Cape Canaveral, Fla. ? NASA’s planet-hunting spacecraft, Kepler, rocketed into space Friday night on a historic voyage to track down other Earths in a faraway patch of the Milky Way galaxy.

It’s the first mission capable of answering the age-old question: Are other worlds like ours out there?

Kepler, named after the German 17th century astrophysicist, set off on its unprecedented mission at 9:49 p.m CST, thundering into a clear sky embellished by a waxing moon.

Its mission will last at least 3 1/2 years and cost $600 million.

The goal is to find, if they’re there, Earth-like planets circling stars in the so-called habitable zone — orbits where liquid water could be present on the surface of the planets. That would mean there are lots of places out there for life to evolve, said Kepler’s principal scientist, Bill Borucki.

On the other hand, “if we don’t find any, it really means Earths are very rare, we might be the only extant life and, in fact, that will be the end of ‘Star Trek.'”