At 07:38 AM 2/19/2003 -0800, Randall Clague wrote:
A BOTE: Kinetic energy in LEO is about 30 MJ/kg, a kW-hr costs about 18 cents, and a kW-hr is 3.6 MJ. So electricity, the cheapest form of energy (and least storable, what a coincidence) costs about 5 cents/MJ. That puts LEO kinetic energy cost at $1.50/kg, or about 68 cents/lb. The question is, how efficiently can you convert electricity into kinetic energy with a laser and a launch vehicle. If your system efficiency can reach 1%, which I doubt (laser efficiency * propagation efficiency * propellant coupling efficiency * vehicle coupling efficiency), you can make orbit for $68.00/lb. If your system efficiency is 0.1% - more believable - it'll cost $680/lb.
Your given electricity cost is the CA residential cost... almost three times the national industrial average, which is more like 5-6 cents/kW-hr.
That assumes a mass fraction of 0%, of course. A mass fraction of 90% - more believable, though optimistic IMVHO (I don't have a good handle on propellant Isp for laser launch) - drives your cost to between $680/lb and $6800/lb. Then you have the cost of developing a laser powerful enough to launch something - again, I don't know how to calculate the power requirement - and the non-trivial problem of steering the beam quickly enough to steer the vehicle when it gets a few hundred km downrange.
That mass fraction is extremely pessimistic. Laser launch tends to have an ISP more characteristic of nuclear thermal than chemical -- 600 to 1000 seconds is not out of the question. Some concepts are also air-breathing part of the way up.
-p
Mars or Bust!
www.marssociety.com
_______________________________________________
ERPS-list mailing list
[EMAIL PROTECTED]
http://lists.erps.org/mailman/listinfo/erps-list
