Study maps assembly dynamics for kilometre-scale solar power satellites

(SpaceEnergy) University of Strathclyde researchers have developed an optimisation method for assembling large modular solar power satellites while accounting for changing spacecraft dynamics and environmental disturbances during construction.

The peer-reviewed study applies the method to ESA’s SOLARIS reference design and the SPS-ALPHA architecture, modelling structures containing thousands of modules in geostationary and geosynchronous Laplace-plane orbits.

Rather than treating assembly as a geometric or logistics problem, the framework recalculates mass distribution, inertia and disturbance sensitivity as modules are installed. It models gravity-gradient torque, solar radiation pressure, Earth’s oblateness and solar and lunar gravitational effects.

For SPS-ALPHA, simulations found solar-radiation-pressure torque could reach about 10,000 Nm. With longer intervals between module installations, radial-axis attitude excursions reached around ±80 degrees despite an optimised assembly sequence.

A geometrically symmetric but dynamically unoptimised SPS-ALPHA sequence produced rotations approaching ±180 degrees, indicating continuous tumbling. The researchers concluded that active attitude control would probably be required to maintain precise pointing during assembly of SPS-ALPHA-type systems.

For the SOLARIS configuration, simulated attitude motion remained below about ±2 degrees without active control.

The incremental optimisation method generated complete assembly sequences in less than 70 minutes for all tested scenarios. The authors said incorporating coupled orbit-attitude analysis into assembly planning is essential for future large-scale space systems.