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BRITE (BRIght Target Explorer) Constellation, the first nanosatellite mission applied to astrophysical research, is a collaboration among Austria, Canada and Poland. The fleet of satellites (6 launched; 5 functioning) performs precise optical photometry of the brightest stars in the night sky. A pioneering mission like BRITE -with optics and instruments restricted to small volume, mass and power in several nanosatellites, whose measurements must be coordinated in orbit -poses many unique challenges. We discuss the technical issues, including problems encountered during on-orbit commissioning (especially higher-thanexpected sensitivity of the CCDs to particle radiation). We describe in detail how the BRITE team has mitigated these problems, and provide a complete overview of mission operations. This paper serves as a template for how to effectively plan, build and operate future low-cost niche-driven space astronomy missions. and multi-filter capability, for a sample of the brightest stars, which tend to be the most intrinsically luminous (i.e., massive and/or highly evolved). BRITE Constellation extends the parameter space of space photometry missions, with nearly all-sky coverage in two wavelength ranges of hundreds of the most luminous stars in the Galaxy -all at relatively low cost (Weiss et al. 2014) . Three partner nations (Austria, Canada and Poland) each contributed a pair of nanosatellites (mass 7 kg; 3-axis-stablized). The BRITE network is designed to collect optical photometry of millimagnitude precision (Popowicz et al. 2016, in prep; hereafter Paper III) in light curves of high cadence (20 -25 s between consecutive exposures) and long duration (up to 6 months) through red and blue filters. The features of the six BRITE nanosatellites are listed in Table 1; only five are currently operating in orbit. The Austrian satellites are UniBRITE (UBr) and BRITE-Austria (BAb), the Polish are BRITE-Lem (BLb) and BRITE-Heweliusz (BHr), and the Canadian are BRITE-Toronto (BTr) and BRITE-Montréal (BMb, which did not deploy correctly into orbit); where r and b refer to the satellites equipped with red and blue filters, respectively. This is Paper II in a series of publications that address the technical aspects of the BRITE mission. The first paper in the series, Weiss et al. (2014), shall hereafter be referred to as Paper I. This paper provides a comprehensive history of the development of BRITE, the overall design of each satellite, and an explanation of the objectives that have been the driving forces behind the mission. Paper III in the series will be a description of the BRITE data reduction pipeline. BRITE's prime directive is to observe bright stars (V ≤ 4 mag), and shed light on their internal and surface dynamics. Among the benefits that BRITE offers are:• A test bed for future astronomical surveys with small satellites. The combination of cutting-edge science with small low-cost instruments in space has come ≈ $600 million price tag (Borucki 2016), albeit with many more limitations, providing the opportunit...

The Colour and Stereo Surface Imaging System (CaSSIS) is the main imaging system onboard the European Space Agency’s ExoMars Trace Gas Orbiter (TGO) which was launched on 14 March 2016. CaSSIS is intended to acquire moderately high resolution (4.6 m/pixel) targeted images of Mars at a rate of 10–20 images per day from a roughly\ud circular orbit 400 km above the surface. Each image can be acquired in up to four colours and stereo capability is foreseen by the use of a novel rotation mechanism. A typical product from one image acquisition will be a 9.5 km×∼45 km swath in full colour and stereo in one over-flight of the target thereby reducing atmospheric influences inherent in stereo and colour products from previous high resolution imagers. This paper describes the instrument including several novel technical solutions required to achieve the scientific requirement

We report on an analysis of high-precision, multi-colour photometric observations of the rapidly-oscillating Ap (roAp) star α Cir. These observations were obtained with the BRITE-Constellation, which is a coordinated mission of five nanosatellites that collects continuous millimagnitude-precision photometry of dozens of bright stars for up to 180 days at a time in two colours (≈Johnson B and R). BRITE stands for BRight Target Explorer. The object α Cir is the brightest roAp star and an ideal target for such investigations, facilitating the determination of oscillation frequencies with high resolution. This star is bright enough for complementary interferometry and time-resolved spectroscopy. Four BRITE satellites observed α Cir for 146 d or 33 rotational cycles. Phasing the photometry according to the 4.4790 d rotational period reveals qualitatively different light variations in the two photometric bands. The phased red-band photometry is in good agreement with previously-published WIRE data, showing a light curve symmetric about phase 0.5 with a strong contribution from the first harmonic. The phased blue-lband data, in contrast, show an essentially sinusoidal variation. We model both light curves with Bayesian Photometric Imaging, which suggests the presence of two large-scale, photometrically bright (relative to the surrounding photosphere) spots. We also examine the high-frequency pulsation spectrum as encoded in the BRITE photometry. Our analysis establishes the stability of the main pulsation frequency over the last ≈20 yr, confirms the presence of frequency f 7 , which was not detected (or the mode not excited) prior to 2006, and excludes quadrupolar modes for the main pulsation frequency.

With the help of numerical simulation a new high-pressure hydraulic axial pump has been developed at Gdansk University. Its unique feature is the total independence of a pressure switching mechanism, which saves weight and provides the possibility to control the pump by computer. To avoid noise and possible damage of the pump through harmful pressure peaks an additional chamber equipped with an elastic wall was introduced. Numerical simulation of the fluid-structure interaction occurring at the elastic wall proved to be very insightful for the development of the new pump. Results of the coupled simulation-using Fluent, Abaqus and Fraunhofer SCAI's multiphysics software MpCCI-are presented in this paper