Winter 2007 Issue

The Orbital classroom

Reinventing the Cube

By Dr. H. Paul Shuch, N6TX

Bob Bruninga, WB4APR, showing off the US Naval Academy’s PCSAT2 engineering prototype at Space Day at the National Air and Space Museum in May 2006. (N6TX photo)

In a previous column (Summer 2006 issue of CQ VHF), we introduced CubeSats, the cheap and easy way to involve students in the design, construction, launch, and operation of ham satellites. In case you missed that minor opus, a CubeSat is a 1-kg picosat in a standardized cubic form factor, 10 cm on a side, designed for cluster launch from a wide range of boosters into any orbit of convenience. So far the cubes all have ended up in Low Earth Orbit (LEO), where minimal path loss makes their signals simple to copy with modest 2-meter or 70-cm equipment.

This time we will introduce a unique science mission that lends itself perfectly to CubeSat support. If your 1-kg picosat project is a solution in search of a problem, have we got a deal for you!

Although the world’s navies are in fact involved in satellite technology, it should surprise no one that their primary mission involves ocean-going vessels. They also engage in oceanographic research. In addition to training the next generation of naval officers, the US Naval Academy in Annapolis, Maryland is involved in such research, and much of it makes use of satellite technology.

One of the projects in which Annapolis midshipmen participate is the deployment of ocean-going buoys for monitoring ocean levels, currents, temperatures, salinity, and composition. Once built and cast adrift on the sea, these buoys have to transmit their data to . . . somewhere. That’s where CubeSats can come in.

Bob Bruninga, WB4APR, heads up the US Naval Academy Satellite Lab. He is also well known to the amateur radio community as the father of APRS® (Automatic Position Reporting System), a technology that marries packet radio digipeaters to GPS for the purpose of tracking moving vehicles (including your mobile 2-meter station). Why not, suggests Bob, use APRS and CubeSats together to keep track of his students’ ocean buoys, and perhaps to collect their scientific data via store-and-forward packet technology?

“For CubeSat missions looking for a neat project,” writes Bruninga, “remember, we welcome more low-duty-cycle packet digital devices on the global satellite packet uplink frequency of 145.825 MHz. The more small satellites providing a bent-pipe relay on this frequency, the better the connectivity for other student school projects, such as ocean buoys, environmental sensors, arctic weather stations, and wilderness explorers using APRS.”

I floated Bob’s suggestion (OK, guilty as charged…) at a recent CubeSat workshop at the California Polytechnic University to a generally favorable response. Most enthusiastic, not surprisingly, were those radio amateurs at the workshop who see packet satellites as a useful augmentation to their own amateur radio pursuits. This is altogether appropriate, but let’s not lose sight of the educational opportunity with which the proposal presents us. The students building the buoys may have no particular interest in ham radio, let alone APRS, as an end unto itself. Is there an opportunity here to turn them on to amateur radio, amateur satellites, and AMSAT? Before we dismiss as non-ham these scientific or educational projects of our fellow radio amateurs, we should remember that broadening the appeal of amateur radio benefits us all.

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