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 CO2 band (1.58 µm) and the CH4 band (1.65 µm). This paper describes the technical characteristics of the device as well as the results of its ground-based calibrations.