Ariel Winter made a “huge mistake” during the Monday (June 5) premiere of Stars on Mars.

The Modern Family star joined an eclectic cast of actors, athletes and television personalities in a Mars simulation on the new reality show. But she was most surprised to see Lance Armstrong there — and not because of his past as a professional cyclist — but because she confused him with astronaut Neil Armstrong, the first person to walk on the moon in 1989.

“Lance Armstrong is a real fucking astronaut. Google him. He is so cool,” she said, per The Daily Mail.

On the episode, Armstrong acknowledged that people in their 20s often confuse him for the astronaut, who died in 2012.

“I’d be dead,” he said.

Later on in a confessional, Winter admitted she was afraid something like this would happen on the show, saying, “That was part of my like fear coming on this show, that I would say something stupid and I literally … I outdid myself.”

Another scene in the episode showed her pulling her castmate Porsha Williams aside and telling her, “I just realized I made a huge mistake.”

Williams asked her who she thought Armstrong was, to which Winter responded, “Neil Armstrong.”

Williams laughed and warned her not to take herself “too seriously.”

Luckily, the mix-up didn’t hurt her chances on the show too much. She was later nominated to become Base Commander, a position she ultimately chose to turn down.

On Stars on Mars, Winter, Armstrong, and their cast mates are taking on a 24-day mission in a Mars simulation to find out who could survive on the red planet.

They’re joined by cast members Marshawn Lynch, Ronda Rousey, Natasha Leggero, Christopher Mintz-Plasse, Adam Rippon, Tom Schwartz, Richard Sherman, Tinashe and Tallulah Willis. The reality show is hosted by William Shatner.

Stars on Mars airs Mondays at 8/7c on Fox.