Capable of receiving optical and radio frequency signals, the DSN hybrid antenna has tracked and decoded the DSOC downlink laser aboard NASA’s Psyche mission.
An experimental antenna has received radio frequency and near-infrared laser signals from NASA. Psyche spaceship while traveling through deep space. This shows that it is possible that the giant satellite dishes of NASA’s Deep Space Network (DSN), which communicate with spacecraft through radio waves, which will be adapted for optical or laser communications.
By including more data in transmissions, optical communication will enable new space exploration capabilities while supporting DSN on demand in the network. it grows.
The 34-meter (112-foot) radio-frequency optical hybrid antenna, called Deep Space Station 13, has tracked NASA’s Deep Space Optical Communications downlink laser (DSOC) technology demonstration from November 2023. The technology demonstration flight laser transceiver travels with the agency’s Psyche spaceship, which thrown out on October 13, 2023.
The hybrid antenna is located at DSN’s Goldstone Deep Space Communications Complex near Barstow, California, and is not part of the DSOC experiment. The DSN, DSOC and Psyche are managed by NASA’s Jet Propulsion Laboratory in Southern California.
“Our hybrid antenna has been able to successfully and reliably lock and track the DSOC downlink since shortly after the launch of the technical demonstration,” said Amy Smith, deputy director of DSN at JPL. “It also received the radio frequency signal from Psyche, so we have demonstrated synchronous radio and optical frequency communications in deep space for the first time.”
By the end of 2023, the hybrid antenna transmitted data from 32 million kilometers (20 million miles) away at a speed of 15.63 megabits per second, about 40 times faster than radio frequency communications at that distance. On January 1, 2024, the antenna transmitted a photograph of the equipment that had been uploaded to the DSOC prior to the launch of Psyche.
To detect laser photons (quantum particles of light), seven ultra-precise segmented mirrors were placed inside the curved surface of the hybrid antenna. Similar to hexagonal mirrors of NASA’s James Webb Space Telescope, these segments mimic the light-gathering aperture of a 3.3-foot (1-meter) aperture telescope. As laser photons arrive at the antenna, each mirror reflects the photons and precisely redirects them toward a high-exposure camera connected to the antenna subreflector suspended above the center of the dish.
The laser signal collected by the camera is then transmitted through an optical fiber that feeds a cryogenically cooled semiconductor nanowire single-photon detector. Designed and built by JPL Microdevice Laboratorythe detector is identical for the one used at Caltech’s Palomar Observatory, San Diego County, California, which acts as DSOC’s downlink ground station.
“It’s a high-tolerance optical system built on a 34-meter flexible structure,” said Barzia Tehrani, deputy manager of ground communications systems and hybrid antenna delivery manager at JPL. “We use a system of mirrors, precise sensors and cameras to actively align and direct the laser from deep space onto a fiber leading to the detector.”
Teherani hopes the antenna will be sensitive enough to detect the laser signal sent from Mars at its farthest point from Earth (2 ½ times the distance between the Sun and Earth). Psyche will be at that distance in June on its way to the main asteroid belt between Mars and Jupiter to investigate the metal-rich asteroid Psyche.
The antenna’s seven-segment reflector is a proof of concept for an expanded, more powerful version with 64 segments (the equivalent of an 8-meter aperture telescope) that could be used in the future.
DSOC is paving the way for higher data rate communications capable of transmitting complex scientific information, videos and high-definition images in support of humanity’s next great leap: send humans to mars. The recent technology demonstration transmitted the first ultra high definition video from deep space at record bit rates.
Retrofitting RF antennas with optical terminals and building purpose-built hybrid antennas could be a solution to the current lack of dedicated terrestrial optical infrastructure. The DSN has 14 antennas distributed in facilities in California, Madrid and Canberra, Australia. Hybrid antennas could rely on optical communications to receive large volumes of data and use radio frequencies for data that requires less bandwidth, such as telemetry (health and position information).
“For decades, we have been adding new radio frequencies to the DSN’s giant antennas located around the world, so the most feasible next step is to include optical frequencies,” Tehrani said. “We can have an asset doing two things at the same time; converting our communication routes into highways and saving time, money and resources.”
DSOC is the latest in a series of optical communications demonstrations funded by NASA’s Technology Demonstration Missions (TDM) program and the agency’s Space Communications and Navigation (SCaN) program. JPL, a division of Caltech in Pasadena, California, manages DSOC for TDM within NASA’s Space Technology Mission Directorate and SCaN within the agency’s Space Operations Mission Directorate.
For more information about NASA optical communications projects, visit:
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Ian J. O’Neill
Jet Propulsion Laboratory, Pasadena, California.