The agency is testing technologies in space and on the ground that could increase bandwidth to transmit more complex science data and even stream video from Mars. NASA’s Deep Space Optical Communications (DSOC) project, due to launch this fall, will test how lasers could accelerate data transmission far beyond the capacity of current radio frequency systems used in space.
In what’s known as a technology demonstration, DSOC may pave the way for broadband communications to help fuel humanity’s next giant leap: when NASA sends astronauts to Mars. DSOC’s near-infrared laser transceiver (a device that can send and receive data) will be “on the back” of NASA’s Psyche mission when it launches to the metal-rich asteroid of the same name in October.
During the first two years of the trip, the transceiver will communicate with two ground stations in Southern California, testing highly sensitive detectors, powerful laser transmitters and new methods of decoding the signals that the transceiver transmits from deep space.
Near-infrared laser communications use electromagnetic waves to transmit data
NASA is focusing on laser, or optical, communications because of its potential to exceed the bandwidth of radio waves that the space agency has relied on for more than half a century. Both radio and near-infrared laser communications use electromagnetic waves to transmit data, but near-infrared light bundles data into significantly tighter waves, allowing ground stations to receive more data at once.
“DSOC was designed to demonstrate 10 to 100 times the data return capacity of the state-of-the-art radio systems used in space today,” said Abi Biswas, DSOC project technologist at NASA’s Jet Propulsion Laboratory in Southern California. “Broadband laser communications for near-Earth orbit and for satellites orbiting the Moon have been demonstrated, but deep space presents new challenges.”
More missions than ever are heading into deep space, promising to produce exponentially more data than past missions in the form of comprehensive scientific measurements, high-resolution images and video. So experiments like DSOC will play a key role in helping NASA develop technologies that can be routinely used by spacecraft and ground systems in the future.
the transceiver aboard Psyche features several new technologies, including a never-before-flown photon-counting camera attached to an 8.6-inch (22-centimeter) aperture telescope that protrudes from the side of the spacecraft. The transceiver will autonomously seek and “lock on” to a high-power near-infrared laser uplink transmitted by the Optical Communications Telescope Laboratory at JPL’s Table Mountain Facility near Wrightwood, California. The laser uplink will also demonstrate sending commands to the transceiver.
“A powerful uplink laser is a critical part of this technology demo for higher spacecraft speeds, and upgrades to our ground systems will enable optical communications for future deep space missions,” said Jason Mitchell, NASA’s Space Communications and Navigation (SCaN) program director. ) program at NASA headquarters.
Once connected to the uplink laser, the transceiver locates the 200-inch (5.1-meter) Hale Telescope at Caltech’s Palomar Observatory in San Diego County, California, about 100 miles (130 kilometers) south of Table Mountain. The transceiver then uses its near-infrared laser to transmit high-speed data down to Palomar. Spacecraft vibrations that might otherwise bounce the laser off the target will be dampened by state-of-the-art struts attaching the transceiver to Psyche.
To receive the high-speed downlink laser from the DSOC transceiver, Hale’s telescope was equipped with a new 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 time of arrival recorded. The laser light, emitted as a train of pulses, must travel more than 200 million miles (300 million kilometers) the farthest the spacecraft will be during this tech demo before the weak signals can be detected and processed to extract information.
“Every component of DSOC exhibits new technology, from the high-power uplink lasers to the pointing system on the transceiver telescope to the ultra-sensitive detectors that can count individual photons as they arrive,” said Bill Klipstein of JPL, DSOC project. manager. “The team even needed to develop new signal processing techniques to squeeze information out of such weak signals transmitted over vast distances.”
The distances involved present another challenge for the technology demo: The further Psyche travels, the longer it will take the photons to reach their destination, creating a delay of up to tens of minutes. The positions of the Earth and the spacecraft will be constantly changing during the path of the laser photons, so this delay will have to be compensated for.
“Pointing a laser and focusing over millions of miles while dealing with the relative motion of the Earth and the psyche presents an exciting challenge for our project,” said Biswas.
More about the mission
DSOC will demonstrate operations for nearly two years following the launch of NASA’s Psyche mission on its way to a flyby of Mars in 2026. While the DSOC transceiver will be hosted by the Psyche spacecraft, the technical demo will not transmit data from the Psyche mission. The success of each project is evaluated independently of the others.
DSOC is the latest in a series of optical communications demonstrations funded by TDM and SCaN. JPL, a division of Caltech in Pasadena, California, manages DSOC for TDM under NASA’s Space Technology Directorate and SCaN under the agency’s Space Operations Directorate.
The Psyche mission is led by Arizona State University. JPL is responsible for overall mission control, systems engineering, integration and testing, and mission operations. Psyche is part of NASA’s Discovery Program.