Some astronomical challenges for the twenty-first century

This paper addresses some of the scientific puzzles that astronomers may face in the next century. Four areas in astronomy are discussed in detail. These include cosmology and galaxy formation, active galaxies and quasars, supernovae and stellar remnants, and the formation of stars and planets. A variety of observatories on the Moon are proposed to attack these astronomical challenges

Astronomy on a manned Mars mission

Three extra-solar-system astronomical experiments onboard a manned Mars mission are proposed. First, a modest, 50 cm aperture optical-ultraviolet-infrared telescope (or pair used as an interferometer) coupled with the Mars-Sun baseline would increase the number (by a factor of 3.4) and a volume of stars with accurately measured distances via stellar parallax and, therefore, greatly improve upon the cosmic distance scale; the darker sky at Mars would also provide nearly a full astronomical magnitude deeper images of distant and low brightness objects (limited by zodiacal light). Second, a gamma-ray burst detector coupled with similar detectors in other parts of the solar system will be used to reduce the position error boxes and to study the nature of these energetic sources. Third, the long baselines on a Mars mission radio interferometer will provide a view of the radio universe at unprescedented resolution, 4 x 10 to the minus 9th arcsec at 1 mm wavelength, which can potentially resolve the engine in nearby active galaxies. Each of these experiments is relatively inexpensive, taking advantage of the human presence for operation and maintenance, and the long Earth to Mars baseline

Numerical simulations of bent, disrupted radio jets

We present preliminary results from three-dimensional hydrodynamical simulations designed to investigate the physics of jet bending and disruption. The specific scenario considered here involves a mildly supersonic jet crossing a contact discontinuity at the interface between the interstellar medium (ISM) and the intercluster medium (ICM) and then encountering a cross-wind in the ICM. The resultant morphologies show many of the features observed in radio sources including jet flaring, bending, and extended tails

Future Astronomical Observatories on the Moon

Papers at a workshop which consider the topic astronomical observations from a lunar base are presented. In part 1, the rationale for performing astronomy on the Moon is established and economic factors are considered. Part 2 includes concepts for individual lunar based telescopes at the shortest X-ray and gamma ray wavelengths, for high energy cosmic rays, and at optical and infrared wavelengths. Lunar radio frequency telescopes are considered in part 3, and engineering considerations for lunar base observatories are discussed in part 4. Throughout, advantages and disadvantages of lunar basing compared to terrestrial and orbital basing of observatories are weighted. The participants concluded that the Moon is very possibly the best location within the inner solar system from which to perform front-line astronomical research

Characterization of lunar surface materials for use in construction

The Workshop on the Concept of a Common Lunar Lander, which was held at the NASA Johnson Space Center on July 1 and 2, 1991, discussed potential payloads to be placed on the Moon by a common, generic, unmanned, vehicle beginning late in this decade. At this workshop, a variety of payloads were identified including a class of one-meter (and larger) optical telescopes to operate on the lunar surface. These telescopes for lunar-based astronomy are presented in an earlier section of this report. The purpose of this section is to suggest that these and other payloads for the Common Lunar Lander be used to facilitate technology development for the proposed 16-meter Aperture UV/Visible/IR Large Lunar Telescope (LLT) and a large optical aperture-synthesis instrument analogous to the Very Large Array of the National Radio Astronomy Observatory