have you guys seen the vactrain?
marsbeyond
I heard your recent interview on the space show.
http://www.thespaceshow.com/detail.asp?q=935
This seems to be the most likely technology for moon rail.
Goddard had patents on it.
http://en.wikipedia.org/wiki/Vactrain
Now the mover and shaker on this seems to be Daryl Oster.
http://www.linkedin.com/profile?goback=%2Econ&viewProfile=&key=10874186&jsstate=.conbro_0_*51_false_*2_2951
http://www.et3.com/scren9.htm
Daryl Oster
Dear marsbeyond and other RRMM group members:
Thank you for introducing me to this interesting group, and for your
inclusion of ETT (evacuated tube transport).
Without ability to get to resources, or to have resources be transported
to us, we perish, therefore transportation is the master key to human
survival -- not only on earth, but anywhere. So, it is an absolute
given that transportation must be a key element of any long term human
activity on the moon or mars.
The most important question is what form of transportation will offer
the highest benefit to cost ratio for the anticipated needs?
I do not know much about moon or mars development, or the likely
transportation needs, yet i believe i can safely say that a traditional
railroad on the moon or mars is ridiculous. It appears (from review of
the files on this site) that at least some of the experts on this group
are in agreement with me on this.
Also, i consider that it would be foolish to specify ETT for initial
moon or mars development unless there were reasons for underground use;
OR, if ETT were first developed on earth to the point of offering LEO
insertion and recovery (reference the ETT Space Elevator (ETT-SE)
abstract i posted to the space elevator Yahoo group in 2002:
http://tech.groups.yahoo.com/group/space-elevator/message/642 ).
The main advantage of ETT (and the "vactrain") is elimination of
aerodynamic drag -- this is NOT a factor on the moon, and not of much
concern on mars either. So, even though i would like to be able to
promote ETT for moon and mars, in my estimation, there are likely better
choices.
I do have a few observations i will share on what is necessary to to
maximize the benefit to cost ratio (value) of a moon or mars
transportation system:
1) minimum practical vehicle design load: Due to the reduced gravity
force, larger vehicles COULD be used -- but why? It sounds impressive to
consider 747 size vehicles, however use of big vehicles increases costs
in MANY ways, yet adds little if any real benefit (especially on the
moon or mars where value will be much more important than on earth). If
you do not have to pay a driver, (or punch through atmosphere), most of
the advantages of big vehicles disappear. The vast majority (about 94%)
of items transported on earth will fit into a car, pickup, or SUV. The
median capacity of a car is around 850lbs. Car size on earth is highly
optimized by many decades of market optimization -- the standard
deviation in maximum payload is around 150lbs. On the moon, the optimal
maximum practical payload will likely be less. The minimum would be
just enough to carry a 95th percentile adult male with life support
equipment. IMO, a max payload of 200kg mass would be on the high side
of the optimum range. If the maximum design load were 200kg, the
empty vehicle mass could be as low as 50kg, for a earth weight of
2500N, and the gross moon weight would be only 400N. It takes much less
materials to produce small vehicles, and much less guideway materials
to support said vehicles. It takes much smaller facilities to produce
small vehicles compared with big vehicles. -- this will be especially
important if produced in pressurized conditions where people can work
without a pressure suit.
2) minimum guideway cross-section: A cantenary cable suspended system to
support at most 800N (2 vehicles passing) would require minimal
materials, time, and energy to produce(much lower cost than tubes).
Think of a ski area chair lift (except more like the overhead power
conductors used to supply electricity to trains or buses that use a
suspension cable and drop wires to eliminate conductor sag between
vertical support towers)-- this is MUCH less resource intensive as
typical railway tracks -- especially with regard to earth work.
3) full speed passive switching: A railroad track must physically move
to switch a vehicle from one route to another. By contrast, a freeway
is static, and the vehicle determines choice of route. The freeway
style of vehicle routing results in much higher vehicle frequency.
