In March 2015, a Liberian woman contracted Ebola via sexual intercourse with a man who had survived the disease. Ebola virus RNA had remained in his semen 199 days after he first became ill. Science journalist and author Maggie Koerth-Baker talks about the public health implications of sexually transmitted Ebola. She also discusses space mining and other selected short subjects in science this week.

Plus, electronic payments systems like Google Wallet and Apple Pay are starting to catch on in the U.S., but in countries like Sweden, where only 40 to 60 percent of cash is being circulated, people are already bucking their banknotes. Journalist Helen Russell weighs the pros and cons of a country going cashless.