The Earth received a laser-beamed message from 16 million kilometres away: What it means

In a landmark achievement, NASA’s Psyche spacecraft, currently en route to the asteroid Psyche, has successfully transmitted a laser-beamed message to Earth from a record-breaking distance beyond the Moon. This breakthrough, orchestrated by the Deep Space Optical Communications (DSOC) experiment, signifies a potential transformation in how spacecraft communicate and opens new frontiers in optical communication technology. The DSOC, a two-year tech demonstration accompanying the Psyche mission, achieved this feat by beaming a near-infrared laser, encoded with test data, from its position approximately 16 million kilometres away — 40 times farther than the distance between the Moon and Earth. The laser signal was directed to the Hale Telescope at Caltech’s Palomar Observatory in California. The “first light” milestone, attained on November 14, marked the successful locking of DSOC’s laser transceiver onto JPL’s powerful uplink laser beacon at the Table Mountain Observatory. This precision enabled the DSOC’s downlink laser to reach its destination at Caltech’s observatory, covering a distance of 130 kilometres. Trudy Kortes, Director of Technology Demonstrations at NASA HQ, highlighted the significance of this achievement, stating, “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.” While optical communications have been utilized in Earth orbit, this demonstration represents the farthest distance covered by laser beams. Laser communication, using the same-wavelength, directional movement of photons, has the potential to transmit vast amounts of data at unprecedented speeds. The DSOC tech demo aims to showcase transmission rates 10-100 times greater than the current top radio communication systems used by NASA. The adoption of optical communication holds the promise of enhancing data transmission for future space missions. Higher-resolution scientific instruments and faster communication on deep space missions, including potential live streams from the surface of Mars, could become a reality. However, challenges such as maintaining pinpoint precision for long-distance optical communication need to be addressed. As the distance increases, the signal strength diminishes, resulting in longer communication lag times. During the November 14 test, photons took approximately 50 seconds to travel from Psyche to Earth. As Psyche continues its journey, this time is expected to extend to around 20 minutes, necessitating adjustments for the changing positions of Earth and the spacecraft. Meera Srinivasan, Operations Lead for DSOC at JPL, acknowledged the formidable challenge and highlighted the successful collaboration between DSOC and Psyche operations teams. Abi Biswas, Project Technologist for DSOC at JPL, encapsulated the achievement by stating, “We were able to exchange ‘bits of light’ from and to deep space,” signalling a potentially game-changing future for space exploration communication. (With input from agencies)