies and mass reductions of Solar are being made all the time. It would be enormous, but Solar has also been proposed for Uranus and Saturn for probes. 

[mikegarrison]

Why not put Crazy Drive -- I mean, Pulsed Nuclear Detonation -- on the list?

[kerbiloid]

As hydrogen is too volatile and incompact for chemical spaceships, and the same story with all cryogenic fuels like methane and oxygen,
and thuswise IRL all near-Earth and Moon ships use (...)hydrazine/NTO fuel (except of Buran with its 30-day oxygen tank),
how could a ship to Mars keep its cryogenical fluids for a year and more?

OK, it can start from LEO using freshly cooked LH2/LCH₄/LO2. Maybe even stop near Mars with this.
But why should we think that 500 days later its tanks would contain anything except traces of oxygen?

 

[Nibb31]

Current plans are to use chemical propulsion, so I don't see why you consider it "not likely". It's the likeliest option. The second likeliest is SEP. None of the other options are anywhere near the TRL level required.

[Kaos]

1 hour ago, fredinno said:

Ever read Voyage? In that novel, they needed to use 8 Saturn VB rockets to launch just the fuel for the Mars Mission (carried by another Saturn VB). Keep in mind each Saturn VB had double the capacity of a Saturn V. And they only used chemical propulsion.

No, I have not read that. But I am aware of the 90 day study, the plan NASA came up in 1989. It includes 8 different rockets types, alone 14 Space Shuttle launches per year, in-orbit assembly base, a lunar base to mine the fuel, nuclear propulsion, and would need over 20 years to bring the first human to Mars.

This 90 day study was the reason, why Zubrin et al developed Mars Direct: One type of rockets, two starts every two years, humans to Mars 10 years after the start of the plan. NASA later admitted somehow that his plan worked and developed the Design Reference Mission with 3 Rockets every two years but other than that essentially a copy of Mars Direct.

This fits a say that is attributed to Sergei Korolev, albeit unknown if he really said that: The simpler a construction the more genius it is. Everyone can come up with something complicated.

[fredinno]

1 hour ago, Kaos said:

No, I have not read that. But I am aware of the 90 day study, the plan NASA came up in 1989. It includes 8 different rockets types, alone 14 Space Shuttle launches per year, in-orbit assembly base, a lunar base to mine the fuel, nuclear propulsion, and would need over 20 years to bring the first human to Mars.

This 90 day study was the reason, why Zubrin et al developed Mars Direct: One type of rockets, two starts every two years, humans to Mars 10 years after the start of the plan. NASA later admitted somehow that his plan worked and developed the Design Reference Mission with 3 Rockets every two years but other than that essentially a copy of Mars Direct.

This fits a say that is attributed to Sergei Korolev, albeit unknown if he really said that: The simpler a construction the more genius it is. Everyone can come up with something complicated.

Right. I feel stupid for forgetting Mars Direct right now..

[HebaruSan]

2 hours ago, Nibb31 said:

Current plans are to use chemical propulsion, so I don't see why you consider it "not likely". It's the likeliest option.

And that commentary is in the poll option itself, so you have to click on the disclaimer to choose it! It felt like answering a political push poll call.