This is part of our five-episode pack on how science and technology can fight climate change. With better air conditioning, more whale poop, souped-up plants, and a giant vacuum. If all else fails, planet B. With David Biello, science curator at TED, author of The Unnatural World: The Race to Remake Civilization in Earth’s Newest Age, and contributing editor at Scientific American.

Mars is the escape hatch, the backup plan. Planet B. Except for one thing. Mars is uniquely hostile to humans. Its surface is basically rocket fuel. Which means that for Mars to sustain human life, it needs a lot of support from Earth. Oops.

So why talk about it at all? Because it sparks innovation - solar panels were an offshoot of the space race. Because it’s freaking cool. And because it inspires. But let’s not put all our eggs in that space shuttle just yet.