We've known about water on Mars for a long time — so why's there all this hype around liquid water? It's not the first time someone's suggested liquid water flows, but this week's result does provide new evidence. Liz and Emily discuss hipster scientists ("Congratulations — you've discovered water on Mars for the 1,000th time!"), the relatively slow pace of scientific discovery and confirmation, and what the finding means for the possibility of extraterrestrial life. Does some extreme bacteria kick around on Mars? We don't know, but we're willing to speculate wildly.
Emily wonders if all the excitement is due to Matt Damon's The Martian, which comes out on Friday — and which is part of a new trend in space movies to examine the nuts-and-bolts problems of survival. And finally, Liz vents some frustration about an error-filled investigation into dietary guidelines committee — one that may have political consequences, since the medical journal that published it is doubling down on mistakes. Given how much we know about the rest of the world, why is food science so hard? (Answer: because food isn't just nutrition.)