Flexible Solar Cell Arrays for Increased Space Power

The importance of solar cells for space power supplies continues with increased emphasis. The need for advances in the design of solar cell arrays becomes more pressing as the requirement for increased power levels is apparent. This paper discusses a flexible solar cell concept, includes a brief history of the development, describes a conceptual design for a 20-kW array, giving weight breakdown, and describes an existing design effort.     

Venus surface power and cooling systems

A mission to the surface of Venus would have high scientific value, but most electronic devices and sensors cannot operate at the 450 °C ambient surface temperature of Venus. Power and cooling systems were analyzed for Venus surface operation. A radioisotope power and cooling system was designed to provide electrical power for a probe operating on the surface of Venus. For a mission duration of substantial length, the use of thermal mass to maintain an operable temperature range is likely impractical, and active refrigeration may be required to keep components at a temperature below ambient. Due to the high thermal convection of the high-density atmosphere, the heat rejection temperature was assumed to be at a 500 °C radiator temperature, 50 °C above ambient. The radioisotope Stirling power converter designed produces a thermodynamic power output capacity of 478.1 W, with a cooling power of 100 W. The overall efficiency is calculated to be 23.36%. The mass of the power converter is estimated at approximately 21.6 kg.     

C3: The Challenge of Change

The power, range, and speed of weapons have increased exponentially during the last 50 or so years. The more powerful the weapon, the more serious becomes its use. The faster the weapon, the shorter the reaction time required of the user. The greater the range of the weapon, the larger the problem of knowing target location. The more quickly these parameters change, the greater the user's learning problem and the less the opportunity to learn through experience. The cultural shock widely recognized in society in general is even more serious to today's military commander, because the consequences of his acts can be global in nature. Technology offers some help in making the use of modern weapons more efficient and in reducing the probability of unwanted effects. But the problem of matching the rapidly changing new technology to the rapidly changing requirements of military command, control, and communications (C3), selecting improvements that will help, and rejecting those just nice to have-all this, in the absence of pertinent experience, is the challenge of change.     

Electronic Logbook for Space System Integration & Test Operations

In the highly technological aerospace world, paper is still widely used to document space system integration and test (I&T) operations. E-Logbook (electronic logbook) is a new technology designed to replace current documentation processes of space system I&T operations, such as connector mate and demate, flight hardware and flight software component installation, material mixes or electronic ground support equipment (EGSE) validation. It also includes new documentation concepts, such as the shift log, which improves project awareness and optimizes the shift hand-over process, and the configuration log, which instantly reports on the global I&T state of the space system and greatly enhances information gathering prior to major test events or project reviews. The design of E-Logbook focuses not only on a reliable and efficient relational database, but also on an ergonomic human-computer interactive (HCI) system of graphical user interfaces (GUI) that can help reduce human error and improve I&T discipline and management oversight. E-Logbook has been used for the I&T of the large area telescope (LAT) of the gamma-ray large area space telescope (GLAST) scientific satellite at the Stanford Linear Accelerator Center (SLAC). After 19 months of operation, more than 41,000 records have been created for the different documentation components or I&T Logs, with no data having been corrupted or critically lost. 94% of the operators and 100% of the management exposed to E-Logbook prefer it to paper logbooks and recommend its use in the aerospace industry.     

The NASA Astrobiology Roadmap

The NASA Astrobiology Roadmap provides guidance for research and technology development across the NASA enterprises that encompass the space, Earth, and biological sciences. The ongoing development of astrobiology roadmaps embodies the contributions of diverse scientists and technologists from government, universities, and private institutions. The Roadmap addresses three basic questions: How does life begin and evolve, does life exist elsewhere in the universe, and what is the future of life on Earth and beyond? Seven Science Goals outline the following key domains of investigation: understanding the nature and distribution of habitable environments in the universe, exploring for habitable environments and life in our own solar system, understanding the emergence of life, determining how early life on Earth interacted and evolved with its changing environment, understanding the evolutionary mechanisms and environmental limits of life, determining the principles that will shape life in the future, and recognizing signatures of life on other worlds and on early Earth. For each of these goals, Science Objectives outline more specific high-priority efforts for the next 3-5 years. These 18 objectives are being integrated with NASA strategic planning.     

The changing face of international space cooperation : One view of NASA

This article looks at how, over the past 20 years, NASA's role in space activities has changed. It looks at trends in NASA's posture towards cooperation with other nations and speculates on current and future behaviour. The Space Station programme in particular is discussed and the way in which NASA reconciles self-interest with cooperation.     

Microbial survival: the paleome: a sedimentary genetic record of past microbial communities

Molecular genetic methods were used to analyze the remnants of microbial ecosystems contained within an ancient oceanic microbial habitat that was recovered from a continental drilled core of black shale approximately 100 million years in age. Bacterial ribosomal RNA genes were vertically amplified from the six different depths of a black shale core associated with a phosphate-rich stratum, defined as one of the mid-Cretaceous oceanic anoxic events (OAEs). Although the black shale core was recovered from a terrestrial coring effort, the recovered 16S rRNA gene sequences showed affinity to microbial communities previously seen in deep-sea sedimentary environments (i.e., the microbial assemblage was easily recognizable as a marine community). In particular, a number of 16S rRNA gene clones of oceanic sulfate-reducing bacteria within the delta-Proteobacteria predominated at the OAE layer. The recovered bacterial DNA signatures are consistent with the interpretation that the sequences are derived from the past microbial communities buried in either sea-bottom or subseafloor environments during the sedimentation process and, after ceasing growth, preserved until the present.     

Deep Impact: The Anticipated Flight Data

A comprehensive observational sequence using the Deep Impact (DI) spacecraft instruments (consisting of cameras with two different focal lengths and an infrared spectrometer) will yield data that will permit characterization of the nucleus and coma of comet Tempel 1, both before and after impact by the DI Impactor. Within the constraints of the mission system, the planned data return has been optimized. A subset of the most valuable data is planned for return in near-real time to ensure that the DI mission success criteria will be met even if the spacecraft should not survive the comet’s closest approach. The remaining prime science data will be played back during the first day after the closest approach. The flight data set will include approach observations spanning the 60 days prior to encounter, pre-impact data to characterize the comet at high resolution just prior to impact, photos from the Impactor as it plunges toward the nucleus surface (including resolutions exceeding 1 m), sub-second time sampling of the impact event itself from the Flyby spacecraft, monitoring of the crater formation process and ejecta outflow for over 10 min after impact, observations of the interior of the fully formed crater at spatial resolutions down to a few meters, and high-phase lookback observations of the nucleus and coma for 60 h after closest approach. An inflight calibration data set to accurately characterize the instruments’ performance is also planned. A ground data processing pipeline is under development at Cornell University that will efficiently convert the raw flight data files into calibrated images and spectral maps as well as produce validated archival data sets for delivery to NASA’s Planetary Data System within 6 months after the Earth receipt for use by researchers world-wide.