NASA is about to test one of their first optical communication systems from the ISS in the hopes of improving the bit rates of communication systems that exist now. Radio transmission has long been a reliable way to beam information to and from spacecraft because it is not scattered by our atmosphere, but as the pressure to beam more information faster increases, radio transmission is just not capable of keeping up. Radio can transmit, as of now, at 200-400 kilobits per second with most spacecraft and the mars rovers.
Laser technology is very promising because scientists will be able to achieve much faster rates, because of the coherence of the laser and the wavelengths involved. OPALS will be able of beaming information at 50 megabits a second, which is a significant increase. Scientists expect as this technology improves, we will see rates of gigabits per second. At these rates, scientists will be able to beam high-definition videos and large amounts of data from experiments. In an age of science where precision, computer modeling, and large data are increasingly necessary to prove anything new, these rates are very necessary.
This technology poses less practical use for cell phones or personal devices, because the laser aspect requires that the information be aimed precisely at the receiver constantly during the upload. Most of NASA’s testing for OPALS in the upcoming test will not only be testing the operation of the device, but the aiming of the laser. A ground telescope will search for the ISS in the sky as it passes overhead, and beam its own laser to the ISS to begin the upload. At that point, OPALS responds the ground laser and starts beaming information down via its laser, and as it orbits pass, it tracks the receiver making sure it is aimed correctly the whole time. As you can imagine, the ISS eventually passes out of view and the transmission is done. Thus, the longest transmission time for the ISS from any receiver is about 100 seconds, but with the improved upload rates, more information is still transferred than by Radio. It will be exciting to see the results of the tests.
Sources:
http://www.sciencedaily.com/releases/2014/04/140414103012.htm
