Design of a Primary Mirror Fine Positioning Mechanism for a Deployable Space Telescope

The TU Delft Deployable Space Telescope proposes to meet increasing demand for high spatio-temporal resolution Earth observation imagery by reducing the mass, volume and launch cost of space telescopes by using segmented deployable optics. A 3DOF piston/ tip/ tilt fine positioning mechanism is proposed to actively align the primary mirror segments in orbit. A preliminary thermo-mechanical design of the mechanism was synthesised and its mechanical performance verified with an efficient, low order finite element model. The results showed that the mechanism can support the mirror through launch without a hold down mechanism; has a piston step size of 10 nm; a range of ±4 µm in piston and ±9 µrad in tip/ tilt with accuracies of 0.005±0.780 µm (2σ) in position and 0.000±0.041 µrad (2σ) in rotation. A Monte Carlo ray tracing analysis showed that the active optics could successfully align the mirror segments in all considered deployment scenarios.Aerospace Engineerin