What is NASA’s Deep Space Optical Communications (DSOC) and Why it is Important
The article reviews recent deep-space optical communication technology innovations for transferring data between Space and Earth.
Introduction
Look up at the stars twinkling in the night sky. Imagine if we could talk to the planets, send messages to the moon, or chat with rovers exploring Mars! That’s what space communication is all about — finding ways to talk and share information with spacecraft and exploring the vastness of space.
It’s like having a really long-distance conversation. But instead of using phones or computers, scientists and engineers use special tools and technologies to send signals, texts, pictures, and even videos across the enormous distances between Earth and other celestial bodies.
Space communication helps us learn more about the universe and the planets beyond our own. It’s an incredible way for us to connect with the wonders of space, sending our curiosity and discoveries out into the cosmos and bringing back the secrets and marvels hidden among the stars.
Space communication is our cosmic chat line, connecting Earth with distant planets and spacecraft. It’s our way of exploring the unknown, exchanging messages, and unraveling the mysteries of the universe hidden among the stars.
NASA’s Deep Space Optical Communications (DSOC)
Deep Space Optical Communications (DSOC) represents a groundbreaking frontier in space communication technology. Unlike traditional radio-frequency systems, DSOC utilizes optical wavelengths to transmit data across vast cosmic distances, promising unprecedented data transfer rates and efficiency in interplanetary communication. This article explores the innovative principles behind DSOC, its transformative potential for space exploration, and the intricate engineering challenges involved in deploying optical communication systems for communicating across the vastness of deep space.
NASA’s DSOC experiment is the agency’s first demonstration of optical communications beyond the Earth-Moon system. DSOC is a system that consists of a flight laser transceiver, a ground laser transmitter, and a ground laser receiver. New advanced technologies have been implemented in each of these elements. [1, 2]
Tried-and-tested radio frequency communications from deep space are approaching their bandwidth limit, raising the need for upgraded communications systems. Future space missions, meanwhile, are expected to transmit huge volumes of science data, including high-definition images and video, significantly increasing the bandwidth required. [1, 2]
DSOC Mission Overview and Key Goals
This mission is an ongoing emerging technology demonstration [1–3]. Existing deep space radio frequency communication systems are nearing their bandwidth capacity. It is insufficient for upcoming missions to transmit extensive scientific data, including high-resolution images and videos, demanding substantially more bandwidth [2, 3]. This experiment demonstrates optical communications beyond the Moon [2]. DSOC system consists of three modern advanced components — a flight laser transceiver, a ground laser transmitter, and a ground laser receiver [2, 3].
This mission is very important because it will place a great base for the following state-of-the-art technologies for deep space communications. It demonstrates that laser transmitters in deep space can successfully lock onto each other’s laser signals during the calibration commissioning phase [2, 3]. Also, data uplink and downlink will be measured while the Psyche spacecraft travels farther from Earth[2, 3]. The mission will be running for two years, and at least one contact per week is planned [2, 3].
The Psyche Mission
The Psyche mission was created to explore a metal-rich asteroid that may shed light on our planet’s formation [3]. Psyche is a distinctive metal asteroid about three times farther away from the sun than Earth. The asteroid Psyche is named after the goddess of the soul in ancient Greek mythology [3]. The asteroid was discovered in 1852 by Italian astronomer Annibale de Gasparis. Because it was the 16th asteroid to be discovered, it is sometimes referred to as 16 Psyche [3].
Traveling through space using an exceptionally effective solar electric propulsion system, the Psyche spacecraft aims to reach the asteroid for scientific operations by 2029. Its plan includes orbiting this extraordinary celestial body for at least 26 months upon arrival [3]. DSOC technology was integrated into the Psyche spacecraft and will be tested several years after the launch.
Since the discovery of the asteroid Psyche, scientists have observed this entity from a distance. Throughout time, they’ve deduced that Psyche is an extraordinary object, probably abundant in metal. However, numerous mysteries persist regarding its formation and structure. The Psyche mission will be the first to explore this kind of asteroid [3].
Based on information gathered through radar and optical telescopes on Earth, scientists theorize that the asteroid Psyche might constitute a segment of the metal-enriched core of a planetesimal — an elemental component forming rocky planets like Mercury, Venus, Mars, and Earth [3].
Scientists eagerly anticipate their inaugural close-up exploration of Psyche to unravel its origins. Should the asteroid represent remnant core material from a planetary precursor, they aim to understand the parallels and deviations in its history compared to rocky planets. Alternatively, if Psyche doesn’t reveal itself as an exposed core, it could signify an exceptionally unique early solar system object — a novelty in astronomical discoveries. The mission’s thrilling prospect lies in the potential unveiling of the unforeseen [3].
The trajectory of the Psyche spacecraft follows a spiraling route towards the asteroid Psyche. This graphic illustrates the path from above the planetary plane, highlighting significant milestones of the primary mission. The test phases for NASA’s Deep Space Optical Communications (DSOC) technology demonstration are marked with red dots [3].
NASA’s Eyes is a web-based visualization tool that dynamically displays the spacecraft’s current position in a Solar System [3]. The image below depicts the Psyche spacecraft on November 30, 2023.
Official Psyche and DSOC Mission Timeline
The mission timeline is taken from the official Technology Demonstration Factsheet [2], Psyche Press Kit [3], and Psyche’s Mission Plan [4]. Please keep in mind that dates may differ after the launch.
- October 2023 — Psyche spacecraft is scheduled to launch from NASA’s Kennedy Space Center on a SpaceX Falcon Heavy rocket.
- Roughly 20 days after launch — the DSOC calibration and commissioning phase is expected to begin, preparing the tech demo for operation.
