Needs in space education for the 21st century

There is increasingly broad concern in the USA today about the quality, vibrancy and appeal of science and technical education in general and space education in particular. There needs to be a robust link between the educational community (i.e. the primary and secondary schools as well as colleges and universities) and a well-defined space research and exploration agenda that is strongly supported by the space industry, NASA and other relevant US governmental agencies. Without such a renewal of mission and new goals it will be difficult to re-invigorate and expand quality space education programs. A workshop was therefore convened in 2003 to analyze the problem, discuss new initiatives, organize a survey inviting suggestions from a range of relevant players and draw conclusions on what the USA needs to do to improve space education in the 21st century. Although the focus of this workshop was on space education in the USA the international dimensions of this problem were also addressed and the firm conclusion was reached that similar issues and concerns apply in Europe, Canada, Japan and other spacefaring nations. This article is an edited version of a White Paper subsequently produced to highlight the problem, summarize the proceedings of the workshop and present the results of the survey. Greater clarity in the definition of national space goals, the upgrading of teachers’ skills and an increase in technical scholarships are among the steps recommended.     

A large area multitechnique experiment for hard X-ray astronomy

A balloon-borne multitechnique large area experiment consisting of 2 co-aligned detectors (3200 cm² NaI and 1800 cm² multiwire proportional counters), is described, which is capble of producing observations of the hard X-ray sky with very high sensitivity and good spectral resolution over the whole operative range (15–300 keV).     

Red edge measurements for remotely sensing plant chlorophyll content

The feasibility of using the wavelength of the maximum slope of the red edge of leaf reflectance spectra (λ_re) as an indication of plant chlorophyll status was examined in the laboratory for single leaves of several species. λ_re for each sample was determined by derivative reflectance spectroscopy. A high positive correlation was found between λ_re and leaf chlorophyll content for all species, although there were some differences in the quantitative nature of the relationship for plants of different types. The position of the red edge was found to be unaffected by simulated change in ground cover, but multiple leaf layers produced a shift in its position. Appropriate spectral measurements and processing for obtaining useful information from the red edge are discussed, and the potential of the red edge in relation to other spectral measurements is considered.     

Exposure of animals to artificial gravity conditions leads to the alteration of the glutamate release from rat cerebral hemispheres nerve terminals.

The biochemical basis underlying the effects of altered gravity on the process of nervous signal transmission is not clear. We have investigated the effect of hypergravity stress (created by centrifugation of rats at l0 g for 1 h) on the basal and stimulated release of L-[14C]glutamate (a chemical transmitter of excitatory signals) from isolated rat brain nerve terminals (synaptosomes). It has been shown that the hypergravity stress exerted a different influence on the Ca(2+)-dependent and the Ca(2+)-independent component of neurotransmitter release. The Ca(2+)-dependent L-[14C]glutamate release evoked by potassium chloride was equal to 14.4 +/- 0.7% of total synaptosomal label for control animals and 6.2 +/- 1.9% for animals, exposed to hypergravity (P < or = 0.05) and was more than twice decreased as a result of the hypergravity stress. We observed no statistically significant difference in the Ca(2+)-independent component of L-[14C]glutamate release. For control group and animals exposed to the hypergravity stress it was equal to 7.7 +/- 2.8% and 12.9 +/- 2.0%, respectively. We have also investigated the effect of the hypergravity stress on the activity of high-affinity Na(+)-dependent glutamate transporters. Km and Vmax of L-[14C]glutamate uptake have been determined. The maximal velocity of glutamate uptake was decreased as a result of hypergravity loading, but no difference in the Km values between control rats and hypergravity exposed animals was observed. These findings indicate that hypergravity stress alters neurotransmitter reuptake and exocytotic neurotransmitter release processes.     

Aerosol observations from Nimbus-7 CZCS along the South African West Coast

In the course of the South African participation in the Nimbus-7 CZCS project, a fair amount of cloud-free data were collected along the South African West Coast, mainly to study upwelling phenomena. Examples of aerosol radiance maps produced during analysis of these data, including some anomalous results, are discussed.     

An imaging telescope for soft gamma-ray astronomy: The preliminary in-flight tests

A large area (6000 cm²) actively shielded low energy gamma-ray telescope is going to be built by an Anglo-Italian collaboration. The telescope, named ZEBRA, will be capable of producing images of the X and gamma ray sky in the energy range 0.015–20 MeV with an intrinsic angular resolution of a few tenths of a degree. A prototype detector has been built in order to experimentally study the main characteristics of the detection plane. The preliminary results obtained during a balloon flight from Trapani, Sicily in July 1981 are presented.     

A review of geostationary satellite alternatives for retrieving data from long duration balloon flights

Low speed data from high altitude scientific balloon flights can be retrieved by geostationary satellites through existing data collection platform systems. Higher speed data of the order of 1 kbit/s create a more difficult problem, particularly if a response is to be made to the balloon payload in near real time. Different geostationary satellite methods to achieve these more demanding requirements are reviewed, and the more interesting cases identified for possible future experiments.     

The position sensitive low energy detector on board the ZEBRA telescope

In order to improve the low energy capability (15 ÷ 150 KeV) of the balloon borne “ZEBRA” low energy gamma imaging telescope (150 KeV-20 MeV), a large area, high spectral resolution (5% at 60 KeV), low background detector has been designed and is now under development.It consists of two MultiWire Spectroscopic Proportional Counter (SPC), escape gated, that have a sensitive area of 6000 cm², and are placed above the large area array of sodiumiodide position sensitive elements.     

An imaging telescope for high energy gamma-ray astronomy

Recent tests of a γ-ray imaging telescope, which incorporated a coded aperture mask and multi-wire proportional counter system produced good images of a tritium target source which was used to generate the 20 MeV protons at a proton Van de Graaff accelerator. This paper indicates what performance one might expect if a large area drift chamber were used in conjunction with a coded aperture mask. The prospects for achieving significant scientific results if such a system were flown on a variety of space vehicles are discussed.     

A prospectus on airborne laser mapping systems

Airborne laser systems have demonstrated enormous potential for topographic and bathymetric mapping. Both profiling and scanning systems have been evaluated for terrain elevation mapping, stream valley cross-section determination, and nearshore bottom profiling. Performance of the laser systems has been impressive and for some applications matches current operational accuracy requirements. Determining the position of individual laser measurements remains a constraint for most applications. Laser technology constrains some terrain and bathymetric applications, particularly for water penetration and frequency of measurements for high-spatial resolution over large areas.