"The most advanced nations are always those who navigate the most."
Deep Space Atomic Clock (DSAC)
-- Ralph Waldo Emerson, 19th century American poet
Precise radio navigation -- using radio frequencies to determine position -- is vital to the success of a range of deep-space exploration missions. The Deep Space Atomic Clock (DSAC) Technology Demonstration Mission will fly and validate a miniaturized, ultra-precise mercury-ion atomic clock that is 100 times more stable than today’s best navigation clocks.
Ground-based atomic clocks have long been the cornerstone of most deep-space vehicle navigation because they provide root data necessary for precise positioning. The Deep Space Atomic Clock will deliver the same stability and accuracy for spacecraft exploring the solar system. This new capability could forever change the way we conduct deep-space navigation -- by eliminating the need to "turn signals around" for tracking. Much the same way modern Global Positioning Systems (GPS) use one-way signals to enable terrestrial navigation services, the Deep Space Atomic Clock will provide the same capability in deep-space navigation -- with such extreme accuracy that researchers will be required to carefully account for the effects of relativity, or the relative motion of an observer and observed objected, as impacted by gravity, space and time (clocks in GPS-based satellite, for example, must be corrected to account for this effect, or their navigational fixes begin to drift).
Over the past 20 years, NASA engineers at NASA's Jet Propulsion Laboratory
in Pasadena, Calif., have been steadily improving and miniaturizing the mercury-ion trap atomic clock, preparing it to operate in the harsh environment of deep space. In the laboratory setting, the Deep Space Atomic Clock's precision has been refined to permit drift of no more than 1 nanosecond in 10 days.
Now the DSAC team is preparing a miniaturized, low-mass atomic clock -- orders of magnitude smaller, lighter and more stable than any other atomic clock flown in space -- for a test flight in low-Earth orbit. The clock will make use of GPS signals to demonstrate precision orbit determination and confirm its performance, promising new savings on mission operations costs, delivering more science data and enabling further development of deep-space autonomous radio navigation.
The investigation will hold its preliminary design review in 2013. It will fly as a hosted payload on an Iridium NEXT spacecraft. Launch is set for 2015.
DSAC: Key Mission Facts
- The Deep Space Atomic Clock will be orders of magnitude smaller, lighter and more stable than any other atomic clock flown in space.
- This NASA Technology Demonstration Mission will shift paradigms for navigating spacecraft to distant destinations, enabling collection of more data with better precision; and enabling autonomous radio navigation for time-critical events such as orbit insertion or landing.
- This mission will deliver the next generation of deep-space radio science.