Can we find Earth-mass planets orbiting our nearest star, alpha centauri?

I will describe a new program at Mt John that aims to find Earth-mass planets orbiting either alpha Cen A or B, which are solar type stars in a well known binary. We are measuring precise radial velocities using the Hercules spectrograph, which I will describe. At least 10000 spectra at S/N ~ 500:1 giving 1 m/s precision will be needed. Theoretical studies show that Earth mass planets can have stable orbits to 3 AU and that such planets will form from a proto-planetary disk, for a wide range of initial conditions.