In late 2023, NASA tested a new hybrid laser/radio antenna to downlink data from 20 million miles (32 million kilometers) away at a rate of 15.63 megabits per second – about 40 times faster than radio frequency communications at that distance. On Jan. 1, 2024, the antenna downlinked a team photograph that had been uploaded to DSOC before Psyche’s launch.
The 34-meter (112-foot) radio-frequency-optical-hybrid antenna, called Deep Space Station 13, has tracked the downlink laser from NASA’s Deep Space Optical Communications (DSOC) technology demonstration since November 2023. The tech demo’s flight laser transceiver is riding with the agency’s Psyche spacecraft, which launched on Oct. 13, 2023.
Two for One
In order to detect the laser’s photons (quantum particles of light), seven ultra-precise segmented mirrors were attached to the inside of the hybrid antenna’s curved surface. Resembling the hexagonal mirrors of NASA’s James Webb Space Telescope, these segments mimic the light-collecting aperture of a 3.3-foot (1-meter) aperture telescope. As the laser photons arrive at the antenna, each mirror reflects the photons and precisely redirects them into a high-exposure camera attached to the antenna’s subreflector suspended above the center of the dish.
The laser signal collected by the camera is then transmitted through optical fiber that feeds into a cryogenically cooled semiconducting nanowire single photon detector. Designed and built by JPL’s Microdevices Laboratory, the detector is identical to the one used at Caltech’s Palomar Observatory, in 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, communications ground systems deputy manager and delivery manager for the hybrid antenna at JPL. “We use a system of mirrors, precise sensors, and cameras to actively align and direct laser from deep space into a fiber reaching the detector.”
Tehrani 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 from the Sun to 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.
An Infrastructure Solution
DSOC is paving the way for higher-data-rate communications capable of transmitting complex scientific information, video, and high-definition imagery in support of humanity’s next giant leap: sending humans to Mars. The tech demo recently streamed the first ultra-high-definition video from deep space at record-setting bitrates.
Retrofitting radio frequency antennas with optical terminals and constructing purpose-built hybrid antennas could be a solution to the current lack of a dedicated optical ground infrastructure. The DSN has 14 dishes distributed across facilities in California, Madrid, and Canberra, Australia. Hybrid antennas could rely on optical communications to receive high volumes of data and use radio frequencies for less bandwidth-intensive data, such as telemetry (health and positional information).
The seven-segment reflector on the antenna is a proof of concept for a scaled-up and more powerful version with 64 segments – the equivalent of a 26-foot (8-meter) aperture telescope – that could be used in the future.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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I’m pleased to see we’re doing this to advance our interplanetary communications potential. But if I have a need to say something, if I may digress, it’s about SETI. I believe in searching around us (at interstellar distances) as best we can for intelligent “signals”. But because our current technology is so limited (based on the speed of light and because we’re just not that smart), I doubt if I live another 25+yrs I will ever live long enough to “hear” ET.
200 years ago, the best way way, the only to send a massage would be by smoke signs. Outside of line of sight? Some guy had a horse to get from point “A” to point “B” The idea that radio is the “best” anyone else can to send any information anywhere, is to me just arrogant.
The question of where the improvement comes in wasn’t answered. Is it the higher frequency of the carrier signal (light vs RF) that affords much higher bandwidth or is it a signal to noise ratio that allows us to pick out more data reliably amongst the noise or other factors?
It’s both. Higher frequency allows better focusing which raises received signal power. Higher bandwidth is a side benefit that is useful in situations where power is sufficient to support very high rates and radio spectrum allocations are limiting.