Thermal net flux measurements on the pioneer Venus entry probes

Corrected thermal net radiation measurements from the four Pioneer Venus entry probes at latitudes of 60°N, 31°S, 27°S, and 4°N are presented. Three main conclusions can be drawn from comparisons of the corrected fluxes with radiative transfer calculations: (1) sounder probe net fluxes are consistent with the number density of large cloud particles (mode 3) measured on the same probe, but the IR measurements as a whole are most consistent with a significantly reduced mode 3 contribution to the cloud opacity; (2) at all probe sites, the fluxes imply that the upper cloud contains a yet undetected source of IR opacity; and (3) beneath the clouds the fluxes at a given altitude increase with latitude, suggesting greater IR cooling below the clouds at high latitudes and water vapor mixing ratios of about 2–5×10^?5 near 60°, 2–5×10^?4 near 30°, and >5×10^?4 near the equator.     

Circumstellar habitable zones: an overview

We review aspects of circumstellar habitable zones based on results reported at the First International Conference on Circumstellar Habitable Zones (held in 1994 at NASA Ames Research Center). Recent advances in atmospheric radiative transfer modeling have shown that circumstellar habitable zones are wider than previously thought. New considerations may allow a much shorter time scale both for the origin as well as the evolution of biological forms. The most abundant M dwarf stars, contrary to previous views, appear to be able to support the necessary conditions for a habitable zone around them. New planet formation models indicate that at least one planet should form within the circumstellar habitable zone of single dwarf stars regardless of mass. Biogenic materials also appear to be widespread and delivery to terrestrial planets via cometary impacts may be a viable mechanism. Finally, biology will modify a planet and provide positive feedback, in general, to increase the habitability of a planet. Overall, new astronomical, planetary, and biological considerations each seem to indicate that habitable zones around other stars may be both more widespread and more stable than previous research had indicated.     

Occurrence of brain tumors in rhesus monkeys exposed to 55-MeV protons.

Twenty-year observation of monkeys exposed to single doses of high energy protons simulating solar particles revealed that the most prevalent fatal cancers were brain tumors in the group of animals exposed to 55-MeV protons. Of 72 animals (50 males and 22 females) receiving 0.25 to 8.0 Gy total body surface dose, nine developed fatal tumors classified as grade IV astrocytoma or glioblastoma multiforme. The latent period for tumor development ranged from 14 months to 20 years, with a median of 5 years. Doses associated with the tumors were 4.0 to 8.0 Gy. Eight males and one female were affected. Depth-dose determinations suggest that the high incidence of cerebral neoplasia is associated with the Bragg Peak energy distribution of the 55-MeV protons. Comparison of the tumor incidence with that in humans with brain exposures incidental to radiotherapy indicates a high biological effectiveness compared with gamma radiation. Studies are in progress to attempt to replicate the results in rodents and establish a dose-response curve for proton-induced brain tumors.     

高超声速飞行器表面气动热和粘性摩擦力计算

本文给出了高超声速飞行器表面摩阻和传热系数 (斯坦顿数 )的计算结果。采用两种方法平面切面法亦即二维边界层近似法和工程方法计算了飞行器高超声速绕流的粘性效应 ,并对两种方法的计算结果作了仔细的比较。由文可见 ,对于在稠密大气层内 ,沿轨道运行头速度恒定的高超声速有翼飞行器 ,能够用本文所采用的两种方法计算其表面摩阻和热载荷。此二法可成功地应用于绕复杂形状物体的流动参数计算。     

The pleurodele, an animal model for space biology studies.

Pleurodeles waltl, an Urodele amphibian is proposed as a model for space biology studies. Our laboratory is developing three types of experiments in space using this animal: 1) in vivo fertilization and development ("FERTILE" project); 2) influence of microgravity and space radiation on the organization and preservation of specialized structures in the neurons and muscle cells (in vitro; "CELIMENE" PROJECT); 3) influence of microgravity on tissue regeneration (muscle, bone, epidermis and spinal cord).     

Analytical definition and proposed concept for the manned infrastructure of a lunar outpost

A recent study made by ESA has reviewed the scientific investigations to be only, or best, performed on the Moon (Return to the Moon, ESA SP-1150, June 1992), and has identified the need for a manned lunar outpost to provide support to field geologists in sampling and in-situ observations of the lunar surface, and to allow the refurbishments of surface stations and rovers. Planning and development for a manned outpost on the Moon requires an in-depth understanding and analysis of the functions this outpost is expected to perform. We therefore analyzed the impact of the proposed scientific investigations on the design of a manned lunar outpost. The specific questions raised in our study were: What are the medical, physiological and psychological risks for a crew to stay and to work on the Moon? What transit and lunar surface infrastructures (habitats and vehicles) are needed to minimize those risks?     

New results for the space radiation environment of MIR space station obtained by Liulin dosimeter-radiometer. Comparison with LET spectrometer NAUSICAA

Since 1988 high sensitivity semiconductor dosimeter-radiometer “Liulin” worked on board of MIR space station. Device measured the absorbed dose rate and the flux of penetrating particles. The analysis of the data hows the following new results:

In October 1989 and after March 24, 1991, two additional stable maximums in flux channel were observed in the southern-eastern part of South Atlantic Anomaly (SAA). These two maximums existed at least several months and seem to be due to trapped high energy electron and proton fluxes. In April 1991 additional maximums were localized in the following geographical coordinates regions: LATITUDE = (−35 °)–(−50 °) LONGITUDE = 332 ° − 16 ° and lat.(−46 °)–(−52 °) long. 360 ° − 60 °. Additional maximums diffusion occurs inside radiation belt. Appearance of these maximums seems to be closely connected with preceding powerful solar proton events and associated geomagnetic dynamics of new belt disturbances. After the series of solar proton events in June 1991 we observed significant enhancement of this new radiation belt formation. To achieve sufficient accuracy of dose rate predictions in low Earth orbits the structure and dynamics of new belt should be carefully analyzed to be included in a new environment model.

From the inter comparison of the data from “Liulin” and French developed tissue equivalent LET spectrometer NAUSICAA in the time period August–November 1992 we come to the following conclusions: Mainly there is good agreement between both data sets for absorbed dose in the region of SAA; Different situation of the instruments on the station can explain the cases when differences up to 2 times are observed; At high latitudes usually the tissue equivalent absorbed dose observations are 2 times larger than “Liulin” doses.     

Study of distribution functions of interplanetary particles accelerated at co-rotating interaction region at∼5A.U.

We report the results of a study of the 12-hour average distribution functions of high Z nuclei as measured over a 10-day interval on the Ulysses spacecraft at a helioradius of5.2 A.U. We use the good time and atomic mass resolution of the composition aperture of the HI-SCALE instrument to determine the form of the distribution functions for C, O, Ne, Mg, Si, and Fe over the energy range 0.5–16 MeV/nucl. We find that the distribution functions of these ions can be organized by characteristic velocities that have values ranging between2000–3500 km/sec over this interval.