What propulsion system should we use for Mars exploration?

[Spaceception]

We all know chemical propulsion isn't viable for our first Mars missions, too slow, too inefficient, and too primitive, so what propulsion system should we use?

NERVA? https://en.wikipedia.org/wiki/NERVA

Solar electric propulsion? https://www.nasa.gov/mission_pages/tdm/sep/index.html

VASIMR? https://en.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket

Or the Fusion Driven Rocket (The coolest one)? https://en.wikipedia.org/wiki/Nuclear_pulse_propulsion#MSNW_Magneto-Inertial_Fusion_Driven_Rocket

Edited January 21, 2016 by Spaceception

[Kaos]

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.

[SargeRho]

Solar Electric.

But not NASA's solar electric. I'd use a solar-powered pulsed Fusion engine: https://en.wikipedia.org/wiki/Nuclear_pulse_propulsion#MSNW_Magneto-Inertial_Fusion_Driven_Rocket

Requiring 100-1000kw, Requiring Big, but still very much manageable solar arrays. And Methane-Oxygen rockets for the lander.

[Kaos]

Well, we could use some electric propulsion systems to bring supply goods on slow missions there. On a five-year trajectory we would get a much better mass ratio for the supplies. And some stuff we want, can be stored that long.

[Ackoli]

Solar electric propulsion would require a HUGE sheet, and may not generate enough thrust. NERVA engines would be good, I would use them (but then you would need nuclear reactors)., but I created this theoretical propulsion system, run by shooting dry ice pellets through a (very!) long tube while being accelerated with lasers. That design could work, (I called it AC propulsion) and the fuel would be almost free, with the advantage of being able to refuel from the Martian atmosphere and waste life support. I would rank NERVA first, VASIMR second, and solar electric propulsion last.

[Spaceception]

10 minutes ago, SargeRho said:

Solar Electric.

But not NASA's solar electric. I'd use a solar-powered pulsed Fusion engine: https://en.wikipedia.org/wiki/Nuclear_pulse_propulsion#MSNW_Magneto-Inertial_Fusion_Driven_Rocket

Requiring 100-1000kw, Requiring Big, but still very much manageable solar arrays. And Methane-Oxygen rockets for the lander.

I considered adding that one, but I figured that since we don't have "working" Fusion reactors yet, it wouldn't be a good choice.

I'll add it anyway

Edited January 20, 2016 by Spaceception

[Ackoli]

Just now, Ackoli said:

Solar electric propulsion would require a HUGE sheet, and may not generate enough thrust. NERVA engines would be good, I would use them (but then you would need nuclear reactors)., but I created this theoretical propulsion system, run by shooting dry ice pellets through a (very!) long tube while being accelerated with lasers. That design could work, (I called it AC propulsion) and the fuel would be almost free, with the advantage of being able to refuel from the Martian atmosphere and waste life support. I would rank NERVA first, VASIMR second, and solar electric propulsion last.

I got confused, I thought solar electric propulsion was having a massive sail, propelled by solar light (which is feasible), not the other type. my rankings still remain the same.

[SargeRho]

3 minutes ago, Spaceception said:

I considered adding that one, but I figured that since we don't have "working" Fusion reactors yet.

I'll add it anyway

Well, the MSNW Fusion Rocket solves the problem of not being able to produce power by ignoring it, using an external energy source, instead of the fusion reaction, to power itself. We've had working fusion reactors for decades, just none that produce any energy. Several components of that particular engine have already been tested.

 

I got confused, I thought solar electric propulsion was having a massive sail, propelled by solar light (which is feasible), not the other type. my rankings still remain the same.

That's a solar sail. Solar Electric propulsion uses solar power to run some other type of engine, usually Ion or Plasma engines.

Edited January 20, 2016 by SargeRho

[Spaceception]

10 minutes 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.

The reason being that if we use chemical propulsion on a manned mission to Mars, their bones would become too weak, and they won't be able to do much for the first couple of weeks on Mars, so if anything goes wrong in that time, they may not be able to act fast enough.

And thanks again for telling me how to make a signature

[Kaos]

Artificial gravity is not complicated. In Mars Direct (1990) it is even shown how to use the empty upper stage of the rocket that is flying the way anyway and a cable of some kg to do that. I prefer to use technology that was 1990 already known for a long time and not technology that has not proven to work today.

[Ackoli]

1 minute ago, Spaceception said:

The reason being that if we use chemical propulsion on a manned mission to Mars, their bones would become too weak, and they won't be able to do much for the first couple of weeks on Mars, so if anything goes wrong in that time, they may not be able to act fast enough.

And thanks again for telling me how to make a signature

put repairing drones on the spacecraft, then if anything does go wrong, the mission is not doomed

[tater]

10 minutes ago, Spaceception said:

The reason being that if we use chemical propulsion on a manned mission to Mars, their bones would become too weak, and they won't be able to do much for the first couple of weeks on Mars, so if anything goes wrong in that time, they may not be able to act fast enough.

