Kate Becker The Visible Universe
Kate Becker The Visible Universe

It's summer, and it's vacation time: Time to go away, and then — the best part — come back to a home that feels more like home than it did before you left.

Home bed, home pillows, home couch; home food in the fridge and home sounds out the windows. And then, after a while, when the routine gets too routine, it's time to do it again, rehashing the annual mini-odyssey of airport shuttles, rental cars and hotel keycards.

Whether the main pleasure of travel is actually the traveling part or the coming home part is, I guess, a matter of taste. But the wheels of every suitcase turn on the push and pull of familiar and unfamiliar, comfort and thrill, newness and routine.

Maybe that's why tourists in New York get dinner at Applebee's and souvenirs at Bed Bath & Beyond. And maybe it's why we dream about going to Mars... and making it more like Earth.

The idea of "terraforming" Mars into a place where humans can live and breathe, no protective suits or pressurized habitats required, goes back at least to the 1940s. One way to do it: Take greenhouse gases that are locked up in the Martian soil or ice, set them loose in the air, and wait for the new and improved atmosphere to trap enough heat to keep the planet nice, cozy and wet.

Sounds easy enough, right?

Not exactly, according to a new analysis led up by the University of Colorado's Bruce Jakosky, principal investigator on the Mars Atmosphere and Volatile Evolution (MAVEN) mission.


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Jakosky and his co-author, Christopher Edwards of Northern Arizona University, estimated how much carbon dioxide could be currently tied up in Mars' polar ice caps, dust, rocks and mineral deposits. The result wasn't encouraging. Even if you did "mobilize" the scant carbon dioxide that does exist on Mars — by, say, heating up the polar caps and strip-mining and cooking mineral deposits — the newly enriched atmosphere would probably only nudge the Martian thermostat up by 10 degrees Celsius or so, not nearly enough to transform the Martian ice into stable liquid water.

"But wait!" you say. "Didn't Mars used to be warm and wet? What happened to that nice, thick atmosphere?"

For years, planetary scientists thought that Mars' ancient, disused carbon dioxide might be buried deep in carbon-containing minerals. But the latest thinking, based on observations from MAVEN and the Mars Express orbiter, is that most of the old atmosphere flew off into space more than a billion years ago. The buried treasure simply isn't there. We will have to put the vision of a green Mars on hold, at least until technology catches up to our imagination.

But the remoteness of the terraforming dream hasn't cooled the debate over whether it's actually a good idea or not. Champions of the concept approach it with near-religious zeal.

"I would say that failure to terraform Mars constitutes failure to live up to our human nature and a betrayal of our responsibility as members of the community of life itself," wrote Robert Zubrin, founder of the Mars Society, in his 1996 book "The Case for Mars."

Other see it as a practical back-up plan for the apocalypse that, given enough time, is surely coming. As Michio Kaku writes in "The Future of Humanity," an appeal for an interplanetary future, "Nature will eventually turn on us."

The natural rejoinder, of course, is that we should solve our problems here on Earth before we start exporting them elsewhere. But while a trip to terraformed Mars may be nothing more than armchair rocketry, it can still have here-and-now consequences. When we contemplate how we would remake Earth; when we imagine ourselves as the aliens; when we ask what we would do if given the chance at a whole-planet do-over; it changes our perspective on today's problems.

And when we open our eyes and come back from the daydream, we may just see home in a new way.

Kate Becker is a science writer living in Boston. Contact her at spacecrafty.com, or connect via facebook.com/katembecker or twitter.com/kmbecker.