at a distance of about 1/6 of a light year. Proxima Centauri is a type dM5e red dwarf, which exhibits sudden changes in magnitude. It is also one of the smallest known stellar masses. Proxima's position should provide and opportunity for the probe to pass relatively close by on its way to its final destination, a close orbit about Beta Centauri. There is also the possibility that this star system contains planets. Advances in astronomy before the probe is launched should provide much more information about the system to help plan the probe's exploration.
Perhaps the greatest contribution that the mission will make to the scientific community will be in the field of astrometry. Sending a spacecraft to the Alpha Centauri system provides an opportunity to make parallax measurements with a baseline of 4.34 light years (see Fig 2.1a). This is over 63,000 times longer than the present method, which uses the semimajor axis of Earth's orbit as a baseline (see Fig 2.1b). At this time, parallax measurements are only accurate to about 20 parsecs from the Sun. The longer the baseline would allow accurate measurements of stellar distances of more than 1.2 million parsecs. If the probe lasts long enough, it has the potential to accurately determine the distance to hundreds of trillions of stars. Knowing the distance to a star is vital in determining its properties. Such an accomplishment would keep astronomers busy for quite some time.
