Field Test of the Water-Wheel IR (WIR) Spectrometer on Evaporative Salt Deposits at Tibetan Plateau

Abstract

The WIR: The Water-Wheel IR instrument is a NIR (1-5 μm) reflectance spectrometer using active sources. The WIR experiment[1] is designed to detect directly water in different forms (liquid, ice, or clathrates, structural H2O and OH, and water adsorbed on mineral surfaces), carbonates, sulfates, and C-H & NH bonds in organic species on planetary surfaces. Technically, there are two ways to deploy a WIR unit. One we called “contact survey”, i.e., to install a WIR unit inside of a well set into the middle wheel of a planetary rover, to take fast measurement without interfering the normal operation of the rover. Thousands patches of disturbed soils can be examined during a rover travel to provide the information on the spatial distribution of the above-mentioned phases. The S/N of the spectra will be high because the measurements will be made at short distance (~ cm). Another way is to deploy a WIR unit onto any desired surface (rock or soil without sample prep) by a robotic arm of a planetary rover or lander. The phase-II version of WIR has a size of 10x7.5x6.5cm, mass of 450 grams, power consumption of 4W, and output data through a USB cable [2]. It covers a spectral range from 1.25 to 2.5 μm in 128 spectral channels. By putting a rugged frame that provides protection against dust and humidity in harsh environments, it has been transformed into a rugged, field portable NIR reflectance spectrometer that is able to operate in tough field conditions, including dusty and cold environments. The field sites in 2008 campaign on Tibetan Plateau: The WIR (Fig. 1) was tested during a field campaign in Da Qaidam Lake, Xiao Qaidam Lake, and Da Langtan playa (Fig. 2), on Tibetan Plateau (China) in the fall 2008. The climatic conditions and salt mineralogy within the lacustrine deposits of the Qaidam basin on Tibetan Plateau indicate that this area can be an excellent analog site for studying the precipitation sequence and subsequent dehydration/degeneration of Martian salts. Related abstracts [3, 4] in this volume provide detailed information on these field sites.