On the Differences in Composition between Solar Energetic Particles and Solar Wind

Although the average composition of solar energetic particles (SEPs) and the bulk solar wind are similar in a number of ways, there are key differences which imply that solar wind is not the principal seed population for SEPs accelerated by coronal mass ejection (CME) driven shocks. This paper reviews these composition differences and considers the composition of other possible seed populations, including coronal material, impulsive flare material, and interplanetary CME material.     

Lunar international science coordination/calibration targets (L-ISCT)

Eight lunar areas, each ∼200 km in diameter, are identified as targets for coordinated science and instrument calibration for the orbital missions soon to be flown. Instrument teams from SELENE, Chang’E, Chandrayaan-1, and LRO are encouraged to participate in a coordinated activity of early-release data that will improve calibration and validation of data across independent and diverse instruments. The targets are representative of important lunar terrains and geologic processes and thus will also provide a broad introduction to lunar science for new investigators. We briefly identify additional cross-calibration issues for instruments that produce time series data rather than maps.     

The African Leadership Conference on Space Science and Technology for Sustainable Development

The African Leadership Conference on Space Science and Technology (known as “the ALC”) is a regional conference to promote intra-African cooperation in the uses of space science and technology to support Africa’s development. The first such conference was held in 2005 in Abuja, Nigeria, followed by South Africa (2007), Algeria (2009) and Kenya (2011). The ALC has come to be regarded as a representative African forum in the global space community. This paper provides an overview of the structure and activities of the ALC and presents the highlights and outcomes of the first four conferences and their contribution to shaping the development of the African space arena. The paper concludes with an analysis of the challenges facing the ALC and some proposed measures to enhance its effectiveness.     

Why we need a space elevator

The goals of and vision for development of a space elevator have been discussed repeatedly. However, why we should develop one has been glossed over. This paper will focus upon the major issue—why build a space elevator infrastructure? It considers why we need a space elevator, what missions it would enable and how far it would reduce costs. There is no doubt that some major missions would be enhanced or significantly enabled by a space elevator infrastructure. Global communications, energy, monitoring of the Earth, global/national security, planetary defense, and exploration beyond low-Earth orbit are a few examples. In the end, if we are serious about extending space development and avoiding limitations on the human spirit, the reason we should build a space elevator is because we must!     

Observations of Climate Variability – Discussion Session 3a

Space Science Reviews -     

Back-scattering of MF electromagnetic energy from the Antarctic stratosphere

A short review of the partial reflection experiment is presented along with the commonly made assumptions regarding the scattering mechanisms of the MF magneto-ionic modes in the mesosphere. It is shown that the traditional method of analysing differential absorption data can give rise to considerable errors in the determination of ionisation density at a particular scattering height. A new analysis approach is presented which yields a profile of the product of electron density and collisional frequency, rather than estimates of the electron density only. A by-product of this analysis technique is an estimate of the reflection coefficient factor F_xo(h) which traditionally has been set identically equal to unity. Analysis of data collected from 1983 to 1998 at Scott Base, Antarctica, has revealed that this reflection coefficient factor exhibits a seasonal dependence and differs substantially from unity, particularly at scattering heights between 40km and 60km. It is shown that neglecting this factor could easily lead to the conclusion that differential absorption is present at certain scattering heights with the consequent implication of the presence of ionisation.     

Variability of spectra in large solar energeticparticle events

Using data from the Solar Isotope Spectrometer on the Advanced Composition Explorer obtained during 36large solar energetic particle events (SEPs) that occurred during 1997–2002 we have examined the spectral characteristics of oxygen and iron. Based on the shape of the oxygen spectrum during the decay phase following the peak in particle intensity, each SEP event was categorized as either exponential (7 events) or power law (29 events). We find that the exponential events were typically the larger events (in terms of peak oxygen intensity) and had Fe/0 ratios that strongly decreased with increasing energy.Event-averaged Fe/0 ratios (integrated over 12 to 60 MeV/nucleon) were at or below coronal abundances for nearly all these events, while the ratios obtained in the power law events were typically enhanced over coronal values. The majority of the power law events had the same spectral index for both 0 and Fe resulting in an Fe/0 ratio independent of energy. However 6 of the 29 power law events had Fe/0 ratios that increased with increasing energy due to an Fe spectral index less negative than that of 0. We consider simple diffusion theory in an effort to understand the nature of these events and obtain preliminary but promising results.     

Infrared irradiance calibration

Infrared astronomical measurements are calibrated against reference sources, usually primary standard stars that are, in turn, calibrated either by direct or indirect means. A direct calibration compares the star with a certified source, typically a blackbody. Indirect methods extrapolate a direct measurement of the flux at one wavelength to the flux at another. Historically, α Lyr (Vega) has been used as the primary standard as it is bright, easily accessible from the northern hemisphere, and is well calibrated in the visual. Until recently, the direct absolute infrared calibrations of α Lyr and those derived from the absolute solar flux scaled to the observed spectral energy distributions of solar type stars increasingly diverged with wavelength from those obtained using a model atmosphere to extrapolate the absolute visual flux of Vega into the infrared. The exception is the direct calibration by the 1996/97 Midcourse Space Experiment of the absolute fluxes for a number of the commonly used infrared standard stars, including Vega.In the mid-1980s, the Air Force Geophysics Laboratory began a program that led to the establishment of a network of stars with which to calibrate infrared space-based sensors. α Lyr and a CMa were adopted as the fundamental references and the absolute 1.2 to 35 µm infrared spectral energy distributions for the 616 secondary standard stars in the network were derived through spectral and photometric comparisons with the primary standards. The stars are also used for calibration at ground-based infrared observatories. For applications in which the network stars may not be bright enough, particularly at the longer infrared wavelengths, planets and the larger asteroids are used. Planets and asteroids move and rather sophisticated thermal modeling of the bodies is required to predict the disk-integrated brightness at a specific time with reasonable accuracy. The Infrared Space Observatory applied such a sophisticated ‘thermo-physical’ model to the largest asteroids to support calibration of the sensors to a claimed accuracy of within 5%. The AFRL program also created a spectral atlas of the brightest stars in the sky that, although they are variable, may be used for calibration if the large(r) attendant uncertainties are acceptable.This revised version was published online in July 2005 with a corrected cover date.     

Experimental investigations on hull-fin interferences of the LOTTE airship

In the present paper experimental aerodynamic investigations on an airship configuration at angle of attack with special emphasis on the hull-fin region are reported. In particular, visualizations of flow phenomena on both hull and fins are studied. Quantitative measurements of the integral force and moment characteristics as well as local pressure coefficients serve to establish a data pool for code validation.