P. R. Lawson 1 , O. P. Lay 1 , S. R. Martin 1 , R. D. Peters 1 , R. O. Gappinger 1 , A. Ksendzov 1 , D. P. Scharf 1 , A. J. Booth 1 , C. A. Beichman 2 , E. Serabyn 1 , K. J. Johnston 3 , W. C. Danchi 4 1 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA 2 Michelson Science Center, California Institute of Technology, Pasadena, CA, USA 3 US Naval Observatory, Washington, DC, USA 4 NASA Goddard Space Flight Center, Greenbelt, MA, USA ABSTRACT This paper provides an overview of technology development for the Terrestrial Planet Finder Interferometer (TPF-I). TPF-I is a mid-infrared space interferometer being designed with the capability of detecting Earth-like planets in the habitable zones around nearby stars. The overall technology roadmap is presented and progress with each of the testbeds is summarized. Keywords: Interferometry, astronomy, extrasolar planets, nulling, formation flying 1. INTRODUCTION AND OVERVIEW The Terrestrial Planet Finder Interferometer (TPF-I) is a concept for a formation-flying interferometer designed to measure mid-infrared spectra of the atmospheres of Earth-like exoplanets. The primary goal of the mission is to find evidence of biological activity on planets around nearby stars. The mid-infrared provides several key biomarkers and a favorable planet-star contrast ratio. An interferometer is a compelling choice for the design of a such a mid-infrared observatory because the interferometric baselines provide unrivaled angular resolution. This is vital for unambiguous orbit determination, distinguishing multiple planets, and discrimination against structure in the exozodiacal disk. This angular resolution also provides a small inner working angle, giving access to a very broad range of target stars. In this regard, TPF-I far exceeds the predicted capability of other proposed planet-finding missions. TPF-I has been developed as a possible future collaboration between NASA and the European Space Agency (ESA). This paper provides an update to the reviews presented at SPIE conferences in 2006 1 and 2007. 2 The major achievements and/or changes in 2007–2008 have included the following: • Completion of Milestone #1: the compensation of intensity and phase demonstrated by the Adaptive Nuller testbed. Intensity was compensated to within 0.2% and phase to within 5 nm rms across a 3-μm band centered at 10-μm. 3, 4 • Completion of Milestone #2: a demonstration of precision formation maneuvers in a ground-based robotic testbed, with performance traceability to flight. 5, 6 • The demonstration of nulling over a 32% bandwidth centered at a wavelength of 10 μm at a level of 1.1 × 10 -5 using the Adaptive Nuller. 4 • An increased emphasis on the design of a reduced-scope mission. 7 • The adoption of the Emma X-Array by both the TPF-I Project and the Darwin proposal team as the baseline mission design for TPF-I and Darwin. 8 Further author information: Send correspondence to Peter Lawson, Jet Propulsion Laboratory, MS 301-451, 4800 Oak Grove Drive, Pasadena CA 91109-8099, USA. E-mail: Peter.R.Lawson@jpl.nasa.gov, Telephone: +1 (818) 354-0747. Optical and Infrared Interferometry, edited by Markus Schöller, William C. Danchi, Françoise Delplancke Proc. of SPIE Vol. 7013, 70132N, (2008) · 0277-786X/08/$18 · doi: 10.1117/12.786822 Proc. of SPIE Vol. 7013 70132N-1 2008 SPIE Digital Library -- Subscriber Archive Copy