Chethana Janith, Jadetimes Staff
C. Janith is a Jadetimes news reporter covering science and geopolitics.
Ships passing in the night used Morse code sent with lanterns and shutters to communicate. That same basic principle has allowed NASA to communicate with Psyche, its mission to a metal-rich asteroid in the main belt. However, the “light” was a version of heat, and instead of being able to see each other, Psyche is 240 million miles away from Earth. Oh, and the upload rate of the data it sent is still better than old dial-up internet connections that were prevalent not so long ago.
This feat was part of the culmination of the first Phase of NASA’s Deep Space Optical Communications experiment. Psyche is carrying a laser transceiver tuned to a specific frequency of infrared light, which can also be transmitted and received by two ground stations based in California. The infrared frequency the mission planner at NASA’s Jet Propulsion Laboratory selected is much higher than the typical radio frequency communications used for deep space missions. In this case, higher frequency also means higher data rate.
As part of its Phase I operations, the experiment transmitted data to and from Psyche at an astonishing 267 megabits per second when the spacecraft was as far away as Mars when the Red Planet is closest to us. That is equivalent to a typical wired broadband connection back here on Earth. But it was made in space – with lasers.
In June, Psyche reached a new milestone for distance from Earth – 390 million km. That is equivalent to Earth and Mars’ farthest distance from each other. During this window, operators managed to maintain a 6.25 megabits per second download link. While that’s a few orders of magnitude slower than the maximum data rate it reached the closer distance, it is still orders of magnitude above the same data rate of a radio frequency connection with the same power output.
As part of this Phase I test, what else would NASA send from its spacecraft but a cat video—in this case, an ultra-high-definition video of a cat named Taters chasing a red laser pointer for 15 seconds straight. As a proof of concept for a high-speed communication line, most of the internet would agree that this is a good use of bandwidth.
Ultimately, the latest successful connection in June was the end of the first Phase of testing for the system. The project team unequivocally proved that, as expected, communication data-rate reduction was proportional to the inverse square of the distance between Earth and Psyche. In other words, the data rate decreases even faster as the distance increases between the spacecraft and the base station.
A second phase of the experiment will pick up in November when the laser transceiver is turned back on again. At that point, it will prove the system can operate for more than a year, and eventually, the system will be brought up into full operational mode later in 2024. Psyche is scheduled to arrive at its target asteroid in 2029, so the team will have plenty of time to prep their system for operation before that time. There is also a backup radio frequency communication system on Psyche in case the laser system fails – and even that is still faster than lanterns and shutters.
