Ever been on a wall of death at a fairground? It works in the same principle, spin the cylinder fast enough that you stick to the inside wall then they remove the floor and you are stuck there, it doesn't spin that fast either and you doo feel the extra "gravity" sticking you to the wall, it is weird sitting up on the wall and seeing the real floor to your side, man it has been a long time since I was on one, about 1971 in the Kelvin Hall Glasgow.

So in other words it would cost over 20 times the current annual budget for NASA. lol

The 2015 budget for NASA is 18.5 billion.

We might have to cut funding for lesbian orangutan weight loss drugs, or the effects of swedish massages on rabbits, or teaching mountain lions how to walk on treadmills.

You can do this in your head. Take a bucket, and half fill
it with water. Now tie a rope onto the handle, and lift it
up. Now start to swing the bucket, and increase the rotation
speed until you can have the rope taut and essentially
horizontal. Where is the water, and what's keeping it there?
The water is trying to flee in a straight line, and if you
put a small hole in the bottom of the bucket, it will escape,
but otherwise the bucket prevents it.

This is inertial mass at work, not gravitational (the fact that
the two behave identically, in respect to the relative force
imparted to different materials, tells us something very deep
about the way the world works), it works this way anywhere,
independent of what local gravity is doing.

There is somewhat of an issue with the chamber shown in the
movie, though: it is too small to generate 1 G, so the crew
should be experiencing a force closer to that of Mars gravity,
or rather even less. As this is really hard to depict when
your movie is being shot on earth, I give them a pass on it
(including the martian gravity, 40% of earth's).

The reason I say it must be a smaller force is that unless
you stay very still, you will get horribly ill if you try to
function in a room where 1 G of gravity is being generated by
spin, unless the radius of rotation is large enough to get
the rotation rate under 1 rpm - a fraction of the population
can tolerate more, very very few can cope with more than 3.
This is due to our sense of balance and acceleration, which
is geared for a life in a very uniform true gravitational
field, not a weird spin field, with large coriolis forces.
The brain gets very unhappy when faced with the latter.

The relationship between rotation radius and g force is
independent of anything else but rotation rate. a 1 rpm
1g requirement gives a radius of just under 1km.

This becomes a serious design problem for space habitats,
as the bigger the radius, the lower the rpm, but the longer
the spokes. And when spokes are at 1 G at the outer end,
they are like cables hanging on earth, and the room becomes
a mass being hung from the cables. You need a cable strong
enough to hold up the room, which requires a larger diameter
the bigger the room, and then the cable has to hold itself
up as well - 1km of cable is a lot of force, though not a
show stopper by itself (steel breaks at around 30-50km hanging
at 1G). But this means for steel, your room should for safe
margin not weigh more than about 10 to 15 times the mass of
your cable. This rapidly becomes a limitation to the size a wheel
space habitat can be built. Now you have a lower limit to the
size, unless you allow a much lower value of ersatz gravity, and
you have an upper limit, which is adjustable to some degree by
keeping down the weight of the living quarters, and the cable
material, but you usually need a minimum mass around a living
quarter for radiation shielding, and no matter how you fiddle
it you will hit a limit, and fairly quickly. So you look at
lightening everything as much as you can get away with, and
sliding up the rpm as much as you can get away with, limiting
the inhabitants to a reasonable fraction of the population who
can tolerate the conditions, and you lower the G value as much
as you can get away with, maybe 1/3 to 1/5 earth G. You can
consider for instance a 100m radius room spinning at 1.5rpm
generating 1/4 G. (here's a handy calculator for working out
possible combinations: http://www.endmemo.com/bio/grpm.php -
the internet has everything).

We could have made two for the cost of fighting in Iraq, plus fewer people would've died.

It's not that we can't do it, it's that we don't want to do it. If we wanted to do it, we would, cost be damned. If we don't, almost no price is palatable.




The Jedi Master

Well if we're making those comparisons we could build 2 A YEAR for what is spent on the welfare state, every year. And fewer people would be enslaved to government dependency.

Yup, we could. But again, people want to keep wasting money as they've been wasting it, not spend it on anything worthwhile that could result in actual advancement. Too many people's jobs depend on the gov't not changing course.

SOP is to make a lot of noise about changing course, to make sure you get into power, or your cronies do, but don't ACTUALLY change anything because you might change your job out from underneath you, and then what would you do? One side promises to turn one way, the other promises to turn the other, but they have zero intention of actually doing it.




The Jedi Master

I'd cut out ALL foreign aid that is currently being given to Pakistan, Afghanistan and Iraq and use those funds to supplement the NASA budget. It's not a huge amount but it would at least add a billion or so.

NASA would just squander it like they do with their current budget. Give it to commercial space instead.

...and that's the truth.

Just saw it. Would be nice if the US had a chance of being first on Mars, but it looks more likely to be Russians or Chinese doesn't it?

Personally I honestly couldn't care less if the Russians or the Chinese landed a manned expedition on Mars first. Actually, China may indeed do it but not Russia. Russia's economy is currently in shambles. They can't even afford to update things like their surface fleet or most of their air force so I highly doubt they would have the money for a manned Mars expedition. Heck, what about the EU space agency? They would have a much better chance than Russia.

Only if they buy a ride from Elon Musk.

Think we have to be careful about writing off the Russians. Aren't they the only ones able to put man in space at the moment with their Soyuz platform? And they aren't the only ones with problems maintaining their strategic capabilities. Sixty Minutes showed that if the US President gives the order to fire a nuclear missile, some of them have to be booted up with 8" floppy disks first.

http://arstechnica.com/information-techn...lear-deterrent/

H

True to a point, but they're not the only ones with the know how. There are a handful of private companies in the US with the know how, with one (SpaceX) that could do so in a couple of months if the need outweighed a few safety concerns. And even then they'd probably still be about as safe as Soyuz.

Also hasn't Russia been unable to get anything to Mars in the last thirty or so years do to a long string of technical failures? Rockets blowing up on the pad, probes failing to respond when they've made it to Earth orbit, etc. etc.

Sigh. I tell my kids they'll probably live to see a man land on mars. Don't care who it is, it would be awesome. But the way things are going, I wonder if they will...

H

PS my 14 yo boy gave the movie 5/5.

I doubt I will live long enough to see it happen.


Wheels

I am 53 and I am still holding out hope that I will see humans walk on Mars should I live a normal lifespan.

Just wondering...




Did I miss something or did I get that part all wrong?