ISCCP cloud analysis algorithm intercomparison

The International Satellite Cloud Climatology Project (ISCCP) will provide a uniform global climatology of satellite-measured radiances and derive a climatology of cloud radiative properties from these radiances. For this purpose, a pilot study of cloud analysis algorithms was initiated to define a state-of-the-art algorithm for ISCCP. This study compared the results of applying the nine different algorithms to the same satellite radiance data. The comparison allowed for a sharper understanding of the process of detecting clouds and shows that all algorithms can be improved by better information about clear sky radiance values (essentially equivalent to surface property information) and by better understanding of cloud size distribution variations. The dependence of all methods on cloud size distribution led to selection of an advanced bispectral threshold technique for ISCCP because this method is currently better understood and more developed. Further research on cloud algorithms is clearly suggested by these results.     

Model QA3000 Q-Flex accelerometer high performance test results

Q-Flex quartz flexure suspension technology has evolved to produce a world class accelerometer with thousands of units delivered in 1991. The Sundstrand Model QA3000 Q-Flex design achieves a new level of inertial grade performance while maintaining a competitive market price. The specification for the QA3000, supported by actual performance data, depicts performance characteristics superior in both bias and scale factor. Long term measurements display bias and scale factor repeatability obtained across temperature over a period of three years. These data exhibit improved thermal behavior with reduced errors. Reaction time and radiation data highlight the performance of the hybrid position detector circuit     

Status of the emerging technology of Stirling machines

The commercialization status of Stirling machines varies from established niche market products to potential products that are in early stages of development. In other words, we are talking about a typical emerging technology. Many organizations are actively pursuing product development based on Stirling machine technology. Stirling machines offer significant performance advantages, but many obstacles remain to be fully resolved, including cost and demonstrated reliability. This article describes the technology upon which Stirling machines are based. Several application areas are then explored, including hot air engines, remote power, solar thermal power, sensor cooling, refrigeration, cogeneration and air-independent propulsion     

HUMEX, a study on the survivability and adaptation of humans to long-duration exploratory missions, part I: lunar missions.

The European Space Agency has recently initiated a study of the human responses, limits and needs with regard to the stress environments of interplanetary and planetary missions. Emphasis has been laid on human health and performance care as well as advanced life support developments including bioregenerative life support systems and environmental monitoring. The overall study goals were as follows: (i) to define reference scenarios for a European participation in human exploration and to estimate their influence on the life sciences and life support requirements; (ii) for selected mission scenarios, to critically assess the limiting factors for human health, wellbeing, and performance and to recommend relevant countermeasures; (iii) for selected mission scenarios, to critically assess the potential of advanced life support developments and to propose a European strategy including terrestrial applications; (iv) to critically assess the feasibility of existing facilities and technologies on ground and in space as testbeds in preparation for human exploratory missions and to develop a test plan for ground and space campaigns; (v) to develop a roadmap for a future European strategy towards human exploratory missions, including preparatory activities and terrestrial applications and benefits. This paper covers the part of the HUMEX study dealing with lunar missions. A lunar base at the south pole where long-time sunlight and potential water ice deposits could be assumed was selected as the Moon reference scenario. The impact on human health, performance and well being has been investigated from the view point of the effects of microgravity (during space travel), reduced gravity (on the Moon) and abrupt gravity changes (during launch and landing), of the effects of cosmic radiation including solar particle events, of psychological issues as well as general health care. Countermeasures as well as necessary research using ground-based test beds and/or the International Space Station have been defined. Likewise advanced life support systems with a high degree of autonomy and regenerative capacity and synergy effects were considered where bioregenerative life support systems and biodiagnostic systems become essential. Finally, a European strategy leading to a potential European participation in future human exploratory missions has been recommended.     

The effects of simulated microgravity on cultured chicken embryonic chondrocytes.

Using the cultured chicken embryonic chondrocytes as a model, the effects of simulated microgravity on the microtubular system of the cellular skeleton, extracellular matrix, alkaline phosphatase activity, intracellular free calcium concentration and mitochondrial ATP synthase activity with its oligomycin inhibition rate were studied with a clinostat. The microtubular content was measured by a flow cytometer. The decrease of microtubular content showed the impairment of the cellular skeleton system. Observation on the extracellular matrix by the scanning electron microscopy showed that it decreased significantly after rotating, and the fibers in the extracellular matrix were more tiny and disorderly than that of the control group. It can be concluded that the simulated microgravity can affect the secreting and assembly of the extracellular matrix. In contrast to the control, there was a time course decrease in alkaline phosphatase activity of chondrocytes, a marker of matrix mineralization. Meanwhile a significant drop in the intracellular calcium concentration happened at the beginning of rotation. These results indicate that simulated microgravity can suppress matrix calcification of cultured chondrocytes, and intracellular free calcium may be involved in the regulation of matrix calcification as the second signal transmitter. No significant changes happened in the mitochondrial ATP synthase activity and its oligomycin inhibition rate. Perhaps the energy metabolism wasn't affected by the simulated microgravity. The possible mechanisms about them were discussed.     

Overview of the space environmental effects observed on the retrieved Long Duration Exposure Facility (LDEF).

The Long Duration Exposure Facility (LDEF), which encompassed 57 experiments with more than 10,000 test specimens, spent 69 months in low Earth orbit (LEO) before it was retrieved by the Space Shuttle in January 1990. Hundreds of LDEF investigators, after studying for over two years these retrieved test specimens and the onboard recorded data and systems hardware, have generated a unique first-hand view of the long term synergistic effects that the LEO environment can have on spacecraft. These studies have also contributed significantly toward more accurate models of the LEO radiation, meteoroid, manmade debris and atomic oxygen environments. This paper provides an overview of some of the many LDEF observations and the implications these can have on future spacecraft such as Space Station Freedom.     

Demonstration of a zinc bromine battery in an electric vehicle

The zinc bromine battery is a high energy density battery that utilizes low cost materials. The battery is of unique construction utilizing plastic storage tanks for the zinc bromide electrolyte and plastic bipolar electrode stacks. This paper briefly describes the zinc bromine battery technology and the experience gained in installing and operating an electric vehicle with this advanced system. The described electric vehicle (The “T-Star”) was tested in March 1993 on the Chrysler Proving Grounds in Phoenix, Arizona and it participated in the May 1993 American Tour de Sol capturing second place over all and first place in the student division