Performance of a single-axis platform for balloon-borne remote sensing

Abstract

The balloon flight performance of the Mark I single-axis platform and telescope is presented. Three performance indicators are examined: inclinometer output, gyro output, and infrared detector signal. We find that the gondola itself experiences periodic angular disturbances with maximum amplitudes in the 0.1°–2.0° range, with peaks occurring at periods of about 1, 2, 7, 20, and 250 s. The 2- and 20-s oscillations are identified with simple and compound pendulum motions, while the 250-s oscillations are speculated to be caused by atmospheric waves. Maximum platform deviations from the horizontal are in the 0.002°–0.02° range, well within the 0.02° design goal, except in the 250-s regime where amplitudes are occasionally several times larger than the design goal because of horizontal atmospheric accelerations. We find that the system meets our basic goal of providing a stable pointing direction within an uncertainty which is much less than the 0.3° telescope beam diameter.