Simon Helberg, Melissa Rauch Simon Helberg, Melissa Rauch

Howard finally returns from space on Thursday's The Big Bang Theory — and if you ask Simon Helberg, he may as well have been in orbit too.

"I was actually isolated, confined to a tiny area, when we were shooting the space station stuff, so it lends itself naturally to that theme," he tells "I was separated from the cast, I was shooting on a different day than the cast. It was like I was in space, or on a completely different show. I was lonely and I was nervous that I would incinerate upon entering their atmosphere or something. I mean, talk about an easy way to kill someone off! It's like Suzanne Somers on Three's Company when everything was shot via phone calls on a separate set."

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Once Wolowitz figuratively comes back down to Earth, he'll have to deal with the most pressing matter at hand: His and Bernadette's living situation. The mama's boy still hasn't worked up the courage to move out, let alone tell his overbearing mother. "He's sort of half in both places at this point," Helberg says. "It's clear to both of them that he technically lives with Bernadette, but he's got enough stuff at his mom's that he hasn't quite cut the cord. It's like the Annie Hall thing: I have my place and the reason I have it is because I know I have it. That starts to create some tension."

But shouldn't knowing your mom is hooking up with her beau next door be enough impetus to move out? "You'd think," Helberg laughs. "You hear enough that it's clear something terrible is happening. I'm warning everyone right now: It's scary."

The Big Bang Theory airs Thursdays at 8/7c on CBS.