Planetary origins and evolution multispectral monochromator (POEMM): optical telescope assembly preliminary design and test plan

Abstract

Planetary Origins and Evolution Multispectral Monochromator is a Pioneer class balloon mission to study planetary formation in protoplanetary disks. To meet the mission’s Level 2 observatory requirement for encircled energy, requires a 1.8-meter diameter optical telescope that is diffraction limited at 70 μm, i.e. with a < 4 μm transmitted wavefront error for all elevation angles. The telescope consists of three aluminum mirrors in a traditional Cassegrain/Nasmyth configuration along with an aluminum support structure. The primary mirror is a f/1 parabola, the secondary mirror is a convex hyperbola, and the third mirror is a fold-flat such that the beam exists to the side along the OTE’s elevation axis allowing the science instrument to remain stationary. The telescope articulates the secondary mirror to scan the focal point at 1 Hz along the virtual spectrometer slits and to compensate for defocus as a function of elevation angle. This paper updates current design and fabrication status and presents preliminary test and verification plan.