Development of spectrometers for the TANGO greenhouse gas monitoring missions

Abstract

The current paper introduces the Twin ANthropogenic Greenhouse Gas Observers (TANGO) instruments and mission. The purpose of TANGO is monitoring and quantifying greenhouse gas emissions, with a focus on characterizing emission sources down to the level of individual facilities. The TANGO mission was developed for the ESA-Scout program by a consortium consisting of ISISpace, TNO, SRON and KNMI. It consists of two agile CubeSat satellites that fly in tandem, with less than 1 minute between observations of the same target, each satellite equipped with a spectrometer of the TNO Spectrolite family of instruments that observes a different part of the spectrum. TANGO-Carbon measures emission of CH₄ and CO₂ in the SWIR1 spectral band. TANGO-Nitro measures emission of NO₂ in the visible spectral range. The Nitro instrument has a multifunctional role, using the NO₂ measurements to improve the detection of (anthropogenic) CO₂ plumes, deriving historic CO₂ emission trends based on available global NO₂ observations, and quantifying the possible CO₂ contribution in mixed CH₄-CO₂ sources. Each TANGO instrument fits in an 8U volume (on a 16U platform) and are all-aluminium, reflective pushbroom spectrometers covering a 30-km swath from a 500-km altitude, with a ground sampling distance of 300 m × 300 m. In this paper we will present the mission, the shared instrument concept, as well as the design and performance of both Carbon and Nitro instruments.