Commentary Magazine

Alpha Centauri, Here We Come

Wikipedia Commons.

You can’t criticize NASA for failing to plan ahead. It is now in the earliest stages of planning an expedition to our nearest stellar neighbor, Alpha Centauri. The hoped-for launch date is 2069, 51 years from now, to celebrate the 100th anniversary of the Apollo 11 expedition to the moon.
The moon is about 225,000 miles away. Alpha Centauri is  4.3 light years away. That’s almost 115,000,000 times as far. The fastest a man-made object has ever moved is about 50,000 miles per hour. At that speed, a space probe would need about 58,000 years to get to Alpha Centauri. Obviously, a radically new propulsion system will be needed, and NASA is hoping to develop one that will push the space probe up to 10 percent of the speed of light. Even then it will take 43 years to get there.
In other words, if it launches in 2069, it will roll into the Alpha Centauri system in 2112. We will learn that it got there in 2116, as it will take 4.3 years for the radio signal to get back to earth. Such a propulsion system would radically reduce the time needed to visit solar system objects. It could get a probe to Pluto in a few days instead of the nine and a half years needed for the New Horizons probe to reach Pluto in 2015.
Alpha Centauri, one of the brightest stars in the night sky, is in the southern hemisphere, and you need to be at least in southern Florida to see it. It’s a double star, one with about 1.1 solar masses and the other about .9 solar mass. They are separated by an average distance about equal to the distance between the sun and Saturn, but the orbit is quite elliptical, and an orbit is completed only once in 79 years. They appear as one star to the naked eye, but ordinary binoculars will separate them.
We understand the stars very well already, thanks to earth-bound observations. Or, at least, we think we do. So the value of the expedition would be in exploring the system’s planets and moons assuming it has some. We’re pretty sure already that the smaller star has a planet.
But, at heart, NASA is planning to go to Alpha Centauri for the same reason people climb Mt. Everest: because it’s there and we can. I can’t wait. After all, I’ll only be 125 when it launches and 172 when we get confirmation of success.