Exoplanet detectability with a space-based 3, 4 and 5 telescope Kernel-Nulling Architecture
Abstract
Detecting thermal emission from terrestrial exoplanets at wavelengths between 5 and 20 microns is one of the key goals for space-based exoplanet instrumentation. The mid-infrared arguably contains more diagnostic capability than optical wavelengths, including a direct measurement of planetary radius, independent of albedo. The baseline configuration of the Emma X-array for Darwin was designed to have a second order null and interferometric chopping for robust background subtraction. Although it wasn't realised at the time, the chopped output of this configuration was a kind of "kernel-null", which is a beam combiner architecture robust to phase or intensity errors to second order (including an imperfect nulling stage). Kernel nullers can also be construed from 3, 4 and 5 telescope arrays. If the number of spacecraft was a strong cost driver, a 3 telescope array would be adequate. We argue that for the numerous temperate exoplanets around low mass stars (e.g. tau Ceti), stellar leakage limits the sensitivity of the Emma X-array configuration, proving a strong argument for a 4th order null if possible. Increasing the number of apertures to 5 greatly improves the survey effectiveness and robustness of a space interferometer, and allowed the inclusion of a 4th order null. Finally, we briefly describe the technological pathway we are taking to demonstrate key components of this architecture, including multi-telescope photonic nullers, interspacecraft metrology and full system demonstration of a space interferometer architecture.
- Publication:
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43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E.506I