NASA’s experimental laser communication system, riding along with the Psyche spacecraft, has hit another milestone. The system was recently used to transmit Psyche data from over 140 million miles (226 million kilometers) away.
The system, called Deep Space Optical Communications, or DSOC, has previously been used to send test data and even to send a video of a cat, to test whether using laser communications in addition to the usual radio communications is possible. But as this is technology is experimental, the Psyche spacecraft has its own radio communications system it has been using to transmit its science data. Now, though, DSOC has been able to interface with the Psyche systems and send Psyche engineering data back to Earth as well.
“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, in a statement. “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 data is duplicated in that it is sent using both the laser and radio communications systems, so that if there is an issue with the new laser system then valuable data won’t be lost. But the test earlier this month was a success, with DSOC able to transmit the data at an even higher rate than expected. As the spacecraft travels farther from Earth, the rate at which it can send data is reduced, so though the system could handle near-broadband speeds of 275 Mbps while near Earth, now it is so far away that the project hoped to demonstrate that just 1 Mbps was possible. In fact, the recent test showed an average rate of 25 Mbps.
It was also possible for both the radio and laser communications systems on Psyche to operate simultaneously, with radio data being passed to NASA’s Deep Space Network and the laser data being received at the Hale Telescope at Caltech’s Palomar Observatory.
The potential advantage of laser communications systems is that they can carry 10 to 100 times more data than radio systems. As more space missions are launched with increasingly sophisticated science instruments collecting large volumes of data, more bandwidth is needed to send this data back to Earth. The hope is that future space missions may be able to use laser systems for more efficient communications, with receiving antenna being upgraded to receive both radio and laser signals.
