Space Transportation - mmmt_transportation.pdf - Moon Society

MMM #4 - April 1987
BOOTSTRAP ROCKETS
WHAT THE LUNAR COLONY WILL NEED MOST URGENTLY:
A LEO-TO-LUNA FERRY THAT RUNS ON 100% LUNAR FUEL
By Peter Kokh kokhmmm@aol.com
J. Alex Gimarc in his December 1st 1985 dated report to SSI on Space Shuttle External Tank Applications,
section IV-A, discusses orbital disassembly of the ET and melting and powdering of the aluminum for use as a fuel to
burn with cryogenics (LH2/LO2) scavenged from the ETs in a hydrogen / oxygen / aluminum based rocket engine in a
1:3:4 mix with a specific impulse Isp) of over 400 seconds. Despite the high costs of engine development and the
orbital melting/powdering facility, the economics of so much ET aluminum available already in orbit are such that this
technology would greatly enhance the possible scope of orbital transfer operations
But why do space enthusiasts continue to espouse and settle for developments which are NOT ON THE ROAD
to ultimate goals? If all that is wanted is a token science base on the Moon and perhaps a robotics-operated mining
facility / mass-driver launch system, okay; but then the hypocrisy about favoring settlement of the Inner Solar System
should stop. Such an engine, discussed by A. H. Cutler (in Aluminum Fueled Space Engines to Enhance Space
Transportation System Effectiveness, Springboard to the 21st Century, NASA / ASEE Summer Study, 1984, by A. H.
Cutler) and alluded to by Gimarc will not serve as the bootstrap rocket needed by a Lunar Colony to support itself
without wholesale handouts from Earth.
Getting to the Moon only counts if we do so in a manner which allows us to stay there and thrive no
matter what non-supportive political-economic decisions are made on Earth. To this end only an engine that
burns Moon-sourced fuels exclusively will do. With such an engine, the Earth to Moon freight bill would reduce
itself ( so far as bottom-line balance of payments are concerned ) to no more than the Earth to LEO ( Low Earth
Orbit ) cost. The Moon could pick up cargo and settlers in LEO and transport them the rest of the way essentially free.
[The above was written more than a decade before Lunar Prospector's confirmation of substantial water-ice
reserves at both lunar poles. Since that discovery, many have called for using this resource to produce liquid
hydrogen and liquid oxygen rocket fuels. This would constitute a one time non-recyclable squandering of a limited
resource that took hundreds of millions of years to be deposited. The "rocket jocks" who couldn't care less about
lunar settlement and only want to jet set around the solar system on voyages of discovery, can scratch their itch
elsewhere. The writer stands adamantly opposed to the production of rocket fuels from lunar polar ices when they
are not necessary. Once we are this far out on the shoulder of Earth's gravity well, hydrogen-free fuel combinations
with a lower Isp produced locally on the Moon will do quite well. PK.]
The aluminum rocket IS the answer, of course, but without the costly Isp enhancing hydrogen purchased from
Earth sources. Burning powdered Lunar aluminum with liquid Lunar oxygen, O2 ( possibly enriched with ozone, O3 ),
in a hybrid engine will not have the high Isp performance we have grown used to, but it will be superior to the CO/O2
fuel system now being favorably considered for Mars based operations.
[Other metallic fuels worth investigating are iron, especially as powdered unoxidized iron is abundant in the surface
regolith and needs only a magnet to harvest. PK]
Whatever problems there are in development of a working Al/O2 engine pale into insignificance in comparison
to the rewards. Those with the right stuff or can-do mind-set will not be discouraged by apparent "obstacles."
Meanwhile, the H2/Al/O2 rocket is but an expensive distraction that wins the battle of orbital transfer operations but
loses the war of space settlement. It must be resisted. - MMM
The above article is online at :http://www.asi.org/adb/06/09/03/02/004/bootstrap.html
Essays in “M”:
Marshall MacLuhan: “The Medium is the Message”
By Peter Kokh < kokhmmm@aol.com >
M is for Marshall MacLuhan, Canadian communications theorist and for his well known dictum: “The Medium is the
Message.” Translated from communications-speak into rocket-jargon, this comes out as
“The Vehicle is the Payload” (If you are at all honest about efficiency!)
Space enthusiasts are known to cry in their beer about the low payload to fuel ratio of the rocket and/or
shuttle system. But it is low because
1) We throw a good deal of the vehicle=payload away, i.e. the External Tank (ET) and
2) We return to Earth more than is necessary (just the engines and cabin) i.e. the shuttle hold or payload bay. Both
ET and hold could be redesigned to do double duty as payload and then, presto, instant heavy lift vehicle.
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