Colony on Mars needed within 46 years

“The sobering facts,” Dr. Gott says, “are that in a 13.7 billion-year-old universe, we’ve only been around 200,000 years, and we’re only on one tiny planet. The Copernican answer to Enrico Fermi’s famous question — Where are the extraterrestrials? — is that a significant fraction must be sitting on their home planets.”

It might seem hard to imagine that humans would invent rockets and then never use them to settle other worlds, but Dr. Gott notes that past civilizations, notably China, abandoned exploration. He also notes that humans have been going into space for only 46 years — a worrisomely low number when using Copernican logic to forecast the human spaceflight program’s longevity.

Since there’s a 50 percent chance that we’re already in the second half of the space program’s total lifespan, Dr. Gott figures there is a 50 percent chance it will not last more than another 46 years. Maybe the reason civilizations don’t get around to colonizing other planets is that there’s a narrow window when they have the tools, population and will to do so, and the window usually closes on them. “In 1970 everyone figured we’d have humans on Mars by now, but we haven’t taken the opportunity,” Dr. Gott says. “We should it do soon, because colonizing other worlds is our best chance to hedge our bets and improve the survival prospects of our species. Sooner or later something will get us if we stay on one planet. By the time we’re in trouble and wish we had that colony on Mars, it may be too late.”