Improving Nanosatellite Imaging with Adaptive Optics

Active and adaptive wavefront control can be useful on space platforms for a variety of observation applications. For example, to achieve high contrast imaging to a level of 1e-10 with a coronagraph (required to image an Earthlike planet around a Sun-like star), space telescopes require high spatial frequency wavefront control systems. To achieve intersatellite links through the atmosphere, wavefront correction is needed to counter the effects of atmospheric turbulence and scintillation. For deployable apertures, active correction is desired to properly align and calibrate optical systems. Deformable mirrors (DMs) are a key element of a wavefront control system, as they correct for imperfections, thermal distortions, and diffraction that would otherwise corrupt the wavefront and ruin the measurement. High-actuator count mirrors are required to achieve the desired level of correction on space telescopes, but this key technology lacks spaceflight heritage. The goal of the CubeSat Deformable Mirror (DeMi) technology demonstration mission is to characterize a microelectromechanical system (MEMS) deformable mirror and to demonstrate its ability to perform modest wavefront correction on a nanosatellite platform. DeMi is a 6U CubeSat that houses a 2U optical payload. The payload is a custom optical bench with a Boston Micromachines deformable mirror and custom-modified driver electronics to fit within a CubeSat system. The payload is expected to draw <8 W when enabled. The payload has both an external aperture and internal laser diode as well as a focal plane sensor and Shack-Hartmann wavefront sensor. The remaining volume in the CubeSat is reserved for the supporting bus, which uses a combination of COTS components and custom interface boards to provide power, pointing knowledge and control, position knowledge, thermal stability, command and data interface,