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Q: Space Travel ( No Answer,   16 Comments )
Subject: Space Travel
Category: Science > Physics
Asked by: ssiva-ga
List Price: $5.00
Posted: 13 Jun 2002 15:05 PDT
Expires: 13 Jun 2003 15:05 PDT
Question ID: 25414
Given todays (6/13/2002) technology, what is the most cost effective
system that could be built by 2010 to provide transportation to and
back from the surface of the moon for millions of people? Please state
the approximate cost and reason for your answer.
There is no answer at this time.

Subject: Re: Space Travel
From: cerebro-ga on 13 Jun 2002 15:56 PDT
Dear ssiva,

The most cost effective way of traveling to space in the year 2010
might be a "scramjet" (an advanced space shuttle with reusable
engines).   Today Lockheed Martin and the NASA are currently working
on a project called the X-33.  Itīs main objective is to reduce the
amount of space needed for the oxygen burnt in the combustion process
therefore reducing the cost of previous tanks disengagements.

Simple economics tell us that not being able to reuse "space aircraft"
parts like a common airliner is one of the reasons why there is not a
single cost effective method of transportation known yet. Although
world wide more than $USD50 billion dollars are spent in space
civilian operations.

"To put a figure on these costs, it is noted that the cost of
launching a payload into low Earth orbit is in the vicinity of $10,000
per kilogram, which is near the price of gold. It means that any
object that we care to place in orbit becomes worth its weight in
gold!" taken from Space travel why is it so expensive.

the cost associated with moon travel might be very difficult to
determine because you should also need to calculte the investment
required to create a moon launching pad.

I dont want to spend the 5 bucks listed here is an interesting site
where you might gather the info
Subject: Re: Space Travel
From: mvguy-ga on 13 Jun 2002 16:46 PDT
I don't know if it would be possible to start transport by 2010, but
almost certainly any plan for placing millions of people on the moon
would have to involve some sort of space elevator in order to be cost
effective.  One of the main problems with any plan is that it takes a
massive amount of energy simply to place someone in orbit, as the
first comment below indicates.  The space elevator, which uses a long
cable whose end is in geostationary orbit about 36,000 kilometers
above the earth, reduces the cost of getting people in orbit to
reasonable levels.

Most of the talk about a space elevator has suggested that one could
be built by the end of the 20th century. However, it may be possible
to build one much sooner than that. In fact, Bradley Edwards, a
physicist from Los Alamos National Laboratories, has developed a plan
that could have an operational cable in place within 10 to 20 years.

"The space elevator appears much closer to reality than has been
suspected in terms of available technology, cost and schedule,"
Edwards said. "The major hurdle is the required carbon nanotubes, but
that's getting closer each day."

Information about Edwards is from an article in

According to a study presented at a 1999 workshop on the subject, the
cost savings are incredible. David Smitherman, a NASA researcher who
presented the paper, said costs could drop to a few dollars per
kilogram to place someone in orbit. A passenger with baggage might add
up to, for example, 150 kilograms and be lifted into orbit for only
$222, he said, instead of the current $3.3 million.

The information on this paper is from an article, "Audacious &
Outrageous: Space Elevators" on the NASA site:

Here are some other sites of interest:

Space Elevator Concept (Flight Projects Directorate)

How Stuff Works: Space Elevators

The Audacious Space Elevator

Space Elevator: Technology Development Needs

Space Elevator (Wikipedia)

Search Strategy
"space elevator"

I hope this helps.  (I was researching this and had to leave suddenly,
so I figured I should share what I have.)

Subject: Re: Space Travel
From: guymac-ga on 13 Jun 2002 16:57 PDT
The X-33 program has been canceled. Furthermore, there was no evidence
it's technology (Single-Stage To Orbit) would dramatically reduce
costs. Nor
was it even a scramjet as you imply.

It would be prohibitively expensive to provide resources to millions
of people on the Moon. A much more suitable choice would be Mars, with
its ample water ice reserves in the southern latitudes (recently
detected by the Odyssey spacecraft).

A promising concept to deliver humans to Mars is the "Mars Direct"
scenario, championed by Robert Zubrin of the Mars Society. In this
plan, the return craft is send ahead, it builds the propellants
necessary for the return trip in situ--i.e. using the resources on the
planet instead of sending them from Earth.
This lessens the prohibitive costs of other plans.

