Space weathering effects on iron-bearing phyllosilicates, iron oxyhydroxide and basalt simulated by nanosecond pulse-laser irradiation

Spectral bidirectional reflectance from 0.5 to 3.6 microns of phyllosilicates (nontronite, antigorite, biotite), goethite and basalt that have undergone laser irradiation experiments to simulate micrometeorite bombardment. 

Data were acquired with the SHADOWS apparatus (Spectro-photometer with cHanging Angles for Detection Of Weak Signals) at IPAG in Grenoble (France). The goniometer part of SHADOWS consists of two arms, one sending the monochromatic light on the sample with an illumination spot of around 1.3x1.7mm in diameter and the other holding two detectors (visible and near-infrared) that collect the reflected light. Our analyses' incidence and emergence angles are equivalent to i =0° and e =30°. The light source is a 250 W commercial quartz-tungsten halogen lamp and, a silicon photodiode detector is used to cover the range up to 1.0 µm, and an InSb photovoltaic detector cooled at 77 K is used for higher wavelengths. The reflectance spectra acquired in this work have a constant spectral sampling of 10 nm with a spectral resolution of 4.8 nm (from 0.5 to 0.67 microns), 9.3 nm (from 0.68 to 1.59 microns), 19.2 nm (from 1.60 to 2.83 microns), and 38.8 nm (from 2.84 to 3.6 microns). Reference material was Spectralon and Infragold from Labsphere for VIS/NIR and MIR ranges, respectively. The absolute photometric accuracy of the instrument is 1 % (Potin et al. 2018).