The Compasso Mission: Operational Strategies for Validating Optical Technologies On-Board the ISS

Abstract

Compasso is an in-orbit validation mission to demonstrate new optical technologies for future GNSS constellations. It is hosted on the Airbus Bartolomeo platform on the International Space Station with a launch scheduled for December 2025. The paper illustrates the main design choices with regards to Compasso operations and the ground segment that where made in the current preliminary design phase of the mission. One of the primary mission goals of Compasso, which drives the operations design the most, is the demonstration of bi-directional time transfer via optical links from space to ground. The paper illustrates the general challenges for the optical links, specifically the ones that come with human spaceflight. Under any circumstances it is strictly prohibited that the crew safety is jeopardised by radiation emitting activities, which is why the current link planning strategy and architecture is designed to ensure that no laser activity is planned and executed during any safety critical activities on board the ISS via a fourfold redundant inhibit concept. Since Compasso is dependent on the Bartolomeo, Columbus and ISS infrastructure in general, the paper also shows how Compasso will be integrated in all these programs. An example for this is the TM/TC data routing via the ISS assets. Besides that, the operations concept shows how a payload on the ISS can be operated safely and how the in-orbit validation will be coordinated and conducted.