Thousands are heading to Washington for Trump's inauguration — many of them to protest the event. Rally, a tech platform that connects riders with transportation to big events, is getting a lot of business right now thanks to anti-Trump activists. Co-founder Siheun Song explains how the service works. Next, we'll step outside of the planet to look at evidence from Mars rover Curiosity about possible mud cracks on the planet, which could tell us something about the possible history of life there.