And thanks again for telling me how to make a signature

This makes no sense whatsoever. Are you proposing that travel to Mars requires 1g constant thrust for the entire trip, with a turn-around at midpoint? No one has proposed anything of the kind. Even NTR proposals are a brief boost phase, with a long coast.

Modern mission plans can include spun habs.

Edited January 21, 2016 by tater

[Robotengineer]

Umm, traditional chemical propulsion can easily take us to Mars. IMO, chemical propulsion with ISRU is better for near term exploration.

[Kaos]

Thanks for quoting, I have not seen the if anything goes wrong in the first part:

If you use a "slow" chemical propulsion system, you can choose your flight plan such that if anything goes wrong, you are already on a free return trajectory back to earth. If you use some of the proposed fast propulsion systems, you are totally doomed as soon as your propulsion system gets problems. So alone from safety reasons I would use a chemical propulsion system.

[tater]

BTW, solar-thermal is also an option for Mars I think.

[Ackoli]

add solar sail and my dry ice propulsion idea to the list.

[Kaos]

And chemical. Obviously some people want to vote for that.

[Ackoli]

3 minutes ago, tater said:

This makes no sense whatsoever. Are you proposing that travel to Mars requires 1g constant thrust for the entire trip, with a turn-around at midpoint? No one has proposed anything of the kind. Even NTR proposals are a brief boost phase, with a long coast.

Modern mission plans include spun habs.

the spun habs would have to be inflatable.

[Spaceception]

15 minutes ago, Kaos said:

Artificial gravity is not complicated. In Mars Direct (1990) it is even shown how to use the empty upper stage of the rocket that is flying the way anyway and a cable of some kg to do that. I prefer to use technology that was 1990 already known for a long time and not technology that has not proven to work today.

I know, artificial gravity isn't complicated, but we have yet to actually test it properly (Or a significant amount deliberately, depending on how you feel about Gemini 11). And NERVA/SEP are the most near term of the four propulsion systems, because we know they work, we've done a lot of testing on the two, so unless some future president/NASA admin forces NASA to use VASIMR or FDR, NERVA/SEP will likely go one our first few manned Mars missions, since they shorten the amount of time in space/exposed directly to radiation.

Edited January 21, 2016 by Spaceception

[Kaos]

I would use the mars direct plan or a pair of aldrin-cyclers with some food production modules. Both do not directly require inflatable modules, while they would be nice to have.

Edited January 21, 2016 by Kaos

[RuBisCO]

If we were mining the moon for water, we could have done it with nuclear water rockets or H2/O2 rockets (ISP of 410-510). A mission would first go to moon-L2, get fueled up, then from there to mars orbit, landers would drop off, then returning it would swing around the earth and go back to moon-L2 to refuel, get new landers from earth, etc. Doing this skips all the energy needed to get up from LEO.

Total delta-V is >830 m/s to mars, verse >3600 m/s needed to go from LEO to Mars. 670 to 2110 m/s to enter Mars orbit (High verse Low Mars Orbit). Total delta-V round trip is 3 to 5.88 km/s.

[Spaceception]

5 minutes ago, Kaos said:

And chemical. Obviously some people want to vote for that.

I'm assuming that we'll scrap chem propulsion (At least for deep space ((Not counting the Moon)) manned missions) by our first manned Mars missions (Which is likely), so no:/

[Kaos]

2 minutes ago, Spaceception said:

I know, artificial gravity isn't complicated, but we have yet to actually test it properly (Or a significant amount deliberately, depending on how you feel about Gemini 11). And NERVA/SEP are the most near term of the four propulsion systems, because we know they work, we've done a lot of testing on the two, so unless some future president/NASA admin forces NASA to use VASIMR or FDR, NERVA/SEP will go one our first few manned Mars missions, since they shorten the amount of time in space/exposed directly to radiation.

Then we should test it.

The amount of radiation is not that bad, by the way. To quote Zubrin again: If we send smokers but leave the tobacco on earth we will actually lower their cancer risk.

Furthermore, while I belief that NERVA could be developed, I think that implementing Mars direct is faster without first waiting to develop Mars Direct. Then I think it is likely that waiting for all that future technology is the reason why we have no manned Mars mission yet.

[gooddog15]

 I think Bimodal NERVA's would be the way to go. Provides propulsion when it's needed, and electrical power when it's in idle.

image from Atomic Rockets

Edited January 21, 2016 by gooddog15

[Kaos]

3 minutes ago, Spaceception said:

I'm assuming that we'll scrap chem propulsion (At least for deep space ((Not counting the Moon)) manned missions) by our first manned Mars missions (Which is likely), so no:/

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.