Characterizing Exoplanets in the Visible and Infrared: A Spectrometer Concept for the EChO Space Mission

TL;DR

This paper assesses the design of a spectrometer for the EChO space mission, aimed at characterizing exoplanet atmospheres through transit spectroscopy in visible and infrared wavelengths.

Contribution

It presents a detailed evaluation of the EChO spectrometer concept, highlighting its design choices driven by the need for high photometric stability for exoplanet atmospheric studies.

Findings

Spectrometer covers 400 nm to 16 microns simultaneously.

Design achieves the necessary photometric stability for EChO.

Performance evaluations confirm suitability for exoplanet characterization.

Abstract

Transit-spectroscopy of exoplanets is one of the key observational techniques to characterize the extrasolar planet and its atmosphere. The observational challenges of these measurements require dedicated instrumentation and only the space environment allows an undisturbed access to earth-like atmospheric features such as water or carbon-dioxide. Therefore, several exoplanet-specific space missions are currently being studied. One of them is EChO, the Exoplanet Characterization Observatory, which is part of ESA's Cosmic Vision 2015-2025 program, and which is one of four candidates for the M3 launch slot in 2024. In this paper we present the results of our assessment study of the EChO spectrometer, the only science instrument onboard this spacecraft. The instrument is a multi-channel all-reflective dispersive spectrometer, covering the wavelength range from 400 nm to 16 microns simultaneously with a moderately low spectral resolution. We illustrate how the key technical challenge of the EChO mission - the high photometric stability - influences the choice of spectrometer concept and drives fundamentally the instrument design. First performance evaluations underline the fitness of the elaborated design solution for the needs of the EChO mission.