Researchers at NASA and MIT have figured out a way to solve one of the great problems of modern space travel – How to get broadband internet and Wi-Fi sent to the moon. As with most awesome technology, they’ve done this using lasers =)
From Ars Technica:
To do this it uses four separate telescopes based at a ground terminal in New Mexico to send the uplink signal to the moon. A laser transmitter that can send information as coded pulses of invisible infrared light feeds into each of the telescopes, which results in 40 watts of transmitter power.
The team has transmitted data across the 384,633km distance between Earth and the moon at a rate of 19.44Mbps and has also managed to download data at a rate of 622Mbps. “Communicating at high data rates from Earth to the moon with laser beams is challenging because of the 400,000-kilometer distance spreading out the light beam,” says Mark Stevens of MIT Lincoln Laboratory. “It’s doubly difficult going through the atmosphere, because turbulence can bend light-causing rapid fading or dropouts of the signal at the receiver.”
Each of the four telescopes used to beam the connection to the moon transmits light through a different column of air, meaning that they all experience different bending effects from the atmosphere and increasing the chance that one of them will hit the receiver, which is hitched to a satellite currently orbiting the moon. The satellite is also equipped with a telescope, which collects the laser beam and focuses it into an optical fibre. A photodetector turns the pulses of light into electrical pulses, and from there they are converted into data.
It all sounds a bit hit and miss, and indeed less than a billionth of a watt from the 40-watt signal is actually received by the satellite. Fortunately, that is ten times the amount of signal needed for reliable communications, according to Stevens.
I joke about the seriousness of this research, but the benefits are obvious. Sensors and antennas on satellites and rovers have historically sent data back to Earth very slowly. Increasing the bandwidth will allow for more data to be returned and studied. The researchers hope to be able to expand this technique for communications to Mars and beyond. This may someday reduce the time needed to send instructions to future Mars rovers.
I’m also excited since NASA research and technology sometimes finds its way into commercial products and services. I look forward to the day when I can hook up 4 laser telescopes to my wireless access point. Maybe then I’ll get signal all over my house!
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