Capacity can be achieved two ways: big vehicles, OR high frequency of
vehicles.
4) off-line stations: A train stopped at a station limits the frequency
of vehicles that may use the track -- unless the station is off-line. A
freeway philosophy allows no stopping on the route -- all stops occur
after the vehicle diverges from the main line, and all merging takes
place at the full design speed.
5) Passive maglev like HTSM (High Temperature Superconductor Maglev):
HTSM uses permanent magnets in the guideway, and crude bulk
superconductor elements on the vehicle for stable levitation without
motion, and without electrical energy or electronic control. On the
moon or mars, the cooling requirements of HTSM would be trivial due to
access to heat sink below the transition temperature of YBCO. HTSM is
ultra reliable, and not prone to wear, also the drag is orders of
magnitude less than wheels (or most other forms of maglev). NOTE: HTSM
(developed in Chengdu China) is not EDS or EMS forms of maglev as
developed in Japan and Germany.
6) LEM (linear electric motor) with regenerative braking for propulsion:
with almost no friction, most of the energy required will be for
acceleration, and most of this energy may be recovered during
deceleration. During most of the trip, the vehicles will coast using
only a few watts of power to maintain speed and relative position to
other vehicles.
7) high design speed: time is valuable on earth, and will be even more
so on the moon or mars. High speed also enables high capacity using
small vehicles since maximum safe frequency is a function of speed.
Transportation value will be much more important on the moon or mars
than on earth. In short, railroads on the moon and mars will not be
practical for transportation needs -- there are much better ways -- like
roads/cars that have displaced trains to niche markets on earth due to
better transportation value. There are proposals for improving on the
transportation value of cars/roads, some of the best proposals for earth
transportation are known as PRT (our patented ETT technology is one form
of PRT).
IMO, ETT will not be the best form of transportation on the moon or mars
unless it is determined best for transportation to take place
underground for other reasons (on earth, underground ETT is about 3
times more costly than above ground). I suggest you consider something
like:
http://www.unimodal.com/ (aero vehicle shape will not be needed)
http://higherway.us/higherway/index.shtml (not maglev)
http://unitsky.ru/ (the small suspended version -- not maglev)
as being illustrative of some of the above principals of optimizing
transportation value for moon or mars use.
--
Best regards,
Daryl Oster
(c) 2008 all rights reserved. ETT, et3, MoPod, "space travel on earth"
e-tube, e-tubes, and the logos thereof are trademarks and service marks
of et3.com Inc. For licensing information contact: POB 1423, Crystal
River FL 34423-1423 Verizon cell(352)257-1310 e...@et3.com www.et3.com
peter_kokh
Thanks for this impressive post. It is to get people like you involved
that we decided to create this site.
I will have to do some studying to respond to some of the things in
your post, as I am not familiar with many of the acronyms you use.
I would like to respond to one point in particular, however.
On point 1) you do not see the need for big loads. However, that is
precisely what I do see. In order to expand frugally on the Moon, we
will need to go to manufactured housing, of the pressurized module
shells at least. And with initially small settlements, it makes zero
sense to me to produce many factories. One factory can initially
produce modules to be used anywhere on the Moon or Mars if there is a
way to transport them to the place of use. The more we limit the size
of modules, and their weight, the more we perpetuate the era of
sardine-can living. If people are going to be attracted to life on the
lunar and Martian frontiers, w must guarantee them reasonable elbow-
room. By building habitat modules out of lunar materials in mass
production fashion, elbow room becomes affordable.
In looking at options for a modular architectural language, yes, we
could restrict ourselves to one-floor modules of short length. But
opening the limits to two-floor longer units, multiplies the options
for layout and use exponentially.
It will take more materials and work to build highways that can handle
such loads, than to build railroads. Simple crude roads might stress
carried modules in a way that compromises their pressurization
capability.
Now grant you, railroad networks are more constrictive of destination
choices than roads. But I think on the early frontier on both worlds,
we will not have settlements helter skelter everywhere. That may come
in time, but at a time when we can also build additional module
factories closer to the point of use.
