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This piece is quite an interesting read, as well as being well structured and well phrased. This makes it all the more unfortunate that the writer is obviously unfamiliar with the technologies which would be used, and the realities of aerospace projects; leading to a slew of errors.

Some of the errors include:

1) Separating oxygen from nitrogen is quite commonly done, and there are at least three distinct methods for doing it. The reference is to an amateurish analysis done by others who had not done any research. Source: http://en.wikipedia.org/wiki/Pressure_swing_adsorption

2) It is quite well known that NASA distributes its contracts around the country, so as to increase political buy-in from governors, congressmen, and senators. In fact, the space shuttle was green-lit because Nixon had cancelled the national aerospace plane, and his administration had a meeting about how that would affect votes in key swing-states, and they decided that the shuttle would benefit his re-election effort. Sources are numerous including https://www.youtube.com/watch?v=Fo8v7juSgRw .

3) Vitamin D would be a problem from lack of sunlight, not vitamin A, and even then supplements and artificial lamps both provide viable long-term alternatives to sun-exposure.

4) Building a vehicle to carry sufficient fuel and supplies for the trip to Mars is not especially technically challenging, when compared to the design of an earth-entry vehicle. Earth orbit rendezvous allows for the assembly of massive (though expensive) space vehicles such as the ISS.

⬐ abraxas7

I worked in industrial nitrogen/oxegen generator provider, and it is not really rocket science to do this. All we had to do was finding optimized pressure and substance for gas distillation.

⬐ lrichardson

> Building a vehicle to carry sufficient fuel and supplies for the trip to Mars is not especially technically challenging, when compared to the design of an earth-entry vehicle. Earth orbit rendezvous allows for the assembly of massive (though expensive) space vehicles such as the ISS.

Of course, they do have to land on mars, don't they? Isn't this roughly similar (and thus similarly as challenging) as earth re-entry?

⬐ NickNameNick

Possibly more so.

I think it was someone working on Curiosity that said mars has just enough of an atmosphere that you have to worry about it, but not quite enough to be useful.

And bearing in mind that when your spacecraft hits the martian atmosphere, it was traveling at interplanetary transit speeds, much greater than orbital speed.

⬐ iwwr

>I think it was someone working on Curiosity that said mars has just enough of an atmosphere that you have to worry about it, but not quite enough to be useful.

It certainly is useful and you can still shed 90-95% of the inbound orbital velocity or even that from an interplanetary trajectory with a reasonable heat shield. It would be far more difficult if Mars were completely airless. You still need retrorockets for landing big payloads but at a discount.

Though the other atmosphered bodies in our solar system: Earth, Venus (cloud deck), Titan can be achieveable with just parachutes.

⬐ Solarsail

I'm pretty sure that was Steve Squyres in the book Roving Mars, discussing Spirit and Opportunity. From memory, a heat shield can get you from escape velocity down to ~mach 3, and then supersonic parachutes can get you down to ~100mph. It's an issue because you've still got to slow down beyond that, but you can't just ignore atmospheric shielding like you could with the Moon (in response to iwwr)

I could be wrong about him saying that in Roving Mars (I can't exactly grep my paperback copy, and Google isn't helping), but I'm pretty sure it wasn't on the subject of Curiosity... I heard it in 2006 or 2007, while Curiosity was still called the Mars Science Laboratory.

⬐ dded

To your point (3), perhaps it is reasonable to bring a lifetime's supply of vitamin supplements for four people. But with an artificial lamp you would have to worry about bulbs burning out (how many would you need?), and the lamps would consume a significant part of what would have to be a limited power supply in the colony.

To your point (4), that there may exist an even more difficult problem does not mean that building a Mars vehicle is "not especially technically challenging." The author explicitly cites the three recent malfunctions with rocket launches, and the older Apollo, Soyuz, and Shuttle programs all had their difficulties too. Building a Mars vehicle is surely challenging.

⬐ XorNot

You wouldn't build such a lamp like on Earth. An oxygen plasma with a spectrum filtered glass case, microwave excited to avoid the need for electrodes, would last pretty much forever and be repairable using only in with materials.

More on said problems:

http://www.youtube.com/watch?v=Fo8v7juSgRw#t=54m55s

"The machine is a beautiful, wonderful piece of hardware. The orbiter system, the most complex system ever built by man to fly has never [...] had a failure that would have prevented that machine from landing safely."