Matthew McConaughey and Jessica Chastain’s dad-daughter relationship in Interstellar

The two stars play a father and daughter who are ripped apart when he goes on a years-long space mission to find a new home planet for humanity.

Jessica Chastain in a scene from Interstellar. Paramount Pictures

Jessica Chastain doesn’t even feel comfortable saying her character’s name.

The Oscar-nominated actress quickly attempts to correct course when she realises she's speaking liberally about Murph, the astrophysicist she portrays in Interstellar.

“I’m just so terrified,” she says. “It’s obvious, right?”

She and Matthew McConaughey play a father and daughter who are ripped apart when he goes on a years-long space mission to find a new home planet for humanity.

“If you’re a parent or even if you just have a parent, everyone has these moments, from lesser to extreme levels,” says McConaughey. “It happens all the time, whether you’re dropping your kids off at school or going on a vacation. This is the most extreme nature of that. This is a father going off for a long time. There’s no guaranteed return ticket.”

Murph was initially envisioned as a boy in early drafts of the script.

“By changing the sex, it made it more complex,” says Chastain. “We’ve seen many Hollywood stories about a son becoming a man with his father’s help. That’s almost every journey in cinema. It’s rare we see the dynamic between a father and a daughter.

“If you’re supposed to be protected and you’re left behind, what kind of relationship does that create?”

Both actors also had to wrap their heads around difficult subjects such as physics and cosmology: “When I watch the film now, I still don’t understand everything in it, but the main part of this film isn’t about science,” says Chastain. “It’s about love. You have to feel it. If you go into the movie – even though the scope is large with space travel – at its core, it’s a story about a father and a daughter. If you let it wash over you, that is enough.”