In the United States, some 10% of people who wish to have children struggle with infertility. It's prevalent in the African American community, and fertility preservation can also be difficult for transgender individuals. But why is this? And what can be done about it? NOVA explores barriers to fertility, from the social to the biological, and the state of assisted reproductive technologies. Follow the journeys of people navigating challenges from structural inequalities and racism to falling sperm counts, egg freezing, and IVF. 

Can new emission-free electric planes replace our polluting airliners and revolutionize personal transportation in our cities? NOVA takes you for a ride in some impressive prototypes that are already in the air, from speedy single-seat planes that can take off like a helicopter but are half as noisy to  "self-flying" air taxis that already taking passengers on test flights in Chinese cities. But if electric airplanes are ever to advance beyond small, short-haul craft, significant hurdles of battery weight, energy storage and cooling remain to be overcome. How long will it be before the dream of super-quiet, super-efficient airliners becomes a reality?