Star tracker based ATP system conceptual design and pointing accuracy estimation

Abstract

A star tracker based beaconless (a.k.a. non-cooperative beacon) acquisition, tracking and pointing concept for precisely pointing an optical communication beam is presented as an innovative approach to extend the range of high bandwidth (> 100 Mbps) deep space optical communication links throughout the solar system and to remove the need for a ground based high power laser as a beacon source. The basic approach for executing the ATP functions involves the use of stars as the reference sources from which the attitude knowledge is obtained and combined with high bandwidth gyroscopes for propagating the pointing knowledge to the beam pointing mechanism. Details of the conceptual design are presented including selection of an orthogonal telescope configuration and the introduction of an optical metering scheme to reduce misalignment error. Also, estimates are presented that demonstrate that aiming of the communications beam to the Earth based receive terminal can be achieved with a total system pointing accuracy of better than 850 nanoradians (3 sigma) from anywhere in the solar system.

Pointing Error Correction for a Moving-Platform Electro-Optical Telescope Using an Optimized Parameter Model

“…With the rapid advancement of photoelectric technology, electro-optical telescopes are increasingly being integrated into vehicles, ships, aircraft, and spacecraft for diverse missions, such as optical communication, aerial photography, astronomical observation, and antenna stabilization [1][2][3][4]. Control systems of moving-platform electro-optical telescopes (MPEOTs) require high-performance pointing directions to achieve accurate target acquisition, tracking, and positioning [5].…”

Beaconless Pointing for Deep-Space Optical Communication

“…2 As a result, alternatives to beacon-based laser communications are being investigated. 2,[5][6][7] The work presented here is motivated in support of the optical communications system for the Integrated Radio and Optical Communication (iROC) project. The iROC project is a research and development effort to couple deep space radio frequency and optical communication elements into an integrated system for communication to Earth at distances from Mars and beyond.…”