Now I could easily be wrong, but my thought that the best, most
efficient way to initially spread settlements outward from an initial
industrial hub would be a railroad network with large capacity.
As to gauge and clearances, on Earth, these became set in stone fairly
early, without consideration of future needs. On the Moon, we have a
blank slate, and it seems more strategic to think in larger terms.
Because gravity on both worlds, Moon and Mars, is significantly less
than on Earth, the chance of derailment is higher as momentum remains
unchanged. A wider gauge, as well as a lower center of gravity would
help address that risk. On Earth, derailments are survivable. On Moon
or Mars, rupture of a passenger car seal would be instantly fatal.
Your point of having all stops on sidings, is totally logical and I
had thought so as well, as some of my illustrations show.
Another consideration besides modular housing needs is modular factory
needs. It will be convenient to ship modular factory units from Earth
to a central cargo spaceport on the Moon, and transship from there.
Some modular ready-to-plug-in-and-use factories (a bakery unit, for
example) might be rather compact. But if we restrict the dimensions
and weight of what our transport system can carry, then we cripple the
options for industries in new settlements.
Now I grant that in time, the lunar and Martian frontiers will be
capable of building their own factories from the ground up with no
limits as to size, etc. But that will come in time.
We will be starting small, with a population of a few hundreds,
growing from that point upwards.
Yes, I do see a strong niche for cable-suspended systems, especially
for tourist passengers. It will be less restrictive of the kind of
terrain that the route can take and provide much better views. But
also for cargo. Some of the illustrations posted are of cable systems
involving suspension cables to greatly reduce up and down riding.
The point of having this group is to flesh out more options. Your
contribution is most significant.
I do believe, however, that we should brainstorm all the options, and
let the technologies pick the winners. What we don't want to do is
settle on any one option, only to find later that something else would
have worked better, but that now it is too late.
We have a great variety of transportation options available on Earth
to fit the many niches, a diversity of cargo sizes and weights, a
diversity of urgency needs, and a diversity of cost considerations.
And evidently there is a place for each, or they would not all be in
use.
As the frontiers develop on Moon and Mars from a few thousands to
millions of people, that will happen there as well.
While we certainly should look at long term needs, it is most
essential to get from here to there. And if there is a better more
efficient way to expand from an original industrial site to other
locations on both worlds, then we should work on that as well.
Our guesses as to what will work best are going to be provisional.
Let's realize that in terms of options that will be available at the
time these frontiers will really open, what we do may seem quaintly
"Victorian" or "Jules Vernish" to those involved at the time. Our job
is to lay foundations, get people thinking. The pioneers will then
have shoulders on which to stand. And in the meantime, by opening up
the possibilities, we will have opened a lot of eyes in the public at
large, essential to the point that without significant public support,
none of these things may come to pass
So I am all for sectioning our tasks and have some working on
cableways/monorails, etc., some working on maglev options, some on
rail-based systems, some on more than one of these, as their interests
lead them. I think that this wide-ranging brainstroming will be of
best service to those who will follow.
A major motive behind establishing this group is to get people with
needed insights and abilities, to start thinking of the Moon and Mars
as future human frontiers, even though they might never have thought
of worlds beyond Earth in that light before.
So please do keep working along the lines you have outlined. And
please do post illustrations for the benefit of those of us not
familiar with the transportation modes you are describing.
Thanks once again for this 5 star post!
Peter Kokh
On May 1, 9:14 pm, Daryl Oster <e...@et3.com> wrote:
> marsbeyond wrote:
> > Peter Kokh,
> > I heard your recent interview on the space show.
> >http://www.thespaceshow.com/detail.asp?q=935
> > This seems to be the most likely technology for moon rail.
> > Goddard had patents on it.
> >http://en.wikipedia.org/wiki/Vactrain
> > Now the mover and shaker on this seems to be Daryl Oster.