Why NASA Is Experimenting with Deep Space Atomic Clocks
Right now, all space travel originates on Earth. That's helpful for logistics, as all current spacecraft determine their paths by calculating their positions from our planet. But that also yields delays.
When trying to navigate in the vast expanse of space, spacecraft can remain motionless for minutes at a time while they wait for signals from the home planet. So NASA is trying to cut the cord to Earth with its new Deep Space Atomic Clock, which is beginning a year-long trial in space.
"Every spacecraft exploring deep space is steered by navigators here on Earth," says Jill Seubert, the Clock's deputy principal investigator at NASA's Jet Propulsion Lab (JPL), in a press statement. "Deep Space Atomic Clock will change that by enabling onboard autonomous navigation, or self-driving spacecraft."
The DSAC will be sent into orbit in late June on the Orbital Test Bed satellite, which will be flying on a SpaceX Falcon Heavy rocket.
Around the size of a toaster, the DSAC wouldn't be the first atomic clock to leave Earth. Every device with a GPS uses an atomic clock, most likely on one of the hundreds of satellites orbiting the planet. But the DSAC offers two things that none of those clocks have: size and stability. It's both small enough to fit compactly on spacecraft, where storage capacity is the ultimate premium, and stable enough to handle the rigors of leaving Earth's orbit.
Spacecraft today rely on large antennas to communicate with distant spacecraft, the type that can be found at the Goldstone Deep Space Communications Complex in California's Mojave Desert. From the nearby OSIRIS-REx to the faraway Voyager 1, Goldstone monitors multiple missions—28, to be exact—by sending out signals that the spacecraft ricochet right back. Precise clocks on Earth measure the signal journey into space and back, and that time allows scientists to determine the craft's distance.
"It's the same exact concept as an echo," says Seubert. "If I'm standing in front of a mountain and I shout, the longer it takes for the echo to come back to me, the farther away the mountain is."
But two-way communication takes time and resources that could be used more efficiently, if there was a way around it. That's where the DSAC comes into play.
"Having a clock on board would enable onboard radio navigation and, when combined with optical navigation, make for a more accurate and safe way for astronauts to be able to navigate themselves," says Deep Space Atomic Clock Principal Investigator Todd Ely.
The technology could free up Earth-based satellites to focus more on Earth, but the most intriguing use is on other worlds, where they could help set a precedent in the establishment of human-based organization. If multiple DSACs were orbiting Mars, for example, they could set up a GPS-like network capable of giving directions to humans and robots on the planet's surface.
"The Deep Space Atomic Clock will have the ability to aid in navigation, not just locally but in other planets as well," says Eric Burt, the ion clock development lead. "One way to think of it is as if we had GPS at other planets."
There's reason to be optimistic. During lab testing, the DSAC proved to be 50 times more accurate than modern GPS clocks. According to NASA, that's an "error of 1 second every 10 million years." The clock's trial run in space will be the first in a long journey toward being used every day on missions.
NASA hopes the DSAC could be guiding spacecraft in the early 2030s. By that point, the Agency expects to have established a permanent presence around the moon and will be looking toward landing on Mars. When the first astronaut steps on the Red Planet, it may be with help from a Deep Space Atomic Clock.
Source: NASA
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