Moon Tourism business plan (was Re: WHAT'S NEW Robert L. Park Friday, 16 Mar 07 Washington, DC)

In sci.physics, jmfbahciv@xxxxxxx
<jmfbahciv@xxxxxxx>
wrote
on Sat, 24 Mar 07 11:20:20 GMT
<eu31hk$8qk_001@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>:
In article <9a4Nh.39$25.143@xxxxxxxxxxxxxxxxx>,
mmeron@xxxxxxxxxxxxxxxxxx wrote:
In article <meked4-q3b.ln1@xxxxxxxxxxxxxxxxxxxxxxx>, The Ghost In The Machine
<ewill@xxxxxxxxxxxxxxxxxxxxxxx> writes:
In sci.physics, mmeron@xxxxxxxxxxxxxxxxxx
<mmeron@xxxxxxxxxxxxxxxxxx>
wrote
on Fri, 23 Mar 2007 06:48:45 GMT
<hLKMh.25$25.95@xxxxxxxxxxxxxxxxx>:
In article <3o6cd4-hmm.ln1@xxxxxxxxxxxxxxxxxxxxxxx>, The Ghost In The
Machine <ewill@xxxxxxxxxxxxxxxxxxxxxxx> writes:
In sci.physics, mmeron@xxxxxxxxxxxxxxxxxx
<mmeron@xxxxxxxxxxxxxxxxxx>
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on Thu, 22 Mar 2007 04:04:57 GMT
<JfnMh.17$25.104@xxxxxxxxxxxxxxxxx>:
In article <ep69d4-pjf.ln1@xxxxxxxxxxxxxxxxxxxxxxx>, The Ghost In The
Machine <ewill@xxxxxxxxxxxxxxxxxxxxxxx> writes:
In sci.physics, mmeron@xxxxxxxxxxxxxxxxxx
<mmeron@xxxxxxxxxxxxxxxxxx>
wrote
on Thu, 22 Mar 2007 01:24:58 GMT
<KVkMh.13$25.69@xxxxxxxxxxxxxxxxx>:
In article <1174525991.021333.222320@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
"Eric Gisse" <jowr.pi@xxxxxxxxx> writes:
On Mar 21, 12:29 pm, Sam Wormley <sworml...@xxxxxxxxx> wrote:

[...]


2. NASA BUDGET: NO ROOM FOR THE ALPHA MAGNETIC SPECTROMETER.
Yesterday, Bart Gordon (D-TN), chair of the House S&T Committee,
noted that the budget reality bears little resemblance to the
"rosy projections" offered by the Administration when the
President announced his "Vision for Space Exploration" three
years ago. Don't scrap the vision - kill the science. One
casualty is the $1.5 billion Alpha Magnetic Spectrometer that was
scheduled to go to the ISS on a 2008 shuttle flight. Griffin now
says there's no room for the AMS on the shuttle because every
flight is crammed with hardware to finish the ISS. It wouldn't
do to drop an unfinished ISS into the ocean. The AMS was
designed to search for antimatter. Nobel prize winner Sam Ting
of MIT, made the case for AMS personally to Dan Goldin. It was
cited repeatedly by NASA to show that the ISS would do basic
sciencehttp://bobpark.physics.umd.edu/WN98/wn061298.html.

Deorbit the ISS onto the VLB containing the shuttles. Two birds, one
stone.

Hmm, the idea has merit:-)

What is the ISS even *FOR* anymore? Not even enough room to stuff on
an experiment designed specifically to work on the ISS...

What do you mean "anymore"? The ISS always had the same purpose, to
keep the shuttle alive. And the shuttle is there to keep the ISS
alive. Perfect symbiosis.

The shuttle is scheduled to die in 2010, IINM. What will replace it
is not clear to me yet.

It is certainly not clear to me and I see no evidence that it is clear
to NASA. One cannot come with a decent design absent a well defined
mission.

A well-defined mission? From our erstwhile President?
Surely you jest... :-)

Much as it pains me to burst your political bubbles, NASA had no well
defined mission since the end of the Apollo project. That's 7
Administrations, quite bipartisan. Note that "continue with general
space research" is not a well defined mission.

