Dynamic wavefront error and line-of-sight performance predictions for the 15-meter segmented Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR) with non-contact vibration isolation

摘要

For the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR) to perform high-contrast direct imaging of habitable exoplanets using a coronagraph instrument, the system must maintain extremely low system dynamic wavefront error (on the order of 10 picometers RMS over the spatial frequencies corresponding to the dark-hole region of the coronagraph) over a long time wavefront control sampling interval (typically 10 or more minutes). Meeting this level of performance requires a telescope vibration isolation system that delivers a high degree of dynamic isolation over a broad frequency range. A non-contact pointing and isolation system called the Vibration Isolation and Precision Pointing System (VIPPS) has been baselined for the LUVOIR architecture. Lockheed Martin has partnered with NASA to predict the dynamic wavefront error (WFE) performance of such a system, and mature the technology through integrated modeling, subsystem test and subscale hardware demonstration. Previous published results on LUVOIR dynamic WFE stability performance have relied on preliminary models that do not explicitly include the effects of a segmented Primary Mirror. This paper presents a study of predicted dynamic WFE performance of the LUVOIR-A architecture during steady-state operation of the coronagraph instrument, using an integrated model consisting of a segmented primary mirror, optical sensitivities, steering mirror and non-contact isolation, and control systems. The design assumptions and stability properties of the control system are summarized. Principal observatory disturbance sources included are control moment gyroscope and steering mirror exported loads. Finally, observatory architecture trades are discussed that explore tradeoffs between system performance, concept of operation and technology readiness.