Development status of the high-speed reentry system-DASH

Despite huge amount of data collected by the previous interplanetary spacecraft and probes, the origin and evolution of the solar system still remains unveiled due to limited information they brought back. Thus, the Institute of Space and Astronautical Science (ISAS) of Japan has been given a commitment to pave the way to an asteroid sample return mission: the MUSES-C project. A key to success is considered the reentry with hyperbolic velocity, which has not ever been demonstrated as yet. With this as background, a demonstrator of atmospheric reentry system, DASH, has been designed to demonstrate the high-speed reentry technology as a GTO piggyback mission. The capsule, identical to that of the sample return mission, can experience the targeted level of thermal environment even from the GTO by tracing a specially designed reentry trajectory. After the purpose of the mission was outlined at the last IAF symposium, the final fitting tests have been conducted in the ISAS Sagamihara Campus involving the flight model hardware. Furthermore, a series of rehearsals for recovery have been already executed. The paper describes the current mission status of the project.     

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.     

Thermal properties of molten InSb,GaSb, and InxGa1−xSb alloy semiconductor materials in preparation for crystal growth experiments on the international space station

The thermal properties of InSb, GaSb and In_xGa_1−xSb, such as the viscosity, wetting property, and evaporation rate, were investigated in preparation for the crystal growth experiment on the International Space Station (ISS). The viscosity of InGaSb, which is an essential property for numerical modeling of crystal growth, was evaluated. In addition, the wetting properties between molten In_xGa_1−xSb and quartz, BN, graphite, and C-103 materials were investigated. The evaporation rate of molten In_xGa_1−xSb was measured to determine the affinity of different sample configurations. From the measurements, it was found that the viscosity of In_xGa_1−xSb was between that of InSb and GaSb. The degree of wetting reaction between molten In_xGa_1−xSb and the C-103 substrate was very high, whereas that between molten In_xGa_1−xSb and quartz, BN, and graphite substrates was very low. The results suggest that BN and graphite can be used as materials to cover InSb and GaSb samples inside a quartz ampoule during the microgravity experiments. In addition, the difference of the evaporation rate of molten In_xGa_1−xSb, GaSb, and InSb was small at low, and large at high temperature.     

Effects of neurectomy and tenotomy on the bone mineral density and strength of tibiae.

The right hindlimbs of 5 or 6-week old Wistar male rats were sciatic/femoral neurectomized, tenotomized or sham operated. The rats were sacrificed 2 weeks after the surgery and the tibiae were removed. pQCT measurement was performed on total, cortical, and trabecular bone separately at different regions. Reduction of the bone mineral density by unloading was observed more significantly at metaphysis than at diaphysis due to histological heterogeneity between metaphysis and diaphysis; metaphysis is rich in trabecular bone and diaphysis is abundant in cortical bone. Trabecular bone might be more sensitive to unloading because the reduction rate of volumetric bone mineral density in trabecular bone was approximately 10 times and 3 times larger than that of cortical bone in both neurectomy and tenotomy rats, respectively, Unloading also reduced the cross-sectional area and stress strain index at metaphysis.     

Retinal photoreceptor and related gene expression in normal and clinostat-treated fish embryos

Medaka fish had performed mating behavior successfully in space for the first time among vertebrate, and the eggs which were laid in space developed normally, and hatched during the space travel of 15 days aboard the space shuttle in the second International Microgravity Laboratory (IML-2) mission in 1994 (Ijiri 1994). But there has been few studies whether microgravity affects the development of rather complex tissues in this fish. Investigating this problem, we focused on the organogenetic events in the retina in developing Medaka under normal and simulated microgravity conditions (by a three-dimensional clinostat, 3D-clinostat). Our results showed that both normal and 3D-clinostat-treated Medaka embryos developed on almost equal time course. Moreover, we investigated the development of the retina in normal and 3D-clinostat-treated embryos, but there were no differences in organogenesis of their retina. Lamination of retina occurred almost at equal timing and the expressions of opsin genes in the 3D-clinostat-treated group also began almost at the same time as control. Our observations suggest that there were no definite effects of simulated microgravity on the organizations of a complex tissue such as retina in developing fish embryos.     

Estimation of orbital parameters of broken-up objects from in-situ debris measurements

Even sub-millimeter-size debris could cause a fatal damage on a spacecraft. Such tiny debris cannot be followed up or tracked from the ground. Therefore, Kyushu University has initiated IDEA the project for In-situ Debris Environmental Awareness, which conducts in-situ measurements of sub-millimeter-size debris. One of the objectives is to estimate the location of on-orbit satellite fragmentations from in-situ measurements. The previous studies revealed that it is important to find out the right nodal precession rate to estimate the orbital parameters of a broken-up object properly. Therefore, this study derives a constraint equation that applies to the nodal precession rate of the broken-up object. This study also establishes an effective procedure to estimate properly the orbital parameters of a broken-up object with the constraint equation.     

利用导流装置降低大后壁车辆气动阻力的实验研究(Ⅰ)

利用1/16缩比的公共汽车模型及两种类型的导流装置，在一带有可移动地面和边界层吸收装置的Eiffel型风洞中进行了在车辆后端面的上下边和侧边分别安装导流装置时车辆后部尾流区的压强恢复及气动阻力降低的实验。应用边界层分离理论比较详细地分析了安装导流装置的车辆后部尾流区的流动机理，综合分析评价了车辆表面与导流装置间的缝隙在空气引流及车辆气动阻力的降低中的作用，为新型车辆的设计和改造提供有利依据。