NASA’s Psyche mission carried a unique cargo when it launched in October of last year: a test of Deep Space Optical Communications (DSOC), a new laser-based communications system. After sending back its first set of data in November, that system has now achieved a new milestone: signals from the experiment are now being picked up by an Earth-based hybrid antenna.
Radio frequencies are a tried-and-true communication method that has been used for decades by the great majority of deep space missions. Radio communications have bandwidth restrictions, though, and in order to transmit the ever-increasing amounts of data that missions gather, new communications technologies are needed. This is where optical or laser communications come into play, as they can increase the available bandwidth over radio by a factor of ten or even hundred.
The feasibility of using laser communications to send signals from deep space craft is being tested by DSOC. On Earth, however, is where the other half of the equation comes in. Today, NASA is testing a hybrid design antenna that can pick up both radio and laser signals. The Deep Space Network (DSN) of NASA receives signals from these deep space missions.
The first time, Psyche’s radio signals and DSOC’s laser signals have been successfully received by this experimental hybrid antenna. Amy Smith, NASA’s Jet Propulsion Laboratory’s DSN deputy manager, said in a statement that “our hybrid antenna has been able to successfully and reliably lock onto and track the DSOC downlink since shortly after the tech demo launched.” For the first time, synchronous radio and optical frequency deep space communications have been demonstrated by it as well, having picked up Psyche’s radio frequency signal.
A collection of segmented mirrors was added to the very center of the dish and the radio antenna hardware that was already in place was retrofitted to create the hybrid antenna. This makes it possible to divert the laser signals to a camera mounted on the lengthy arms that protrude from the dish’s framework.
“To actively align and direct laser from deep space into a fiber reaching the detector, we use a system of mirrors, precise sensors, and cameras,” said Barzia Tehrani, JPL’s deputy manager of communications ground systems and delivery manager for the hybrid antenna.
The objective is to upgrade more DSN network dishes to support radio and laser communications, or in the future, to build brand-new hybrid antennae specifically for this purpose. Tehrani stated, “We can have one asset doing two things at the same time; converting our communication roads into highways and saving time, money, and resources.”