Laser communication systems
Lasers could one day carry interplanetary communication signals between Earth and Mars.
Current Mars rovers and satellites send and receive signals from Earth via radio waves at a data rate of a few megabits per second. If lasers could be used instead, the transmission would form a tighter beam, with more of the total energy being delivered to the receiving antenna and less wasted. This means a higher data rate, for the same power consumption. With current technology, at Earth-Mars range, a laser could increase bandwidth by a factor of 10 compared to radio waves, making high-definition video streams possible. Future refinements in the technology could lead to a data rate 100 times that of radio waves.
Laser communication has never been tried at this distance. NASA plans to test long-distance communication using an infrared laser in conjunction with an upcoming mission that will send a probe to an asteroid, scheduled to launch in 2022 and arrive at its destination in 2026.
Engineering challenges for Earth-Mars laser communication include interference from sunlight, precise pointing of the narrow beam despite spacecraft motion and vibrations, interference from Earth's atmosphere, space temperature extremes, radiation, and forces on delicate equipment during launch.
Alternatively, if enough power is available then radio communications may continue to be used for high bandwidth communications.
- Carter, J., 2020, NASA Will Soon Use 'Space Lasers' To Give Us Live Video From Mars And The Moon, Forbes, https://www.forbes.com/sites/jamiecartereurope/2020/02/11/how-space-lasers-will-bring-the-solar-system-its-broadband-moment-and-live-video-from-mars.
- Seffers, G.I., 2018, NASA Counts Down to Laser Communications for Mars, SIGNAL Magazine, https://www.afcea.org/content/nasa-counts-down-laser-communications-mars.