Come to think of it, I think you're right; NASA hasn't
really been the same since the Apollo-Soyuz affairs.

Right.

The "space truck" is at best uninspiring -- sort of
like the difference between Lewis & Clark, and a modern
diesel driving down the highway (10-4 good buddies; is
there a smokey on my tail? C'mon back...) Granted, the
latter perform a very useful service, but it's not quite
as romantic.

Indeed. And by now the bulk of our space activities is in the
category of "useful services", a space trucking industry. "Take this
satellite and deliver it to orbit, pronto". Nothing wrong with this
but it is quite separate from exploration. Different type of
priorities, different type of people involved, etc.

I'm not sure a Martian trip will be all that exciting either, especially
since it will take half a year to a year to get there.

And since there doesn't appear to be, in the public eye, a compelling
reason to get there.

In truth, I'm not sure what could serve as a mission, comparable to
"getting to the moon", right now.

Tourism.

I'm not sure that counts as a mission though it might be
an interesting business to develop -- the main problem
at this point is that, if it costs $20M to travel to the
space station, how much would it cost to get to the moon?
I'd suspect something in the $40M-$50M range, per tourist,
using conventional technology. Not all that many tourists,
I suspect, will get up there.

This contrasts rather pleasantly with the estimated $135B
for the Apollo program, which delivered all of 18 people
to the vicinity of the moon (and killed three: Gus Grissom,
Edward H. White the 2nd, and Roger B. Chaffee).

I'm frankly not sure how one could get that down to $500
per passenger, as

http://www.time.com/time/magazine/article/0,9171,939195,00.html

suggests. $500 translates into 5 megawatthours (the US
average is $0.10/kWh for electricity, though it varies).
Earth orbit is about 8km/s, or 32 megaJoules per kg, or
3.2 GJ for a 100 kg passenger such as myself. (Yeah, I'm a
bit hefty. :-) I'm also 6'1", so can't help some of it.)

6.4 GJ will achieve escape velocity for a 100 kg payload,
which is what is needed to escape Earth's gravitational
pull, to put it simplistically. That's 1.78 megawatthours.

Hm. Interesting. Of course there are a fair number of other
considerations.

- Oxygen. A sedentary human will consume less oxygen than an active
one, and I'm frankly not sure how much is enough, but clearly the
amount of calories consumed during a day can be variable but is
usually stipulated as about 2500 kcal/day, or 10.46 MJ/day.
One might estimate O2 consumption using the (rather naive) glucose reaction

C6H12O6 + 6O2 => 6CO2 + 6H2O + 2.87 MJ/mole

which means one can consume about 3.645 moles or 656 grams
of glucose and survive for a day.

Counterbalancing that is the 6 moles of oxygen (96 grams)
per mole of glucose; this means that our hypothetical
occupant would be consuming 349 g of oxygen during
that day. Since a moon roundtrip takes about 8 days
(though it could be whittled down a bit), one can budget
maybe 8 kg extra for oxygen and food, or 20 kg if one
wants a goodly safety margin.

If one uses tristearin (
(CH3(CH2)7CH=CH(CH2)7COOH)3(HOCH2HOCHHOCH2) or
C57H110O6), which is a form of animal fat, one gets
34 MJ per mole, but 1 mole of tristearin will set one
back 890 g and the oxygen (since 163 additional atoms
are needed to burn it completely) will set one back an
additional 2.608 kg.

Given that regime one would need 2.19 kg of fat and
6.42 kg of oxygen.

This doesn't look like a significant expense, although
going without is not an option.

- Water. I frankly don't know how much water a human
should drink. Some have suggested 32 oz (or about
3.85 liters) per day; in hot, arid climes one might
consume as much as 5 liters. Since air travel is
naturally dessicating one might budget an additional
6 kg/day/passenger here, or about 50 kg. Some of this
might be budgeted as glucose drinks or sodas. The water
will come out as vapor and as urine. It is possible
waste might be dumped on the moon, and reprocessed,
giving the moonbase a somewhat inconvenient but
necessary source of hydrogen, oxygen, nitrogen, carbon,
and some salts.

