月球磁异常区的光学特性探讨

A Study of Reflectance Characteristics in Regions of Several Lunar Magnetic Anomalies

月球无全球性磁场,在某些大型撞击坑的对峙区域存在较强的磁场强度。这些磁场异常区域往往与光学异常区域呈地理相关,推断与磁异常诱发的微磁层弱化空间风化效应有关。嫦娥一号卫星携带的干涉成像光谱仪获取了月球表面可见光-近红外波长范围内32个波段的光谱,为研究月球空间风化效应提供了一个可能物理量——月表反射率。通过对几个常见磁异常结构磁场内外区域的平均光谱对比发现,磁场内区域反射率一般高于磁场外区域。这一结果对月球表面空间风化效应的研究产生了新的推动。

The Moon does not have a global magnetic-field pattern.However, at anitpodes of some large lunar craters there are magnetic fields of high strengths.The lunar magnetic anomalies are also regions of unusual lunar albedo features, which has been hypothesized to be due to the local weakening of space weathering by mini-magnetospheres induced by magnetic anomalies.The Interference Imaging Spectrometer （ IIM） onboard the Chang’E-1 lunar exploration spacecraft obtained optical spectra of various parts of the lunar surface in 32 bandpasses covering visible to near-infrared wavelengths.The IIM data allow us to study effects of lunar space weathering through local reflectance curves of the lunar surface.By comparing average reflectance curves within regions of four selected magnetic anomalies to those in their close vicinities （ outside the magnetic anomalies） , we have found that the reflectance values within the regions of magnetic anomalies are consistently larger than in the vicinities.Considering that mini-magnetospheres shield the regions within the anomalies against space winds, our result supports the hypothesis that lunar mini-magnetospheres reduce influences of space weathering.Our study could provide new insights into effects of space weathering on the lunar surface.