Inside YouTuber Mark Rober’s workshop, rocket-powered golf clubs and a giant Nerf gun

Some people might call Mark Rober the world’s biggest kid.

The former NASA engineer turned YouTube sensation has amassed 15 million subscribers through videos of larger than life science experiments, like building the world’s largest Nerf gun or a bowling ball that only makes strikes.

Rober says he makes these videos because he’s “passionate” about getting people “just stoked” about science and engineering.

“That’s kind of my M.O. Like, all of my videos essentially drive back to that point,” Rober said. “So I’ll suck people in with something big, like, world’s largest Nerf gun, world’s largest Super Soaker, but at the end of the day, it’s about telling them about the science of what’s going on there.”

“Nightline” caught up with Rober last year, before the coronavirus pandemic began. But while much of the world stopped, Rober, who has been making videos for nine years, continued experimenting. The scientist even documented his isolation following a positive COVID-19 test in a Shark Week video.

Rober says he discovered his gift for physics, chemistry and math at a young age.

“High school physics was a big deal for me,” he said. “That’s when it finally clicked for me that you could just explain the world around you… And so, a lot of my videos come down to physics principles. I’m trying to explain to people, like, ‘This world is magical but magical in a way that if you understand how it works, you can predict the future and you can make cooler things.”

Rober spent nine years at NASA, working in its jet propulsion lab. For seven of those years, he worked on the Curiosity rover, which was sent to Mars in 2011. He said that every so often, he’ll sit in his backyard and look up at the sky at a “little dot” that is Mars.

“To know that something I’ve touched and designed and tested is roving on that little dot in the sky, 90 million miles away, it’s a cool feeling,” he said.

It was while Rober was working for NASA that he produced his first video, in which he demonstrated a Halloween costume that used two iPads to make it seem as if he’d had a hole blown through his torso. The video racked up nearly 10 million views.

“That was a cool feeling,” he said.

The response to the video made Rober want to make more, and he says he’s done a video a month ever since -- even quitting from NASA along the way.

“There was a survey that went out recently that was like, ‘More kids want to be professional YouTubers than astronauts,’ and everyone, even I’m like, ‘Man, that’s so lame.’ But then I was like, ‘Hold up, I quit my dream job at NASA to make YouTube videos, so I’m not really one to judge.”

Along with making videos, Rober also advocates for certain causes, such as climate change. He says his platform is too big not to use it for good.

“It’s weird to think that I can tap a microphone and 25 million people will listen, right. That’s the position I’m in once a month,” he said. “There’s some level of responsibility, I think, that comes with that. So, I can’t just sit by and not do something knowing that I could, right. I have the power to do something about it.”

Baked into each of Rober’s videos is a childlike excitement that’s meant to engage kids.

“I joke sometimes in the videos that my quest is to just be the favorite uncle with my nieces and nephews,” he said. “I started with a lot of times having them in videos. I love having kids and young people in my videos because they’re sucky actors. So when they give a reaction, it’s genuine and authenticity comes across.”

“If I make a Jell-O pool and I’m like, ‘I ain’t jumping in it,’ that’s one thing,” he added. “But when you see the sheer enjoyment of a kid doing a belly flop into a Jell-O pool, that’s just magic.”

At his workshop in San Francisco’s Bay Area, Rober showed “Nightline” all of the toys and gadgets he’d accumulated over the years, from a glitter bomb used in a video to prank a package thief to rocket-powered golf clubs.

When asked what his 8-year-old self would think of him now, Rober said, “He’d be real stoked.”