Technology for large space systems: A special bibliography with indexes (supplement 05)

This bibliography lists 298 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1981 and June 30, 1981. Its purpose is to provide helpful, information to the researcher, manager, and designer in technology development and mission design in the area of the Large Space Systems Technology (LSST) Program. Subject matter is grouped according to systems, interactive analysis and design, structural concepts, control systems, electronics, advanced materials, assembly concepts, propulsion, solar power satellite systems, and flight experiments

Large Space Antenna Systems Technology, part 1

A compilation of the unclassified papers presented at the NASA Conference on Large Space Antenna Systems Technology covers the following areas: systems, structures technology, control technology, electromagnetics, and space flight test and evaluation

Technology for large space systems: A special bibliography with indexes (supplement 06)

This bibliography lists 220 reports, articles and other documents introduced into the NASA scientific and technical information system between July 1, 1981 and December 31, 1981. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design in the area of the Large Space Systems Technology (LSST) Program. Subject matter is grouped according to systems, interactive analysis and design, structural concepts, control systems, electronics, advanced materials, assembly concepts, propulsion, solar power satellite systems, and flight experiments

The 1982 NASA/ASEE Summer Faculty Fellowship Program

A NASA/ASEE Summer Faculty Fellowship Research Program was conducted to further the professional knowledge of qualified engineering and science faculty members, to stimulate an exchange of ideas between participants and NASA, to enrich and refresh the research and teaching activities of participants' institutions, and to contribute to the research objectives of the NASA Centers

Cellular Senescence in Health, Disease and Aging: Blessing or Curse?

Dear Colleagues, When Hayflick and Moorhead coined the term “cellular senescence” (CS) almost 60 years ago, this phenomenon was understood as a mechanism, usually induced by activation of the DNA-repair machinery, to prevent uncontrolled proliferation. Meanwhile, additional beneficial roles for CS have been identified, such as embryonic development and wound healing. The senescence associated secretory phenotype (SASP) activated in most senescent cells (SC) signals to the immune system “come here and remove me”. In organisms with young and functional immune systems, occurring SC are usually detected and removed. If SC remain in the tissue expressing the SASP, this will cause not just a damaging local inflammation but can also induce remodeling and regeneration of the surrounding tissue as well as spreading of senescence. Old organisms show reduced regenerative potential and immune function which leads to accumulation of SC. Accordingly, accumulation of SC was observed in tissues of aged individuals, but importantly also in the context of age-related disorders, neurodegenerative, or cardiovascular diseases and others. Because of its detrimental effect of the surrounding tissue, accumulation of SC is not just a consequence, but can rather been understood as a major driver of aging. In line with this, recent studies described that removal of SC showed beneficial effects on healthspan and lifespan. This exciting research led to the discovery of “senolytics”, drugs which can kill SC. Given the heterogeneity of cell types that show senescence-like phenotypes, including heart muscle and post-mitotic neuronal cells, further research is required to unravel the molecular background that renders a cell type vulnerable to senesce. Additionally, it will be important to understand how senescence is cell type-specifically induced and which molecules serve as drug targets to prevent senescence and its spreading, or actively kill SC. This special issue will shed light on the molecular pathways of CS and inflammaging and on possible strategies to interfere with these processes. Dr. Markus Riessland Guest Edito

Data collection system: Earth Resources Technology Satellite-1

Subjects covered at the meeting concerned results on the overall data collection system including sensors, interface hardware, power supplies, environmental enclosures, data transmission, processing and distribution, maintenance and integration in resources management systems

Passive Switched Capacitor RF Front Ends for Spectrum Sensing in Cognitive Radios

This paper explores passive switched capacitor based RF receiver front ends for spectrum sensing. Wideband spectrum sensors remain the most challenging block in the software defined radio hardware design. The use of passive switched capacitors provides a very low power signal conditioning front end that enables parallel digitization and software control and cognitive capabilities in the digital domain. In this paper, existing architectures are reviewed followed by a discussion of high speed passive switched capacitor designs. A passive analog FFT front end design is presented as an example analog conditioning circuit. Design methodology, modeling, and optimization techniques are outlined. Measurements are presented demonstrating a 5 GHz broadband front end that consumes only 4 mW power

Research reports: The 1980 NASA/ASEE Summer Faculty Fellowship Program

The Summer Faculty Fellowship Research Program objectives are: to further the professional knowledge of qualified engineering and science faculty members; to stimulate an exchange of ideas between participants and NASA; to enrich and refresh the research and teaching activities of participants and institutions; and to contribute to the research objectives at the NASA centers. The Faculty Fellows engaged in research projects commensurate with their interests and background and worked in collaboration with a NASA/MSFC colleague

A power-scalable variable-length analogue DFT processor for multi-standard wireless transceivers

In the Orthogonal Frequency-Division Multiplexing (OFDM) based transceivers, digital computation of the Discrete Fourier Transform (DFT) is a power hungry process. Reduction in the hardware cost and power consumption is possible by implementing the DFT processor with analogue circuits. This thesis presents the real-time recursive DFT processor. Previously, changing the transform length and scaling the power could only be performed by digital Fast Fourier Transform (FFT) processors. By using the real-time recursive DFT processor, the decimation filter is eliminated. Thus, further reduction in the hardware cost and power consumption of the multi-standard transceiver is achieved. The real-time recursive DFT processor was designed in 180 nm CMOS technology. Results of device mismatch analysis indicate that the 8-point recursive DFT processor has a yield of 97.5% for the BPSK modulated signal. For the QPSK modulated signal, however, yield of the 8-point recursive DFT processor is 8.9%. Moreover, doubling the transform length reduces the average dynamic range by 3dB. Accordingly, the 16-point recursive DFT processor has a yield of 43.4% for the BPSK modulated signal. Power consumption of the recursive DFT processor is about 1/6 of the power consumption of a previous analogue FFT processor

Satellite Services Workshop, Volume 1

Key issues associated with the orbital servicing of satellites are examined including servicing spacecraft and equipment, servicing operations, economics, satellite design, docking and berthing, and fluid management