The Decade of Discovery in Astronomy and Astrophysics (1991) / Chapter Skim
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6. Astronomy From the Moon
6. Astronomy From the Moon
Pages 100-109
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From page 100... ...
The committee believes that a lunar astronomy program should complement the earth-orbiting satellite program, that both technology and science should proceed in a step-by-step fashion, and that NASA should devote an appropriate fraction of the funding for its Space Exploration Initiative to scientific endeavors, including astronomy. The committee outlines an evolutionary program that will develop necessary technologies and increase the scientific return from a lunar program.
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From page 101... ...
During the lunar night, telescopes can attain the low temperatures, less than 70 K, needed to improve infrared sensitivity. A major advantage of the moon compared with orbital observatory sites is the large, rigid lunar surface on which could be built arrays of telescopes extending over many kilometers to form interferometers.
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From page 102... ...
. TABLE 6.2 Environmental Attributes of the Moon Lunar Feature Advantages Disadvantages No atmosphere Access to all wavelengths No protection from No atmospheric distortion cosmic rays of images No moderation of thermal No wind loading of telescopes effects No ionosphere No long-wave radio cutoff Line-of-sight transmission Size Large, disconnected structures can be built Momentum from pointed telescopes is absorbed Seismically quiet compared to the earth Solid surface Radiation and thermal Possible dust contamination shielding Raw construction materials Lunar gravity Lightweight structures possible Telescopes require support Slow, synchronous Two weeks of thermal stability 300 K diurnal temperature rotation Long integration times change Far side isolated from Very slow aperture synthesis terrestrial interference No solar power at night Distance from Long baseline for radio Expensive transportation the earth interferometry Human presence Construction, operation, repair, Expense, safety requirements, refurbishment environmental degradation
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From page 103... ...
Interferometry at Visible and Near-infrared Wavelengths The techniques of interferometry can be used to link widely separated telescopes on the lunar surface to produce the spatial resolution of a single large telescope many kilometers in size. With an array of telescopes spread over a 10-km baseline, distortion-free images can be obtained for faint sources with
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From page 104... ...
Five passively cooled, 1.5-m telescopes operating together in this wavelength region could revolutionize many research topics in astronomy by combining high sensitivity with unprecedented spatial resolution (Figure 6.1~. Such an instrument could map protoplanetary disks around young stars in the constellation of Taurus with a resolution better than 0.004 of the earth-sun separation, more than enough resolution to find gaps in the disks indicative of the presence of forming planets, to detect planets around stars out to a few thousand lightyears by astrometric motions, to measure distances and motions of stars and star-forming regions in nearby galaxies, and to resolve the environment around the energy sources of quasars.
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From page 105... ...
An array of small, modular submillimeter telescopes spread over the lunar surface would allow thousandth-of-an-arcsecond imaging, adequate to search for evidence of planets forming in the disks surrounding nearby stars or to probe the energy sources of luminous infrared galaxies. Radio Observations The far side of the moon could provide a uniquely quiet environment for a large radio telescope after the initial development of a lunar base.
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From page 106... ...
~. Advanced technology development is needed to achieve the science described above.
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From page 107... ...
· The committee recommends that NASA formulate its plans for a lunar initiative in a way that protects the base program in astrophysics from disruptions caused by problems in the Space Exploration Initiative.l The scientific potential of the ongoing and planned earth-orbiting observatories should be exploited before committing resources from the science budget to major lunar facilities that will not be operational until at least 2010. Initial funding for advanced technology development and for scientific missions that are precursors to lunar facilities should come from the Space Exploration Initiative.
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From page 108... ...
Operation from the moon may represent a significant advance over terrestrial or orbiting telescopes for interferometry at wavelengths ranging from the submillimeter to the optical. · The committee recommends that an appropriate fraction of the funding for a lunar initiative be devoted to fundamental scientific projects that will have a wide appeal, to supporting scientific missions as they progress from small ground-based instruments, to modest orbital experiments, and finally, to the placement of
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From page 109... ...
· NASA should initiate science and technology development so that facilities can be deployed as soon as possible in the lunar program. The NASA office responsible for space exploration and technology should support the long-term development of technologies suitable for possible lunar observatories.
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