Astronomy and solar physics: solar irradiance observations

The absolute radiometer on Spacelab 1 was used to obtain solar irradiance observations from space. A number of effects must be taken into account in the data reduction. A provisional value was obtained for the mean solar constant during the observation period (6 to 8 December 1983).     

Astronomy and solar physics: very-wide-field ultraviolet sky survey

Very-wide-field photographs of the sky were taken on Spacelab 1 at 1650, 1930, and 2530 angstroms with a limiting magnitude of 9.3 at 1930 angstroms. A 1.2 by 2.4 kiloparsec ultraviolet extension of the Shapley wing of the Small Magellanic Cloud is seen in some of the photographs.     

Atmospheric physics and Earth observations: atmospheric spectral imaging

An array of imaging spectrometers flown on the Spacelab 1 mission was capable of providing spectra of the atmospheric emissions over a broad wavelength range from 300 to 12,700 angstroms and acquiring each complete spectrum nearly simultaneously. The instrument was used to make observations on the day side and night side of the earth, looking down in the nadir direction, radially away from the earth, and in various limb-scanning modes. Observations were made looking at various angles to the vehicle velocity vector and during thruster firings and water dumps as well as at times when such events were inhibited. As a result of the mission a data base has been acquired that is valuable for studies of both the upper atmosphere and the shuttle-Spacelab vehicle environment.     

An empirical model of total solar irradiance variation between 1874 and 1988

An empirical model of variations in the total solar irradiance caused by observed changes in photospheric magnetic activity between 1874 and 1988 is presented. The model provides a remarkably good representation of the irradiance variations observed by satellite-borne radiometers between 1980 and 1988. It suggests that the mean total irradiance has been rising steadily since about 1945, with the largest peak so far at about 1980 and another large peak expected during the current solar cycle 22. But it is doubtful whether even this rise can contribute significantly to global warming, unless the temperature increase of about 0.02 degrees C that it produces in current energy balance models seriously underestimates the sensitivity of climate to solar irradiance changes.     

Band-gap engineering: from physics and materials to new semiconductor devices

Band-gap engineering is a powerful technique for the design of new semiconductor materials and devices. Heterojunctions and modern growth techniques, such as molecular beam epitaxy, allow band diagrams with nearly arbitrary and continuous band-gap variations to be made. The transport properties of electrons and holes can be independently and continuously tuned for a given application. A new generation of devices with unique capabilities, ranging from solid-state photomultipliers to resonant tunneling transistors, is emerging from this approach.     

Space plasma physics: isotopic stack: measurement of heavy cosmic rays

A stack of plastic nuclear track detectors was exposed to heavy cosmic rays on the pallet of Spacelab 1. Some layers of the stack were rotated with respect to the main stack to determine the arrival time of the particles. After return of the stack the latent particle tracks are revealed by chemical etching. Under the optical microscope the charge, mass, energy, and impact direction of the particles can be deduced from the track geometry.     

Observations in particle physics from two neutrinos to the standard model

The two-neutrino experiment established a relationship between particles, muon and muon neutrino, electron and electron neutrino, which evolved into the standard model of particle physics. The theme of this article is a personal one, which reviews a series of experiments at the Columbia Synchrocyclotron, the Brookhaven Cosmotron, the Alternating Gradient Synchrotron, the CERN intersecting storage rings, the Fermilab 400-gigavolt proton synchrotron, and the Cornell electron storage rings, all of which were important in the evolution of the standard model. In some cases the fermion particles were discovered (the second neutrino vmicro, b quark); in other cases fields of research were opened (muon spin resonance, neutral kaons and charge-parity violation, dimuons and the Drell-Yan process), which led to further development of the standard model. Finally, the current ignorance about the properties of now three neutrinos is reviewed.     

Atmospheric physics and Earth observations: mapping from space: the metric camera experiment

The Spacelab metric camera experiment acquired stereoscopic high-resolution black-and-white and color infrared photographs of various regions of the world. In total, an area of about 11 million square kilometers was covered. Because of the delay in launching the shuttle until 28 November, illumination conditions were frequently poor over many candidate targets. However, unique high-quality images with a ground resolution of about 20 meters were obtained by increasing camera exposure time. Initial image analysis has shown that these images may be used for earth mapping at the scale 1:100,000.