The DSOC experiment, launched in 2023 aboard the Psyche spacecraft, was designed to test next-generation laser communications in space. While Psyche continues toward its 2029 rendezvous with a metal-rich asteroid in the main belt, the optical demo has now concluded—proving that high-bandwidth laser transmissions can operate reliably over immense interplanetary distances.

Unlike traditional radio waves, which are relatively slow and broad, infrared laser signals offer much higher data rates—but require extreme precision. The final downlink wasn’t the farthest achieved by Psyche, but it confirms that DSOC technology remains viable even as the spacecraft follows its solar orbit, sometimes moving closer to or farther from Earth depending on planetary alignment.

Pushing the Boundaries of Optical Space Communication

In December 2024, Psyche successfully transmitted a laser message from 494 million kilometers (307 million miles)—more than twice the average Earth-Mars distance. According to ScienceAlert, this was the farthest such signal ever received by NASA. The DSOC system managed to deliver an ultra-high-definition video at 267 megabits per second from over 30.5 million kilometers away—another first. This marks the last in a series of 65 successful laser transmissions—each pushing the limits of how data can be sent across the solar system.

Overall, the DSOC experiment transmitted 13.6 terabytes of data back to Earth, showcasing a level of performance that far exceeds current radio-based systems. Clayton Turner, associate administrator of NASA’s Space Technology Mission Directorate, said the project “surpassed our expectations,” noting that the data rates were “comparable to those of household broadband internet.”

Still, performance varied with distance. As Psyche moved deeper into space, the downlink rate decreased—dropping to 25 megabits per second by April 2024, when the spacecraft was 225 million kilometers away. The precision required to keep the laser beam aligned across these distances is one of the major technological hurdles addressed by the test.

A Shift From Radio to Laser-Based Systems

NASA currently relies on the Deep Space Network (DSN), a group of large radio antennas spread across the globe, to communicate with spacecraft. But this system is facing increasing demand and limited bandwidth. Optical communication offers a potential alternative, with the ability to transmit far more data using narrower, focused beams of light.

Sean Duffy, NASA’s acting administrator, explained that laser technologies are part of the agency’s broader plan to prepare for human missions to Mars: “Advancing laser communications technologies brings us one step closer to streaming high-definition video and delivering valuable data from the Martian surface faster than ever before.”

The tradeoff is that laser systems are far less forgiving than radio transmissions. While a radio signal can scatter and still reach its destination, lasers need pinpoint accuracy. Earth’s atmosphere, weather, and even light pollution can affect reception—factors that make the technology both promising and technically demanding.

Lessons for Future Deep Space Missions

The DSOC test also highlighted the limitations of Earth-based reception systems. Laser beams degrade as they travel through space, and only a small number of photons may ultimately reach Earth’s surface. This calls for highly sensitive ground receivers, such as those used at NASA‘s Optical Communications Telescope Laboratory.

There’s also the possibility that future missions might need space-based relays to bypass the effects of Earth’s atmosphere entirely. For now, the test demonstrates that such systems are already operationally viable—even if improvements are still needed to handle longer distances and more complex mission scenarios.

Now that the demonstration phase has ended, the Psyche spacecraft will rely on traditional radio communications for the rest of its mission.