Some molecules - ammonia, carbon dioxide, water - show up everywhere in the universe, whether life is present or not. But others pop up especially in the presence of life itself. Among the biomarkers in Earth's atmosphere are ozone-destroying chlorofluorocarbons from aerosol sprays, vapor from mineral solvents, escaped coolants from refrigerators and air conditioners, and smog from the burning of fossil fuels. No other way to read that list: sure signs of the absence of intelligence.
Neil deGrasse TysonTo view space as, "Well, let's go to Mars now," or "Let's do this now," maybe we should rethink of space as our backyard and have a suite of launch vehicles that can enable any ambition a person has regarding space. It's the same way you can go to buy a car: I want to go offroading, I'll buy this model. I'm a city driver, that's this model. I want to use less fuel, well, that's this model. They're not selling you one car, you have options. So when I think of space, I think of having options.
Neil deGrasse TysonMy goal is not to shove information into your head. It's to find ways to reignite the curiosity that we all had as children for the natural world. You don't have to tell a child to explore the backyard.
Neil deGrasse Tyson