NASA Sends Tiny Atomic Clock to Space
Traveling through space isn’t just about knowing where you are. You also need to know what time it is, and a wristwatch won’t do. Spacecraft rely on extremely accurate measurements of time to coordinate maneuvers, and these systems will become even more important as we aim for distant destinations. That’s why NASA is testing a new type of mercury-ion atomic clock, which is smaller and more versatile.
NASA’s new clock headed into space earlier this week aboard the second commercial Falcon Heavy launch. That rocket carried 24 different payloads including a prototype light sail spacecraft, NOAA temperature monitoring satellites, a NASA test of hydrazine fuel alternatives, and more. The Deep Space Atomic Clock was a very small part of the Falcon Heavy’s total payload, but it could be one of NASA’s most important current experiments.
Most current spacecraft rely on signals from Earth-based systems to do all the work. A signal goes to the spacecraft from Earth, and the spacecraft sends one back. Atomic clocks on Earth measure the time it took for the signal to come back, allowing controllers to calculate distance and speed for the probe. The problem with this system is how long it takes light to travel between Earth and the probe. On a trip to Mars, it would take about 40 minutes for each navigation measurement, which is impractical for real-time autonomous navigation and crewed missions.
To fix this, you need an atomic clock on the spacecraft, and that’s what the Deep Space Atomic Clock is. It’s about the size of a toaster oven, attached to the General Atomics Electromagnetic Systems Orbital Test Bed satellite. Atomic clocks on Earth are usually the size of a refrigerator. It could effectively make navigation calculations a one-way system. Signals from Earth could allow the spacecraft to instantly measure its speed and position.
NASA says the Deep Space Atomic Clock has a high degree of stability, so it should remain accurate far longer than any mission would last. It should only be off by one or two nanoseconds in nine million years. NASA will gauge the clock’s performance in the coming months with the aim to integrate similar devices with small and mid-sized satellites. Atomic clocks may also end up on spacecraft in the Artemis program’s moon missions.