The effects of atmospheric turbulence on precision optical measurements used for antenna-pointing compensation

Blind pointing of the Deep Space Network (DSN) 70-meter antennas can be improved if distortions of the antenna structure caused by unpredictable environmental loads can be measured in real-time, and the resulting boresight shifts evaluated and incorporated into the pointing control loops. The measurement configuration of a proposed pointing compensation system includes an optical range sensor that measures distances to selected points on the antenna surface. The effect of atmospheric turbulence on the accuracy of optical distance measurements and a method to make in-situ determinations of turbulence-induced measurement errors are discussed.