Proceedings Article | 29 July 2016
KEYWORDS: Space telescopes, Image segmentation, Telescopes, Spherical lenses, Satellites, Space operations, Mirrors, Space telescopes, Optical instrument design, Hubble Space Telescope, Off axis mirrors
The Configurable Aperture Space Telescope, CAST, is a concept that provides access to a UV/visible-infrared
wavelength sub-arcsecond imaging platform from space, something that will be in high demand after the retirement of
the astronomy workhorse, the 2.4 meter diameter Hubble Space Telescope. CAST allows building large aperture
telescopes based on small, compatible and low-cost segments mounted on autonomous cube-sized satellites. The concept
merges existing technology (segmented telescope architecture) with emerging technology (smartly interconnected
modular spacecraft, active optics, deployable structures). Requiring identical mirror segments, CAST’s optical design is
a spherical primary and secondary mirror telescope with modular multi-mirror correctors placed at the system focal
plane. The design enables wide fields of view, up to as much as three degrees, while maintaining aperture growth and
image performance requirements. We present a point design for the CAST concept based on a 0.6 meter diameter (3 x 3
segments) growing to a 2.6 meter diameter (13 x 13 segments) primary, with a fixed Rp=13,000 and Rs=8,750 mm
curvature, f/22.4 and f/5.6, respectively. Its diffraction limited design uses a two arcminute field of view corrector with a
7.4 arcsec/mm platescale, and can support a range of platescales as fine as 0.01 arcsec/mm. Our paper summarizes
CAST, presents a strawman optical design and requirements for the underlying modular spacecraft, highlights design
flexibilities, and illustrates applications enabled by this new method in building space observatories.
