Precise Pointing and Stabilization Performance for the Balloon-borne Imaging Testbed (BIT): 2015 Test Flight

TL;DR

This paper reports on the design, implementation, and successful testing of the attitude control system for the Balloon-borne Imaging Testbed, achieving high-precision pointing and stabilization during a 2015 test flight, with plans for further improvements.

Contribution

It presents a detailed analysis of the ADCS performance for the BIT, demonstrating sub-arcsecond stabilization in a balloon-borne astronomy platform and outlining enhancements for future flights.

Findings

Pointing stability of 0.68 arcseconds (rms) achieved during flight.

Coarse pointing accuracy within 0.1 degrees.

System modifications planned for improved future performance.

Abstract

Balloon-borne astronomy offers an attractive option for experiments that require precise pointing and attitude stabilization, due to a large reduction in the atmospheric interference observed by ground-based systems as well as the low-cost and short development time-scale compared to space-borne systems. The Balloon-borne Imaging Testbed (BIT) is an instrument designed to meet the technological requirements of high precision astronomical missions and is a precursor to the development of a facility class instrument with capabilities similar to the Hubble Space Telescope. The attitude determination and control systems (ADCS) for BIT, the design, implementation, and analysis of which are the focus of this paper, compensate for compound pendulation effects and other sub-orbital disturbances in the stratosphere to within 1-2$^{\prime\prime}$ (rms), while back-end optics provide further image stabilization down to 0.05$^{\prime\prime}$ (not discussed here). During the inaugural test flight from Timmins, Canada in September 2015, BIT ADCS pointing and stabilization performed exceptionally, with coarse pointing and target acquisition to within < 0.1$^\circ$ and fine stabilization to 0.68$^{\prime\prime}$ (rms) over long (10-30 minute) integrations. This level of performance was maintained during flight for several tracking runs that demonstrated pointing stability on the sky for more than an hour at a time. To refurbish and improve the system for the three-month flight from New Zealand in 2018, certain modifications to the ADCS need to be made to smooth pointing mode transitions and to correct for internal biases observed during the test flight. Furthermore, the level of autonomy must be increased for future missions to improve system reliability and robustness.