NASA's optical communications demonstration has hit 25 Mbps in a test transmitting engineering data back to Earth from 140 million miles (226 million kilometers) away.

The payload is riding aboard the Psyche probe, which is headed for an asteroid of the same name. On December 11, when the spacecraft was 19 million miles (31 kilometers) away, it reached 267 Mbps, which NASA described as "comparable to broadband internet download speeds."

NASA has better broadband than this writer, it would seem.

However, as Psyche has continued on its trajectory, the distances have become greater, and the rate at which data can be transmitted and received has tumbled. At 140 million miles, the project's goal was to reach a lofty 1 Mbps. Instead, engineers managed to get 25 Mbps out of the demonstration.

Earlier demonstrations tested the technology using preloaded data, such as a cat video. The latest experiment used a copy of engineering data also sent via Psyche's radio transmitter.

"We downlinked about 10 minutes of duplicated spacecraft data during a pass on April 8," said Meera Srinivasan, the project's operations lead at NASA's Jet Propulsion Laboratory (JPL) in Southern California.

"Until then, we'd been sending test and diagnostic data in our downlinks from Psyche. This represents a significant milestone for the project by showing how optical communications can interface with a spacecraft's radio frequency comms system."

The demonstrator is only along for the ride - Psyche uses conventional radio technology for its mission. However, the demonstration does point to the potential for higher-bandwidth communications in future projects.

Assuming the weather cooperates.

"We've learned a great deal about how far we can push the system when we do have clear skies, although storms have interrupted operations at both Table Mountain and Palomar on occasion," said Ryan Rogalin, the project's receiver electronics lead at JPL.

Relatively clear skies are required for optical communications, whereas slower radio communications are less weather-dependent. In one recent experiment, engineers arranged an antenna in one location and a detector in another to receive the same signal in concert. The approach could also be applied to ground stations to handle a receiver being forced offline by weather conditions. ®

https://www.theregister.com//2024/04/27/nasa_psyche_data_speeds/