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Moon Is Stepping Stone, Not Alternative to Mars, NASA Chief Says

scientificamerican.com

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Re: Moon Is Stepping Stone, Not Alternative to Mars, NASA Chief Says

#41

Post by quacked »

superkuh wrote: post #14
stcredzero wrote: post #13

Earlier quoted context omitted.

"Braking," not breaking. Some of the most difficult challenges have to do with maintaining life support long term. The Moon isn't a bad place for that. If we're able to deal with operations in conditions dealing with vacuum, that experience is still applicable. Also, the human side of the procedures for preventing lunar dust and grit from entering the living space will be important and applicable to Mars. Mars soil i…

> "Braking," not breaking. Ah jeez. That's what I get for commenting right after rolling out of bed. > ... the most difficult challenges have to do with maintaining life support long term. The Moon isn't a bad place for that. The moon is a bad place for that because now you have to carry all that extra fuel for landing/etc. Low earth orbit is just fine for figuring out life support as has been done on the ISS already…

ECLSS designs for a moon base would be very, very different from the ISS, there's no "we've already figured out life support" in LEO. The ISS is frequently restocked with consumables, which is less of an option for a moon base and not an option for Mars base, requiring an entirely different top-down design.

Re: Moon Is Stepping Stone, Not Alternative to Mars, NASA Chief Says

#42

Post by chr1 »

cuboidGoat wrote: post #19
zwieback wrote: post #16

Human space flight - what a waste of resources. Send robots for the next 100 years.

By the end of this century I suspect there will be more than a million people living off earth, with the majority in orbitals. In about 200 years or so, I wouldn't be at all surprised if there were more people off earth than on it.

What would be the incentive for living off earth for such a large number of people?

I really wish for you to be right, but with population growth slowing down, and possibility of building floating cities or terraforming Sahara, building large orbital stations or going to mars in large numbers may be economically not viable, unless we invent something radically new.

Re: Moon Is Stepping Stone, Not Alternative to Mars, NASA Chief Says

#43

Post by cookingrobot »

kodablah wrote: post #33
davedx wrote: post #20

Ugh. Zubrin's 'The Case For Mars' (which on reading, it's obvious SpaceX have based a lot of their strategy on) is categorically against going back to the Moon and using it as a 'stepping stone'. Zubrin's 'Mars Direct' architecture shows quite plainly that it is possible using current technology readiness levels and funding to send a significant scientific mission to Mars directly , without the need for huge orbital…

I think there should be a distinction between "stepping stone" in the project management sense and "stepping stone" in the capabilities sense. While technology has made the latter unnecessary, I'm not convinced humans and lack of incremental extra-orbit progress haven't made the former necessary.

Milestone might be a better word then.

Re: Moon Is Stepping Stone, Not Alternative to Mars, NASA Chief Says

#44

Post by Latteland »

tomatotomato37 wrote: post #31
xefer wrote: post #24

A couple of interesting points to consider when thinking about putting a base on the Moon: "Each Apollo mission increased the mass of the lunar atmosphere by about 30%, and it took several weeks for the atmosphere to return to its natural state. Highly sensitive measurement or communication instruments may be affected by the additional atmospheric particles." [1] "Studies have also revealed that the balance is very d…

I'm not really convinced this is something to worry about. If the vaccuum is this unstable it would be eventually be inflated anyway by a comet or gaseous asteroid collision, and it's a happy coincidence that the moon hadn't lately had a significant collisions in the period of history that we were able to get up there and measure it.

I agree, is there really that much value in the moon being sterile and having no atmosphere. If it had one that was much denser, we could use aero braking. This would be far away from that.

Re: Moon Is Stepping Stone, Not Alternative to Mars, NASA Chief Says

#45

Post by Nomentatus »

logfromblammo wrote: post #36
fireismyflag wrote: post #6

The moon has 1/6th of Earth's gravity and 0% of our atmospheric pressure. Mars has 1/3rd of the gravity and 0.6% of the pressure. Those 2 factors make them very similar to each other and the distance makes the moon the clear candidate for a first step.

Transport between bodies in space is measured by kilometers per second as delta-V, not kilometers. Earth LEO 9.3 km/s LEO escape 3.22 km/s escape MTO 0.6 km/s MTO MCO 0.9 km/s MCO LMO 1.4 km/s LMO Mars 4.1 km/s ----- 19.5 Earth LEO 9.3 km/s LEO LLO 4.04 km/s LLO Moon 1.87 km/s ----- 15.2 Moon LLO 1.87 km/s LLO escape 1.40 km/s escape MTO 0.6 km/s MTO MCO 0.9 km/s MCO LMO 1.4 km/s LMO Mars 4.1 km/s ----- 10.3 (Earth -…

Thanks for the numbers.

30% of delta-V but much more than 30% more fuel used (etc) since "compound interest" applies as you're using fuel to ship fuel out of orbit and then much of that fuel again to change your orbit to mars, etc.

Similarly, Napoleon came up against the limits of using horses to pack hay for horses invading Russia - compound interest; you can only do so much.

