BOREALIS: Phase-B Results of a Dual-Orbit 6U CubeSat for In-Orbit Biofilm Radiation Experiments

BOREALIS (Biofilm Onboard Radiation Exposure Assessment Lab In Space) is a 6U CubeSat mission developed under the Italian Space Agency (ASI) ALCOR program, aimed at enabling controlled biological experimentation across multiple radiation environments in space. The mission adopts an innovative dual-phase orbital concept, performing biofilm exposure experiments first in Low Earth Orbit (LEO) and subsequently in Medium Earth Orbit (MEO), allowing comparative in-orbit assessment of radiation-driven biological effects.

This paper presents the Phase-B outcomes of the BOREALIS program, focusing on the consolidation of the system architecture, subsystem design maturity, and verification strategy supporting the LEO-to-MEO mission profile. Key results include the finalized satellite architecture, propulsion and attitude control integration, payload accommodation and interfaces, and the definition of the mission operations concept for both orbital phases. Particular attention is given to the propulsion subsystem based on a water-fueled pulsed plasma thruster and to the Attitude Determination and Control System (ADCS), whose coupled performance has been extensively analyzed through numerical simulations and Hardware-in-the-Loop (HIL) testing.
Phase-B verification activities demonstrate the feasibility of maintaining stable attitude control and payload pointing during prolonged low-thrust maneuvers, a critical requirement for the orbital transfer and biological experiment integrity. Payload-level interfaces, thermal control strategies, and radiation-tolerant design choices are also discussed, highlighting the system-level trade-offs adopted to comply with CubeSat constraints while achieving mission objectives.

The results confirm BOREALIS as a mature 6U CubeSat platform capable of supporting advanced bio-space experimentation beyond LEO, providing a scalable reference architecture for future low-cost missions targeting higher-radiation orbital regimes.