کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8138298 | 1523557 | 2014 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Upper limits for a lunar dust exosphere from far-ultraviolet spectroscopy by LRO/LAMP
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
علوم فضا و نجوم
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![عکس صفحه اول مقاله: Upper limits for a lunar dust exosphere from far-ultraviolet spectroscopy by LRO/LAMP Upper limits for a lunar dust exosphere from far-ultraviolet spectroscopy by LRO/LAMP](/preview/png/8138298.png)
چکیده انگلیسی
Since early 2012, the Lyman-Alpha Mapping Project (LAMP) far-ultraviolet spectrograph on the Lunar Reconnaissance Orbiter (LRO) spacecraft has carried out a series of limb observations from within lunar shadow to search for the presence of a high altitude dust exosphere via forward-scattering of sunlight from dust grains. Bright “horizon-glow” was observed from orbit during several Apollo missions and interpreted in terms of dust at altitudes of several km and higher. However, no confirmation of such an exosphere has been made since that time. This raises basic questions about the source(s) of excess brightness in the early measurements and also the conditions for producing observable dust concentrations at km altitudes and higher. Far-ultraviolet measurements between 170 and 190 nm, near the LAMP long wavelength cutoff, are especially sensitive to scattering by small (0.1-0.2 μm radius) dust grains, since the scattering cross-section is near-maximum, and the solar flux is rising rapidly with wavelength. An additional advantage of ultraviolet measurements is the lack of interference by background zodiacal light which must be taken into account at longer wavelengths. As of July 2013, LAMP has completed several limb-observing sequences dedicated to the search for horizon glow, but no clear evidence of dust scattering has yet been obtained. Upper limits for vertical dust column abundance have been estimated at less than 10 grains cmâ2 (0.1 μm grain radius), by comparing the measured noise-equivalent brightness with the results of Mie scattering simulations for the same observing geometries. These results indicate that Lunar Atmosphere Dust Environment Explorer (LADEE) UVS lunar dust observations will be considerably more challenging than planned.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Icarus - Volume 233, 1 May 2014, Pages 106-113
Journal: Icarus - Volume 233, 1 May 2014, Pages 106-113
نویسندگان
Paul D. Feldman, David A. Glenar, Timothy J. Stubbs, Kurt D. Retherford, G. Randall Gladstone, Paul F. Miles, Thomas K. Greathouse, David E. Kaufmann, Joel Wm. Parker, S. Alan Stern,