If you’d like to be in the first human colony on the Moon but can’t bear the thought of missing the latest episode of “The Big Bang Theory,” you can send in your application because the Moon is getting a wireless broadband connection.
Next month at CLEO: 2014 (Conference on Lasers and Electro-Optics), researchers from the Massachusetts Institute of Technology's (MIT) Lincoln Laboratory will present the first overview of the laser-based communication uplink between the moon and Earth which they demonstrated for the first time last fall. That record-setting link, the Lunar Laser Communication Demonstration (LLCD), transmitted data over the 384,633 kilometers at a download rate of 622 megabits per second, faster than any radio frequency (RF) system, and transmitted data from the Earth to the moon at 19.44 megabits per second, a factor of 4,800 times faster than the best RF uplink ever used.
The CLEO: 2014 presentation will show how a ground terminal at White Sands, New Mexico, uses four separate telescopes to send data coded as pulses of infrared light to a receiver mounted on a satellite in lunar orbit. The receiver collects the light, focuses it into optical fiber, amplifies the signal 30,000 times and uses a photodetector to convert the pulses into data bit patterns. Although the 40-watt signal transmitted is less than a received is less than a billionth of a watt by the time it reaches the Moon, Mark Stevens of MIT says that's 10 times more than required for error-free communication, even through cloud cover.
We demonstrated tolerance to medium-size cloud attenuations, as well as large atmospheric-turbulence-induced signal power variations, or fading, allowing error-free performance even with very small signal margins.
While the LLCD currently needs the receiver to be mounted in an orbiting satellite, the team predicts it will one day be usable on missions to Mars and beyond.
That’s good news for space travelers who can’t imagine months without kitten memes or porn.