Should we be putting humans on Mars? A panel of space experts brings up the big questions we need to ask before we blast off.

People are obsessed with Mars. But … why? Two confessed super-fans, Andy Weir, author of “The Martian,” and Stephen Petranek, author of “How We’ll Live on Mars,” share thoughts on why being Mars-mad is a reasonable state of mind.

Author Stephen Petranek makes the case that humans will live on Mars in the not-too-distant future. He explains how and when this might happen — and what risks those who head there first might face.

Humans are off to live on Mars. At least, that’s the case journalist Stephen Petranek makes in his TED Book, “How We’ll Live on Mars.” According to Petranek, the move is no less than an “essential back-up plan for humanity.” Here, he shares just some of the factors those who make the first trip will have to manage.

Nathalie Cabrol looks for life on Mars by studying extreme places on Earth, where the atmosphere is thin, ultraviolet radiation is high and the temperature is varied. See photos from her expeditions.

And you think your commute is bad. On November 12, 2014, the Philae probe finally landed on a comet some 10 years after it left Earth. Fred Jansen, who manages the mission for the European Space Agency, remembers some of the key moments that led up to the landing. | Gif by Cesar Pelizer for TED

Take a look at the companies and spacecraft that NASA thinks might help lead humanity’s journeys into space.