This imaginative drawing liked by Elon Musk reveals just how crazy SpaceX's first missions to Mars will be

Oberg said drawing is a creative outlet for him when he's not using computer programming to study moon formation around planets like Jupiter.

He created the SpaceX ship graphic bit-by-bit over the course of about two months, drawing inspiration from Stephen Biesty's popular cross-section books that show the insides of castles, war ships, the Titanic, and other elaborate structures.

But Ober noted that he "is not in any way an engineer" and his graphic of the Big Falcon Spaceship "almost certainly has completely ridiculous things in it that make no sense."

Nevertheless, his vision of Big Falcon Spaceship's guts has grown popular in the absence of official details from SpaceX.

"Some people take these diagrams very seriously," he said. "I'm glad I've gotten people arguing about things they hadn't thought about before."

"I figured it would be a vital need to leave the ship and make repairs to, say, a micrometeorite hit to a fuel tank," Oberg said.

"I made the cargo bay a bit empty so you can see inside of the ship. I imagine this cargo bay will be much more full than I have imagined it, though," Oberg said. "They'll have to come up with clever packing arrangements. Food will fill a large amount of this volume."

Oberg said the crane was a treat to illustrate, despite its utilitarian nature.

"If you follow really nerdy spaceflight forums, people argue over all of the details — they've literally had a years-long argument about how people will get down from the ship," he said. "Elon [Musk] eventually said, 'A crane.' So I imagine the first people will make it down on some kind of pallet. But maybe a simple rope ladder would suffice?"

Oberg wasn't sure how to illustrate a life support system. (SpaceX still has a lot of thinking to do there, too.)

"This just shows a bunch of random boxes and pipes that I managed to fit into this shape," Oberg said. "What will be key is that life support systems are easily accessible to the crew for repair. Things will break."

Oberg said astronauts have sometimes described fresh fruits and vegetables as "manna from heaven."

"As a student I've gone weeks eating stuff like pizza and noodles, and your body starts to reject it after awhile. You need fresh food," Oberg said. "These people will be eating dehydrated food for years. Even if plants can't sustain them entirely, they're going to want fresh produce."

Musk and his companies are known for sleek design, but Oberg thinks a lot of that will go out the window once a crew is on the way to Mars.

"People's little rooms are going to get messy. That's real-life," he said. "If you're stuck for a few months at a time, people will need a private space to hide from each other."

Oberg had to think how the rooms could function both while a crew is flying through space and living on Mars. A SpaceX engineer said in August that the first crews would likely use the spaceship as their habitat.

"You have to remember this whole ship design has to work standing up on the surface of Mars, too," he said. "I imagine these walls are very moveable and temporary, that this wouldn't be a super fixed structure on the inside."

"Astronauts on the space station just scrub themselves with a wet towel. Now imagine you have to scrub for six to eight months," Oberg said. "You're going to want a normal shower. But in zero-gravity that's going to be difficult."

Oberg said the zero-gravity toilet he drew borrows from the one on the International Space Station.

"I added hand grips so people can hold themselves down," he said. "It never looks fun, especially the way the astronauts describe it."

Oberg added a person to the toilet in his drawing after a fan of his work pointed out that Biesty, the author of the well-known cross-section books, "almost always has someone pooping in the background" of his illustrations.

Oberg said the communal area will be fun — an essential place to keep physically and mentally healthy during the voyage to Mars.

"People will absolutely need to exercise. They'll spend a good fraction of their time working out and keeping fit because they'll have to," he said, referring to the bone and muscle loss that happens in zero-gravity.

Ober warned, though, that once on Mars, the large open space in the middle of the ship could become a "pit of death" that people could fall into. "They'll have to set up some kind of net," he said.

An inscription on the cork board says "Jeff who?" — a phrase used jokingly by Musk when people ask about Jeff Bezos or Blue Origin, which is also working on reusable rockets.

Oberg said he doubts the bridge will be very big, since SpaceX is automating so much of its current spacecraft.

"But it's a staple of science fiction that in every spaceship there is a bridge," he said. "Maybe it will be more of a utility room than a bridge — all the stuff needed to keep a close eye on things like life support."

Oberg said the storage area, including a torus of water next to it, could be used to shelter astronauts during a solar storm, which spews high-energy protons that can harm people.

Radiation from deep space will be difficult to defend against during the trip to Mars and on the planet's surface.

"I can't imagine how people are going to be protected from cosmic rays. No idea how SpaceX is going to do this," Oberg said. "I don't see how they can't prevent people's brains from being damaged."

The green bar drawn in the storage area, he added, is an homage to a "Simpsons" episode in which Homer Simpson saves a space mission with a radioactive fuel rod.

Oberg said he borrowed some of the design elements from NASA's space shuttle orbiters, including the telecommunications array.

Oberg borrowed the look of the thrusters from SpaceX's Dragon spaceship design and NASA's space shuttles.

"I know they're going to need to reorient this thing in space," he said. "They're also very loud, so you want to keep them away from the crew."

Oberg added lingering droplets of propellant to the large, 30-foot-diameter tanks to indicate that they'd used up more or less all the fuel.

The Raptor engines for the Big Falcon Spaceship are one of the most "real" parts of the spacecraft so far, since engineers have already built and fired smaller-scale versions.

Oberg said he hopes Musk and SpaceX succeed in taking people to Mars.

"I've been waiting for what feels like most of my life for people to go beyond the moon, and it looks like it's finally going to happen," he said. "Every decade there's a new plan of, 'within a decade well send people to Mars' or the moon or an asteroid — and then it fizzles out."

He added: "Nothing came close to reality. We never saw parts of a manned Mars mission, never saw components of a spacecraft. But SpaceX has shown us. We get peeks every now and then of what they're working on in a tent."