In space, a one-millisecond error can turn a mission that has cost hundreds of millions of euros, and years of work, into failure.
One of the wonders of the Universe is its precision. The perfect synchrony and constancy of the orbits of the celestial bodies, and the speed at which they travel through space.
Thanks to the very precise (and predictable) movements of the celestial bodies we can know the exact date on which a comet will appear, or when will there be a eclipse Sun, for instance. And also, how to travel to the moon or mars, describing very precise orbits and trajectories.
In space, where almost all heavenly bodies move at tens of thousands of kilometers per second, an error of one millisecond means deviating 300 kilometers from the trajectory. This can cause a ship to be affected by the gravity of a planet or a moon, and lose it forever.
Therefore NASA uses atomic clocks to calculate times and trajectories, the most accurate in the world.
But there’s a problem: atomic clocks are too big to put them in a small unmanned spacecraft, like those that travel through the Solar System.
For these cases NASA performs measurements with Earth’s atomic clocks, and sends them to the ship at the speed of light. But in spatial distances the data can take several seconds to arrive, so complex calculations must be made to compensate.
All of this will change with the use of DSAC, the Deep Space Atomic Clock, a compact device that can be integrated into a spacecraft.
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Finally NASA probes will be able to carry their own atomic clocks, with which the measurements and calculations of times and trajectories will be immediate.
An atomic clock works by measuring the energetic oscillations of the atoms, which are very constant. Cesium atoms are normally used, but DSAC uses mercury ions. It is so precise that only delayed 1 second every 10 million years. Even so, it must be recalibrated once a week, to avoid this delay.
Atomic clocks used by GPS, for example, have to be reset several times a day.
The DSAC already has a year of testing. NASA is going to include it in the probe that will explore Venus in a few years. A major improvement for navigating the Solar System.