Mars

Mars is the 4th planet of the Solar System and was featured prominently during Season Twenty.

Background
After having all of his electronic devices broken, Eric Cartman forms a close relationship with Heidi Turner. She briefly shows him her vagina, prior to "Wieners Out", and in that instant he realizes that humans can colonize Mars.

Mars is mentioned again in "Douche and a Danish", when Heidi and Eric have a sing-along in the school cafeteria making danishes for Denmark.

In "Fort Collins", Heidi and Eric are at M Burgers eating, when Eric has a daydream about Mars. In his dream, he imagines a Mars colony with rollercoasters and numerous buildings. Later, after realizing Heidi may be able to access his internet history, Cartman's daydream about Mars becomes clouded with a severe dust storm.

With TrollTrace.com coming online soon, Heidi and Eric rush to SpaceX's headquarters in "Oh, Jeez". They are desperate to get to Mars immediately, where there is no access to the internet.

In "Members Only", Heidi and Eric are given a tour of SpaceX by Elon Musk. They are joined by Butters Stotch, who not only has a change of heart, but is also interested in going to Mars. Much to their chagrin, they do not get to go to Mars.

Prominence

 * "Wieners Out"
 * "Douche and a Danish"
 * "Oh, Jeez"
 * "Members Only"