Psyche asteroid probe uses lasers to phone home from 218 million miles away

Final tests of NASA's laser beam communication technology offer a promising new way to keep in touch with astronauts and spacecraft venturing into deep space, including future missions to Mars.

NASA's Deep Space Optical Communications (DSOC) experiment, a technology demonstration carried aboard the Psyche mission, has completed its 65th and final test, successfully exchanging laser signals across 218 million miles (351 million kilometers), surpassing all technical goals after two years of operations, according to a statement from the space agency.

"NASA is setting America on the path to Mars, and 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," Sean Duffy, acting NASA Administrator, said in the statement. "Technology unlocks discovery, and we are committed to testing and proving the capabilities needed to enable the Golden Age of exploration."

During its run, DSOC achieved 65 successful passes between Earth and Psyche as the spacecraft journeyed toward its asteroid target. The system encodes data into pulses of laser light, transforming digital information into streams of photons that can travel millions of miles — a significant shift from the radio frequencies used by NASA's Deep Space Network for decades.

A high-powered uplink laser at NASA's Table Mountain Facility in California helps Psyche's transceiver lock onto the signal and aim its own laser back at ground-based telescopes, where sensitive detectors capture the faint light. Advanced decoding systems then reconstruct the original data, allowing information sent from distances comparable to Mars to be received with remarkable accuracy. Across those tests, DSOC downlinked a remarkable 13.6 terabits of data — far more than anticipated, according to the statement.

DSOC hit a major milestone on Dec. 11, 2023, just two months after launch, when it streamed an ultra-high-definition video from 19 million miles (30.6 million kilometers) away at 267 megabits per second — faster than many home internet connections. Nearly a year later, on Dec. 3, 2024, it set a new benchmark by transmitting data from 307 million miles (494 million kilometers), farther than the average distance between Earth and Mars.

The constant motion of Earth and Psyche required extreme precision in aiming the laser beams at ground-based receivers — a challenge made even more difficult by poor weather and wildfires in Southern California. To help overcome these obstacles, an experimental hybrid radio-optical antenna at the Goldstone Deep Space Communications Complex tested new ways to capture the signals, providing a glimpse of future systems that could combine both technologies for greater flexibility and resilience as missions venture deeper into the solar system.

"As space exploration continues to evolve, so do our data transfer needs," Kevin Coggins, deputy associate administrator for NASA's SCaN (Space Communications and Navigation) program, said in the statement. "Future space missions will require astronauts to send high-resolution images and instrument data from the moon and Mars back to Earth. Bolstering our capabilities of traditional radio frequency communications with the power and benefits of optical communications will allow NASA to meet these new requirements."