- Roughly 50 days after launch — first expected contact opportunity between DSOC ground systems and the flight transceiver aboard Psyche.
- June 2024 — the first phase of this technology demonstration ends.
- January 2025 — the second phase of the tech demo begins.
- October 2025 — DSOC tech demo ends.
- May 2026 — The spacecraft is expected to fly by Mars, using the planet’s gravity as a slingshot to increase velocity.
- Late July 2029 — If all goes as planned, the asteroid Psyche’s gravity will capture the spacecraft after a journey of about 2.2 billion miles (3.6 billion kilometers).
- August 2029 to November 2031 — The spacecraft conducts its prime mission, gathering science data while orbiting the asteroid.
The spacecraft was successfully launched on October 13, 2023, and is on it’s way to Psyche [5].
Deep Space Optical Communication Technology
The system consists of a flight laser transceiver for sending data, a sensitive photon-counting camera to receive the data, and a powerful near-infrared transceiver at the Jet Propulsion Laboratory’s Table Mountain facility near Wrightwood, California [2, 3, 6–8].
Laser communication systems present distinctive benefits and obstacles. While both radio and near-infrared laser communications utilize electromagnetic waves for data transmission, near-infrared light compresses data into much denser waves, allowing ground stations to receive larger data volumes simultaneously. However, employing this more focused laser beam from space necessitates extraordinarily precise pointing and tracking to efficiently transfer data to a ground station [3, 6-8].
Furthermore, when the gap between the laser transmitter and receiver widens, the laser signal weakens, demanding extremely sensitive sensors to perceive and capture the diminished laser light. Due to the signal’s feebleness across extensive distances, extraneous sources, such as scattered sunlight and atmospheric interference, can overpower the data conveyed by the minimal laser photons reaching the detector [3].
To overcome challenges and prove the effectiveness of deep space laser communications, DSOC’s flight laser transceiver is secured with stabilizing mechanisms to counter spacecraft vibrations. This isolates the hardware from minor movements, ensuring precise downlink laser alignment. Additionally, the transceiver’s telescope, equipped with an extended sunshade, stands out as one of Psyche’s recognizable features, preventing stray light from reaching the receiver [3, 6–8].
During operations, the spacecraft aids in roughly orienting the DSOC flight transceiver by turning it towards the ground-transmitted beacon at Table Mountain. The DSOC transceiver can autonomously locate and fixate on the beacon, stabilizing its view and transmitting a focused high-rate data downlink beam to Palomar’s 200-inch (5.1-meter) Hale Telescope [3, 6–8].
The Hale Telescope captures the faint signal and directs it to a superconducting nanowire photon-counting detector. This highly accurate detector precisely measures the arrival time of photons. Using sophisticated signal processing at the backend, it decodes the data modulated and encoded in the deep space laser beam, converting it into usable information on the ground [3, 6–8].
Psyche spacecraft
The transceiver on the Psyche spacecraft can send and receive high-rate data. The transceiver’s 8.6-inch (22-centimeter) aperture telescope is mounted on an isolation-and-pointing assembly that stabilizes the optics and isolates it from spacecraft vibrations. The flight hardware is fitted with a sunshade and protrudes from the side of the spacecraft, making it one of Psyche’s easily identifiable features [2, 3].
DSOC technology demonstration’s flight laser transceiver was shown at NASA’s Jet Propulsion Laboratory in Southern California in April 2021. Then, it was installed inside a box-like enclosure and integrated with NASA’s Psyche spacecraft [3, 6–8].
The flight laser transceiver on Psyche spacecraft inside a clean room at the agency’s Jet Propulsion Laboratory in Southern California in December 2021. The spacecraft shows a tube-shaped sunshade in gray/silver color jutting out from its side. This extension holds DSOC’s transceiver, which includes a laser transmitter using near-infrared light to send lots of data to Earth. It also has a highly sensitive camera that catches low-rate data sent from the ground [3, 6–8].
Ground system
The second system’s component is a laser transmitter at the Jet Propulsion Laboratory’s Table Mountain facility near Wrightwood, California. This laser will uplink a modulated laser beam to the flight transceiver and demonstrate low-rate data transmission. It also acts as a beacon for the flight transceiver to lock onto. The data sent back by the DSOC transceiver on Psyche will be collected by the 200-inch (5.1-meter) Hale Telescope at Caltech’s Palomar Observatory in San Diego County, California, using a sensitive superconducting nanowire photon-counting receiver to demonstrate high-rate data transfer [3, 6–8].
The Overall System
The current image below depicts the overall system connected together [3, 6–8]. Here is a visualization of how the laser beam sends data to Earth's receiver.
The following image below illustrates the Psyche spacecraft with its components mounted. This illustration was created before the spacecraft was created, therefore differences may apply [3, 6–8].
Conclusions
This is a very important project and a big step towards deep space communications. DSOC is a continuation of laser communications that have come before it but from another point of view.
Deep Space Optical Communication will allow us to communicate with many spacecrafts in deep space and receive high-quality images and video streaming in the future. Just imagine a set of spacecrafts and probes in deep space around the ring of asteroids or planets. They communicate together and with the Earth. Scientists will use this data to continue the high-quality exploration of the space. And people who can’t go into deep space, except astronauts, can see much more in deep interplanetary space.
References
- Deep Space Optical Communications (DSOC) - NASA
- Deep Space Optical Communications (DSOC) Technology Demonstration Factsheet
- Psyche Press Kit
- Psyche’s Mission Plan
- NASA’s Psyche Spacecraft, Optical Comms Demo En Route to Asteroid
- DSOC’s Flight Laser Transceiver
- DSOC Flight Laser Transceiver Integrated with NASA’s Psyche Spacecraft
- Deep Space Communications via Faraway Photons
