Miguel Nunes, Hawaii Space Flight Laboratory, University of Hawaii at Manoa; Piper Kline, Hawaii Space Flight Laboratory, University of Hawaii at Manoa; Mohammed Irfan Rashed, Hawaii Space Flight Laboratory, University of Hawaii at Manoa
https://doi.org/10.64861/BNRQ6324
Keywords: Neutron detector, CubeSat Swarm, Cislunar space, Radiation Environment Monitoring, Model-Based Systems Engineering (MBSE)
Abstract:
The operational space domain is expanding beyond Low Earth Orbit (LEO) into highly elliptical trajectories and cislunar space, where spacecraft, human exploration systems, and national security assets encounter dynamic and poorly characterized radiation environments. Current radiation models rely on sparse historical data and large monolithic platforms, limiting temporal responsiveness and spatial resolution. As distributed architectures expand into highly elliptical orbit (HEO) and cislunar regimes, spatially resolved environmental intelligence becomes a prerequisite for resilient Space Situational Awareness (SSA) and Space Domain Awareness (SDA) operations.
Neutron-3 proposes a distributed CubeSat swarm mission architecture designed to perform near real-time, three-dimensional reconstruction of the neutron and secondary radiation environment across extended orbital regimes. Building upon the flight heritage of the Hawaiʻi Space Flight Laboratory (HSFL) Neutron-1 mission and the dual-satellite formation concept of Neutron-2, Neutron-3 advances the architecture into a coordinated swarm of small spacecraft operating across a range of altitudes and inclinations. Each spacecraft carries a compact neutron-detection payload optimized for secondary-neutron flux measurement, time-correlated event detection, and angular discrimination.
By distributing identical sensors across spatial baselines ranging from tens to thousands of kilometers, the constellation enables tomographic inversion of radiation gradients rather than single-point sampling. This paper describes the Neutron-3 mission concept, the science and swarm-architecture rationale, and the application of Model-Based Systems Engineering (MBSE), using the Arcadia method implemented in Capella, to define, allocate, and verify the swarm architecture. A digital-thread framework links operational concepts, swarm-level requirements, subsystem allocations, and verification matrices, extending the SmallSat MBSE methodology and digital artifacts previously developed and matured on Neutron-2.
Preliminary simulation studies indicate that a five-spacecraft swarm with sub-millisecond synchronization accuracy can reconstruct radiation gradients with spatial resolution below approximately 150 km in representative highly elliptical orbits, including transient solar particle event conditions. The paper closes with a description of the coordinated MBSE, radiation-transport/inversion, and swarm-communications work tracks planned to mature the concept toward a quantitative architecture assessment.
Date of Conference: September 15-18, 2026
Track: Space-Based Assets