The Explorer Program for Astronomy and Astrophysics (1986) / Chapter Skim
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CURRENT AND FUTURE ASTRONOMY AND ASTROPHYSICS EXPLORERS
CURRENT AND FUTURE ASTRONOMY AND ASTROPHYSICS EXPLORERS
Pages 25-32
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From page 25... ...
form absolute primary calibration in flight without the neces sity of windows to avoid condensation of the atmosphere on () calibrators and instruments, and e sufficient time both to per form tests for systematic errors and to gain the increase in sen sitivity permitted by extended observation time.
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From page 26... ...
This low density extends for considerable distances and the interstellar medium in general is very patchy. A number of stellar objects were detected at extreme ultraviolet wavelengths by an experiment on the Apollo-Soyuz mission, by subsequent rocket experiments, by the Voyager spacecraft, and by the European X-Ray Astron omy Satellite ( EXOSAT )
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From page 27... ...
The experiments will feature a large photon collection area and an all-sky point ing capability with a complement of three instruments: a 1-m2 effective area xenon proportional counter array, an all-sky mon itor, and a high-energy array of phoswich Nai /Csl detectors with a total effective area of 2000 cm2. Previous studies of compact sources, based upon relatively brief observations with detectors of modest area ( typically a few hundred cm2 or in one case, HEA0-1 , with large areas on a spacecraft with very limited pointing capability )
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From page 28... ...
Both the High Resolution Imager and the German built position-sensitive proportional counter represent signifi cant improvements in sensitivity over the comparable instru ments on Einstein, but cover a narrower energy band. These imaging detectors can be used to carry out studies of the x-ray emission from stellar coronae, globular clusters, supernova rem nants, normal galaxies, active galactic nuclei and quasars, and clusters of galaxies.
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From page 29... ...
The Astronomy Survey Committee identified a number of scientific areas that appear to offer special promise for future Explorer-class missions. These include spectroscopic studies of high energy x-ray sources, determination of isotopic and ele mental composition of cosmic rays, soft x-ray measurements, high energy transient phenomena, submillimeter wavelength missions, and optical and infrared interferometers.
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From page 30... ...
NASA has issued a Dear Colleague Letter that solicits mission concepts for new Explorers. We expect that the call for proposals to define future Explorer missions will be met with a great response, involving both those missions identified by the Astronomy Survey Committee and new concepts that have been developed since then.
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From page 31... ...
in the cosmic radiation were measured on the IMP The relative abundances of heavy elements from helium through nickel series or Explorer satellites . These values (solid circles)
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From page 32... ...
SPECIFIC COST DRIVERS Increases in the costs of carrying out Explorer projects have escalated significantly over the past decade, resulting, in many cases, in long delays in carrying out missions. For the Explorer Program to continue to provide the maximum scien tific return, the factors driving these cost increases must be understood and controlled.
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