Back to Volume
Paper: Flat mirror optics to study extra-solar terrestrial planets from space
Volume: 194, Working on the Fringe: Optical and IR Interferometry from Ground and Space
Page: 389
Authors: Angel, R.; Burge, J.; Woolf, N.
Abstract: The Terrestrial Planet Finder (TPF) is currently envisioned as a 75-1,000 m, interferometer with four free-flying elements to detect and obtain spectra of extra-solar Earth-like planets. Because of the ambitious nature of the mission, a low-cost, precursor interferometer capable of detecting the nearest extra-solar planets would be very beneficial. It has been argued (P. Bely et al, N. Woolf et al) that a modestly sized nulling interferometer with two to four elements could be built within the budget of a Discovery mission. We consider here a promising new design with three elements extending over 12 m. The unique feature of the design is an asymmetric beam pattern, allowing distinction of planetary signals from zodiacal emission. The interferometer could fit into a Δ-class rocket with a single fold, and be light enough for insertion into a 1 x 3 AU elliptical orbit. Even at 3 AU, the nulling precision would only need to be 104, to get the residual stellar flux below the solar zodiacal level, relaxing the more stringent requirements (106) for the TPF. Observing in the 7-13 micron range, the instrument would use single-pass beam-splitters, keeping the throughput of the system high. The beam-splitter design allows common path, simultaneous phase monitoring at 2 microns. Integration times of approximately 7.5, 3.9, and 0.8 days would be needed to detect Earth-like planets at 10 pc with relatively simple, passive mirror elements of 0.85, 1, and 1.5 m respectively. Thus the mission could find the first Earth-like planets, if they are common. In addition, it would test the critical nulling technologies needed for any spectroscopic follow up missions.
Back to Volume