A New "Atomic Clock" Transforms Deep Space Exploration

The clock is as accurate in space as it is on Earth.
Ameya Paleja
Deep Space Atomic Clock ready for its space sojournNASA

In June 2019, the National Aeronautics and Space Administration (NASA) a toaster oven-sized instrument aboard the Falcon X Heavy rocket from SpaceX. Two years later, results from the experiments carried out using the instrument have been published that could potentially change the way we travel in deep space in the future. 

Space probes that have been launched from Earth currently cannot self-determine their locations in space. To know where they are, they first need to receive signals from Earth which they then bounce back. The signals are then received back on Earth and specially designed clocks then compute the time taken for the signals to travel back. Based on the calculated time, the location of the probe is determined and then communicated back to the probe.

Called atomic clocks, the specially designed clocks are as big as refrigerators and super precise in how they measure time. But carrying these big clocks on human missions is cumbersome. Additionally, sending signals back and forth is time-consuming. A round trip to a signal to Mars is about 40 minutes. One can only imagine the painful wait when drifting away in deep space. 

To overcome this potential problem, NASA reduced the size of the atomic clock and decided to test it in space. After the FalconX put the clock in its orbit, NASA activated it and began comparing it with another atomic clock on the ground. After comparing results for over a year, NASA found that the atomic clock in space drifted from the one on the ground by 26 picoseconds a day. This is comparable to the drift observed in other ground-based atomic clocks. It was also 10 times more stable than clocks used on GPS satellite systems.  

In the future, spacecraft carrying this toaster-oven-sized atomic clock would have to send signals back and forth to determine its location.  Instead, it would just receive a signal from Earth and calculate its own location using the onboard atomic clock. This would be like having its own GPS that could be used to navigate deep space. 

Last year, scientists in Germany introduced a more accurate nuclear clock. However, it consumes more energy than atomic clocks. 

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