NASA to test deep space atomic clock
- By Susan Miller
- Jun 07, 2019
To make sure spacecraft can navigate accurately and autonomously on journeys to Mars and beyond, NASA will be conducting a year-long test of its toaster-sized deep space atomic clock (DSAC), launching it on the SpaceX Falcon Heavy rocket June 22.
Current space navigation relies on Earth-based atomic clocks to measure the time it takes electromagnetic signals traveling at light speed from ground stations to reach a spacecraft and travel back. Using the known time and speed of light, distance can be accurately calculated.
Today's atomic clocks use the frequency of light released by specific atoms for their accurate measurements, but they are subject to magnetic fields and temperature changes – and they can be the size of a refrigerator. Spacecraft currently in low-Earth orbit receive signals from ground stations or Global Navigation Satellite Systems, which carry multiple atomic clocks, but the number crunching and back-and-forth transmission of data and instructions as spacecraft travel farther from Earth can take hours, NASA said.
Deep space travel, however, requires a much smaller and lighter clock that can also navigate when it's beyond the range of navigation satellites. The DSAC uses mercury ions in electromagnetic traps that allow for a much smaller device that is less vulnerable to external forces, making the highly accurate DSAC better suited for deep space exploration.
And accuracy is critical. A clock whose timing is off by even a single second could mean missing a landing site on Mars by miles, NASA said. During the test, NASA will use the navigation signals from U.S. GPS satellite system coupled with detailed knowledge of those satellites' orbits and clocks to monitor DSAC's performance. Researchers expect the test will show that the DSAC can maintain time accuracy to better than two nanoseconds over a day.
A spacecraft carrying its own highly accurate atomic clock could receive a signal from Earth and determine its location using an onboard navigation system. Having access to near-immediate location data will improve efficiency and allow more precise autonomous maneuvering.
Susan Miller is executive editor at GCN.
Over a career spent in tech media, Miller has worked in editorial, print production and online, starting on the copy desk at IDG’s ComputerWorld, moving to print production for Federal Computer Week and later helping launch websites and email newsletter delivery for FCW. After a turn at Virginia’s Center for Innovative Technology, where she worked to promote technology-based economic development, she rejoined what was to become 1105 Media in 2004, eventually managing content and production for all the company's government-focused websites. Miller shifted back to editorial in 2012, when she began working with GCN.
Miller has a BA and MA from West Chester University and did Ph.D. work in English at the University of Delaware.
Connect with Susan at [email protected] or @sjaymiller.