Tiny, Laser-Beaming Satellites Could Communicate With Mars

Last August, Masahide Sasaki and his team instructed a satellite to shoot laser beams at a suburb of Tokyo. No, not like that. The laser beam, made of infrared light, was invisible to the human eye. By the time it had traveled through hundreds of miles of outer space and atmosphere, the light was harmless: It had spread out like a spotlight, about as wide as 10 soccer fields. Some of that light made its way into the end of a telescope, where it bounced off mirrors and flew through lenses and filters onto a photon-measuring detector.

Someday, Sasaki hopes, that light could be more than invisible wavelengths hitting a telescope—it could be encoded with information. Today, the radio waves beamed in satellite communications have limited bandwidth, which means they can’t transmit a lot of data at once. But if you can encode a message in infrared photons, you can transmit a million times more data per second, says Sasaki, a physicist at the National Institute of Information and Communications Technology in Japan.