Earth received a first laser message from 16 million kilometers away

The Deep Space Optical Communications (DSOC) experiment on NASA's Psyche spacecraft has for the first time transmitted a laser message to Earth from a point far beyond the Moon. Scientists believe this achievement could change the way spacecraft communicate.

The Deep Space Optical Communications (DSOC) employs advanced near-infrared lasers, demonstrating their capability by transmitting a coded test message to Earth from a distance of approximately 16 million kilometers — 40 times farther than the Moon's distance. The Hale Telescope at the California Institute of Technology's Palomar Observatory successfully received the signal.

In DSOC's laser beam, photons travel uniformly in the same direction and at the same wavelength. When directed towards a signal receiver, the system can efficiently transmit large volumes of data at unprecedented speeds.

While space communication from Earth orbit has used similar methods in the past, this marks the first instance of employing this technology over such an extensive distance. Typically, missions beyond the Moon rely on radio waves for communication. With lasers, the data transmission speed from space can potentially increase by 10-100 times. This technological advancement promises future missions with scientific instruments boasting higher resolution and enables faster communication during deep space missions, including live video feeds from Mars' surface. 

"Achieving first light is one of many critical DSOC milestones in the coming months, paving the way toward higher-data-rate communications capable of sending scientific information, high-definition imagery, and streaming video in support of humanity's next giant leap: sending humans to Mars," said Trudy Kortes, director of Technology Demonstrations for the Space Technology Mission Directorate at NASA Headquarters in Washington.

However, this communication channel faces challenges. Precision becomes more critical as the distance from the signal sender increases. The laser beam demands high precision for guidance. Additionally, the photon signal weakens with greater distance, resulting in longer transmission times and potential delays in communicating with the transmitter.

During the Psyche test, it took approximately 50 seconds for photons to reach Earth. As the mission progresses towards its destination, the system will require about 20 minutes. Given the changing positions of the planet and spacecraft during this period, DSOC must anticipate and adjust accordingly. The success and methods of overcoming these challenges will become clearer closer to the final mission in 2029, with numerous tests planned leading up to that point.