Now of course the bottleneck is first getting humans to orbit in large
A number of promising concepts have been generated as a result of the
X-Prize foundation which is offering a ten-million dollar prize to the
first organization demonstrating viable space tourism by sending a
two-person crew to orbit twice within two weeks.
Subject: Re: Space Travel
From: dannidin-ga on 14 Jun 2002 03:54 PDT
You might want to take a look at the fascinating book "Islands in the
Sky", edited by Robert Zubrin and Stanley Schmidt (see
reference below). It's a collection of papers about space travel,
discussing the technical (and financial) aspects of the ideas
discussed above (space elevator, Mars Direct plan, etc) and many more.
Some of them, especially towards the end of the book, border on the
ridiculous or at least very far off in the future (such as: how to
direct our planet to a different star once the Sun is about to burn
out...), but many are quite "down-to-earth" proposals about the very
near future of space travel. I seem to remember the space elevator
idea was dismissed there as impractical, because of the exponentially
growing thickness the elevator cable would need to support its own
weight 36,000 kilometers down, but maybe this problem can be resolved
with the advent of new material science discoveries?

Hope this helps,
Subject: Re: Space Travel
From: andrewxmp-ga on 14 Jun 2002 08:09 PDT
Just a note- A scamjet engine will most certainly not work on a trip
to the moon.  It's design is based around compressing air and oxygen
into a jet, as a gross simplification.  Their is no oxygen, nor any
form of atmosphere, in space.  Perhaps a scramjet-based craft could
gain momentum enough in the atmosphere to make it to the moon, but it
could enver return.  I believe that the X33 and related designs rely
on more convential propulsion for reentry.
Subject: Re: Space Travel
From: cliffclavin-ga on 16 Jun 2002 14:00 PDT
Following up on mvguy-ga's comment on "space elevators:"

There is an excellent novel by Arthur C. Clarke (of "2001: A Space
Odyssey" fame) titled "The Fountains of Paradise," which delves into
the engineering considerations of building a space elevator or space
tower in an entertaining and easy-to-understand manner.  As mvguy
pointed out, the major engineering hurdle -- a material with enough
tensile strength that it wouldn't snap under its own weight -- is
still just out of reach.  It *could* be possible by 2010...

Barring that, I doubt there is such a thing as a cost-efficient method
for people to travel to the Moon, using current technology.  Space
vehicles are built pretty much on a "one-shot" basis; i.e., designed
and constructed for one particular mission.  There is a trend towards
standardized, reusable spacecraft, beginning with the Space Shuttle;
but even that is not a practical vehicle for passenger service to the
Moon.  Even if it were economically feasible to start such a service,
it would be decades before the initial investment would be paid back.

If someone was determined to do it, however, I would recommend a
3-vehicle system: one vehicle to take passengers up into orbit,
another to make the trip to Moon orbit, then a third shuttle to make
the surface landing and return.  This would be much more efficient
than trying to design one vehicle to do all three jobs, with
two-thirds of the vehicle's systems acting as dead weight at any given
Subject: Re: Space Travel
From: marduky-ga on 21 Jun 2002 23:20 PDT
I don't know about the exact technologies and cost, but there is a
competition to build a reuseable launch vehicle.  I think the best bet
would be to monitor the progress of the participants.  Perhaps talking
to some of them will help.  They are trying to build their vehicles
for maximum performance and minimal cost.
Subject: Re: Space Travel
From: kjack-ga on 24 Jun 2002 12:54 PDT
By 2010 the transportation of 'millions' of people to the moon will
not be possible. If were asked today and just 'had' to do it my view
would be we would transport sections of the space transport system to
be used into space on the shuttle. We would then build the spacecraft
in low earth orbit (say 200-300miles altitude). This would then run a
mission profile very similar to the Apollo mission (free return loop
with option to insert into moon orbit). The spacecraft would do an
orbit insertion ( just slow itself down by burning the rockets in the
direction of travel to allow Moon's gravity to hold it in an orbit
around it). A part of the craft would go down to the Moon and part
would wait in orbit around it. How big would the crew be? Well, 3-5
people maximum. The less the better. If the sun gives of a burst of
solar radiation while they are in transit to or from the Moon it could
prove fatal for the crew. As for millions, I don't think so yet. By
the time we are thinking of transporting millions of people off of the
Earth to another body it will be to a much further destination. The
reason would be that either our Sun was at the end of its life or
another large body was going to hit that point funding
would not be an issue!
Subject: Re: Space Travel
From: chennes-ga on 25 Jun 2002 15:28 PDT
Just a quick note about the X-33/VentureStar project:

This project was cencelled last year due to massive cost overruns (as
a previous reader mentioned). Further, its aim was to reduce the price
of launching to orbit - it was certainly not capable of the velocity
change required to get to the moon. Lastly, it was to be powered by a
linear aerospike engine, not a scramjet (supersonic combustion
ramjet). Again, as a previous reader mentioned, a scramjet is an
airbreather, and isn't much good for anything but atmospheric flight.

