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

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.