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I. G. Mitrofanov A. Bartels Y. I. Bobrovnitsky W. Boynton G. Chin H. Enos L. Evans S. Floyd J. Garvin D. V. Golovin A. S. Grebennikov K. Harshman L. L. Kazakov J. Keller A. A. Konovalov A. S. Kozyrev A. R. Krylov M. L. Litvak A. V. Malakhov T. McClanahan G. M. Milikh M. I. Mokrousov S. Ponomareva R. Z. Sagdeev A. B. Sanin V. V. Shevchenko V. N. Shvetsov R. Starr G. N. Timoshenko T. M. Tomilina V. I. Tretyakov J. Trombka V. S. Troshin V. N. Uvarov A. B. Varennikov A. A. Vostrukhin 《Space Science Reviews》2010,150(1-4):183-207
The design of the Lunar Exploration Neutron Detector (LEND) experiment is presented, which was optimized to address several of the primary measurement requirements of NASA’s Lunar Reconnaissance Orbiter (LRO): high spatial resolution hydrogen mapping of the Moon’s upper-most surface, identification of putative deposits of appreciable near-surface water ice in the Moon’s polar cold traps, and characterization of the human-relevant space radiation environment in lunar orbit. A comprehensive program of LEND instrument physical calibrations is discussed and the baseline scenario of LEND observations from the primary LRO lunar orbit is presented. LEND data products will be useful for determining the next stages of the emerging global lunar exploration program, and they will facilitate the study of the physics of hydrogen implantation and diffusion in the regolith, test the presence of water ice deposits in lunar cold polar traps, and investigate the role of neutrons within the radiation environment of the shallow lunar surface. 相似文献
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Mitrofanov IG Sanin AB Golovin DV Litvak ML Konovalov AA Kozyrev AS Malakhov AV Mokrousov MI Tretyakov VI Troshin VS Uvarov VN Varenikov AB Vostrukhin AA Shevchenko VV Shvetsov VN Krylov AR Timoshenko GN Bobrovnitsky YI Tomilina TM Grebennikov AS Kazakov LL Sagdeev RZ Milikh GN Bartels A Chin G Floyd S Garvin J Keller J McClanahan T Trombka J Boynton W Harshman K Starr R Evans L 《Astrobiology》2008,8(4):793-804
The scientific objectives of neutron mapping of the Moon are presented as 3 investigation tasks of NASA's Lunar Reconnaissance Orbiter mission. Two tasks focus on mapping hydrogen content over the entire Moon and on testing the presence of water-ice deposits at the bottom of permanently shadowed craters at the lunar poles. The third task corresponds to the determination of neutron contribution to the total radiation dose at an altitude of 50 km above the Moon. We show that the Lunar Exploration Neutron Detector (LEND) will be capable of carrying out all 3 investigations. The design concept of LEND is presented together with results of numerical simulations of the instrument's sensitivity for hydrogen detection. The sensitivity of LEND is shown to be characterized by a hydrogen detection limit of about 100 ppm for a polar reference area with a radius of 5 km. If the presence of ice deposits in polar "cold traps" is confirmed, a unique record of many millions of years of lunar history would be obtained, by which the history of lunar impacts could be discerned from the layers of water ice and dust. Future applications of a LEND-type instrument for Mars orbital observations are also discussed. 相似文献
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R. Herrmann P. Rudolph H. Krüger G. Schneider R. Röstel R. Kuhl A.S. Okhotin V.T. Khryapov E.V. Markov I.P. Kazakov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(5):163-166
Two sublimation experiments with PbTe were performed at 850°C and 750°C under microgravity conditions during the “Salyut-6”-“Soyuz-31” mission in 1978. The sublimation took place on the (100)-face of a PbTe crystal. The condensate grown at 850°C shows in the upper part the formation of a pyramidal habit. The bulk consists of parallel growth colums with [100]-boundary faces. The charge carrier concentration of the electrons (N=1,5·1019 cm?3) is higher than the homogeniety limit for 800°C should permit. This is in contrast to the result obtained on the PbTe crystal of the parallel experiment on the earth. At 750°C a laminated condensate is grown with a low growth rate. The microphotograph of the substrate shows the beginning whisker formation according to the VLS-mechanism. 相似文献
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