An Impacting Descent Probe for Europa and the other Galilean Moons of Jupiter

We present a study of an impacting descent probe that increases the science return of spacecraft orbiting or passing an atmosphere-less planetary body of the solar system, such as the Galilean moons of Jupiter. The descent probe is a carry-on small spacecraft (< 100 kg), to be deployed by the mother spacecraft, that brings itself onto a collisional trajectory with the targeted planetary body in a simple manner. A possible science payload includes instruments for surface imaging, characterisation of the neutral exosphere, and magnetic field and plasma measurement near the target body down to very low-altitudes (~1 km), during the probe's fast (~km/s) descent to the surface until impact. The science goals and the concept of operation are discussed with particular reference to Europa, including options for flying through water plumes and after-impact retrieval of very-low altitude science data. All in all, it is demonstrated how the descent probe has the potential to provide a high science return to a mission at a low extra level of complexity, engineering effort, and risk. This study builds upon earlier studies for a Callisto Descent Probe (CDP) for the former Europa-Jupiter System Mission (EJSM) of ESA and NASA, and extends them with a detailed assessment of a descent probe designed to be an additional science payload for the NASA Europa Mission.Comment: 34 pages, 11 figure

Evaluating different water-land-boundary approximations to improve sar-derived digital elevation models

The coastline of the German Wadden Sea is constantly subjected to the tides and the tidal-induced environmental changes like erosion and accumulation of sediments need to be monitored constantly. This task requires digital elevation models (DEMs), which are derived from remote sensing data. To model those DEMs, a separation of data collected over landmasses and water bodies is required. In the GeoWAM project the potential of airborne SAR-data (F-SAR) is investigated for monitoring purposes in the Wadden Sea. As part of the project, this paper focuses on the suitability of F-SAR data regarding the derivation of water-land-boundaries (WLBs). Therefore, water-land-boundaries based on independent data sets are compared and evaluated. Analyzed data sets include data collected via F-SAR, airborne laserscanning (ALS), on site GNSS measured WLB points and sea-level data from two acoustic gauges. The algorithms were tested on a study site on Spiekeroog island. Our results show, that the accuracies of the derived WLBs mostly depend on the on-site topography and sediments. The spatial deviation between the reference data and the approximated WLBs is mostly less than 2 m horizontally and 0.15 m vertically. Identified challenges to overcome are mostly related to processing of F-SAR data in areas with highly water saturated sediments. Our results suggest, that F-SAR data in tidal flats is not necessarily dependent on further supplementing surveys, as one of the main advantages of the F-SAR data is the potential to derive DEMs and WLBs from the same data set

Vanadium (β-(Dimethylamino)ethyl)cyclopentadienyl Complexes with Diphenylacetylene Ligands

Reduction of the V(III) (β-(dimethylamino)ethyl)cyclopentadienyl dichloride complex [η5:η1-C5H4(CH2)2NMe2]VCl2(PMe3) with 1 equiv of Na/Hg yielded the V(II) dimer {[η5:η1-C5H4(CH2)2NMe2]V(µ-Cl)}2 (2). This compound reacted with diphenylacetylene in THF to give the V(II) alkyne adduct [η5:η1-C5H4(CH2)2NMe2]VCl(η2-PhC≡CPh). Further reduction of 2 with Mg in the presence of diphenylacetylene resulted in oxidative coupling of two diphenylacetylene groups to yield the diamagnetic, formally V(V), bent metallacyclopentatriene complex [η5:η1-C5H4(CH2)2NMe2]V(C4Ph4).

Emil und die Detektive: Early German sound cinema aesthetic

In 1931 Gerhard Lamprecht directed the film version of Erich Kaestner's popular novel Emil und die Detektive. A hugely successful fil

An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime

The Hayabusa2 spacecraft investigated the small asteroid Ryugu, which has a rubble-pile structure. We describe an impact experiment on Ryugu using Hayabusa2’s Small Carry-on Impactor. The impact produced an artificial crater with a diameter >10 meters, which has a semicircular shape, an elevated rim, and a central pit. Images of the impact and resulting ejecta were recorded by the Deployable CAMera 3 for >8 minutes, showing the growth of an ejecta curtain (the outer edge of the ejecta) and deposition of ejecta onto the surface. The ejecta curtain was asymmetric and heterogeneous and it never fully detached from the surface. The crater formed in the gravity-dominated regime; in other words, crater growth was limited by gravity not surface strength. We discuss implications for Ryugu’s surface age