Return to the moon or mars landing: what first?

[magnemoe]

Using the Moon as a launchpad might not be a good idea:

1) A Moon base would have to be on the poles, because it is the only place with semi-permanent sunlight (for solar power) and it also has more water. This would make for an awkward location for BEO flights.

2) If you are heading for BEO, it doesn't make much sense to land on the Moon first. Although the gravity well is smaller than the Earth, it's still wasteful to launch from.

3) An Exploration Gateway station at EML-2 makes more sense as a refueling point for BEO missions. You could resupply it from the Moon Polar Base if you managed to achieve ISRU.

Moons poles are interesting because of the water who can be used for fuel for follow up flights, also an commercial resource as you could use it for an LEO to GEO transfer tug and other uses.

[metaphor]

A Moon base with ISRU capability would be the best thing to have in the long term. It could be used to lower the costs of both manned Mars missions and missions to anywhere else in the solar system, by providing much of the fuel, effectively canceling out ~10 km/s of the needed delta-v.

However, a manned Moon base would be very expensive. The current cost estimates are around $400 billion. An unmanned outpost which only did ISRU could probably be done with much less money, but it would still be a significant expense.

If the Moon base doesn't provide fuel for Mars missions, there is not really any advantage of having a Moon base before a Mars mission. There aren't many technologies that would be developed for a Mars mission that would benefit from being tested on the Moon.

For a Mars mission, you would need to develop: a deep-space habitat; a surface habitat; a way to do entry, descent, and landing (EDL) for big payloads; a Mars ascent vehicle; and some optional technologies that would make it a lot easier, like nuclear thermal rockets (NTR) and solar electric propulsion (SEP) for cargo. Having a base on the Moon would not help develop any of these technologies. You don't need a deep-space habitat to go to the Moon. The surface of the Moon is as different from the surface of Mars as the surface of Mars is from the surface of the Earth, so a Moon surface habitat would not be very helpful for developing a Mars surface habitat. Landing on the Moon is very different from EDL on Mars, so that would not help either. A Mars ascent vehicle might have some similarities to a Moon ascent vehicle, but would not be the same. SEP might be developed to send cargo to the Moon, but I don't see NTR developed for Moon missions.

The cheapest way to get to Mars is pretty much what the administration's plan is right now. Using asteroids or the moons of Mars as an intermediate step. The proposed asteroid retrieval mission's biggest cost is developing the large SEP stage that would take the asteroid back to cis-lunar space. A version of that SEP stage could later be used to transport cargo to Mars (or the Moon). Afterwards, a mission to a deep-space asteroid would be a good test for a deep-space habitat that would be pretty much identical to the one needed for a Mars mission. It would also demonstrate the capability to perform operations with significant light-time delay to Earth, which is what is needed for a Mars mission. A Mars EDL system for large payloads could be demonstrated by a Mars robotic sample return mission. A surface habitat and a Mars ascent vehicle would have to be developed on Earth. This series of missions would pave the way towards a human Mars landing and return around 2035, and would probably cost less than $100 billion overall.

A Moon base with ISRU would cut the costs of any single Mars mission since all of the Mars return fuel could be gotten from the Moon. But provided such a Moon base exists, developing the capability to go to Mars would still need to take the same steps as without a Moon base. So it would still take around $100 billion to develop the capability to land and return from Mars. The individual missions would just get cheaper, maybe from $10 billion to $5 billion apiece.

For a manned Moon base, we would need to develop a Moon lander and a Moon surface habitat. The Moon lander has been estimated at $8-10 billion, and the surface habitat probably more than that. Since the delta-v to get to the Moon is a little more than the delta-v to get to Mars, each individual Moon mission would have a pretty high cost, maybe $3-5 billion.

The problem right now is that there's currently no money to build a lunar lander. The ISS and the SLS are taking up most of the human spaceflight budget in NASA, and it would take at least 10-12 years to get to a short Apollo-style mission to the Moon, working with the scraps left over by the ISS and SLS programs. After that, the most NASA could do with its budget would be one short Moon mission every 1-2 years, and maybe start building a permanent base 10 years later. This is assuming a flat NASA budget. Of course the politicians could always raise NASA's budget and make more things possible, but it doesn't seem like they want to do that.

In answer to the OP's question, we should be doing both. There isn't really any reason not to work towards both a Moon base and a Mars landing at the same time, besides politics. If restricted to the current anemic budget, a Mars landing might be better just because it would achieve more milestones faster than a Moon base, and would also have higher technology development.

(some sources: this document from 2009 estimates the development of Mars landing and return capability at $60 billion. this one and this one have a detailed discussion of the technologies for a human mission to Mars. it's hard to find a reliable source for Moon base cost estimates.)

[EmissionGeneration]

Despite the cost difference between going to Mars and Building a Moon Base, sure, Mars might be less expensive, but to be honest to succeed in life, you need to work your way up, not just take the short and easy route. Sending people to Mars will be extremely Dangerous, and for what? To plant a Flag so some Country can have it as a Trophy? Honestly that's not how I want Astronomy to be seen in the eyes of everyone. We've flown to another Celestial Body, and planted a Flag, now the next step will be living comfortably on 1 [Within a Safe Distance to Earth]. Once we have Achieved that, THEN we should be considering another Planet.

[Apollo1391]

NASA already announced that 2023 they are doing a manned mars mission and in 2025 they will begin construction of moon base alpha

[Apollo1391]

NASA already announced that 2023 they are doing a manned mars mission and in 2025 they will begin construction of moon base alpha

[The Jedi Master]

NASA already announced that 2023 they are doing a manned mars mission and in 2025 they will begin construction of moon base alpha

Assuming Mars One doesn't get there first, only ten years to go!

[GJames]

NASA already announced that 2023 they are doing a manned mars mission and in 2025 they will begin construction of moon base alpha

Any sources? Sounds interesting, although a bit too good to be true...

I think that if the target is Mars, then we should go straight to Mars. That way we get there sooner and we don't need to spend billions on infrastructure because let's face it, the first thing space agencies need to do is convince the politicians, and it's easier to get funding if you ask for less. If the USA or the EU really wanted to go to Mars then they could, but they're held up by parliament/congress and red tape.

Edited July 9, 2013 by GJames

[jwenting]

NASA has announced a lot of things they wished to do as "definite" only to later (have to) cancel them because congress cut their funding or assigned them different priorities.

That includes manned mars missions in the 1970s, Nova, Space Shuttle replacements, Space Station Freedom, etc. etc. etc.

[Dockillar]

Moon Base, Humans are going to need to learn how to live without any connections of supplies from earth before we can send people off for almost a year and a half to Mars.