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International audience; The increased focus on supersonic and hypersonic flows necessitates methods to study such flows in laboratory-based facilities, thus motivating researchers to find effective, efficient, and affordable methods to produce them in laboratories. It is desirable for the rocket nozzles to operate efficiently at different altitudes, which made the Altitude Compensating Nozzles emerge as a solution. In this work, we propose a new design for such nozzles, namely, the ringed nozzle. The proposed nozzle consists of a stack of parallel rings that serve as a nozzle with bleeding slots. This design can be utilised to obtain different exit Mach numbers and attain the desired performance according to the pressure ratio, serving as an Altitude Compensating Nozzle. The stack of rings might be altered to tailor nozzle shape and area ratio corresponding to the nozzle requirement. The nozzle is analysed from an engineering perspective by comparing the thrust coefficient and specific impulse, and the numerical simulations show promising results.

Exploration of outer space is a mesmerizing and thought-provoking endeavor. The fascination about what may be out there is only matched by asking who might be out there. Exopsychology is concerned about how humans think about extraterrestrials but also how extraterrestrials may think, feel, and behave. It strives to find generalizable psychological theories to enrich and extend the Search for Extraterrestrial Intelligence (SETI). Producing technosignatures requires that a species skillfully realizes the relevant possibilities for action, which the environment offers in all its socio-material richness. These possibilities are called affordances. They are not fixed but relational to individual and collective available abilities and customs. We apply an affordance perspective to specify the relation between information processing, body, environment, and material engagement in the context of space exploration and SETI. In this way, we can uncover aspects of the psychological configurations that SETI requires from its extraterrestrial targets, but which are also critical to the human practice of space exploration. Moreover, we elaborate on arguments against employing the concept of “intelligence” in SETI. A successful first contact requires a mutual attunement to species-typical diachronic backdrops, which constitute meaning. One possibility for a meaningful message form and content is the reference to the material environment and its respective engagement. Meaningfulness of affordances is conserved in a form of life and transmitted via social interaction. Considering affordances within SETI fosters an understanding of how the thinking, feeling, and behavior of life forms in the Universe emerge in relation to their socio-material environment.

The Helmholtz-Zentrum Potsdam GFZ German Research Centre for Geosciences is one of the Associate Analysis Centers of the International Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) Service (IDS). In the framework of a recent reprocessing campaign for the International Terrestrial Reference Frame (ITRF) the suite of DORIS-derived satellite products was extended and improved with respect to reference frame determination. Among others the Copernicus Sentinel-3A/3B and 6A Michael Freilich (MF) satellites were used for this purpose. The orbits were generated based on DORIS-only and on the combination of DORIS and Satellite Laser Ranging (SLR) observations, and attempts were made to optimize their accuracy. Also for these satellites, GFZ generates Global Positioning System (GPS) based orbits within the Copernicus Precise Orbit Determination (CPOD) quality working group (CPOD-QWG). The GPS orbits contribute to a combined CPOD orbit solution, which is assumed to have superior absolute accuracy and minimal residual systematic errors. The DORIS-only, the combined DORIS and SLR, and the GPS-only orbits are compared to the CPOD combined solution serving as reference solution. The accuracy of the orbits shows up in radial direction for all techniques and combinations with values of 0.60 to 0.82 cm. In transverse and normal direction the RMS values achieved with GPS are up to around 50% lower as with DORIS, which sizes at around 1.5-2 cm. Subsequently the reference points of the observation techniques were estimated. With a multi-technique approach, a center-of-mass deviation according to Montenbruck et al. (2017) could be reproduced for Sentinel-3A. In addition, for both Sentinel-3 satellites the DORIS reference point values show a deviation in normal direction of 8-9 mm and a drift in radial direction of about 3mm/year with respect to manufacturer’s data, reference point values for Sentinel-6A (MF) show a good agreement. With the confidence gained on the DORIS-only orbit solutions, weekly local reference frames are computed for each of the three satellites as well as a combined solution and evaluated in terms of the reference frame defining parameters, i.e. origin, scale, and orientation. The accuracy achieved here is in the range of a few mm to cm region. The scale remains stable, except for Sentinel-3A, which shows a scale drift of about -1.5 , whose cause is not clear yet. Standard deviations of station coordinate residuals (North, East, Up) are in the range of 2-4 mm, 5-9 mm and 5-7 mm respectively.