Top-class technology that inspires

Trying to explain atomic clocks in a way that everyone can understand is at least as difficult as trying to grasp how they actually function. For thousands of years, humankind has used natural constants to structure their lives according to time. Initially, the focus was on establishing the best days for sowing and harvesting. Later, it shifted to general curiosity about the world. The natural constants used by humans to measure time soon faded into the background. In 1736, a maritime clock developed by John Harrison laid the basis for the navigation principle still used today. The measurements made with his ‘H1’ and its follow-up models made it possible very early on to determine the East–West position of ships on their journeys in addition to their North–South position, which was determined using star maps. Ever since then, the accuracy of clocks has also been a gauge of position, not only on ships. Some time later the atom, along with its properties in different states, was discovered as a constant for measuring temporal cycles. This led to the development of a hydrogen atom clock in the mid-20th century that measures time a thousand times more accurately than even the most precise atomic clock in the world. Such a ‘hydrogen maser’ will also be applied in the Galileo programme. In theory, this maser only errs by one second every million years.

This atomic clock is the ideal companion for any navigation satellite when it comes to ensuring the best possible positioning accuracy. Car drivers who have so far relied on GPS to guide them can now look forward to even more reliable navigation systems. The more accurately satellites and ground stations are temporally coordinated with one another, the more precise the maps and directions become. A deviation of just one millisecond, i.e. one thousandth of a second, in space results in an error of 300 metres on Earth.