Demonstration of the exoplanet detection process using four-beam nulling interferometry

The Planet Detection Testbed has been developed to simulate and test the detection process for an infrared nulling interferometer observing an earthlike planet orbiting a nearby star within about 15 pc of the solar system. The testbed combines eight beams of infrared light, four from the star and four from the planet, simulating an ‘Xa-rray’ telescope spacecraft formation. The detection process involves stable nulling of the starlight, rotation of the spacecraft formation, averaging over a few hours and testing of the signal against predicted exoplanet signatures. The testbed simulates all parts of the detection process except operation in broadband light, which is a planned upgrade for the future. This paper describes the latest results and plans for exoplanet signal simulation, deep starlight nulling and planet detection at star to planet contrast ratios of one million to one. These results are planned to demonstrate the feasibility of exoplanet detection using nulling interferometry at near-flightlike contrast ratios.