Menlo Launches Optical Clock into Space

Menlo Systems GmbH has launched a next-generation optical clock into space for a 10-min journey.

The payload consisted of two separate units, a fully automated dual comb system (FOKUS II), and an iodine-stabilized laser (JOKARUS). Iodine-based optical clocks can achieve better precision than rubidium gas cells used previously. Rubidium clocks are used for GNSS (global navigation satellite systems) such as GPS and GALILEO. With further improvement underway, Menlo aims to outperform the space-grade hydrogen maser (H-maser) developed for GALILEO.

On its journey carried by a sounding rocket, the scientific payload reached an altitude of 238 km and experienced 6 min of microgravity. The payload with the comb sustained vibrations up to 9 g rms, shocks of up to 21 g, and constant accelerations up to 12 g. Under these conditions, the fully automated comb system successfully performed its mission and compared the iodine optical reference with a standard radio frequency atomic clock. The device remained operational over the full flight.

This is the third time that an optical clock from Menlo Systems has visited space; other flights took place in April 2015 and January 2016. Compared to the previous missions, the system has been reengineered for largely reduced size and power intake. Although much more compact, the system consists now of two independent comb units, offering experimental flexibility and redundancy.

Laser optics were redesigned from scratch and built with low outgassing materials. The system has also been qualified for operation under vacuum. Despite its small size and low power intake, the performance of the combs is comparable to latest commercial systems of Menlo Systems.