The RUSALKA device for measuring the carbon dioxide and methane concentration in the atmosphere from on board the International Space Station

Abstract

The high-resolution near-IR RUSALKA spectrometer is intended for developing a technique for measuring the carbon dioxide and methane concentrations in the atmosphere from on board the International Space Station. It consists of two main elements: an echelle spectrometer and an acoustooptic tunable filter used to select the diffraction orders of the grating. The device provides high resolving power (at least 20 000) in the 0.73–1.68 −µ m region, is compact, has low weight, and contains no moving parts. The concentrations of the gases are determined from the unsaturated lines of the CO<sub>2</sub> band (1.58 µm) and the CH<sub>4</sub> band (1.65 µm). This paper describes the technical characteristics of the device as well as the results of its ground-based calibrations.