DSOC's Table Mountain Facility Uplink Laser – Infrared vs. Visible Light

This infrared photograph shows the uplink laser beacon for NASA's Deep Space Optical Communications (DSOC) experiment beaming into the night sky from the Optical Communications Telescope Laboratory (OCTL) at NASA Jet Propulsion Laboratory's Table Mountain Facility near Wrightwood, California. Attached to the agency's Psyche spacecraft, the DSOC flight laser transceiver can receive and send data from Earth in encoded photons. As the experiment's ground laser transmitter, OCTL transmits at an infrared wavelength of 1,064 nanometers from its 3.3-foot-aperture (1-meter) telescope. The telescope can also receive faint infrared photons (at a wavelength of 1,550 nanometers) from the 4-watt flight laser transceiver on Psyche. Neither infrared wavelength is easily absorbed or scattered by Earth's atmosphere, making both ideal for deep space optical communications. To receive the most distant signals from Psyche, the project enlisted the powerful 200-inch-aperture (5-meter) Hale Telescope at Caltech's Palomar Observatory in San Diego County, California, as its primary downlink station, which provided adequate light-collecting area to capture the faintest photons. Those photons were then directed to a cryogenically cooled superconducting high-efficiency detector array at the observatory where the information encoded in the photons could be processed. Managed by JPL, DSOC was designed to demonstrate that data encoded in laser photons could be reliably transmitted, received, and then decoded after traveling millions of miles from Earth out to Mars distances. Nearly two years after launching aboard the agency's Psyche mission in 2023, the demonstration completed its 65th and final "pass" on Sept. 2, 2025, sending a laser signal to Psyche and receiving the return signal from 218 million miles (350 million kilometers) away. https://photojournal.jpl.nasa.gov/catalog/PIA26662