COMPASSO: demonstrating key optical technologies for the future of space-based navigation systems

Global Navigation Satellite Systems (GNSS e.g. GPS, Galileo, etc.) have become an essential service for most of the world. Providing precise timing and positioning to every point of the globe enabled numerous industrial innovations and scientific advancements. The microwave-based clocks (e.g. Cesium, Rubidium or passive Hydrogen maser) used in the current systems are limited to an accuracy of 10 to the minus 13 for short integration timescale (<100s). In addition, the present distribution of the signal by means of radio-frequency (e.g. L1 at 1.575 GHz) has some limits in terms of bandwidth and range.
Moving away from the RF to the optical domain is the next step to improve the frequency stability of the clocks. Optical communication is also a promising candidate to replace the RF broadcast of the signal in some applications. Laser links present a number of advantages over RF: 1) a much higher bandwidth, 2) the possibility of highly focalized beam for long-distance communication (e.g. to the Moon or to Mars), 3) the possibility to transfer the stability of the optical frequency via the laser itself, 4) preventing jamming/spoofing and 5) enabling secure communication.
COMPASSO is a DLR mission to demonstrate these key optical technologies required for the future generation of space-based navigation systems. COMPASSO will use an ultra-stable iodine-based optical reference as its main frequency reference. This frequency reference will be converted to an RF clock signal using an optical frequency comb. This frequency comb will also be used to compare optical frequencies and to transfer the frequency stability of the iodine reference to a laser terminal for optical communication to the ground. COMPASSO is currently under development and should be deployed outside of the International Space Station in 2025.
This talk will present the COMPASSO mission in more details, focusing on explaining these key-technologies and opening into their potential application beyond the field of navigation.