PS - that 30% assumes a path that I don't, and no solar power used to catapult oxygen off the moon. I'd go for a Lagrange point you're ignoring.

PPS - you've assumed Mars, not, say, near-earth asteroids or trojans with a very different, far lower delta-V. Vastly different problem.

Re: Moon Is Stepping Stone, Not Alternative to Mars, NASA Chief Says

#46

Post by Nomentatus »

tomphoolery wrote: post #17
lostmsu wrote: post #5

I profoundly disagree. IMHO, the destination is open space, not another planet, and the gravity well on the Moon is waaay easier to overcome.

Everyone knows this, but as far as PR is concerned you want to limit the amount of information you're trying to get across. People, generally, are really stupid. Example: FB events for my shows have, in the description of the event, the location/date/time/cover charge/ticket link. All of that information is present well above that, but people will STILL post on the event wall asking where/when/how much if I don't do…

I can agree that Musk's Mars mantra had its place when nobody was paying any attention but "Mars" meant something and "let's move to dead rocks" wouldn't have been appealling. It's nearing time to drop it, though, I suspect.

Re: Moon Is Stepping Stone, Not Alternative to Mars, NASA Chief Says

#47

Post by Nomentatus »

yazr wrote: post #28

How "self sustaining" will a Mars base ever be ? So let assume they can make oxygen, water, maybe even calories. Great. Self supporting base. But other than that. Everything will have to be trucked in. Pipes, electrical wires, valves, medical supplies, antennas, plastics, etc. Will any of these be manufactured on-site in say 2050 ?!

Nearly all will be. On either moon or Mars. Mars soil isn't that different from (rich) lunar soil. Pipes and wires and plastics they can make easily enough (carbon dioxide ice is available seasonally, for plastics.)

Re: Moon Is Stepping Stone, Not Alternative to Mars, NASA Chief Says

#48

Post by aaron_m04 »

stcredzero wrote: post #13
superkuh wrote: post #7

Earlier quoted context omitted.

It really doesn't though. Descent, entry and landing on the moon is completely different than Mars. You have you use entirely propulsive breaking to get rid of your orbital velocity. On Mars for very large payloads propulsive breaking is needed but aerobreaking is a huge part of it too. The Moon is not practice for Mars. It's a waste of time for political posturing.

"Braking," not breaking. Some of the most difficult challenges have to do with maintaining life support long term. The Moon isn't a bad place for that. If we're able to deal with operations in conditions dealing with vacuum, that experience is still applicable. Also, the human side of the procedures for preventing lunar dust and grit from entering the living space will be important and applicable to Mars. Mars soil i…

> Mars soil isn't as bad, but some of it you don't want in your living space either.

It's probably worse, since Martian soil has perchlorates, which are toxic and cause thyroid problems at low concentrations.

Re: Moon Is Stepping Stone, Not Alternative to Mars, NASA Chief Says

#49

Post by njarboe »

martythemaniak wrote: post #25
davedx wrote: post #20

Ugh. Zubrin's 'The Case For Mars' (which on reading, it's obvious SpaceX have based a lot of their strategy on) is categorically against going back to the Moon and using it as a 'stepping stone'. Zubrin's 'Mars Direct' architecture shows quite plainly that it is possible using current technology readiness levels and funding to send a significant scientific mission to Mars directly , without the need for huge orbital…

Depends on what the moon missions are. Building moon-specific infrastructure (ie adapting things to 14 day long light / dark cycles, 0.3g) would be a distraction. Using it as a close - by testing ground probably doesn't matter except it had the upside of possible getting people excited. For example, spacex wants to test the BFS. They could send it on a wide orbit 2 days away, or they could orbit around the moon inste…

If the moon's gravity was 0.3g, that would be close enough to Mars'(0.38g) that it would be useful as a prelude to a Mars landing/exploration/occupation. Unfortunately the Moon's gravity is 0.17g, so not as relevant.

Re: Moon Is Stepping Stone, Not Alternative to Mars, NASA Chief Says

#50

Post by tomp »

cheeko1234 wrote: post #37

Robert Walker on Quora is a prolific writer regarding this. https://www.quora.com/profile/Robert-Walker-5 Specific answer to why moon first: http://qr.ae/TUGvkb

I find his answer entirely unconvincing.

> I think we are best not rushing into space, there’s no hurry about that. Let’s find out about space first, explore, learn, learn about our own capabilities too, [...]

Exactly the same argument can be made then.

> [...] have settlements in space when and where they are acutally needed, as the needs arise.

By then it will be too late. The idea is that we learn by doing.

> All this is hugely expensive and Earth would have to foot the bill. Because there is no way that they are going to turn a profit on Mars.

All this is hugely expensive and UK would have to foot the bill. Because there is no way that they are going to turn a profit in America.

> Not many peopole could afford a $200,000 spacsesuit.

"640K ought to be enough for anybody"

The most convincing part of his argument is weeks-long Martian dust storms.

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