A sub-arcsecond pointing stability fine stage for a high altitude balloon platform

High-altitude balloons (HABs) are platforms for collecting astrophysical and planetary science data that offer a number of advantages compared to conventional ground-based or space-based systems. However, they also pose a set of new environmental challenges that must be addressed in order to offer a viable alternative to ground-or space-based assets. In particular, maintaining science-quality pointing stability is a critical challenge for HAB platforms. For these missions, dynamic errors must be limited to a fraction of the observation wavelength, so as the wavelength becomes smaller, it becomes more difficult to meet the needed performance. As a result, there are very few existing pointing stabilization solutions that use visible-spectrum guide stars, despite their relatively wide distribution across the sky. This paper describes the results achieved with the STABLE (Sub-arc second Telescope And BaLloon Experiment) project whose goal is to provide the fine pointing stage for a balloon-borne platform observing in the visible wavelength.