Nuts and Volts - March 2008

by 50% last year, the prize purse for the Materials Challenge this year was also worth $500,000.

LIGHT RACERS CHALLENGE

Unlike the first two challenges, Spaceward’s Light Racers Challenge isn’t part of their NASA Centennial Challenge contract. Instead, non-NASA donors sponsored this fun challenge. To win, Light Racers had to drive down a 60 foot long track solely under beamed energy. Their energy source was the light of a high intensity spotlight. The prize purse for this year’s Light Racers competition was worth $10,000.

THE 2007 CLIMBERS

I didn’t realize how serious these climber teams were until I learned their registration fee was $5,000 — which increased to $7,500 or even $10,000 as competition day approached. A total of 22 teams applied for the 2007 challenge. Of them, eight completed their climbers in time for the two qualifying rounds held before we arrived. The first qualifying round took place indoors on a short ribbon suspended from the ceiling. The second qualifying round took place outdoors on a 100 foot tall ribbon suspended from a crane.

Of the eight climbers at the qualification rounds, all qualified indoors but only four qualified outdoors. We were able to visit the eight climber teams and two climber displays during our Saturday and Sunday visit. Here’s what we learned from these enthusiastic teams.

SIDE NOTE

Since it’s important that climbers carry a large payload at high speed, the Spaceward Foundation developed the following scoring equation.

Score = (payload weight x speed) / (climber weight + payload weight)

So for example, a 10 kg climber carrying a five kg payload at an average speed of 2.5 meters per second (m/s) would earn a score of ( 5 x 2.5)/( 5 + 10), or 0.83.

space. Their 10 kg ( 22 pound) climber is square in shape and nearly 12 feet across. This was the Kansas City Space Pirate’s second year at the Spaceward Games. They built their climber last year for $50,000 and spent an additional $35,000 upgrading it for the 2007 games. The Space Pirate’s climber contains a mix of 800 dual and triple junction solar cells. To protect their fragile solar cells, the cells are mounted within balsa wood frames and suspended within the climber’s airframe.

The climber travels the ribbon via two drums clamped to the ribbon and driven by an electric motor. The drums pinch the ribbon hard enough that the climber cannot slip down the ribbon. Commands to climb or descend are sent to the climber through a standard hobby remote control (R/C). To even out power fluctuations, the Space Pirates incorporated several 2.7 volt super capacitors into the climber’s avionics.

Sunlight is beamed to the climber through an array of 19 mirrors. Each mirror array consists of nine closet mirrors mounted into a frame that allows team members to tip and swiv-

■ FIGURE 2. The Technology Tycoons climber, ready to strut its stuff.

el them. Each mirror array incorporates a targeting system built from reflective tape and two pieces of glass.

Because of the spacing between the tape and glass, mirror operators see a projected red dot at their array’s target. Each operator only has to keep his or her dot fixed on the climber. The combined light from the mirror array creates a beam of light at the climber 15 times more intense than natural sunlight.

TECHNOLOGY TYCOONS

Our next visit was to the Technology Tycoons of Westmont

■ FIGURE 4. Notice that the arrays of solar cells are mounted within balsa wood frames in this upside down view of this climber. Each frame is free to jostle to a small extent within the climber’s airframe.