- Heat. I will have to research this but the spacecraft
will radiate heat to its environment -- namely, space.
Absent a heat source, it might get a tad chilly therein.
The good news: a sedentary passenger will act as a
heat source, about the same as a 120 watt light bulb.
The bad news: dehumidification will also be necessary,
and the only way I know of to do so is by a standard
air conditioning unit, which also chills the air.

I will budget nothing here for now.

- General mass overhead. Obviously, one can't stick a
human on the outside of a rocket (Wile E. Coyote and
Doctor Strangelove notwithstanding) and blast him
into space. The Airbus A380 can carry 853 passengers
(total weight might be 145,000 kg, including 70kg total
of food, oxygen, and water per passenger -- unfortunately
this is above the A380's maximum payload of 90,800 kg)
and weighs 276,800 kg empty. Maximum takeoff weight is
560,000 kg, but that includes fuel.

http://en.wikipedia.org/wiki/Airbus_380

This suggests a "weight budget" of about 325 kg to
surround that passenger.

- Propellant. I think we've got everything else, but
can't do much without actually putting something into
the rocket. Isaac Asimov used the rather interesting
idea of steam power, with a "micropile" as the heat
source. Deep Space 1 uses xenon propellant, with a
very very gentle thrust delivered during a long flight.
More conventional rockets use a combination of hydrogen
and liquid oxygen.

Tsiolkovsky developed, long ago, an equation for rockets
using very basic physics and some calculus. This so-called
Rocket Equation can be expressed

v_f = v_e * log(M_i/M_f)

from a standing start (v_i = 0).

http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation

This can of course be rewritten:

M_i = M_f * exp(v_f/v_e)

For chemical rockets a la the Saturn V, v_e = about 2.5 - 3 km/s.
For various reasons we'll actually want

M_i = M_f * exp(4*v_f/v_e)

because the classical Rocket Equation exhausts all of
its propellant to get to that final velocity, whereas a
moon trip will require at least four burns (two of them
to slow down). Since v_f = 11.2 km/s and v_e = 3 km/s,
one gets the rather ugly result

M_i/M_f = 3000000 .

Small wonder the Apollo program cost so much.

If one assumes v_e = 30 km/s, one gets the much more reasonable

M_i/M_f = 4.45

Given improvements in rocket technology so that we can get this
performance, one can now budget an additional 1400 kg. Total
budget thus far: 1800 kg. Total energy per passenger
is about 1400 * 1/2 * (30000)^2 = 630 GJ. All of this energy
goes into spewing propellant all over the place.

If one develops a rail launcher on the Moon, one might
have a chance at eliminating one of the burns, though.
However, that launcher would have to be deployed
somewhere near the Moon's edge, probably straddling the
near and far sides.

- Fuel. It turns out uranium is not all that clean a fuel;
the main problem is getting it out of the rock.
Crushing, chemical extraction, and purification all take
their toll on the environment; the tailings from mine
extraction alone are radioactive and highly polluting.

Nevertheless, we need a power source.

The energy liberated from 1 kg of uranium appears to be
about 560 GJ. Therefore, for every passenger we'll need
about 1.125 kg of U235, which isn't all that much from
a weight standpoint. Of course there's the little issue
of shielding the reactor, which for now I'll ignore.

Considering the screaming regarding the Callisto mission
-- which admittedly used plutonium, not uranium, as a
power source, and radioactive decay, not fission, to
produce the energy for various parts of the spacecraft
(not the rocket), a uranium-based spacecraft isn't
going to happen anytime soon anyway. Irrational bunch,
we humans -- but not totally irrational.

TOTAL BUDGET: 630 GJ, or 175 megawatt-hours, or $17,500 per
passenger -- and that's assuming a rocket engine 100 times
as powerful (and with 10 times better exhaust velocity)
than the ones we have now.

That's a lot more than $500, though still reasonably
affordable. It would be the trip of a lifetime for many,
but there's a lot that would need to be done first, such
as actual construction of the moonbase and development of
the rocket.


/BAH


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