Scientific Uses of the Space Shuttle (1974) / Chapter Skim
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INFRARED ASTRONOMY
INFRARED ASTRONOMY
Pages 83-101
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From page 83... ...
The Space Shuttle will permit observations throughout the infrared and submillimeter spectral range without atmospheric interference and with considerably greater aperture, observing time, and sensitivity than would currently be possible on existing high-altitude platforms. In particular, orbital operation provides the unique circumstance of both low residual atmosphere and very low infrared sky radiance, making a large cryogenically cooled telescope both feasible and advantageous.
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From page 84... ...
A Solar-System Formation High-resolution spectroscopy of planets and comets over the broad spectral regions that are available in space can give molecular abundances and hence atomic abundances and isotopic ratios for the solar system.
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From page 85... ...
Existing technology is adequate to commence immediately with the design and construction of two classes of telescopes capable of making ir observations from space, one to operate at ambient temperature and the other to be cryogenically cooled. Each of these types of instruments is peculiarly suited to specific types of measurement, and both can be used to great advantage for ir observations outside the atmosphere.
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From page 86... ...
Beamswitching techniques, which provide discrimination between a faint discrete source and a bright uniform background cannot overcome this fundamental limitation. Full utilization of current and anticipated broadband detector technology requires the use of a Cryogenically cooled telescope operating above the atmosphere.
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From page 87... ...
The temperature to which the telescope should be cooled for broadband diffraction-limited operation depends on the anticipated detector noise equivalent power (NEP) , detector quantum efficiency, detector size, wavelength interval, temperature of the detector cavity, and telescope emissivity.
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From page 88... ...
A field of view of approximately 15 min of arc is required to permit fine acquisition and position objects in the focal plane and to allow for multiple detectors and imaging devices. The cooled telescope is to be the prime experiment on the particular flight because of pointing demands and weight.
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From page 89... ...
feasible with uncooled telescopes. A cooled telescope with 10-m aperture, although desirable from a scientific point of view, seems not to be feasible from an economic point of view in the 1980's.
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From page 90... ...
While not optimized for infrared observations, regular use of the LST with cryogenically cooled detectors could provide some of the capability of the 3-m infrared telescope in terms of large aperture for narrow-band spectroscopy and spatial resolution of bright sources throughout the infrared and submillimeter region. It will also be possible to take advantage of the high optical quality of the LST to obtain sensitivity and resolution superior to what can be done from the ground by using efficient imaging detectors that should be available in the next decade for the near infrared.
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From page 91... ...
-100 Mount Fully gimbaled Gimbaled or Free-flying free-flying 3. TEN-METER-DIAMETER AMBIENT-TEMPERATURE TELESCOPE The long-range goal in the development of ambient-temperature telescopes is a very large instrument that would provide the collecting area needed for high-resolution spectral studies and the aperture for good spatial resolution.
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From page 92... ...
A Cosmic Background Radiation The 3 K cosmic background radiation affords astronomers a unique opportunity to study a fundamental problem.
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C Spatial Interferometer To obtain spatial resolution in the far infrared that is comparable with that obtained at optical and radio wavelengths, it is necessary to increase the size of the collecting optics in proportion to the wavelength.
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These considerations suggest that only the minimum crew of two pilots, a mission specialist, and a payload specialist be used for ir astronomy sortie missions. There is adequate room in the Shuttle cabin for the payload control console, display units, and some data analysis and storage equipment.
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From page 95... ...
If the 2.5-m cooled telescope is used in the sortie mode, its weight, power, and volume requirements on the Shuttle obviously would be much greater. It would occupy the full diameter of the Shuttle bay for a length of at least 12 m.
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From page 96... ...
1. THE RESIDUAL ATMOSPHERE The large cryogenically cooled telescope imposes the most severe requirements on contaminants.
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From page 97... ...
For example, a single dust particle of 10-Mrn diameter at ambient temperature is readily detectable up to tens of kilometers with the sensitive systems envisaged (NEP ~W Hzt /2)
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From page 98... ...
VII. SUPPORTING RESEARCH AND TECHNOLOGY Orbiting cryogenic telescopes will offer an unparalleled opportunity for astronomical observations in the infrared.
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From page 100... ...
Infrared telescopes are especially sensitive to potential gaseous and particulate Shuttle contamination. It appears that the infrared requirements on contamination levels can be met with some specialized Apollo-type contamination control.
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From page 101... ...
4. We recommend the creation of a Shuttle contamination board composed of engineers and astronomers to establish standards for contamination based on the requirements of astronomy and to participate in reviews of Shuttle design.
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