STARI: STarlight Acquisition and Reflection toward Interferometry

We introduce the NASA-funded mission STARI (STarlight Acquisition and Reflection toward Interferometry). We plan to demonstrate the first transfer of starlight between two separate spacecraft, a key technology step towards long-baseline interferometry. Consisting of two propulsive 6U CubeSats flying in Low Earth Orbit separated by ∼100 meters, STARI will reflect a small beam of starlight from the Chief spacecraft toward the Deputy spacecraft, where the light will be collected by an off-axis parabola and focused into a single-mode fiber. With the use of differential Global Positioning System (GPS), visual LED beacons and fast-steering-mirrors (FSMs), we aim for continuous high-throughput fiber coupling to demonstrate both diffraction-limited control of the starlight beam angle and mm-level control of the beam’s trajectory, paving the way for a science-focused space interferometer in a follow-up mission. Here, we give an overview of the top-level science and technical requirements for STARI, along with an update to our Concept of Operations. Novel orbital geometries are proposed that advance the state-of-the-art for conducting interferometry operations in LEO. Lastly, we provide mission-specific requirements and details for each payload subsystem. We hope that a successful STARI mission (expected launch 2029) will accelerate the development of the Large Interferometer for Exoplanets (LIFE) Mission, our best chance for detecting biomarkers in the atmospheres of nearby Earthlike planets.