Status of the STUDIO UV balloon mission and platform

Abstract

Stratospheric balloons offer accessible and affordable platforms for observations in atmosphere-constrained wavelength ranges. At the same time, they can serve as an effective step for technology demonstration towards future space applications of instruments and other hardware.The Stratospheric UV Demonstrator of an Imaging Observatory (STUDIO) is a balloon-borne platform and mission carrying an imaging micro-channel plate (MCP) detector on a 0.5 m aperture telescope. STUDIO is currently planned to fly during the summer turnaround conditions over Esrange, Sweden, in the 2022 season. For details on the ultraviolet (UV) detector, see the contribution of Conti et al. to this symposium. 1 The scientific goal of the mission is to survey for variable hot compact stars and flaring M-dwarf stars within the galactic plane. At the same time, the mission acts as a demonstrator for a versatile and scalable astronomical balloon platform as well as for the aforementioned MCP instrument. The gondola is designed to allow the use of different instruments or telescopes. Furthermore, it is designed to serve for several, also longer, flights, which are envisioned under the European Stratospheric Balloon Observatory (ESBO) initiative.In this paper, we present the design and current status of manufacturing and testing of the STUDIO platform. We furthermore present the current plans for the flight and observations from Esrange. STATE OF THE ART IN BALLOON-BORNE ASTRONOMYThe idea of using stratospheric balloons to overcome the opacity of Earth's atmosphere for astronomical observations is not new. Historically, the advantages were obvious: spacecraft did not exist or were hardly available and capabilities of airplanes were limited, leaving balloons as the only option to move instruments above most of the atmosphere. Nowadays, the benefits do not seem as clear: both spacecraft and airplanes provide powerful observation platforms and ground-based telescopes invest large efforts into compensating atmospheric influences. However, even in the era of nano-and microsatellites, space observatories are intrinsically expensive and bear operational limitations: development times are long, updates or corrections of the instrumentation are usually not possible after launch, and consumables, such as cryogenic coolant fluids, cannot be refilled or replaced, as seen with the Herschel Space Observatory. Furthermore, rather conservative approaches towards new technologies are used to minimize risks of expensive failure. Ground-based and airborne telescopes, on the other hand, still suffer from fundamental limitations imposed by the atmosphere at certain wavelengths.On the other hand, technological advances have made balloon-borne telescopes more attractive over the last couple of years. These particularly include more reliable balloons and the opening of long-duration flight routes, allowing flight durations of 30 to 40 days on "conventional" long duration routes and promising 50 to 100 days on ultra long duration routes. Consequently, the last couple of...