Nanosatellite optical downlink experiment: design, simulation, and prototyping

The nanosatellite optical downlink experiment (NODE) implements a free-space optical communications (lasercom) capability on a CubeSat platform that can support low earth orbit (LEO) to ground downlink rates>10  Mbps. A primary goal of NODE is to leverage commercially available technologies to provide a scalable and cost-effective alternative to radio-frequency-based communications. The NODE transmitter uses a 200-mW 1550-nm master-oscillator power-amplifier design using power-efficient M-ary pulse position modulation. To facilitate pointing the 0.12-deg downlink beam, NODE augments spacecraft body pointing with a microelectromechanical fast steering mirror (FSM) and uses an 850-nm uplink beacon to an onboard CCD camera. The 30-cm aperture ground telescope uses an infrared camera and FSM for tracking to an avalanche photodiode detector-based receiver. Here, we describe our approach to transition prototype transmitter and receiver designs to a full end-to-end CubeSat-scale system. This includes link budget refinement, drive electronics miniaturization, packaging reduction, improvements to pointing and attitude estimation, implementation of modulation, coding, and interleaving, and ground station receiver design. We capture trades and technology development needs and outline plans for integrated system ground testing.United States. National Aeronautics and Space Administration. Research Fellowship ProgramLincoln Laboratory (Lincoln Scholars)Lincoln Laboratory (Military Fellowship Program)Fundación Obra Social de La Caixa (Fellowship)Samsung FellowshipUnited States. Air Force (Assistant Secretary of Defense for Research & Engineering. Contract FAs872105C0002

Electronics development for the Deformable Mirror Demonstration Mission (DeMi)

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018.Cataloged from PDF version of thesis.Includes bibliographical references (pages 157-158).This thesis describes the design and implementation of compact high voltage drive electronics for a multi-actuator microelectromechanical systems (MEMS) based deformable mirror (DM) for the 6U CubeSat Deformable Mirror Demonstration Mission (DeMi) with the objective of increasing the NASA Technology Readiness Level (TRL) of the MEMS DM toward its use for direct exoplanet imaging on a future large aperture space telescope mission. This thesis outlines the key requirements for DM performance, successfully develops a commercial-component based DM drive electronics board for a 140-actuator MEMS DM that is scalable to higher actuator count DMs, discusses the attributes of alternative designs in the initial trade study that were not further pursued, and summarizes the plan toward fully integrating and testing the MEMS DM drive electronics into the optical payload.by Christian Alexander Haughwout.S.M

Laser-Guide-Star Satellite for Ground-Based Adaptive Optics Imaging of Geosynchronous Satellites

In this study, the feasibility and utility of using a maneuverable nanosatellite laser guide star from a geostationary equatorial orbit have been assessed to enable ground-based, adaptive optics imaging of geosynchronous satellites with next-generation extremely large telescopes. The concept for a satellite guide star was first discussed in the literature by Greenaway and Clark in the early 1990s ("PHAROS: An Agile Satellite-Borne Laser Guidestar," Proceedings of SPIE, Vol. 2120, 1994, pp. 206-210), and expanded upon by Albert in 2012 ("Satellite-Mounted Light Sources as Photometric Calibration Standards for Ground-Based Telescopes," Astronomical Journal, Vol. 143, No. 1, 2012, p. 8). With a satellite-based laser as an adaptive optics guide star, the source laser does not need to scatter, and is well above atmospheric turbulence. When viewed from the ground through a turbulent atmosphere, the angular size of the satellite guide star is much smaller than a backscattered source. Advances in small-satellite technology and capability allowed the revisiting of the concept on a 6UCubeSat, measuring 10 × 20 × 30 cm. It is shown that a system that uses a satellite-based laser transmitter can be relatively low power (∼1 W transmit power) and operated intermittently. Although the preliminary analysis indicates that a single satellite guide star cannot be used for observing multiple astronomical targets, it will only require a little propellant to relocate within the geosynchronous belt. Results of a design study on the feasibility of a small-satellite guide star have been presented, and the potential benefits to astronomical imaging and to the larger space situational awareness community have been highlighted.United States. Air Force Office of Scientific Research (Contract FA8721-05-C-0002)Air Force Office of Scientific Research (Contract FA8702-15-D-0001