Summer 2006 Issue


1000-cc Science

By Dr. H. Paul Shuch,* N6TX

Do you think maybe you’d like to build a satellite, but are not quite sure where to start? That was the situation facing engineering students at Cuesta College on the central California coast a few years back. Cuesta was well suited to hosting a satellite program, being just under an hour’s drive from the U.S. Western Test Range launch facilities at Vandenberg Air Force Base. Our earliest OSCARs had been launched from Vandy. Two Cuesta faculty members—Cliff Buttschardt, W7RR, and Ed English, W6WYQ—had been OSCAR-active since the dawn of the space age. Space was clearly the place, but where to start?

The students’ confusion was understandable. It stemmed from the simple fact that every ham satellite to date had been custom-designed around a specific launch opportunity. It was common practice to fit a piggyback payload into a well-defined nook or cranny on a particular vehicle. OSCARs 1 and 2, for example, had semi-pyramidal bodies with curved top surfaces, optimized in mass and form factor to serve as ballast for military AGENA satellites. The Cuesta students and their advisors had no particular launch in mind. They simply wanted to build a ham satellite, stick out their thumbs, and hitchhike into orbit.

Ed and Cliff had an answer, although it involved a clean break from past practice. Why not, they proposed, come up with a standard package for a small satellite, one compatible with launch from a wide range of boosters? With sufficient standardization, military and civil launch authorities could accommodate such payloads as the ham community might generate, and we could ride aloft on a space-available basis. Thus, the CubeSat concept was born.

Educational ham satellites are not new. Early examples emanated from university labs in Melbourne, Australia, Surrey, England, and Marburg, Germany as far back as the early 1970s. However, the CubeSat concept meant that for the first time anyone could play. The actual package constraints were formalized by Bob Twiggs, KE6QMD, and his students at Stanford University. Bob previously had taught at Weber State College in Utah, was the father of their small satellite program, and was the motivating force behind the WeberSat WO-18 satellite. Building upon the Cuesta College concept, the Stanford team came up with a standard cube, 10 cm on a side, 1 kg in mass, to which a whole generation of ham educational satellites was to conform.

By the time the cube was codified, Ed and Cliff both had retired from Cuesta College and had moved across town to the California Polytechnic University, where they set up a satellite program to further refine the Stanford design. Recognizing that multiple pico-satellites could be accommodated by a single launch vehicle, they set about developing a common launcher interface, which doubled as an orbital insertion mechanism—P-POD, the Poly Picosat Orbital Deployer. This hollow rectangular frame, three CubeSats long, would mount to a variety of launchers with standardized hardware and a well-defined electrical connector. When triggered by a launch-sequence command, its internal ejection spring would spit three peas from the pod and into their individual orbits. Compatible with everything from Delta rockets to converted American and Russian ICBMs, the P-POD concept and CubeSat architecture together began to make satellites, and launching them, truly affordable.

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