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.
The Institute for Astronomy and Astrophysics in Tübingen (IAAT) has a long-term experience in developing and building space-qualified imaging and photon counting microchannel-plate (MCP) detectors, which are sensitive in the ultraviolet wavelength range. Our goal is to achieve high quantum efficiency and spatial resolution, while maintaining solar blindness and low-noise characteristics. Our flexible detector design is currently tailored to the specific needs of three missions: For the ESBO DS (European Stratospheric Balloon Observatory – Design Study) we provide a sealed detector to the STUDIO instrument (Stratospheric Ultraviolet Demonstrator of an Imaging Observatory), a 50 cm telescope with a UV imager for operation at an altitude of 37-41 km. In collaboration with the Indian Institute of Astrophysics we plan a space mission with a CubeSat-sized farultraviolet spectroscopic imaging instrument, featuring an open version of our detector. A Chinese mission, led by the Purple Mountain Observatory, comprises a multi-channel imager using open and sealed detector versions. Our MCP detector has a cesium activated p-doped gallium-nitride photocathode. Other photocathode materials like cesium-telluride or potassium-bromide could be used as an alternative. For the sealed version, the photocathode is operated in semi-transparent mode on a MgF2 window with a cut-off wavelength of about 118 nm. For missions requiring sensitivity below this cut-off, we are planning an open version. We employ a coplanar cross-strip anode and advanced low-power readout electronics with a 128-channel charge-amplifier chip. This publication focuses on the progress concerning the main development challenges: the optimization of the photocathode parameters and the sophisticated detector electronics.
This paper presents the concept of a community-accessible stratospheric balloon-based observatory that is currently under preparation by a consortium of European research institutes and industry.
The planned European Stratospheric Balloon Observatory (ESBO) aims at complementing the current landscape of scientific ballooning activities by providing a service-centered infrastructure tailored towards broad astronomical use. In particular, the concept focuses on reusable platforms with exchangeable instruments and telescopes performing regular flights and an operations concept that provides researchers with options to test and operate own instruments, but later on also a proposal-based access to observations. It thereby aims at providing a complement to ground-, space-based, and airborne observatories in terms of access to wavelength regimes – particularly the ultraviolet (UV) and far infrared (FIR) regimes –, spatial resolution capability, and photometric stability. Within the currently ongoing ESBO Design Study (ESBO DS), financed within the European Union’s Horizon 2020 Programme, a prototype platform carrying a 0.5-m telescope for UV and visible light observations is being built and concepts for larger following platforms, leading up to a next-generation FIR telescope are being studied. A flight of the UV/visible prototype platform is currently foreseen for 2021.
We present the technical motivation, science case, instrumentation, and a two-stage image stabilization approach of the 0.5-m UV/visible platform. In addition, we briefly describe the novel mid-sized stabilized balloon gondola under design to carry telescopes in the 0.5 to 0.6 m range as well as the currently considered flight option for this platform.
Secondly, we outline the scientific and technical motivation for a large balloon-based FIR telescope and the ESBO DS approach towards such an infrastructure.
The Stratospheric Observatory for Infrared Astronomy SOFIA started in December 2010 with the first series of science
flights, and has successfully completed about 38 science missions until fall 2011. The science instruments flown included
HIPO, FORCAST, GREAT and FLITECAM. Beside their scientific results (see related papers in these proceedings)
the flights delivered an extensive data base which is now used for the telescope performance characterization and the
operational optimization of the telescope in its unique environment. In this progress report we summarize recent
achievements of the observatory as well as the status of the telescope and give an update of the SOFIA pointing system
completed by intended future pointing optimization activities.
SOFIA, the Stratospheric Observatory for Infrared Astronomy, is an airborne observatory that will study the universe in
the infrared spectrum. A Boeing 747-SP aircraft will carry a 2.5 m telescope designed to make sensitive infrared
measurements of a wide range of astronomical objects. In 2008, SOFIA's primary mirror was demounted and coated for
the first time. After reintegration into the telescope assembly in the aircraft, the alignment of the telescope optics was
repeated and successive functional and performance testing of the fully integrated telescope assembly was completed on
the ground. The High-speed Imaging Photometer for Occultations (HIPO) was used as a test instrument for aligning the
optics and calibrating and tuning the telescope's pointing and control system in preparation for the first science
observations in flight. In this paper, we describe the mirror coating process, the subsequent telescope testing campaigns
and present the results.