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NASA's Psyche spacecraft, farther away than the Sun, has sent data through a laser over a record-breaking distance, and done so even faster than expected. Radio frequencies remain the most reliable medium for deep space communication, connecting Earth with Mars rovers, planetary orbiters, and all the way out to interstellar space with the Voyager probes. But it can be slow to beam huge amounts of data across the solar system - for example, it took New Horizons 15 months to send the 50 GB of data from its close encounter with Pluto back to Earth. Using light could drastically speed up that process, at least in some cases. Data can be encoded more densely into light waves than radio waves, allowing larger packets to be sent in a shorter time. So far, high speed tests have beamed data in lasers between satellites and the ground, and even from lunar orbit to Earth, but things get trickier over longer distances. Now, NASA has broken the distance record for data transmission via lasers. On April 8, the Psyche spacecraft, currently en route to the asteroid belt, beamed data back to Earth from over 140 million miles (225 million km) away. That's about one and a half times the distance to the Sun, and 14 times farther than the first test of the equipment back in November.
NASA/JPL-Caltech The goal was to prove that the spacecraft could transmit at up to 1 Megabit per second (Mbps), but that was far surpassed, with the test clocking speeds of up to 25 Mbps. The Deep Space Optical Communications (DSOC) instrument onboard Psyche sent a copy of engineering data to Palomar Observatory in California, while simultaneously sending the same data to NASA's Deep Space Network via radio. For context, Netflix recommends 25 Mbps to stream the service in 4K. "We downlinked about 10 minutes of duplicated spacecraft data during a pass on April 8," said Meera Srinivasan, operations lead on the project. "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." Other recent experiments include sending data from ground stations to Psyche and back - a round trip of 280 million miles (450 million km) - in a single night, and using multiple receivers in different regions to pick up the signal at the same time, which could be important if weather conditions in one area interrupt the connection. The team says this tech demo is a key step towards faster communication of high resolution images and data that will be needed when humans eventually set foot on Mars. Source: NASA