Minimal Propellant SSTO - Using space power to boost from Earth

Ranger_2833 · 2003-07-09 14:42:30

Laserlight/Microwave-craft are not a new idea, but it seems that they have fallen out of the spot light. They are a enviromentally friendly, energy efficient, and cheap means of boosting mass to orbit.

The primary cost would involve setting up an infrastructure, but afterwards the only cost is maintaining the infrastructure, the craft itself, and a small amount of propellant.

The basic idea for the Lightcraft is that a high power laser superheats the air beneath the craft causing it to combust thus propelling the craft at an increasing velocity. The laser could be powered by ground based sources, or more cheaply by space based solar power. Using a space based solar station would provide free (neglecting the construction cost of course) electricity, that when not being used/stored for a launch can be diverted the the local power grid.

Microwave powered lightcraft work in a somewhat similar manner except they heat the air from above and also provide electrical power for ion propulsion.

Research at Rennsayler Polytechnical Institute has found that a 1km diameter solar station that could produce up to 20 gigawatts of power. Approximately 4.3 gigawatts (Two orbits worth of stored power) would be able to lift a 12 person crew to orbit. Excess power would be used to accelerate the slipstream along the edge of the craft to cancel the sonic shock, thus making it silent at supersonic speeds.

The spacecraft could be propelled from the earth's surface to the moon in about 5.5 hours! Using free electricity and minimal propellant. Of course one would need a way to slow down upon lunar injection, solutions include electromagnetic rings that would convert the crafts velocity back into power for another launch. But a mission to Mars could rely on aerobraking, or even chemical/nuclear propulsion to slow its approach and enter orbit.

A dissadvantage (well sort of) of the microwave craft is its high accelerations, but those problems are being worked on as we speak by the military. Neverless, we can use the craft for unmanned payload at the onset. Thus being able to lift massive amounts of payload (in small chuncks) for 1/1000 of the cost of current techniques. That is equivalent to a person spending the same on a ticket from the US to Australia as they would on a ticket to orbit!

In terms of a Mars mission, one could lauch a Zubrin type mission at an even lower cost. Microwave-light propulsion could lift equipment for a LEO staging area (i.e. add to the ISS and lift the Mars transit vehicle to wait) for the human team to meet up with, until the acceleration problems are solved. The initial unmanned equipment could be lifted with microwaves, using stored propellant for transit and Mars generated return propellant. Thus limiting the use of chemical rockets to lifting personnel. Later when clonization begins, modules (unmanned) could be lifted every two days to be sent to Mars in sections.

I do not have the time or inclination at this time to figure the exact numbers for savings that this system would provide, but I think it is fairly evident that they would be drastic.

Laser/Microwave lightcraft are not in the realm of science fiction, prototypes have flown sucessfully in the last couple years. The technology could easily be put into action before 2015, perfect for a Mars mission time frame. I feel that the cost and efficientcy benefits of a similar type plan could drastically change our ideas on wheter or not we go to Mars, and how much it will cost.

I await your ideas and criticisms on this subject, and I shall try to do some calculations in some of my free time in the near future (when I'm not doing work for the Evil Classes of Engineering ).

Free Spirit · 2003-07-09 20:32:57

Research at Rennsayler Polytechnical Institute has found that a 1km diameter solar station that could produce up to 20 gigawatts of power.

Another option could be to use giantsolar pumped lasers in orbit that might be able to power the light craft directly even though your method would probably reduce the chance of passengers being fried enroute.

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#1 2003-07-09 14:42:30

Re: Minimal Propellant SSTO - Using space power to boost from Earth

#2 2003-07-09 20:32:57

Re: Minimal Propellant SSTO - Using space power to boost from Earth

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