Astronomy and Astrophysics for the 1970s Volume 1: Report of the Astronomy Survey Committee (1972) / Chapter Skim
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5. THE HIGH-PRIORITY PROGRAM
5. THE HIGH-PRIORITY PROGRAM
Pages 76-111
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From page 76... ...
VERY LARGE ARRAY The Committee recommends construction of a very large radio telescope array with the ability to observe the u.niverse to great depth with unprecedented clarity. Such an instrument can break through existing observational barriers on a broad front and reveal important new lines of enquiry.
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From page 77... ...
10ese discoveries owe mueh to the union ofenJineerlng and electronies, ,.bicb has produced large radio telescopes capable ofdeteetlna lncrodibly faint signals. Indeed, all the radio-sianal en~ detected in our radio·astronomical history is linle more than the energy released by the silent impact of a few snowflakes on the ground.
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From page 78... ...
allowing us to trace tht t\'Oiution of these vast radiating region.s as they art created by th• violent uplosh-e evenu in these objects. There will be high· resolution radio pictures of normal galaxies to compaft' with tbe radio galaxies and with our theories of the radio emission or nonnaJ gaJuies and of the objects in them.
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From page 79... ...
By measuring the radiation of individual radio spectral lines, such as that of atomic hydrogen at 21-cm wavelength, the VLA will be able to give pictures of the gas clouds of our galaxy in such detail that we will see the processes taking place in them; the effects of heating, cooling, and supersonic collisions should all be discernible. The structure of the gas system of nearby galaxies will be sharply defined, testing theories of galactic dynamics and evolution.
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From page 80... ...
small millimeter-wave antennas and interferometers, centimeter-wave inter· fcromcters and receivers, adaptable to the new atomic nnd molecular lines disc.'O\'tred, and vcry-fong-bascline interferometric terminals and arrays. A balanced program in radio astronomy requires a variety of less expensh·e racHides and innovative, Oexible research projecrs, in addition to the large national facilhy described.
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From page 81... ...
before the space age and even before the first nuclear accelerators or radio telescopes. Some of the smaller telescopes still in active use in the country are nearly 100 years old.
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From page 82... ...
The major effecl of the new detectors will not be to observe the same objecls in shorter time but rather to study much fainter objects and to use higher spectral resolution. This will permit critical investigations not thought possible 10 years ago, such as analyzing individual stars in nearby galaxies for element abundances.
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From page 83... ...
INFRARED ASTRONOMY Although Herschel detected infrared radiation from the sun "ilh a thermometer more than 170 years ago. it is only in the past decade that infrared observations have become important to the mainstream of uuonomkal research.
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From page 84... ...
Photometric studies aimed initially at improving temperature and luminosity determinations for cool stars led to the discovery of excess infrared radiation from circumstellar dust shells. A ground-based sky survey found some enormously luminous "infrared stars" that are barely detectable with optical telescopes.
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From page 85... ...
During that hour it had become apparent that the • · ray sky is extraordinarily rich in new phenomena, and that vast and vital aspects of many optical and radio objects had not been appreciated from observations in those wavelengths. The Crab nebula is not only one of the brightest objects in the x-ray sky.
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From page 86... ...
Pulm! x rays aro emitted from the pulsar created in the spectacular supernova explosion of A..
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From page 87... ...
the unwanted detector background counting rate can be greatly reduced, facilitating measurements of extended sources and of the apparently isotropic x·ray background. With this major instrumentation.
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From page 88... ...
radio, and perhaps infrared observations from the ground. They will take ttdvanttlge of focusing x-ray optics to concentrate the x·ray photons onto small detectors.
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From page 89... ...
some of the principles of this approach have been applied successfully in the new 100-m radio telescope of t he Ma.x Planck lnstitut fiir Radio-astronomie in Gennany. The very large radio telescope recommended for observations a t millimeter wavelengths would very likely be a fully steerable parabolic reflector with an aperture of 215ft.
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From page 90... ...
g a lunar eclipse of the n Crab nebula revealed that the x rays were not a point source. At the present time, rockets are proving essential to the further study of some x· ray phenomena discovered by the UhuTV x-ray satellite.
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From page 91... ...
infrared telescope, which should produce important new results. The Committee recom· mends that a first, crude, long-wavelength infrared sky survey be carried
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From page 92... ...
quick· response rocket instrumentation. Thus essentially all che major are.as of space astronomy have an ex· panding need f'or small researeh vehicles: aircraft, balloons, or rockets.