To get millions of people to the moon by 2010 is (for obvious reasons)
never going to happen. But if the world pooled all of its resources,
2020 might be more reasonable.

Now, branching into the realm of complete fantasy: If it were to
happen in that kind of short-term, conventional or nuclear rockets are
a must, and probably some combination of both. Zubrin's Mars Direct
mission is expected to cost on the order of 50 billion US dollars
(this is somewhere in the middle of several other people's cost
estimates). This will land 6 people on Mars (actually, there are a lot
more details than that - read the book if you want more).

While not really comparable to a moon mission, an enormous amount of
that money is spent just getting off the planet. So figure that 10
million people would require .1 million times this amount (a
conservative estimate, I think). That puts you in the ballpark of
about 5 quadrillion USD. This is not really taking into account any
economies of scale, and is obviously just a blind napkin-calculation
guess, but hey...

Subject: Re: Space Travel
From: orbitalelement-ga on 27 Jun 2002 06:11 PDT
Dear ssiva,

It's interesting that no-one appears yet to have mentioned the Moon

which is dedicated, inter alia, to: "the creation of a space-faring
civilization which will establish communities on the Moon; promotion
of large-scale industrialization and private enterprise on the Moon."

The Moon Society's objectives are a little more modest than those
posed in your question.   Their "Project Leto" is a "full-scale
simulation of an initial lunar lunar exploration base ... [it] will be
marketed for outreach purposes, analog research, and as a tourist
destination" (

The Moon Society is working with Artemis Society International on the
"Artemis Project" which aims to go beyond the simulation stage and to
establish a permanent base.  See:

Again, this is more modest than your question implies (i.e. it *won't*
be a colony for millions of people) although their timescale is,
more-or-less, in line with your question, aiming to establish this
base within 10 - 15 years or so (see

I am not personally familiar with the detail of these projects (I am a
communications satellite engineer and not involved in manned or
interplanetary projects) but it seems to me that, given the paucity of
government funding (both in the US and outside) for returning to the
Moon, it may well be that the good old commercial imperative is what
finally gets the dream underway.

Oh... and by the way...

When your colonists do arrive on the Moon they'll find that a republic
has already been declared, elections held, citizenship granted and
real estate sold off!  :-)   See:

It's a funny old World, isn't it!
Subject: Re: Space Travel
From: ssiva-ga on 27 Jun 2002 11:24 PDT
I just wanted to thank all the contributors so far.  I have been doing
some of the recommended reading, especially the web links and have
been truly intrigued by the results.  When I initially approached this
question myself, I started doing the mathematics behind a giant linear
magnetic accelerator for people pods that could get someone going fast
enough on earth to leave the atmosphere without using rocket
propulsion.  If anyone has any comments on this, I would be very

Thanks again,
Subject: Re: Space Travel
From: remoran-ga on 01 Jul 2002 07:19 PDT
The space elevator looks like the best bet at this point in time
though I doubt if it will be built by 2010 due to the amount of
nanaotubes (or equivalent) needed to be manufactured to build it. I
think the persson who described this tech in great detail has the
answer you are looking for. That was great reasearch. I learned a lot
from that material.
Subject: Re: Space Travel
From: justinoogle-ga on 14 Sep 2002 12:51 PDT
Orbit is easy.

balloons... lots of them.  

The actual orbital travel cost to and from the moon could be cheap..
To and from the moon, hydrogen feul cells, solar power, lots of way to
keep shuttles powered up for earth to moon orbital trips though re
entering earths atmosphere would be tough.
but it's simple (ok nothings simple) 

If you launch a rocket from sea level it will have to me many times
larger and more powerfull than if you launch from say, 100,000 ft.

A launch platform raised by balloons is already putting small
satalites into space.  Grapefruit sized satalites launched by rockets
comparable to a hobbiests.  What once cost millions now a mere 10,000
or less.

Are we next?

We have the technology, but there are too few casinos, rollercoasters
and theme park attractions to get dad to shout;
"pack up the suburban kids, we're going to disney moon!"
Subject: Re: Space Travel
From: prof_moriarty-ga on 28 Sep 2002 13:01 PDT
The simple answer is:
It can't be done. Not putting millions even into orbit by 2010, let
alone to the moon.

There are a number of launch technologies:

1) The successor to the space shuttle. Due to be finished by about
2015. Will probably still cost a fortune to launch things into space
knowning NASA.

