Will humans be going to planets around other stars?

by Salman Hameed

Well, I believe in the Star Trek universe - and so I do think that we will be able to figure out a way to travel to planets around other stars. But the author of the fantastic Mars Trilogy (Red Mars, Green Mars, and Blue Mars), Kim Stanley Robinson doesn't think so. From last week's Nature:

Kim Stanley Robinson, author of the bestselling Mars Trilogy, takes a radical view. He suggests that we get over the idea of interstellar travel altogether: a probe would take 28,000 years to get to Alpha Centauri. “We can't go fast enough to get to any of these places,” he says. 

Barnard's star was once “the place for nearby space”, Robinson says, as his novel Icehenge (Ace, 1984) — in which characters build a starship headed for it — attests. Now that researchers have identified some 840 exoplanets, and NASA's three-year-old Kepler space telescope has spotted 2,320 candidate planets, “there may never again be a single default destination”, Robinson continues. 

In his recent book 2312, which imagines humanity three centuries from now, spread across terraformed planets, asteroids and moons in our own Solar System, Robinson writes frankly about the galactic hinterland we inhabit. “The stars exist beyond human time, beyond human reach,” says the narrator. “We live in the little pearl of warmth surrounding our star; outside it lies a vastness beyond comprehension. The solar system is our one and only home.” 

Of the idea that we are destined to go to the stars and inhabit, if not the whole Universe, maybe the whole galaxy, Robinson cautions “it's a fantasy, of power, transcendence and a kind of species immortality. We have to get more realistic.”

May be the problem lies in our neighborhood. We live on a minor spiral arm located about 30,000 light years from the center of the Milky Way (see the schematic below).

In a denser part of the Galaxy, we would have needed a much shorter time to get to an exoplanet. But then, we would also have been exposed to a greater probability of having a star explode nearby destroying most of the life on the planet. A globular cluster, containing a 100,000 to a million stars, would also have been an interesting place. But then there may not be many stars with planets in the globular clusters (Messier 80, below).

Okay - but in any case, we are now stuck here, in the suburbs of our galaxy. I think we will be able to figure out a way to beat the speed of light - or somehow work around it. Otherwise, we are looking at slow solar system expansion for the next several centuries...