Moon Base baby steps

(Russell Wallace) writes:

On 29 Jan 2004 15:27:59 -0800, (Alex Terrell)
wrote:

Carbon is abundant in many NEOs. Nitrogen is a problem, but not a
major problem until we move from Torus colonies to Cylinder colonies
with their large volumes. Until then, a Heavy Lift Vehicle delivering
NH3 is enough.

As far as air-filler goes, wouldn't argon be an adequate substitute
for nitrogen? I've a feeling the moon and asteroids ought to contain
argon. (Someone correct me if I'm wrong.)

Why would you have that feeling? Argon is an inert gas, so it doesn't bond
to anything (well, except for fluorine and chlorine, under contrived laboratory
conditions), and its melting point is not that much higher than nitrogen's.
You won't find frozen argon lying around until you're almost out to Neptune...


-- Gordon D. Pusch

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In article ,
Greg D. Moore \(Strider\) wrote:

"Joe Strout" wrote in message
...
In article ,
(Russell Wallace) wrote:

On 24 Jan 2004 06:30:13 -0800, (Alex Terrell)
wrote:

........................

No. People have stayed in microgravity for extended periods of time;
staying on the Moon will be no worse than that (and may be quite a bit
better, for all we know).


"Ah we sure?" Seriously, we may find the 1/6 g isn't enough to prevent
calcium loss, but is enough to make bone breaks more likely than in orbit?

So we take lots of calcium pills. At any rate, we are not
likely to get answers unless we try, and there will be
plenty of volunteers.

This is not likely to be the only problem with living in
reduced g. The answer is not on earth.
--
This address is for information only. I do not claim that these views
are those of the Statistics Department or of Purdue University.
Herman Rubin, Department of Statistics, Purdue University
Phone: (765)494-6054 FAX: (765)494-0558

(Henry Spencer) wrote in message ...
In article ,
Ross A. Finlayson wrote:
I'm trying to get an understanding of the relationship of exit
velocity, launch track length, G forces, and power. Anybody have a
chart of that?

v^2 = 2*a*d, where v is exit velocity, a is acceleration, d is distance
(length). Something that can reach orbital velocity, assuming fairly
low atmospheric-drag losses, ends up being around 4600 G-km, so getting
the length down to 10km or so requires operation at several hundred Gs.
NB, this assumes constant acceleration.

Note that you would need a small rocket stage in the projectile, because
an Earth-surface catapult *cannot* put something directly into orbit -- it
can reach only orbits that intersect the atmosphere, so a bit of rocket
fuel is needed to finish the job.

P = m*a*v, where v and a are as before, m is projectile mass, and P is
peak power. This is up in the gigawatts even for m=100kg; clearly one
needs local power storage that can be charged up slowly and discharged
very quickly. (t = v/a, so that 10km track is covered in about 2s.)
Neglecting losses, energy is 0.5*m*v^2, so for m=100kg we need about
1250kW-hr per shot.

Note that 100kg is almost certainly much too small to get acceptable
atmospheric drag losses, and for that matter the drag loss assumed in the
above example numbers is probably too low even with higher mass.

This is different from a rocket which also makes a sonic boom and
spews tons of poisonous gasses onto the launch pad, at irregular
intervals.

There's nothing particularly poisonous about the exhaust from a
LOX/kerosene or LOX/LH2 rocket.

The Earth to Orbit Mass Driver is a better environmental alternative
to unassisted rocketry.

A point of terminology: this is a catapult, not a mass driver. The two
terms are not synonymous. A mass driver is a particular type of catapult,
which accelerates its payloads in payload carriers, "buckets", which are
decelerated and returned to the head end for re-use.

The launch apparatus is completely reusable,
hundreds, thousands, and perhaps hundreds of thousands of times.

It's also extremely expensive.

Its use introduces no toxins directly into the environment.

Its exit shock wave will be rather hard on the surrounding environment.

...Electricity may be from greener sources...

Or not, as the case may be.

Ten kilometers is around six miles, let's say that the goal is to
provide orbital velocity and also exit velocity, the orbital insertion
booster is presumably robust, but on failure the ballistic projectile
should not return to Earth.

I can see why you think a mass driver is O'Neill's "High Frontier"
electric racetrack with the regolith bucket, but an electromagnetic
catapult is still a mass driver. I prefer to call it a mass driver
personally.

Thanks a lot for those calculations.

The shockwave seems to be the Earth-to-orbit mass driver's drawback,
in terms of operation and not construction. Again, to reiterate, in
comparison with the alternative, rocket launch, they each suffer that
issue.

