Europe's atomic clocks in space: Einstein's theory is being tested on the ISS!

Europe's atomic clocks in space: Einstein's theory is being tested on the ISS!

Today the European Space Agency ESA launched a groundbreaking project to explore the relationship between gravity and time. As part of this project, two high-precision atomic clocks were sent into space. The instrument, called ACES (Atomic Clock Ensemble in Space), was successfully attached to the Columbus module of the International Space Station (ISS) to send the most accurate time signal from space. The calibration work for ACES is expected to take about half a year, before the first scientific results are expected in about a year and a half.

ACES combines two specially developed atomic clocks: the cesium atomic clock Pharaoh, which measures seconds precisely, and the hydrogen maser clock SHM (Space Hydrogen Maser), which is very stable but does not have the same accuracy as Pharaoh. The main goal of the project is to study the time differences between Earth and the ISS, which could provide essential insights into testing Albert Einstein's general theory of relativity. Einstein postulated that gravity slows down time, which was supported by previous experiments showing that time passes faster at higher altitudes.

Mission and scientific background

The space capsule carrying ACES lifted off from the Kennedy Space Center in Florida on Easter Monday. After about 28 hours of flight, it docked with the ISS. ACES is one of the most accurate timing systems ever sent into space. With daily signal transmissions to multiple ground stations, scientists will be able to compare time measurements and thus find clues to support Einstein's theories.

As Simon Weinberg from ESA points out, the project is also of great practical relevance. It is intended to enable worldwide networking of all accurate clocks to create a uniform and precise time system for applications such as navigation and high-frequency trading. Previous tests on Earth have already shown that clocks tick faster at higher altitudes than on the ground.

Technical details and next steps

The ACES system is about one cubic meter in size and is mounted on the ISS by a robotic arm. The calibration phase will give researchers the opportunity to check how the clocks work before starting measurements in the actual experimental phase.

The results of these measurements could potentially have far-reaching implications for our understanding of time, gravitational fields and their influence on time perception. The project not only contributes to science, but also to the standardization of global time measurement. The findings from the ISS could provide deeper insights into the theory of relativity and thus open a new chapter in physical research.