KEYWORDS: Mirrors, Satellites, Space operations, Control systems, Ranging, Space telescopes, Interferometry, Laser resonators, Crystals, Laser development
One economically and technologically feasible bedrock structure for constructing large (diameter > 10 m) space
telescopes is a segmented or sparse aperture system with subcomponents in precision formation flight. For
UV/Visible/IR systems, initial targeting and targeting new objects to establish initial fringes requires the positioning
precision to nm - μm accuracy, thus the control system should be capable of the required precision positioning and
attitude controls without producing contaminations from thruster exhaust plumes. A nanometer accuracy contaminationfree
formation architecture, Photon Tether Formation Flight (PTFF), based on Photonic Laser Thrusters (PLTs) and
tethers has been proposed to exploit a force equilibrium formed by PLT thrust and tether tension for forming precision
persistent 3-D formation structures ideal for the large UV/Visible/IR space telescopes. The range of the PLT force can
theoretically extend over several kms. Under previous NASA sponsorship, we have successfully demonstrated a proofof-
concept PLT. In addition, the demonstrations of required laser components, optics and tracking technologies
developed under military laser applications now support that implementation of PLTs for large space telescopes is one
step closer to reality.
Photonic Laser Thruster (PLT) is an innovative photon thruster that amplifies photon thrust by orders of magnitude by
exploiting an active resonant optical cavity formed between two mirrors on paired spacecraft. PLT is predicted to be able
to provide the thrust to power ratio (T/P) approaching that of conventional thrusters, such as laser ablation thrusters and
electrical thrusters. Yet, PLT has the highest Isp of 3x107 sec, which is orders of magnitude larger than that of other
conventional thrusters. We have demonstrated the photon thrust amplification in PLT for the first time. The T/P obtained
with an OC mirror with R= 0.99967±0.00002 was 20±1 μN/W, and the maximum photon thrust obtained was 35 μN,
resulting in an apparent photon thrust amplification factor of 2,990±150. Scaling-up of PLT is promising, and PLT is
predicted to enable wide ranges of space endeavors. Low thrust (T<N) PLTs may enable nanometer precision spacecraft
formation for forming ultralarge space telescopes and radars, and provide economically viable solution to Fractionated
Spacecraft Architecture, the System F-6. Medium thrust (N<T<kN) PLTs may enable precision propellantless orbit
changing and docking. High thrust (T>kN) PLTs may enable propelling spacecraft at speeds orders of magnitude greater
than that by conventional thrusters.
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