So I'm trying to get a better idea of what the launch tube would look
like. I can agree that we would want pretty much constant
acceleration, I think that means that each of the coils, say ten feet
diameter rings, about six inches thick, spaced a couple feet apart,
for say, one coil per meter or ten thousand coils. Here you may be
able to tell I only have encountered the notion of using a gauss gun
for orbital velocity recently. So anyways there are these coils, and
then there are guide rails that the supercooled payload levitates upon
via superconducting electromagnetic levitation, or plain old magnetic
levitation, or a sled or wheeled cart sabot, thus that the hypersonic
payload does not actually contact the coils.

The coils are completely inerchangeable, they are each identical.
They are also one piece construction with no moving parts.

The power storage and perhaps generation facility is nearby, it must
be able to incrementally store and quickly release the power into the
coils in a carefully synchronized way. I guess this is the role of
the capacitor and one of the issues to be resolved in the five year
design stage of the multi-million dollar project.

Let's see, orbital velocity is, uh..., let's see, the mass of the
Earth is 6*10^24 kg. F = G m1 m2 / r^2, the "Universal Law of
Gravitation", I thought it was little g, the gravitational constant G
is 6.7 * 10^11 Newton meters^2/kilograms^2. F = ma. Escape velocity
is that instantaneous velocity which will be decelerated by gravity
between Earth and the pod thus that when it reaches the point where
Earth's gravity is nominal it still has non-nominal velocity, where
Earth in its own orbit around the sun does not catch up with it.
That's about not an orbit but shooting it away from Earth, directly
away from the center of the planet, and having it near balance there.

http://www.physlink.com/Education/AskExperts/ae158.cfm

ETOMD doesn't shoot the pod straight up, that would require a ten
kilometer launch tower or sunken shaft. Instead, it should take
advantage of the topography to get as steep an angle as it can get on
pod exit from the launch tube. Also the tube could be straight or
constant curvature, preferably for simplicity of computation. So it
has initial velocity components in two dimensions, the vertical
velocity component, that being the one directly away from the center
of Earth's mass, being required to be escape velocity or greater.
This is what it would be designed to do on every single pod that is
massed and balanced the same, for repeatibility and no pods falling
back short on Earth. So anyways, the pod has left the atmosphere a
couple hundred kilometers downrange from the launch track, maybe even
in U.S. airspace.

These kind of back-of-the-envelope/paper napkin calculations well make
use of assumptions like "the Earth is spherical", "Earth's centroid is
its center of mass" and "gravity is constant over the Earth" (re
geodetic variation), "Earth orbital plane is at 23.5 degrees",
etcetera. Maybe it should be launched at 23.5 degrees angle, or,
well, whatever, depending on its latitude, perpendicular to Earth's
orbit around the Sun. Also the Moon is sitting there in Earth orbit
somewhere and its default escape path should either be in a path clear
of the moon, or, perhaps it could take advantage of the Moon's
location to shoot directly to Moon's orbit. That would be asking too
much, as Moon orbits around the Earth in ways I don't know, ETOMD is a
fixed emplacement, but many are obviously familiar with moon periods.

I have to relearn a bunch of stuff to calculate escape velocity, the
force applied by each coil to some hypothetical pod, by the energy,
and what happens when the pod hits the air, depending on its
composition, profile, velocity and atmospheric conditions. I have to
relearn how to read a book because I know how to do none of that stuff
except calculate escape velocity.

"Dynamics of Multibody Systems - 2'nd Ed.", Tsuboi's "Gravity", Dover
classics "Theoretical Kinematics", three or four tensor books, "Fluid
Mechanics", this might help a lot: "Electrodynamics: A Modern
Geometric Approach". Cripes, all this just to figure out what to put
on the purchase orders for ten thousand ferromagnet or high
temperature superconductor coils.

Dang, if the coils each cost five thousand dollars then that's already
ten percent of the project budget of five hundred million dollars,
assuming the coils have no defects and need no replacement. In that
case the track could be shortened to one kilometer, using one tenth
the track length and having frighteningly higher acceleration. Or,
maybe that's OK. The other project costs are the prepared track site,
the presumably concrete footing for the thing, the power
infrastructure, the capacitors, the capacitor synchronization
instrumentation, shell and fairing for the launch track, perhaps
airtight, cooling if superconductors are used, and command and control
structures.

I think the force is strongest between the coil and the pod when the
pod is nearest to the coil, or is it inbetween that and distant? That
is to say, I know a coil should be deenergized by the time the pod
actually passes it, and not flip-flopped as this is pull design and
not a pull-push design, that might use less power, but when should it
be energized? What are realistic dimensions for the coils given the
pod is to be designed to have a minimal aerodynamic profile, that is
the droplet shape, the pod is to mass 2000 kilograms, etcetera?
Please give your guesstimates on what the nuts and bolts of an Earth
to escape velocity mass driver would be.

