Development status and application of the electric propulsion system RIT-10 used for station-keeping

The German 10 mN high frequency ion thruster system RIT-10 designed at Giessen University, constructed at MBB, and tested essentially at DFVLR, has attained an engineering model status and stands shortly before qualification for space flight. First application is planned for RIT-10 as a north-south stationkeeping system in TV-Sat preoperational version where it is flown as an experiment in order to acquire experience for subsequent operational communication satellite missions. The paper first describes the existing hardware, then shortly discusses application aspects, the respective test program, and preflight and flight procedures considered to guarantee safe and efficient operation in space.     

Why does the perpendicular electric field increase at the edge of auroral arcs?

Radar, rocket and satellite measurements often indicate that there is a strong increase and subsequent decrease in the perpendicular electric field when traversing one edge of an auroral arc. The analysis of rocket measurements, presented here, shows that above an auroral arc there is a small gradient in the electric field due to polarization effects in the ionosphere, but that the strong increase at the edge of the arc can only be explained if the field-aligned currents associated with the arc are taken into account.     

Numerical investigations on the VFE-2 65-degree rounded leading edge delta wing using the unstructured DLR TAU-Code

The numerical simulation of the flow around a 65° delta wing configuration with rounded leading edges is presented. For the numerical simulation the DLR TAU-Code is used which is based on an unstructured hybrid mesh approach. Within this paper several numerical results are shown, solving the steady RANS equations by different turbulence models. The simulations are carried out within the RTO/AVT-113 task group focusing on experimental and numerical research on delta wing configurations with rounded leading edges. Within this paper the focus is related to the flow topology depending on the angle of attack as well as on Reynolds number effects. Finally the results are compared and verified by experimental data.     

Atmospheric Science with InSight

In November 2018, for the first time a dedicated geophysical station, the InSight lander, will be deployed on the surface of Mars. Along with the two main geophysical packages, the Seismic Experiment for Interior Structure (SEIS) and the Heat-Flow and Physical Properties Package (HP³), the InSight lander holds a highly sensitive pressure sensor (PS) and the Temperature and Winds for InSight (TWINS) instrument, both of which (along with the InSight FluxGate (IFG) Magnetometer) form the Auxiliary Sensor Payload Suite (APSS). Associated with the RADiometer (RAD) instrument which will measure the surface brightness temperature, and the Instrument Deployment Camera (IDC) which will be used to quantify atmospheric opacity, this will make InSight capable to act as a meteorological station at the surface of Mars. While probing the internal structure of Mars is the primary scientific goal of the mission, atmospheric science remains a key science objective for InSight. InSight has the potential to provide a more continuous and higher-frequency record of pressure, air temperature and winds at the surface of Mars than previous in situ missions. In the paper, key results from multiscale meteorological modeling, from Global Climate Models to Large-Eddy Simulations, are described as a reference for future studies based on the InSight measurements during operations. We summarize the capabilities of InSight for atmospheric observations, from profiling during Entry, Descent and Landing to surface measurements (pressure, temperature, winds, angular momentum), and the plans for how InSight’s sensors will be used during operations, as well as possible synergies with orbital observations. In a dedicated section, we describe the seismic impact of atmospheric phenomena (from the point of view of both “noise” to be decorrelated from the seismic signal and “signal” to provide information on atmospheric processes). We discuss in this framework Planetary Boundary Layer turbulence, with a focus on convective vortices and dust devils, gravity waves (with idealized modeling), and large-scale circulations. Our paper also presents possible new, exploratory, studies with the InSight instrumentation: surface layer scaling and exploration of the Monin-Obukhov model, aeolian surface changes and saltation / lifing studies, and monitoring of secular pressure changes. The InSight mission will be instrumental in broadening the knowledge of the Martian atmosphere, with a unique set of measurements from the surface of Mars.     

KEY MEASUREMENTS IN THE FUTURE – Working Group Report

The experimental basis of cosmic-ray astrophysics consists of detailed measurements of the cosmic-ray intensity arriving near earth, of observations of photons in all wavelength bands generated by cosmic ray interactions in the interstellar medium or in the cosmic-ray sources, and of laboratory studies of high energy particle interactions. In addition, a large body of astronomical information on the composition of stellar atmospheres and of the interstellar medium, including interstellar dust grains, is required to bring cosmic-ray data into context with subjects such as nucleosynthesis and evolution of the galaxy. This report will summarize some of these observational questions, will discuss specific experimental needs in current research, and will review some of the key measurements that can be expected for the near future. This review will neither be complete nor attempt to establish observational priorities. However, it will illustrate the variety of observational activities that are required to achieve progress.     

Quantification of spatial structure of human proximal tibial bone biopsies using 3D measures of complexity

Changes in trabecular bone composition during development of osteoporosis are used as a model for bone loss in microgravity conditions during a space flight. Symbolic dynamics and measures of complexity are proposed and applied to assess quantitatively the structural composition of bone tissue from 3D data sets of human tibia bone biopsies acquired by a micro-CT scanner. In order to justify the newly proposed approach, the measures of complexity of the bone architecture were compared with the results of traditional 2D bone histomorphometry. The proposed technique is able to quantify the structural loss of the bone tissue and may help to diagnose and to monitor changes in bone structure of patients on Earth as well as of the space-flying personnel.     

High energy cosmic ray nuclei results on Ulysses: 1. Mission overview

The cosmic ray flux observed with the Kiel Electron Telescope on board the ULYSSES spaceprobe varies with solar activity as well as with heliospheric position. Determination of the latitudinal gradients requires a careful analysis of the influences of the current sheet tilt angle, the number of major solar flares, interplanetary shocks and interaction regions evolving in the expanding solar wind. In this paper we concentrate on nuclei with rigidity above 1 GV. We discuss the effects of the variable solar activity in the declining phase of the present solar cycle and the variation with radial distance as a basis for separating latitudinal effects. We show that during this phase of the solar cycle modulation of GV nuclei is ordered by temporal evolution, radial distance and negligible latitudinal effects even at latitudes between 30° and 50° South.