CONCEPT OF OPERATIONS FOR THE VISORS MISSION: A TWO SATELLITE CUBESAT FORMATION FLYING TELESCOPE

The Virtual Super-resolution Optics with Reconfigurable Swarms (VISORS) is a National Science Foundation (NSF) space physics mission which will detect and study fundamental energy-release regions in the solar corona. The VISORS mission will image extreme ultraviolet (EUV) features on the Sun at a resolution of at least 0.2 arcseconds from Low Earth Orbit (LEO). To accomplish this objective, VISORS will use a pair of formation flying 6U CubeSats: one of which carries the observatory optics while the other contains the detector instrument. VISORS will serve as a proof of concept for this distributed instrument approach by obtaining at least one 10-second exposure image during its six-month mission lifetime. Meeting the strict relative orbit requirements during science observations will demonstrate several technologies key to precise formation flying including intersatellite link, relative navigation, and autonomous maneuver planning. To satisfy these stringent mission requirements, a concept of operations has been established that requires maneuvering between a standby orbit where housekeeping tasks are performed and an actively maintained science orbit where observations are conducted. Formation acquisition, re-acquisition, fault recovery, and escape operations are also planned. This paper provides a description of the VISORS formation flying concept of operations: explaining the function and rationale of each operation mode, how these modes are designed, and how they collectively meet the mission requirements. Specific challenges and mission trades related to performing precision formation flight with CubeSats are discussed. A Failure Mode Effects and Criticality Analysis (FMECA) is conducted to assess the risk of collision under the most probable fault scenarios, which is used to inform the development of operational mitigation strategies and on-board fault tolerant collision avoidance (COLA) logic.