A clock that fell by a second every 300 million years may be equivalent, for the average citizen, to kill flies with a cannon. At no time do we need to measure a temporal event with such precision.
However, the idea behind the Aces mission is not that astronauts know exactly how long it takes their coffee to warm up, But to test Einstein’s theory of relativity and to open new research fields On the foundations of physics since the orbit of our planet.
“The launch of Aces represents a turning point not only for European space science, but also for international collaboration and technological innovation.
Daniel Neuenschwander, director of human and robotic exploration at ESA.
The clock is made up of two instruments, including the Pharao, a 91 kg clock that works thanks to the measurement of ultra-referified cesium atoms using lasers. The use of this type of clock is not trivial, because according to the international system of current units, A second corresponds to the duration of 9,192,631,770 oscillation cycles of a cesium atom.
Pharao will be accompanied by Space Hydrogen Maser (SHM), an instrument capable of measuring time using hydrogen atoms. Separately, these clocks are extraordinarily precise, but together, They reach another level, that necessary to redefine global time measurement standards.
Why do we want such a precise clock in space?
These instruments arrived on April 25, 2025 at the Columbus laboratory of the International Space Station, and a robotic arm will install them in the Nadir external loading system, which faces our planet. In this way, Floor laboratories can connect using microwaves (MLW) and lasers to synchronize their clocks with unprecedented precision.
Once installed, Aces will accompany the ISS for 30 months in his trip around the planet, which he goes around 16 times a day. During this period, he should carry out at least 10 measurement campaigns of 25 days each, In order to capture the minimal temporal variations caused by the influence of the gravity and the orbital speed of the earth. In other words, Aces will quantify the effects of Einstein’s theory of relativity and will test its predictions.
But it’s not just theory: these instruments also have concrete applications. For example, such a stable measurement of orbital time will allow better synchronization of global satellite positioning systems and considerably increase the precision of GPS systems.
In addition, other telecommunications systems that also need orbit objects, such as the Internet, could benefit from a clock of this type to operate more reliably. In other words, This clock could be the cornerstone of the coordinated operation of the digital world.
How does Einstein the theory affect satellites?
Depending on the relativistic effects, the speed of a body and its position in relation to a gravitational source affect its perception of passing time. Thus, the “gap towards gravitational red” that the satellites feel the passage of time differently from us on the surface of the planet.
The effect is particularly visible on the Galileo and GPS satellites, which orbit approximately 20,000 kilometers from the surface. Accordingly, Their atomic clocks are shifted by around 40 microseconds per day compared to that of the earth, which forces them to constantly correct their date.
Using Aces, Researchers hope to better understand the time fluctuations caused by the Einstein effect and thus increase the accuracy of satellite measures. They also hope to use clocks to create more precise geodesic cards or to measure the small variations that occur due to phenomena linked to the interactions between gravity and the earthly atmosphere. Mecânica Quântica.
Article reference:
ACES: Atomic Clock Ensemble in Space. Science & Exploration.
