Optical Clock Travels to Space for the First Time
For the first time, an optical clock was tested in space, demonstrating that the precise technology could be used in space-based applications.
The space-borne optical clock is equipped with a new frequency comb technology- the "gears" that make clocks tick at optical frequencies. According to the researchers, who wrote the report published in Optica, the new compact, robust and automated frequency comb laser system had successfully survived the harsh conditions of a rocket launch and operated in microgravity before falling back to Earth.
"Our device represents a cornerstone in the development of future space-based precision clocks and metrology," Matthias Lezius of Menlo Systems GmbH and first author of the paper, said in a statement. "The optical clock performed the same in space as it had on the ground, showing that our system engineering worked very well."
Phones and other GPS-enabled devices communicate with satellites that bear atomic clocks, which are based on natural oscillation of the cesium atom - a frequency in the microwave region of the electromagnetic spectrum. Each satellite provides a time stamp and the system calculates the person's location based on the relative difference among those times.
But optical clocks have higher frequencies - using visible light instead of microwave - and tick faster than atomic clocks, which could provide more accurate time stamps and improve GPS precision.
Frequency combs are the key to the operation of optical clocks, but conventional frequency combs have been too large and too complex to be used outside a laboratory. But Lezius and Menlo Systems developed an automated optical frequency comb that measures only 22 by 14. 2 centimeters and weighs 22 kilograms, and is rugged enough to withstand extreme acceleration forces and temperature changes when being launched into space.
"We think that it's not so far away that such clocks will be space-qualified to fly on satellites," Lezius said in a report by Space.com.
In April 2015, the system launched on a research rocket for a 6-minute parabolic flight into space. While in microgravity, the system started taking measurements automatically and was controlled from the ground station through a low-bandwidth radio link.
While the experiment did not have the desired level of accuracy, the researchers are planning to relaunch a more accurate version by the end of 2017.