C.E.B.A.S., a closed equilibrated biological aquatic system as a possible precursor for a long-term life support system?

C.E.B.A.S.-AQUARACK is a long-term multi-generation experimental device for aquatic organisms which is disposed for utilization in a space station. It results from the basic idea of a space aquarium for maintaining aquatic animals for longer periods integrated in a AQUARACK which consists of a modular animal holding tank, a semi-biological/physical water recycling system and an electronical control unit. The basic idea to replace a part of the water recycling system by a continuous culture of unicellular algae primarily leads to a second system for experiments with algae, a botanical AQUARACK consisting of an algal reactor, a water recyling and the electronical control unit. The combination of the zoological part, and the botanical part with a common control system in the AQUARACK, however, results in a "Closed Equilibrated Biological Aquatic System" (C.E.B.A.S.) representing an closed artificial ecosystem. Although this is disposed primarily as an experimental device for basic zoological, botanical and interdisciplinary research it opens the theoretical possibility to adapt it for combined production of animal and plant biomass on ground or in space. The paper explains the basic conception of the hardware construction of the zoological part of the system, the corresponding scientific frame program including the choice of the experimental animals and gives some selected examples of the hardware-related research. It further on discusses the practical and economical relevance of the system in the development of a controlled aquatical life support system in general.     

Mass Profiles of Galaxy Clusters from X-ray Analysis

We review the methods adopted to reconstruct the mass profiles in X-ray luminous galaxy clusters. We discuss the limitations and the biases affecting these measurements and how these mass profiles can be used as cosmological proxies.     

Overview of Differential VLBI Observations of Lunar Orbiters in SELENE (Kaguya) for Precise Orbit Determination and Lunar Gravity Field Study

The Japanese lunar explorer SELENE (Kaguya), which was launched on September 14th, 2007, was the target of VLBI observations over the period November 2007 to June 2009. These observations were made in order to improve the lunar gravity field model, in particular the lower degree coefficients and the model near the limb. Differential VLBI Radio sources, called VRAD instruments, were on-board the subsatellites, Rstar (Okina) and Vstar (Ouna), and the radio signals were observed by the Japanese VERA (VLBI Exploration of Radio Astrometry) network, and an international VLBI network. Multi-frequency and same-beam VLBI techniques were utilized and were essential aspects of the successful observing program. Multi-frequency VLBI was employed in order to improve the accuracy of the orbit determination obtained from the phase delay from the narrow-band satellite signals, while the same-beam VLBI method was used to resolve the cycle ambiguity which is inherent in the multi-frequency VLBI method. The observations were made at three S-band frequencies (2212, 2218 and 2287 MHz), and one X-band frequency (8456 MHz). We have succeeded in correlating the recorded signals from Okina/Ouna, and we obtained phase delays with an accuracy of several pico-seconds at S-band.     

Results of dosimetric measurements in space missions.

Detector packages consisting of plastic nuclear track detectors, nuclear emulsions, and theromoluminescence detectors were exposed at different locations inside the space laboratory Spacelab and at the astronauts' body and in different sections of the MIR space station. Total dose, particle fluence rate and linear energy transfer (LET) spectra of heavy ions, number of nuclear disintegrations and fast neutron fluence rates were determined of each exposure. The dose equivalent received by the Payload specialists (PSs) were calculated from the measurements, they range from 190 microSv d-1 to 770 microSv d-1. Finally, a preliminary investigation of results from a particle telescope of two silicon detectors, first used in the last BIORACK mission on STS 76, is reported.     

The GFZ real-time GNSS precise positioning service system and its adaption for COMPASS

Motivated by the IGS real-time Pilot Project, GFZ has been developing its own real-time precise positioning service for various applications. An operational system at GFZ is now broadcasting real-time orbits, clocks, global ionospheric model, uncalibrated phase delays and regional atmospheric corrections for standard PPP, PPP with ambiguity fixing, single-frequency PPP and regional augmented PPP. To avoid developing various algorithms for different applications, we proposed a uniform algorithm and implemented it into our real-time software. In the new processing scheme, we employed un-differenced raw observations with atmospheric delays as parameters, which are properly constrained by real-time derived global ionospheric model or regional atmospheric corrections and by the empirical characteristics of the atmospheric delay variation in time and space. The positioning performance in terms of convergence time and ambiguity fixing depends mainly on the quality of the received atmospheric information and the spatial and temporal constraints. The un-differenced raw observation model can not only integrate PPP and NRTK into a seamless positioning service, but also syncretize these two techniques into a unique model and algorithm. Furthermore, it is suitable for both dual-frequency and sing-frequency receivers. Based on the real-time data streams from IGS, EUREF and SAPOS reference networks, we can provide services of global precise point positioning (PPP) with 5–10 cm accuracy, PPP with ambiguity-fixing of 2–5 cm accuracy, PPP using single-frequency receiver with accuracy of better than 50 cm and PPP with regional augmentation for instantaneous ambiguity resolution of 1–3 cm accuracy. We adapted the system for current COMPASS to provide PPP service. COMPASS observations from a regional network of nine stations are used for precise orbit determination and clock estimation in simulated real-time mode, the orbit and clock products are applied for real-time precise point positioning. The simulated real-time PPP service confirms that real-time positioning services of accuracy at dm-level and even cm-level is achievable with COMPASS only.     

Space station MMOD shielding

This paper describes the International Space Station (ISS) micro-meteoroid orbital debris (MMOD) impact shielding including the requirements for protection as well as technical approaches to meeting the requirements. Current activities in providing MMOD protection for ISS are described, including efforts to augment MMOD protection by adding shields on-orbit. Another activity is to observe MMOD impact damage on ISS elements and returned hardware, and to compare the observed damage with predicted damage using Bumper code risk assessment software. A conclusion of this paper is that ISS will be protected adequately from MMOD impact after completing augmentation of ISS shielding for service module, and after improving MMOD protection for Soyuz and Progress vehicles. Another conclusion is that impact damage observed to the ISS mini-pressurized logistics module matches the distribution of impacts predicted by Bumper code.     

Towards a high spatial resolution limit for pixel-based interpretations of optical remote sensing data

The divergence of horizontal radiation in vegetation canopies is generally considered to be of negligible consequence in algorithms designed for the physically-based interpretation of space borne observations. However, non-zero horizontal radiation balances are likely to occur if the internal variability of a vegetation target and the typical distances that photons may travel horizontally within such three-dimensional (3-D) media extend to spatial scales that are similar to or larger than those of the nominal footprint of the measuring sensor. Detailed radiative transfer simulations in 3-D coniferous forest environments are presented to document the typical distances that photons may travel in such media, and to quantify the impact that the resulting net horizontal fluxes may have with respect to the local and domain-averaged canopy reflectance. Based on these simulations it is possible to identify a fine spatial resolution limit beyond which pixel-based interpretations of remote sensing data over tall forested areas should be avoided because the horizontal radiation transport at the surface may contribute to 10% or more of the measured reflectance signature of the target pixel.     

一种近壁理论湍流模型初探

在传统的k-ε湍流模型基础上,在近壁区放弃求解ε方程而代之以根据共振三波理论模型在近壁区系统计算的ε值构成封闭,通过对NACA0012二维翼形流场的计算,初步验证并适当修正了新的理论模型,由于注意到了理论模型计算结果的无量纲性,从而改善了该流场的计算结果,得到了与实验更为相符的C_p分布。本文的分析还表明,逆压力梯度对ε的影响非常显著,验证了理论分析和计算得到的结论。