On Wed, Dec 08, 1999 at 01:27:59PM -0800, Robert J. Bradbury wrote:
> Its on my todo list to re-examine this but the priority is
> rather low. What you really want for this is self-assembly
> (no nanotech required). Then you use the laser-boost
> approach NASA is working on to launch self-assembling
> intelligent-bricks into near-earth-orbit. When you start
> being able to launch 1-10kg hunks into orbit at high
> frequency without any rockets and have a resonable amount
> of intelligence on those pieces then the game gets very
> different. If you really wanted to assemble a Mars
> shipment, this would be the way to do it.
Cough, cough ...
Laser boost requires (a) honking great big lasers, and (b) reliability. Neither of these has been demonstrated on the scale required -- not saying it's impossible, but we're at 1901 Lilienthal glider stage and discussing what we can do with a DC-3.
Why not go the tried and tested route and steal a leaf from Gerald Bull's book?
Yes, explosive-powered guns look crude and old-fashioned. But they're also a _practical_ technology, even with 1980's tech. Before Bull was assassinated he'd designed and ordered the supergun test item for Project Babylon; we have no reason to believe it wouldn't have worked, given Bull's history (as probably the pre-eminent artillery designer of the 20th century, and an expert on the hypersonic aerodynamics of ballistic re-entry vehicles -- he helped design the Minuteman-III and Titan-II RV's).
It's worth noting that Bull's design _wasn't_ a pure gun -- it was a discarding-sabot high-velocity cannon designed to launch a very simple two-stage solid-fuel rocket. The goal was to ultimately be able to put a robust 100Kg payload into orbit every 90 minutes. This sounds to me a lot like a 1Kg intelligent brick every minute, and it was feasible any time from the mid-seventies on. (Anyone else remember Project HARP?)