You gave a figure of 1250 kwh for 100 kilograms, twenty times that for
2000 kg is around 25000 kwh, neglecting losses is several thousand
dollars for electricity. That already puts a big dent in the launch
cost, which is to be economical.If the pod, which has avionics and
control systems, costs a hundred thousand, as they are produced by the
thousands, that puts the actual launch costs at around a hundred
thousand for the electricity and the pod, and then there are all the
costs to run the command and control systems. Let's imagine: 250 000
for 1800 kilograms into space, that's around $140/kg.

Nothing has ever been launched past Earth's gravity well for less than
a hundred dollars a pound. The mass driver could run every daylight
hour for years. People could launch their pets' ashes into space. On
holidays it could coat the pod with pyrotechnic sparkle. It would be
a good light show any day of the week.

The Shuttle is currently, not including design, construction, and
shelf maintenance costs, of billions and billions of dollars, running
around some 25000 per kilogram, or 500 000 000 dollars to launch some
24000 kilograms.

If the capacitors exist, the mass driver could be designed to launch
instead of two thousand ten thousand kilogram payloads. That might
just be twisting the knob.

Of course, the mass driver is not designed for people, the
acceleration forces we discuss would jellify a man. That would
require a longer track, and perhaps a ten or fifteen second launch
boost at less than four G's, it wouldn't make a louder noise.

Well, I guess it's not exactly Earth to orbit, it's more Earth to
escape velocity. There, it has control systems, of various kinds,
special occasion launches, particularly if variable power could be
used to apply different escape velocities, could help put the pods on
their way to specific destinations.

A hundred years ago the internal combusion automobile had to stop at
an intersection, and the driver then had to get out and step into the
intersection, light a firework and blast a horn, and offer all right
of way to horsedrawn traffic. Two hundred years ago there wasn't a
train track from coast to coast of North America or Europe and Asia.
Fifty years ago no man had even been to space.

It took almost seventy-five years after Wright's powered flight for a
man to get to space. Today airports have decibel limits.

Could building a coilgun system for beyond Earth escape velocity
really cost less than one shuttle mission, and launching 250 tons with
it to the moon less than two?

Ross F.

On 31 Jan 2004 09:20:21 -0600,
(Gordon D. Pusch) wrote:

Why would you have that feeling? Argon is an inert gas, so it doesn't bond
to anything (well, except for fluorine and chlorine, under contrived laboratory
conditions), and its melting point is not that much higher than nitrogen's.
You won't find frozen argon lying around until you're almost out to Neptune...

But it's produced by the decay of potassium-40, so shouldn't rocks
pretty much everywhere contain some? (Is that where Earth's argon
supply comes from? Our atmosphere is ~1% argon IIRC.)

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
http://www.esatclear.ie/~rwallace

On Sat, 31 Jan 2004 10:42:06 +0000, Cardman
wrote:

On Fri, 30 Jan 2004 21:16:57 GMT, (Russell
Wallace) wrote:

I'd have thought a modest-sized satellite would provide adequate
living space and consumables for some mice for a few months?

Hopefully such an experiment can be done aboard the ISS, when they
have the right equipment that is. As that would be related to human
sciences and can be better studied on the ISS.

Then hopefully someone will do it there.

Survive in the technical sense of "not dead yet", but I wouldn't call
having your health seriously and to some extent permanently damaged
"just fine". (Particularly since most of their waking hours have to be
spent on keeping it at the "not dead yet" stage.) It's certainly not a
viable basis for long-term human habitation of space, and if that's
not the end goal, why are we spending money putting people in space at
all?

Taking claim of our rightful property? Why have just one planet, when
there are countless numbers for the taking?

Exactly - and to do that, we need to aim for viable long-term human
habitation of other worlds, in environments that meet the requirements
for sustaining health - which means we need to find out what those
requirements are, particularly in terms of gravity.

If putting people in space is to be more than a meaningless publicity
stunt, it should be focused on viable long-term objectives,

Since NASA cannot afford long term objectives, then that is why they
are running "one step at a time" in order to build and support what
they can afford in the future.

Fine, but it would be more helpful to take one step at a time in the
right direction rather than the wrong one.

and that
means coming up with ways to enable people to _live_ (as opposed to
marginally survive) in space.

Yes, just attach heavy weights to their ankles, wrists and torso, when
1/6th G will suddenly seem a lot heavier.

