ISSN:0094-243X    

DOI:10.1063/1.39360

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Within the Life Sciences Division of NASA, the Exobiology Program seeks to understand the origin, evolution and distribution of life in the universe. Given the current state of our own technology, there are only two feasible methods of searching for life beyond the Earth. The first is to return to Mars and systematically explore its surface and sub‐surface with instrumentation capable of identifying extinct as well as extant life. The second is to search for advanced forms of life in other planetary systems that have developed a technology capable of modifying their environment in ways that make it detectable across the vast interstellar distances. The Exobiology program is currently pursuing both of these options.

ISSN:0094-243X    

DOI:10.1063/1.39361

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.39342

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Extremely‐high‐resolution observations are required in order to make significant progress in solving some of the major problems in solar magnetoconvection. Temporal resolution demands a data stream that is uninterrupted for a minimum of thirty days, collected at very high rates of at least 100 megabits per second. Spatial resolution must be better than 35 km (0.05 arcsec). Finally, spectral resolution of at least 105is needed. Since the magnetic structures of interest are very much three‐dimensional, extending from below the solar surface up into the corona, observations from the IR, visible, EUV, XUV, and X‐ray portions of the spectrum are essential.The above requirements preclude the use of Earth‐based observatories, which are handicapped by turbulence (seeing) in the Earth’s atmosphere, absorption of EUV and X‐ray radiation, and the 24 hour day‐night cycle. Thus the relevant facilities must operate from space. Whether they should be free‐flyers or lunar‐based depends partly on specific experiment requirements, and also on factors of cost, logistics, and timing.The results of an informal poll of some two dozen solar physicists regarding the advantages of solar observations from the Moon are discussed.

ISSN:0094-243X    

DOI:10.1063/1.39343

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

High‐energy processes, involving a rich variety of accelerated particle phenomena, lie at the core of the solar flare problem. The most direct manifestation these processes are high‐energy radiations, gamma rays, hard X‐rays and neutrons, as well as the accelerated particles themselves, which can be detected in interplanetary space. In the study of astrophysics from the moon, the understanding of these processes should have great importance. The inner solar system environment is strongly influenced by activity on the Sun; the physics of solar flares is of great intrinsic interest; and much high‐energy astrophysics can be learned from investigations of flare physics at high energies.

ISSN:0094-243X    

DOI:10.1063/1.39344

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The study of solar flares will be extremely important for a lunar base. Not only are solar flares interesting from a scientific point of view, but, perhaps even more importantly, the energetic particles from solar flares will bombard the lunar base and at times make it extremely hazardous, even fatal, to astronauts working unprotected on the lunar surface. Of course, the two motivations are coupled; with better understanding of solar flare physics, predictions of solar flares and their consequences can be improved. To reduce telecommunications that would other wise be necessary between a lunar base and the Earth, there is value in monitoring the Sun from the lunar base and analyzing the data to make predictions on‐site.

ISSN:0094-243X    

DOI:10.1063/1.39345

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Radio sources of solar origin are the dominant feature of radio emissions at low frequencies. Solar radio sources are sporadic and very frequent during the maximum phase of the solar cycle; they may be very intense (more than 40 dB above the background) and they can be localized almost anywhere in the interplanetary medium. They represent a unique means to detect perturbations originating from the solar activity and to track their progression through the interplanetary medium and particularly into the Earth’s environment.

ISSN:0094-243X    

DOI:10.1063/1.39346

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.39348

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

This paper considers the opportunities offered by proposed lunar observatories for studies of the origin of stars and related objects. We summarize the principal advantages to be gained by astronomical observations from the Moon. We then give a brief outline of the working hypothesis that present‐day star formation in the Galaxy involves four conceptually distinct stages. We conclude by emphasizing that the greatest strides forward in understanding will probably come from interferometric investigations that can be carried out with at least 10 milliarcsecond angular resolution at submillimeter and far infrared wavelengths, and 10 microarcsecond resolution at ultraviolet, optical, and near infrared wavelengths.

ISSN:0094-243X    

DOI:10.1063/1.39349

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Using increasingly sophisticated observing strategies, astronomers have begun to observe brightness inhomogeneities on the surfaces of stars indicative of starspots, active regions, and chemically‐anomalous patches with size scales far smaller than the diffraction limits of the present generation of telescopes. While tantalizing, these first glimpses of stellar surface structures are very crude and not unique. Modest‐sized optical and ultraviolet inteferometers located on the lunar surface could resolve these surface structures on nearby, bright stars to provide ‘ground truth’ to the present crude images and to extend these studies to much smaller and physically interesting scales. The combination of broad and narrow‐band imaging (where feasible) will provide qualitatively new information on the physical processes that occur in stellar atmospheres by observing phenomena on stars with properties (mass, radius, convective zone depth, rotation rate) far different from the Sun. An intermediate scale optical/ultraviolet interferometer on the lunar surface with 10−3to 10−4arcsecond angular resolution would provide unique and spectacular results concerning stellar surface structures. This intermediate scale interferometer could be a very useful device for learning how to build larger interferometers that could address more difficult questions.

ISSN:0094-243X    

DOI:10.1063/1.39350

出版商:AIP    

年代:1990

数据来源: AIP