Mission to Alpha Centauri

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A system of planets with masses and orbital periods similar to Venus, Earth and Mars should be detectable in the nearby alpha Centauri star system using the current Doppler precision of 2 m/s and extreme cadence: hundreds of observations per night, every possible night. This observing cadence could achieve an effective (phase-binned) precision of a few centimeters per second, which would be sufficient to detect the reflex motion caused by such planets.This award will fund an initial 12-month program in which Dr. Fischer and collaborators will use the recently decommissioned Blanco spectrometer, fiber-coupled to the 1.5-m Small and Moderate Aperture Research Telescope System (SMARTS) consortium telescope at the Cerro Tololo Interamerican Observatory (CTIO). Preliminary observations made in August 2007 provided a promising set of radial velocities for the Sun, suggesting that this spectrometer should be capable of producing high precision radial velocities. This program has the potential to catalyze dramatic changes in the strategy for ground-based Doppler surveys that will help inform future allocation of science funding and resources.This program is a critical step for assessing whether the Doppler technique can be extended to the search for potentially habitable, terrestrial planets. The results could impact funding and programmatic decisions about space missions and could contribute to informing the next Decadal Review about planet detection strategies. This program will also re-invigorate use of a currently undersubscribed 1.5-m telescope at CTIO, providing an important new capability to SMARTS and the user community in general. The observations will also provide unprecedented information about stellar structure and convective zones, differentially comparing the GO star, alpha Centauri A, and the KO star, alpha Centauri B.