Nulling interferometry for extra-solar planet detection: sensitivity & image reconstruction

A typical star is more than a million (in infrared) to a billion (in optical) times brighter than a planet. As a result, without special efforts to suppress the starlight, a planet is undetectable in the star's glare. Nulling interferometers suppress starlight by pointing a null in the interference fringe pattern on the star while pointing a fringe maximum in the direction of the planet. Images of planetary systems are not formed by direct imaging; instead, these are reconstructed after measurements have been with the multiple orientations in and configurations. This paper addresses the image reconstruction issues for nulling interferometer arrays and the sensitivities for planet detection. Nulling interferometers operating in 1 AU Orbit with four 3.5-m telescopes can both detect Earth-like planets at distances as far as 15 parsec and characterize the planet's atmospheric emission for biosignatures. Smaller versions of the nulling interferometer arrays will have the potential to study the giant planets around nearby stars. A 3-element nulling interferometer with telescope sizes 0.5 m-1 m, on 20 m baseline will have the sensitivity to study Jupiters up to 10 parsec with a few hours integration and to detect Earth-size planets at 6 parsec with longer integration of 2 days.