Development of an Ultra-Stable Mid-Infrared Spectrometer for Space-Based Exoplanet Transit and Phase Curve Spectroscopy

We have built an ultra-stable laboratory spectrometer, called MIRASET (Mid-IR Array Spectrometer demonstration for Exoplanet Transits), that will demonstrate a new method to extract mid-infrared spectral lines observed in the atmospheres of transiting planets around M-stars. Those lines potentially indicate the presence of life on the planet. This goal is achieved by using a black body source as a calibration reference, which in the laboratory experiment also simulates the emission of the M-star. The black body emission source will be tuned to dissipate the equivalent power on the detectors that would be observed from Proxima Cen B and Trappist-1 if they were observed with a space-based observatory such as ORIGINS or a dedicated MIR exoplanet mission such as MIRECLE. Furthermore, we use a laser that simulates a spectral line from the planet. We constantly monitor the temperature of the black body with high precision by using a photodiode measuring the black body in the visible. We will demonstrate the ability to monitor the black body emission over a several hour period, superimposed with a laser-generated spectral line, down to a photometric precision of 5ppm, while demonstrating the spectral stability of the spectrometer. This precision constitutes the requirement for the detection of important atmospheric lines from earth-like planets around M-stars