The Heroes of the world were the first group of people selected to go on the Mars One mission. After it's successful launch in 2023 the term was coined by then President Jon Huntsman and was used to describe the team ever since.
The team of astronauts are regarded higher than rockstars in popularity and their lifestreams are watched daily by more than 3 Billion people on Facebook. If they wanted to come back to Earth they would be worshipped as Gods, but that's part of the deal. When you go on the Mars One mission, you don't come back to Earth!