2) SuperGuns: Huge guns that can fire things into orbit the same way a
normal gun fires projectiles. Many countries don't like the idea of
this as it could potentially be used to launch projectiles to other
Note: There is no way this technology could be used to launch people.
The g-forces would squish them.

3) The space Elevator. My personal favourite. Arthur C Clarke famously
said: "It will be built 50 years after people stop laughing at it".
People stopped laughing a few years ago. The first conference was held
this year (
This on has the most potential. It produces virtually not pollution
(depends on the power plant used) and is always there.
There is quite a lot of technology that would be required to allow
this to be built, including: a strong enough material to hold the
stuff: Carbon Nanotubes are the best idea, but they can't be produced
in bulk just yet. The method of transport used to get up it would
probably be magnetic levitation. Meaning superconducters and other
related fields also need work.
I believe this could be done by 2030 given the funds.
This one also gives the cheapest method of getting into space. Lots of
energy is required to get the goods to the top, but when the cars come
down again, they get most of that energy back.

The space elevator could also be used as a slingshot to throw things
to the moon and other places along the ecliptic.

4) Electromagnetic launcher (ssivas intial idea). But this couldn't be
used for humans because of the G's involved. People would get
squished. Of course a very long runway thingy could be used which
would lower the G's, but i think that that would result in huge
amounts of wasted energy. In the first few hundred meters after
leaving the launch rails the projectiles velocity would be halfed by
the atomosphere and gravity. This would be best for places like the

5) A plane that has jets (stationary to mach 3), ramjets (mach 3 to
mach 5), scramjets (mach 5 to mach 25), and rockets to get it from
mach 25 to orbit (just a little push).
This one is probably the closest and most cost effective.

Subject: Re: Space Travel
From: theinvisibleman-ga on 16 Oct 2002 06:49 PDT
Easy! well I guess if you take into count that you have to make an new
source of propulsion or engine its not so easy. But that is the way to
solve your problem: find a more efficient way of moving at high speeds
and (something often overlooked but could help a lot) create a
reusable cheap re-entry heat tile for spacecraft, or maybe just one
that can do like 1000 re-entries or something.

Both technologies could be discovered in a year and mass produced in
five years but they have to be discovered first and that requires
someone with the genius to this.

Here are my crazy ideas on a new engine:
I think we should figure out a way of easily creating positrons
(Currently the only way is to collect radiation off certain elements,
needless to say very in efficient). This is a tall order and might
never get filled but if someone somewhere ever did this then the rest
is feasible. You create a system of superconductor accelerators to
create a beam of elections (not that difficult basically man made
lightning - been done since the 1890's, of course this will be a
little more controlled) then collide that beam with either another
beam of positrons made in the same way (possible because
superconductors repel all magnetic forces and positrons act the same
way electrons do but with opposite charge) or have a cloud of
positrons. Which ever way is more efficient. If this is done correctly
with all the right angles and math then the result should be a beam of
energy E=mc^2 style. This is because positrons are the electrons
anti-matter and when they collide with electrons they both turn into
pure energy, that is there mass (which is very small) X the speed of
light squared (a really big number) = the amount of energy you get but
here's the kicker: its in focused in a certain direction! So instead
of the big boom of a nuke you get the power of say 20,000kt of TNT
focused to push an object in the other direction. The resulting thrust
could be regulated by how much electrons are used and the g-forces
problem could be solved by only using enough energy to go orbital on
earth and then hit full thrust in space.

NOTE: the process could be more efficient with a 'heavier' particle
like a neutron but the problem still lies with finding a good source
of anti-neutrons or any antimatter.

ALSO: If you think my numbers are off then correct me I just pulled
them out of my head and didn't calculate anything so I am probably

ONE MORE THING: Do not automatically say its impossible because its
not, It could be done with radiation as the source of positrons but
that’s so inefficient the mass to energy ration wouldn't work.
Subject: Re: Space Travel
From: ldavinci-ga on 06 Nov 2002 15:45 PST
I feel that the space travel has to be done in two stages.
i) Some means of transport from earth's surface level to one that is
already in the orbit.  It could be done by various means but will be
the one that does not involve fuel for accelaration due to safety issues.
It could be multilevel magnetic acceleration, where the intermediate
stages after provinding thrust float back to earth for reuse.
ii) From the gravitationless orbiting platform, It could be again magnetic
acceleration with electrical energy collected through high efficiency solar
cells.  There will not be any intermediate stage involved except at the
collection point(ie. moon).
iii) Conventional fuel based thrust will be used only for emergencies,
micro manouvers and decelaration during re-entry.

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