Pushing the Limit

When SMART-1, the European Space Agency's first mission to the moon, launched in September 2003, astronomers hailed it as the testing ground for a revolutionary and efficient solar-electric-propulsion technology. While this technological leap absorbed the attention of scientists and the news media, a second, quieter revolution aboard SMART-1 went almost unheralded. Only a small band of mathematicians and engineers appreciated the quantum leap forward for digital communications. Incorporated into SMART-1's computers was a system for encoding data transmissions that, in a precise mathematical sense, is practically perfect.