NASA’s Deep Space Optical Communications project will test the use of near-infrared lasers as potential replacements for the current radio frequency systems. The technology demonstration, scheduled to piggyback on the Psyche mission launching Oct. 5, could pave the way for broadband communications to support future missions to Mars. NASA is focused on laser, or optical, communication because of its potential to surpass the bandwidth of radio waves, upon which the space agency has relied for more than half a century. Near-infrared light packs data into significantly tighter waves, enabling ground stations to receive more data within a given time period. The Deep Space Optical Communications (DSOC) flight transceiver is inside a large tube-like sunshade and telescope on the Psyche spacecraft, as seen here inside a clean room at JPL. An earlier photo, inset, shows the transceiver assembly before it was integrated with the spacecraft. Courtesy of NASA/JPL-Caltech. “DSOC was designed to demonstrate 10 to 100 times the data-return capacity of state-of-the-art radio systems used in space today,” said Abi Biswas, DSOC’s project technologist at NASA’s Jet Propulsion Laboratory (JPL) in Southern California. “High-bandwidth laser communications for near-Earth orbit and for moon-orbiting satellites have been proven, but deep space presents new challenges.” The transceiver riding on Psyche features several new technologies, including a never-before-flown photon-counting camera attached to a 22-cm aperture telescope that protrudes from the side of the spacecraft. The transceiver will autonomously scan for, and “lock” onto, the high-power near-infrared laser uplink transmitted by the Optical Communication Telescope Laboratory at JPL’s Table Mountain Facility. The laser uplink will also demonstrate sending commands to the transceiver. Once locked onto the uplink laser, the transceiver will locate the 5.1-m Hale Telescope at Caltech’s Palomar Observatory. The transceiver will then use its near-infrared laser to transmit high-rate data down to Palomar. Spacecraft vibrations that might otherwise nudge the laser off target will be dampened by state-of-the-art struts attaching the transceiver to Psyche. The Hale Telescope at Caltech’s Palomar Observatory in San Diego County, California, will receive the high-rate data downlink from the DSOC flight transceiver. The telescope is fitted with a novel superconducting detector that is capable of timing the arrival of individual photons from deep space. Courtesy of Caltech. To receive the high-rate downlink laser from the DSOC transceiver, the Hale Telescope has been fitted with a novel superconducting nanowire single-photon detector assembly. The assembly is cryogenically cooled so that a single incident laser photon (a quantum particle of light) can be detected and its arrival time recorded. Transmitted as a train of pulses, the laser light must travel more than 300 million km — the farthest the spacecraft will be during this tech demo — before the faint signals can be detected and processed to extract the information. The distances involved pose another challenge for the tech demo: The farther Psyche journeys, the longer the photons will take to reach their destination, creating a lag of up to tens of minutes. The positions of Earth and the spacecraft will be constantly changing while the laser photons travel, so this lag will need to be compensated for. DSOC will demonstrate operations for nearly two years after NASA’s Psyche mission launch while traveling to its Mars flyby in 2026. While the DSOC transceiver will be hosted by the Psyche spacecraft, the tech demo will not relay Psyche mission data. The success of each project is evaluated independently of the other.
