(Credit: NASA)
It turns out a laser can beam data back to Earth even if it’s based as far away as Mars, according to a new test from NASA.
The NASA spacecraft Psyche pulled off the feat over the summer as it traveled to an asteroid inside the solar system. The craft has also been outfitted with a near-infrared laser system, which is designed to beam back data through space.
NASA has now revealed Psyche was able to send a laser signal from about 290 million miles away, or the distance between Mars and Earth when the two planets are farthest apart. The test also broke the record for the “farthest laser communication ever sent,” according to NASA Administrator Bill Nelson.
(Credit: NASA)The agency didn’t break down the full details, but noted that when the Psyche craft was about 240 million miles away from Earth, the laser system “achieved a sustained downlink data rate of 6.25 megabits per second, with a maximum rate of 8.3 megabits per second.” This shows the laser can outperform traditional radio-based frequencies for space communications, NASA says.
The laser system's data transfer speeds do degrade as Psyche gets farther away from Earth. In December 2023, the spacecraft reached downlink rates of "62.5Mbps, 100Mbps, and 267Mbps" while it was about 19 million miles away from Earth. But by April 2024, the downlink rate of the laser reached only 25Mbps as Psyche traveled farther out to the solar system.
Still, NASA says it "maintained an error-free downlink at 6.25Mbps for approximately 38 minutes," a pretty impressive length of time. Psyche depends on ground-based observatories back on Earth to send and receive the data. Specifically, the craft’s transceiver needs to search for and lock onto a laser beacon emitted by one of the observatories and then “stabilize its line of sight” to begin transmitting data, NASA says.
(Credit: NASA)The tests have been important since it was previously unclear how well space-based laser communication would perform over such vast distances. “Now the techniques we use to track and point have been verified, confirming that optical communications can be a robust and transformative way to explore the solar system,” says Meera Srinivasan, a projection operations lead at NASA’s Jet Propulsion Laboratory.
SpaceX is also using lasers for space-based communication; it's incorporated them into Starlink to improve the satellite internet system. Last month, the SpaceX-supported Polaris Dawn mission showed the same lasers can be used as a way for orbiting spacecraft to connect to the internet through Starlink. This included sustaining a 40-minute livestream between the Polaris Dawn crew and SpaceX staff on Earth.