The case for a rectangular format space telescope for finding exoplanets

We suggest that rectangular primary-mirror telescopes provide a clearer path to discovering habitable worlds than other designs currently being pursued. We show that a simple infrared ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:mi>λ</mml:mi><mml:mo>∼</mml:mo></mml:mrow></mml:math> 10 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m2"><mml:mrow><mml:mi>μ</mml:mi></mml:mrow></mml:math> m) telescope design with a rectangular mirror 20 m in length and 1 m in width, combined with technology already developed for JWST, can discover <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m3"><mml:mrow><mml:mo>∼</mml:mo></mml:mrow></mml:math> 11 habitable exoplanets and measure ozone in their atmospheres in a mission of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m4"><mml:mrow><mml:mo>∼</mml:mo></mml:mrow></mml:math> 1 year. A mission of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m5"><mml:mrow><mml:mo>∼</mml:mo></mml:mrow></mml:math> 3.5 years could plausibly discover <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m6"><mml:mrow><mml:mo>∼</mml:mo></mml:mrow></mml:math> 27 habitable exoplanets closer than 10 pc to the Earth, and determine whether there is ozone in their atmospheres. A square primary mirror with the same collecting area cannot resolve exoplanets that are within 0.23″ of the host star, making it impossible to detect most of the nearby Earth-like exoplanets. The idea of collecting light with a high aspect ratio rectangular mirror could be used at any wavelength. It is particularly useful for measuring point sources with very small angular separations, as is required for exoplanet observation.