Mission building blocks for outer solar system exploration

Summary A meaningful outer-planet exploration program can be conducted within expected economic constraints. The spacecraft needed can be developed in an evolutionary manner from the existing Pioneer and Mariner families. Advanced propulsion capability may reduce the costs associated with constrained weight margins and long trip times.This is one of the publications by the Science Advisory Group.     

Infrared spectra and radiation stability of H2O2 ices relevant to Europa

In this paper we present spectra of H2O2-containing ices in the near- and mid-infrared (IR) regions. Spectral changes on warming are shown, as is a comparison of near-IR bands of H2O and H2O2-containing ices. An estimate of the A-value (absolute intensity) for the largest near- IR feature of H2O2 is given. Radiation-decay half-lives are reported for 19 K and 80 K, and are related to the surface radiation doses on Europa. The radiation data show that H2O2 destruction is slower at 80 K than 19 K, and are consistent with the claim that icy material in the outermost micrometer of Europa's surface has been heavily processed by radiation.     

Human space exploration - A global trans-cultural quest

This Viewpoint is a slightly edited version of the ‘Statement by Space Explorers on Human Space Exploration’ produced in the wake of a workshop organized by the European Space Policy Institute and held in Vienna in May 2010. While noting the cultural differences in understandings of ‘exploration’ around the world, it also affirms the phenomenon as a globe-wide, human urge, emphasizing that only the physical presence of a human being can assure the full emotional quality of exploration. It calls upon decision makers to regard human space exploration as a global trans-cultural quest that should be supported and furthered.     

The passenger aircraft cargo hold environment: the implications of a fire on lithium-ion battery shipments

Although very rare events, fires in aircraft cargo holds are a concern for regulators, aircraft operators, and passengers. Lithium-ion cells and batteries are often shipped as cargo aboard passenger aircraft. This paper provides an overview of cargo hold configurations and fire suppression systems in passenger aircraft. Next, ways in which a cargo hold fire might affect a shipment of lithium-ion cells or batteries, and the degree to which the cells or batteries might interact with a fire are discussed. Finally, the results of FAA simulated cargo hold fire testing are presented and discussed in the context of lithium-ion cell or battery shipments.     

Successful deployment of commercial ATE to an Air Force I-level (back-shop) repair facility

In today's world of constrained budgets, one of the problems the military faces is the challenge of trying to maintain organic maintenance capabilities. Historically, the US Air Force has desired to achieve an autonomous capability to maintain the equipment it uses. This has been achieved, traditionally, by setting-up three levels of maintenance: organizational; intermediate (back-shop); and depot. The I-level back-shops often utilize militarized automatic test equipment (ATE) and test program sets (TPSs) to test today's complex aircraft line replaceable units (LRUs). And even though this is still a cost-effective maintenance philosophy, it has become costly to develop militarized ATE. The Department of Defense (DoD) has been very active in trying to reduce the total ownership cost of ATE in the government inventory. One approach is to utilize commercial, instead of Mil-Spec, ATE. However, utilizing commercial ATE at an USAF back-shop is not without its tradeoffs and challenges as it represents a significant deviation from the way the USAF maintenance squadrons are accustomed to "doing business." This paper documents the current success story of replacing the legacy C-17 I-level ATE with a commercial ATE.     

The structure of the solar corona as observed by the Solar Extreme ultraviolet Rocket Telescope and Spectrograph

Data from the Solar Extreme-ultraviolet Rocket Telescope and Spectrograph (SERTS) have been used to address a number of important scientific problems. The primary strength of the SERTS data is the fact that this spectral range is rich with emission lines. Over 270 lines are seen in the SERTS active Sun spectrum, from 57 different ions. For example, multiple (≥4) lines are observed for all ionization states of iron from Fe IX to Fe XVII. Temperatures and densities have been derived for a number of active and quiet Sun regions, the coronal magnetic field strength has been estimated for both a plage region and an active region.     

Scanning Spaceborne Synthetic Aperture Radar with Integrated Radiometer

Spaceborne synthetic aperture radar systems are severely constrained to a narrow swath by ambiguity limitations. Here a vertically scanned-beam synthetic aperture system (SCANSAR) is proposed as a solution to this problem. The potential length of synthetic aperture must be shared between beam positions, so the along-track resolution is poorer; a direct tradeoff exists between resolution and swath width. The length of the real aperture is independently traded against the number of scanning positions. Design curves and equations are presented for spaceborne SCANSARs for altitudes between 400 and 1400 km and inner angles of incidence between 20° and 40°. When the real antenna is approximately square, it may also be used for a microwave radiometer. The combined radiometer and synthetic-aperture (RADISAR) should be useful for those applications where the poorer resolution of the radiometer is useful for some purposes, but the finer resolution of the radar is needed for others.     

A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms

Investigation of coupling mechanisms between the troposphere and the ionosphere requires a multidisciplinary approach involving several branches of atmospheric sciences, from meteorology, atmospheric chemistry, and fulminology to aeronomy, plasma physics, and space weather. In this work, we review low frequency electromagnetic wave observations in the Earth-ionosphere cavity from a troposphere-ionosphere coupling perspective. We discuss electromagnetic wave generation, propagation, and resonance phenomena, considering atmospheric, ionospheric and magnetospheric sources, from lightning and transient luminous events at low altitude to Alfvén waves and particle precipitation related to solar and magnetospheric processes. We review ionospheric processes as well as surface and space weather phenomena that drive the coupling between the troposphere and the ionosphere. Effects of aerosols, water vapor distribution, thermodynamic parameters, and cloud charge separation and electrification processes on atmospheric electricity and electromagnetic waves are reviewed. Regarding the role of the lower boundary of the cavity, we review transient surface phenomena, including seismic activity, earthquakes, volcanic processes and dust electrification. The role of surface perturbations and atmospheric gravity waves in ionospheric dynamics is also briefly addressed. We summarize analytical and numerical tools and techniques to model low frequency electromagnetic wave propagation and to solve inverse problems and outline in a final section a few challenging subjects that are important to advance our understanding of tropospheric-ionospheric coupling.     

Atmospheric tides below 80 km

Measurements and theory of diurnal and semidiurnal tidal oscillations between about 25 and 80 km are reviewed. At latitudes greater than about 30°, meridional (N-S) wind components are consistently in quadrature with and similar to the zonal (E-W) components. The tidal structures are interpreted as a superposition of quasi-steady higher-order modes excited in the troposphere by sources of limited extent (1,000–10,000 km). At latitudes less than about 30°, steady or quasi-steady diurnal and semidiurnal components are not necessarily the dominant components of the daily variation. At high latitudes diurnal phases generally show little change with height in comparison with observations at lower latitudes, in accord with the latitudinal properties of diurnal modes with positive and negative equivalent depths.     

Cool luminous stars

A broad theme emerging from $\text{IUE}$ and $\text{Einstein}$ observations of cool stars is that magnetic fields control the structure and energy balance of the outer atmospheres of these stars. I summarize the phenomena associated with magnetic fields in the Sun and show that similar phenomena occur in cool luminous stars. High dispersion spectra are providing unique information concerning densities, atmospheric extension, and emission line widths. A recent unanticipated discovery is that the transition lines are redshifted (an antiwind) in β Dra (G2 Ib) and perhaps other stars, which I interpret as indicating downflows in closed magnetic flux tubes as are seen in the solar flux tubes above sunspots. Finally, I classify the G and K giants and supergiants into three groups — active stars, quiet stars, and hybrid stars — depending on whether their atmospheres are dominated by closed magnetic flux tubes, open field geometries, or a predominately open geometry with a few closed flux tubes embedded.