期刊
SCIENCE
卷 294, 期 5548, 页码 1914-1917出版社
AMER ASSOC ADVANCEMENT SCIENCE
DOI: 10.1126/science.1065569
关键词
-
Four hydrogen (H-2) lines have been detected in a spectrum of Mars observed with the Far Ultraviolet Spectroscopic Explorer. Three of those lines are excited by the solar Lyman beta photons. The line intensities correspond to a column H-2 abundance of 1.17 (+/-0.13) x 10(13) per square centimeter above 140 kilometers on Mars. A photochemical model for the upper atmosphere that simulates the observed H-2 abundance results in an H-2 mixing ratio of 15 +/- 5 parts per million in the lower atmosphere. The H-2 and HD mixing ratios agree with photochemical fractionation of D (deuterium) between H2O and H-2. Analysis of D fractionation among a few reservoirs of ice, water vapor, and molecular hydrogen on Mars implies that a global ocean more than 30 meters deep was lost since the end of hydrodynamic escape. Only 4% of the initially accreted water remained on the planet at the end of hydrodynamic escape, and initially Mars could have had even more water (as a proportion of mass) than Earth.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据