Dr Ciaccio (not a doctor) looks at a new form of levitation that uses carbon nanotubes to harness light energy to float on a little puff of excited air. Also, what's causing cacao trees to produce fewer seeds, threatening our supplies of delicious chocolate and cocoa? In some good environmental news, The Great Green Wall of Africa just got a big boost. And in Space Madness, NASA's Perseverance Rover is mere days from a dramatic and dangerous unassisted landing on Mars.