The serious government search for UFOs. What the death of Keystone XL could mean for Big Oil. And, what we know about how covid affects the brain. Read more:Are we alone in the universe? The U.S. government has been investigating that question for years. Reporter Jacqueline Alemany on the serious search for UFOs. The company behind the Keystone XL pipeline is shutting down the project after years of lawsuits and public blowback. Juliet Eilperin reports.Scientists are still trying to understand how the coronavirus affects the brain. Frances Stead Sellers reports.