That won't help. For example, it won't stop your immune system falling
apart because cell division is botched without gravity to provide cues
for the cytoskeleton.

NASA certainly does need artificial gravity in Space though, when we
known that lack of gravity is harmful.

Yep.

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
http://www.esatclear.ie/~rwallace

On 31 Jan 2004 11:40:22 -0500, (Herman Rubin)
wrote:

[living in 1/6 G]

So we take lots of calcium pills.

That won't necessarily help...

At any rate, we are not
likely to get answers unless we try

But that's why I pointed out an easy way of getting a lot of the
answers in advance.

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
http://www.esatclear.ie/~rwallace

"Gordon D. Pusch" wrote in message ...
(Russell Wallace) writes:
On 29 Jan 2004 15:27:59 -0800, (Alex Terrell)
wrote:

Carbon is abundant in many NEOs. Nitrogen is a problem, but not a
major problem until we move from Torus colonies to Cylinder colonies
with their large volumes. Until then, a Heavy Lift Vehicle delivering
NH3 is enough.

As far as air-filler goes, wouldn't argon be an adequate substitute
for nitrogen? I've a feeling the moon and asteroids ought to contain
argon. (Someone correct me if I'm wrong.)

Why would you have that feeling? Argon is an inert gas, so it doesn't bond
to anything (well, except for fluorine and chlorine, under contrived laboratory
conditions), and its melting point is not that much higher than nitrogen's.
You won't find frozen argon lying around until you're almost out to Neptune...


Actually there's always a little argon floating around the Moon as a
product of nuclear decay, so some may be trapped in the ground. But I
doubt that you could collect it, considering the Moon's atmosphere
compressed to Earth pressure would fill only about a sports stadium,
and that's mostly hydrogen from the Sun. Also the argon might be ra-
dioactive isotopes themselves; I don't know that much about it...


--
__ "A good leader knows when it's best to ignore the __
('__` screams for help and focus on the bigger picture." '__`)
//6(6; ©OOL mmiv :^)^\\
`\_-/ http://home.t-online.de/home/ulrich....lmann/redbaron \-_/'

In article ,
(Russell Wallace) wrote:

don't need to do that, we know that people survive a year just fine in
much less than 1/6 G.

Survive in the technical sense of "not dead yet", but I wouldn't call
having your health seriously and to some extent permanently damaged
"just fine". (Particularly since most of their waking hours have to be
spent on keeping it at the "not dead yet" stage.) It's certainly not a
viable basis for long-term human habitation of space, and if that's
not the end goal, why are we spending money putting people in space at
all?

Well obviously, people are not going to be living (in the long-term
habitation sense) in microgravity (*). But this is not a difficult
problem to solve: you spin the habitat. We've known how to solve that
problem for decades.

Now, that doesn't work quite as elegantly on the Moon, and this may or
may not turn out to be a problem for long-term habitation there. If it
is, then maybe the Moon will never have many long-term inhabitants, but
only term workers. I'm OK with that. But we won't know until we go set
up base there and see how we do.

- Joe

(*) At least in biological form. Once mind uploading is developed, of
course, we can build ourselves to be perfectly comfortable in a wide
range of environments, including microgravity. But that probably won't
happen in this century.

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(Gordon D. Pusch) wrote in message ...
(Russell Wallace) writes:

As far as air-filler goes, wouldn't argon be an adequate substitute
for nitrogen? I've a feeling the moon and asteroids ought to contain
argon. (Someone correct me if I'm wrong.)

Why would you have that feeling? Argon is an inert gas, so it doesn't bond
to anything (well, except for fluorine and chlorine, under contrived laboratory
conditions), and its melting point is not that much higher than nitrogen's.
You won't find frozen argon lying around until you're almost out to Neptune...

The Moon was formed in an impact with Earth so it
has very few volatiles. In fact, the Earth has
fewer volatiles than it should due to this event
(compare with Venus). Mars, however, has plenty
of easily accessable Nitrogen, and Argon. If
extraterrestrial production and shipping of
atmospheric components are at all economically
worthwhile from any off-Earth location in the
Solar System then the same from Mars would likely
be very competitive.

Also, Argon may not make the best filler gas for
breathing. It's slightly heavier than air and
also a mild anasthetic gas. Not really the best
combinations.

On 31 Jan 2004 11:40:22 -0500, (Herman Rubin)
wrote:

At any rate, we are not
likely to get answers unless we try

Ah, looks like someone agrees with me about the best way to start
getting answers ^.^

http://www.spacedaily.com/news/mars-general-04c.html

--
"Sore wa himitsu desu."
To reply by email, remove
the small snack from address.
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