Deep-Space Optical Communications (DSOC) & Psyche Spacecraft
Overview
DSOC, short for Deep Space Optical Communications, is a NASA laser-based space communications program currently in space, consisting of a FSO transceiver aboard the Psyche program spacecraft. The DSOC terminal is expected to operate at 10 to 100 times the speed of current RF downlink/uplink speeds. NASA’s Jet Propulsion Laboratory (JPL) leads the project, consisting of both the deep space optical transceiver and a ground station operating at 1550nm or near-infrared. The DSOC system is NASA’s first demonstration beyond the earth-moon system. [1] The DSOC is carried onboard The Psyche spacecraft as part of the Psyche mission, which is lead by Arizona State University and managed by JPL. [2][3]
Key Technologies
The DSOC program contains a few key technologies. To minimize System Weight and Power (SWaP), it will contain a low-mass spacecraft disturbance isolation and pointing assembly. To achieve the desired 10 to 100 times greater link speed, DSOC will include a highly efficient laser transmitter and two photon-counting arrays for both the optical space transceiver and the ground receiver. DSOC’s Flight Laser Transceiver (FLT) and the accompanying ground-based receiver are the primary modules in the subsystem. A vibration control/isolation system, designed for isolating orbital experiments from vibrations was developed by a company called Controlled Dynamics Inc. (CDI) for use with the DSOC beginning in 2012 under NASA research programs. [4] A similar CDI system is used aboard the ISS for experiment isolation. [5]
Timeline
After validation testing in 2018 and 2019, the DSOC payload was planned to launch with NASA’s Psyche mission in mid-2022, which will study the metal heavy asteroid “16 Psyche” and give information about how planets and other astronomical bodies formed crusts, mantles, and cores. Psyche’s designation “16” comes from it being the 16th asteroid to be discovered, in 1852 by Annibale de Gasparis. [8] This asteroid, 173 miles across at it’s widest point, is thought to potentially be a planetesimal, the building block of an early planet. Due to the difficulty of reaching the core of a planet, these types of environments are otherwise unexplored. The DSOC payload’s primary purpose is to transmit the information obtained back to NASA faster than ever before, setting precedent for a new age of solar system exploration. [6] Some believe that this mission will spur on the use of optical communications technologies around Mars. [7] On February 28, 2020, NASA announced that SpaceX’s Falcon Heavy rocket will be the launch vehicle for the Psyche mission. [8]
The DSOC experiment was launched October 13th 2023 aboard the Psyche spacecraft. This experiment was the first of a series to be launched as the primary payload aboard a SpaceX Falcon Heavy. [9] It’s destination is the metal heavy asteroid called Psyche, thought to potentially be the partial core of an early planet, with an ETA of August 2029.
On December 11th 2023 the system sent a 15 second transmission back to earth at a distance of 19 million miles, achieving a maximum transmission rate of 267 megabits per second. [10] At this distance the video took 101 seconds to reach earth. The signal was transmitted the Hale Telescope at Caltech’s Palomar Observatory in San Diego County. [11]
On April 8th 2024 the Psyche spacecraft and DSOC, at a distance of 140 million miles, was able to transmit data at a maximum rate of 25Mbps. [12]
On June 24th 2024 at a distance of 240 million miles a maximum downlink rate of 8.3 megabits was achieved, and sustained rate of 6.25 megabits. [13] This data rate reduction is equivalent to the inverse square of distance. [13]
On October 3rd 2024 a signal was transmitted from the seven kilowatt Optical Communications Telescope Laboratory at the JPL Table Mountain facility near Wrightwood California to the Psyche spacecraft at a distance of 290 million miles. [13]
Currently the Psyche spacecraft is accelerating towards it’s asteroid belt destination using hall effect ion thrusters, which use electricity to emit charged ions of xenon. Currently the craft is moving at roughly 84,000 mph. [14] The energy used for this comes from folding solar panels aboard the Psyche spacecraft, making it roughly the size of a tennis court. These panels produce 21 kilowatts of power near the earth, and roughly 3 kilowatts of power while orbiting the Psyche asteroid. [15]
In Spring of 2026 [14] the Psyche spacecraft will use Mars’ gravity to slingshot itself towards it’s final destination, with an ETA of 2029. After reaching the Psyche asteroid the spacecraft will spend about 2 years orbiting it and collecting data.
Related Links
Article: Update on the Psyche mission and DSOC integration
Paper: Discovery DSOC Transceivers
Deep Space Optical Communications (DSOC) – NASA
https://scienceandtechnology.jpl.nasa.gov/optical-communications-laboratory
https://time.com/7094951/nasa-deep-space-optical-communications/
https://www.jpl.nasa.gov/missions/psyche/
https://ieeexplore.ieee.org/document/10536009
https://ssed.gsfc.nasa.gov/IPM/2014/PDF/1010.pdf