The Nanosatellites in Formation Flight (NanoFF) mission, launched in December 2023, comprises two 2U CubeSats designed to demonstrate close-proximity formation flight under realistic operational constraints. Each spacecraft is equipped with a fully redundant satellite bus and a propulsion system, enabling controlled relative motion in low Earth orbit. Following deployment by the D-Orbit ION orbital transfer vehicle into a partial helix configuration, the mission has progressed through Launch and Early Orbit Phase (LEOP) and commissioning into a phase focused on refining and maintaining the formation geometry.

A key flight-dynamics performance metric for close formation flight is the maximum cross-track (normal, out-of-plane) separation between the spacecraft. This separation is governed by the relative inclination vector and defines the normal envelope of the helix orbit. Reducing the magnitude of this vector enables tighter formations while preserving bounded relative motion and collision safety. This paper addresses the ongoing planning and implementation of out-of-plane maneuver strategies aimed at reducing the maximum cross-track distance in the NanoFF formation.

The approach is based on the complementary use of publicly available Two-Line Elements and precise orbit determination using Global Navigation Satellite System data. Two-Line Elements provide immediate, low-latency access to relative orbit information without operational dependencies, while GNSS-based solutions offer higher accuracy but are limited by onboard data availability and downlink constraints. Together, these data sources are used to estimate relative motion and to monitor the evolution of the relative inclination vector components within the relative orbital elements framework. Normal delta-v maneuvers are planned to selectively reduce the dominant components of the relative inclination vector while minimizing undesired coupling into in-plane relative motion due to attitude control and thruster nozzle geometry errors. During future out-of-plane maneuver execution, attitude determination based on coarse onboard sensors will be supplemented by post-processed analysis of star tracker data and Earth observation camera imagery to assess attitude accuracy relevant to normal-direction velocity execution. Particular attention is given to maneuver timing and location to preserve the desired helix characteristics, especially the inclination difference between the two satellites.

The execution of out-of-plane maneuvers is subject to significant operational constraints inherent to nanosatellite missions. These include limited ground contact opportunities, restricted availability of attitude modes, propulsion system limitations, safety-driven constraints on minimum relative distances, and the need to coordinate maneuvers with ongoing subsystem and payload activities. The paper discusses how these constraints influence maneuver design, sequencing, and validation, and how safety considerations are integrated into the operational planning process.

The current status of the ongoing activities is presented, including analytical assessments, maneuver trade-offs, and early operational observations. The NanoFF mission provides an in-orbit test case for cross-track control strategies in nanosatellite formations, offering insights into the practical challenges of implementing out-of-plane maneuvers under real operational constraints. The lessons learned from this work are expected to inform future formation-flying missions relying on small satellites for Earth observation and other distributed spacecraft applications.