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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

#31

Post by tomatotomato37 »

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.

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

#32

Post by monocasa »

sp332 wrote: post #18
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.

What's interesting about open space? To me it's the stuff in space that makes interesting destinations.

There's a lot of stuff in space that isn't in a deep gravity well of a spherical body. For instance mining asteroids enough to have a self sustaining manufacturing base at micro-g could allow for the earths manufacturing and power generation needs to be met somewhere that's not on the Earth, decreasing pollution.

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

#33

Post by kodablah »

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.

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

#34

Post by stcredzero »

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…

Low earth orbit is just fine for figuring out life support as has been done on the ISS already.

Entirely false. On the Moon, we can exploit in-situ resources for life support. Regolith can be used for radiation shielding and the extraction of oxygen. We can even harvest water in certain locations. Crops can be grown using hydroponics. Doing these things while maintaining a spaceport on another world isn't going to be nothing. Getting experience doing ground based operations is going to be valuable. It's not just "dust." It's probably literally tens of thousands of things we will have to learn through hard won experience.

Ground-based operations. Better to get the experience where help is only 3 days away.

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

#35

Post by ng12 »

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 ?!

I'm far from an expert on either chemistry or manufacturing, but there's credible arguments that almost everything you need can be obtained locally: http://canada.marssociety.org/winnipeg/plastics.html

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

#36

Post by logfromblammo »

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 -> Moon -> Mars = 25.5 km/s)
In order for the Moon to be a stepping stone, it would have to be a refueling station where most of the mass involved ultimately comes from the Moon, rather than Earth. As it is now, the Lunar industrial plant produces 0 Mg of rocket fuel annually. For 30% more delta-V, a rocket from Earth can just go to Mars directly.

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

#38

Post by maxxxxx »

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…

I agree. Having a permanent station on the Moon would be a great prep for a Mars station. In case there is a problem you have a reasonable chance to send repair material or a rescue whereas on Mars one single failure will be the end of it. I think a Moon station should be routine before we go any further.

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

#39

Post by abecedarius »

gpvos wrote: post #9
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.

Mars is obviously a stepping stone for open space or other planetary systems.

There are asteroids about as close or closer in delta-V terms. Mars is the easiest other planet, but planets just aren't as useful as asteroids and comets right now, because of those pesky giant wells they live in.

And Mars in particular is better left pristine until we've had a really good look for signs of life.

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

#40

Post by cjensen »

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.

The Moon also has far better solar energy potential. If you're going to have to live underground, better to do it someplace with lots of energy and close to help.
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