Detection and characterization of extra-solar planets: Future space missions

Various techniques are being used to search for extra-solar planetary signatures, including accurate measurement of positional (astrometric) displacements, gravitational microlensing, and photometric transits. Planned space experiments promise a huge increase in the detections and statistical knowledge arising from transit and astrometric measurements. Direct detection of even nearby Earth-mass planets in the habitable zone and the measurement of their spectral characteristics, typified by the TPF and Darwin missions, represents a considerable challenge. Beyond TPF/Darwili, Life Finder would aim to produce confirmatory evidence of the presence of life, while an Earth 'imager', some massive interferometric array providing resolved images of a distant Earth, appears only as a distant vision. A 10 nano-aresec astrometric mission would detect 'Earths' systematically out to 100 pc.