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From page 93... ...
We envisage this continued oso program, together with the expanded solar rocket program discussed in the space astronomy recommendation, as the bac.kbone of the solar space program. It is of the greatest im· portance, however, that improved observations from space go hand in hand with the improvement and extension of observations from the ground.
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From page 94... ...
Any balanced program for progress in astronomy wiU necessarily contain a vital, if relatively inexpensive, program of theoretical research. Much theoretical astrophysics today is concerned with model building.
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From page 95... ...
The High-1+/orlty Ptogram 95 A related activity is theoretical work in dynamical astronomy-the application of Newton's equations of motion (with small relativistic corrections) to the positions of planets and satellites of the solar system.
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From page 96... ...
special seminars should be designed. A National Institute of Theoretical Astrophysics has been suggested.
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From page 97... ...
and reactor design, among othen. The needs of astronomy should be considered when such an over all national computing system is discussed .
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From page 98... ...
since much of the information that they would have liked to have obtained was in the inaccessible ultraviolet r-ange of wavelengths. The mlssing spectroscopic information oonsists of two classes: one is the spectral lines in the ultraviolet due to elements and stages or ionization of elements that do not have lines in the visible region of the spectrum: the other is the general shape of the spectrum ln the ultraviolet and the relation of this to the distribution of emitted energy In the visible and Infrared wavelength regions.
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From page 99... ...
2. 'The extinction of ultraviolet light by the interstellar medium has turned out to be dllferent from that predicted on the basis of observations made In the visual region.
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From page 100... ...
If there is to be an extended delay between the launch of OAO.C and the first of these intermediate in.struments. then it is most desirable that an interim ultraviolet telescope be launched.
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From page 101... ...
If we cannot alford the largest diffraction·limited instrUment soon. then a much more vigorous rocket and lntermediate·size ultraviolet and infrared telescope program is needed to avoid losing all opportunities in this aru.
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From page 102... ...
possess lines that could be observed with either system, although tho grcater angular rtsolving powor of the 440-fi telescope would give it an advantage for certain problems. The large centimotor-wave paraboloid would certainly servo as the hub of many VLII observing programs, and its large area would inertase ononnously the classes of objtct accessible to study.
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From page 103... ...
and ..en with the rapid spac:e m(l(ions of elttrmle halo nars, thdr angular proper m(l(ions are small-approximately 0.25 sec of arc: pu year. The modons must be determined ..;th high indmdual accuracy.
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From page 104... ...
'1tem is detectable in the accurate observations of the radio pulsars. Jmpro'lcd planetary orbits are necessary to take full advantage or this technique.
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From page 105... ...
it has adopted the view that, w;lhio the main program. the emphasis on the LST is at a moderate level of som< SJS million per year.
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From page 106... ...
Therefore, the best chance for success lies in a merging of academic talent with that in the NASA centers. We suggest that NASA select one or more centers to carry out the engineering phases of the program and that the National Academy of Sciences encourage the formation of a new corporate entity representing universities with strong programs in space astronomy.
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From page 107... ...
It is the only large. university-based plan that goes bac.k to the Whitford report-the completion of the Owens Valley aperture-synthesis interferometer of 130-ft radio telescopes.
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From page 108... ...
. It will be sensitive enough to study nearby Seyfert galuies and bright
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From page 109... ...
Beyond these preliminary investigations, worthy goals of a teo-year program include a sensitive 10-km infrared interferometer, and perhaps a IO'·km infrared VLBt, and for visible wavelengths a J or 2-km intensity interferometer and a Michelson interferometer with a similar baseline.
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From page 110... ...
This will provide high spectral resolution in the optical and near ultraviolet a nd will permit very fi ne-scale study of the rapidly fluctuating solar plasma, iu excitation temperature, velocity, and magnetic field . This is a large project, of the order of S200 million, but it is one that will both provide experience use~ ful for the UT and be a nearly ultimate solar space telescope.
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From page 111... ...
since the efficiency and costs of high-speed longdistance lines are not yet known, but the 't'ery large computer is at the heart of much theoretical model building in astrophysics. To take advantage of the presently available theoretical talent among young astronomers and physicists, we also urge that an expanded postdoctoral and senior postdoctoral program be considered.
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