A conceptual drawing of the MarCO cubesats orbiting Mars. NASA
You’re an astronaut bound for Mars, a dusty and barren planet with an atmosphere composed almost entirely of carbon dioxide that on a good day is 139,808,518 miles from Earth, a stone’s throw from a galactic perspective but a nine-month trip for you and your crewmates.
As your spacecraft—perhaps it’s NASA’s Orion crew vehicle or SpaceX’s Big Falcon Rocket or a variation of Boeing’s Starliner—hurtles away from home, communication becomes increasingly delayed. At first the lag is only a few seconds, but as the weeks go by, real-time communication becomes impossible. Depending on the relative position of Earth and Mars as they orbit around the Sun, the delay by the time you reach Mars could exceed 20 minutes, creating 40-minutes of silence in a two-way conversation. Incredibly, the 3 to 22 minutes it takes—again, depending on the positions of the planets—for information to travel from Earth to Mars at the speed of light is nothing compared to the 4 days it took a message to travel from New York City to Washington DC at the speed of stagecoach in 1800.
Although our communications capabilities have evolved greatly in the last 200 years, it’s operationally and psychologically critical to continue searching for new ways to achieve reliable communication between explorers and our pale blue dot. A study conducted by NASA on the International Space Station in 2014, for example, found that even a 50-second delay frustrated crewmembers and that real-time communication improves both performance and morale.
Yet, the time delay isn’t the only communications challenge you’ll face on the journey to Mars. Another is the quality of the signal you receive. The radio waves that currently carry wireless transmissions—including your WiFi signal—aren’t very data efficient and lose strength over distance due to their longer wavelengths. That’s why NASA is investing heavily in laser communications research. Lasers operate on shorter wavelengths, allowing for more data per wave and superior signal fidelity. They also require smaller transmitters and receivers and use less energy than radio technologies. One day, these laser communications systems could theoretically enable HD video to be streamed between Earth and Mars.