GPS coupled with precise knowledge of GPS satellite orbits and clocks to confirm DSAC’s performance. While in orbit, the DSAC mission will use the navigation signals from U.S. The DSAC test flight will take this technology from the laboratory to the space environment. DSAC is about the size of a four-slice toaster, and could be further miniaturized for future missions. The atomic clocks at ground stations in the Deep Space Network are about the size of a refrigerator. In certain scenarios, the accuracy of that tracking data would exceed traditional methods by a factor of five.ĭSAC is an advanced prototype of a small, low-mass atomic clock based on mercury-ion trap technology. This paradigm shift enables spacecraft to focus on mission objectives rather than adjusting their position to point antennas earthward to close a link for two-way tracking.Īdditionally, this innovation would allow ground stations to track multiple satellites at once near areas like Mars, crowded with NASA science missions. Timely location data and onboard control allows for more efficient operations, more precise maneuvering and adjustments to unexpected situations. A spacecraft could use a signal sent from Earth to calculate position without returning the signal and waiting for commands from the ground, a process that can take hours. Spacecraft using this new technology would no longer have to rely on two-way tracking. The DSAC project aims to provide accurate onboard timekeeping for future NASA missions. Doing this in space is what DSAC is all about.”Ī glimpse of the Deep Space Atomic Clock in the middle bay of the General Atomics Electromagnetic Systems Orbital Test Bed spacecraft. Atomic clocks have done this routinely on the ground for decades. Since radio signals travel at the speed of light, that means we need to measure their time-of-flight to a precision of a few nanoseconds. “Navigating routinely requires distance measurements accurate to a meter or better. “Navigating in deep space requires measuring vast distances using our knowledge of how radio signals propagate in space,” said Todd Ely of JPL, DSAC’s principal investigator. This requires spacecraft to wait for navigation commands from Earth rather than making those decisions onboard and in real-time. For example, a ground station must wait for the spacecraft to return a signal, so a station can only track one spacecraft at a time. This method, though reliable, could be made much more efficient. NASA uses the difference in time between sending a signal and receiving a response to calculate the spacecraft’s location, velocity and path. Ground antennas send narrowly focused signals to spacecraft, which, in turn, return the signal. It’s the Deep Space Atomic Clock (DSAC), an instrument being built for deep space exploration.Ĭurrently, most missions rely on ground-based antennas paired with atomic clocks for navigation. It’s not a wristwatch not something available in a store. For 20 years, NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, has been perfecting a clock. In deep space, accurate timekeeping is vital to navigation, but not all spacecraft have precise timepieces aboard.
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