Wanted: Inventors to Build Space Elevator

Team: University of British Columbia

Climber: A 1.7-pound aluminum disk hugs the cable. It's driven by a 60-watt DC motor, controlling one roller. Payload: ~15 kg.

Power System: The xenon beam strikes 320 silicon photovoltaic cells connected like Christmas lights so that failure in one cell won't knock out the whole system.

Stumblink Block: Complicated clutch/gear system improves lift but wastes nearly 70 percent of available energy.

Brad's Take: "The total power is a bit low. It doesn't sound as if it's going to go really fast, but in this first test, if you make it up to the top, that's a success."

Team: MNK Scientific

Climber: A three-foot, Mylar-coated parabolic dish focuses the beam onto a solar engine, which powers the climber. Payload: ~30 kg.

Power System: The beam powers a highly efficient Stirling engine, heated to 1,202