Elon Musk, the billionaire CEO of the commercial spaceflight company SpaceX and the electric car company Tesla, made a guest appearance on The Simpsons on Monday.

While the episode, titled "The Musk Who Fell To Earth," calls Musk "possibly the greatest living inventor," it didn't hold back on poking fun at many of the famous inventor's ideas.

At the beginning of the episode, Musk arrives in Springfield as a washed-up inventor who uses Homer's bizarre ramblings for inspiration.

Some of his amazing suggestions: violin-playing quadcopters, luggage that can pack itself, a yoga mat that rolls itself up, and baseball tickets that guide you to your seat.

Musk suggests building a high-speed transportation system called the Hyperloop for Springfield (perhaps that's Musk's hinted-at test track for a proposed high-speed rail system of the same name that would connect Los Angeles to San Francisco).

The Hyperloop is a system of sealed tubes designed to cut down on drag and transport people between Los Angeles and San Francisco in a record-breaking 35 minutes.

But a small mouse takes a ride on The Simpsons' version of the Hyperloop and throws up.

This spectacular loss launches the city into a depression, and Musk ends up leaving in disgrace. At the end of the episode, Musk takes off in his company's Dragon spacecraft, and Lisa Simpson comments that "for a man who likes electric cars, he sure burns a lot of rocket fuel."



This final joke compelled Musk to take to Twitter for a good-old debunking:







Musk says that because space is a vacuum, there's nothing to push against. That means something as heavy as a spacecraft needs a huge ejected force to propel it through space. Electric rockets would not produce enough force for the spacecraft to react against.

Musk also points out that ion thrusters aren't up to the task of propelling a spacecraft because they generate a very small force. Anything being launched into space "must have more thrust than weight or you don't go up," Musk wrote on Twitter.

Musk also took the opportunity to point out his big problem with space elevators — essentially cables running from the Earth's surface to a weight floating high above the atmosphere. Carbon nanotubes, a strand of carbon atoms that are 100 times stronger than steel, might be the right material to use for space elevators, but the research has a long way to go.







I'm all about this self-packing luggage, though:





Watch the episode on Hulu here:



