How Rosetta can help decipher a comet’s secrets

After a 10-year journey, the space probe Rosetta is orbiting a comet 250 million miles away from Earth. The spacecraft is slated to follow the comet for more than a year on its way toward the sun. Hari Sreenivasan talks to Mark McCaughrean, senior scientific advisor of the European Space Agency, about sifting through a cosmic “garbage pile” in hopes of learning about the building blocks of life.