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An article at SpaceNews.com asks Is the Gateway the right way to the moon? — the "Gateway" is The Lunar Orbital Platform-Gateway.
This article originally appeared in the Dec. 17, 2018 issue of SpaceNews magazine.
Sometime in 2028, competing for attention alongside a presidential election and the return of the Summer Olympics to Los Angeles, NASA will return humans to the surface of the moon.
A lunar lander will depart the cluster of modules in an elliptical orbit around the moon, called Gateway, and descend. One stage will take the lander to a low lunar orbit and then separate, after which the descent module will handle the rest of the journey to the lunar surface. A crew of up to four will spend days — perhaps up to two weeks — on the surface before boarding the ascent module, which will take them back to the Gateway.
At least that’s NASA’s plan for now. A year after President Donald Trump formally directed NASA to return humans to the moon in Space Policy Directive (SPD) 1, the agency has developed the outlines of a plan to carry that out, while emphasizing the language in the policy to do so in a “sustainable” manner and with international and commercial partners. But as the agency describes two of the biggest elements of the plan, the Gateway and a “human-class” lunar lander, it’s still struggling to sell the proposal to its various stakeholders, including its own advisers.
[The somewhat long article is well worth a read. Notable members of NASA as well as former astronauts weigh in on their views of the pros and cons of such an approach as opposed to direct flights to and from the moon. To my eye, NASA was instructed to make the Deep Space Gateway happen so there was a destination for the Space Launch System (SLS) which currently costs something like $2 billion per year in launch and development costs. By comparison, I recall reading that SpaceX anticipates it can develop its next-generation Big 'Falcon' Rocket (BFR) and Big 'Falcon' spaceship (BFS) — now called "Super Heavy" and "Starship", respectively — for about $2 billion total. --martyb]
(Score: 2) by Immerman on Thursday January 03 2019, @02:03AM
As you say, that's not the lack of pressure that's bothering you, it's the lack of oxygen.
That's where the oxygen partial pressure comes in - it's the pressure the oxygen in the room would be at if you magically removed all the other gasses in the room. Basically it's the total pressure multiplied by the percentage of molecules that are oxygen. So long as that number doesn't change, neither does the amount of oxygen in a breath of air.
Flammability is also tied very closely to partial pressure (all reactivity is, really). Pressure is basically a measure of how many molecules are hitting a surface per second (and how fast, which depends only on temperature). So long as the number of oxygen molecules hitting a surface in a second is constant, so is the number of potential chemical reactions that could contribute more heat to the flame. Inert gasses would alter the thermo-fluid dynamics of the flames themselves to some extent, but I *think* the effect on fire hazards would be relatively minor.
Regardless though, if you want a full 1atm of pressure, it's not *that* much more difficult - you only have to double the tensile strength of your walls.
As for the boiling point of water, no worries. Body temperature is ~40C, if we call 60C a nice wide safety margin, then we can drop the pressure to about 3 psi - or pure oxygen at Earth-normal partial pressure.