Spoiler Alert: Do not read if you haven’t watched “Polaris,” the season premiere of “For All Mankind,” now streaming on Apple TV+.

The mission is Mars in the third season of Apple TV+’s “For All Mankind,” and if this week’s premiere left viewers gasping for air, co-creator Ronald D. Moore warns it was only the beginning.

“This is the biggest step so far in our story, and it is the one that has the biggest potential for major setbacks,” said Moore, who also serves as writer and executive producer. “The whole space program could be put into jeopardy if this doesn’t work.”

Viewers already know astronauts make it to Mars in 1995, as glimpsed in the flashforward to the Red Planet at the end of Season 2. Who gets there first, however, is the show’s mystery, as the United States again finds itself racing Russia into history.

But before the mission lifts off, the third season premiere stuck a bit closer to home — or at least a few miles above it.

The new season picks up in 1992, after the U.S. and Russia have struck a lunar peace agreement on the moon. In the ensuing decade, a lot has happened, as shown in the show’s annual opening montage, including the reveal that Meg Ryan and Dennis Quaid starred in a biopic about the doomed love story of Gordo (Michael Dorman) and Tracey (Sarah Jones), who sacrificed their lives to avert nuclear disaster on the moon last season.

But perhaps the most pressing news is that private corporations have started dabbling in space tourism, led by the launch of the Polaris Orbital Hotel.

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Shantel VanSanten as Karen Baldwin.

Co-founded by former Outpost owner and astronaut’s wife Karen Baldwin (Shantel VanSanten), Polaris is poised to become the next big vacation destination, where every room comes with a view. But first, it hosts a trial run wedding with some of NASA’s finest on the guest list — Ed (Joel Kinnaman), Danielle (Krys Marshall) and the groom himself Danny (Casey W. Stevens), who is not marrying former lover Karen, but rather a new character named Amber (Madeline Bertani). Not much is known about the bride, but with Danny’s legacy astronaut status as the son of the late Gordo and Tracey, there’s bound to be more than just marital bliss in the newlyweds’ future.

The festivities are appropriately out of this world until space debris from a failed North Korean rocket compromises the station’s gravity control, threatening to rip apart the rotating hotel and suffocate its guests. Luckily, Danny performs a spacewalk in the nick of time — but not before Karen’s second husband and Polaris co-founder Sam (Jeff Hephner) is among the dead.

It’s a cautionary tale only “For All Mankind” can deliver, and it will have reverberations as the series charts a path to the next frontier.

“It’s hard to say without being a spoiler, but Polaris and its fate is going to definitely figure into the larger story of Mars,” Moore said, hinting there will be another player in the race to Mars.

For Karen, specifically, the Polaris disaster is going to be a major setback for a woman well-versed in trauma and transformation. As the series looked even deeper into the heavens in Season 2, Moore said the writers had to redefine Karen in order to keep her integral to the space-bound story. While her foray into space tourism was teased last season, its tragic launch in the premiere will only fortify her place in the field.

“Karen is going to take this as a major loss, but then there is an opportunity out of that loss that will still keep her within the frame of the story,” Moore said. “That journey is going to be a very different one than the one she took with Sam or the one she took when she was married to Ed. It’s going to ultimately lead Karen to some fairly profound consequences this season.”

But she isn’t alone in barreling toward the unknown. The premiere revealed that NASA Director Margo (Wrenn Schmidt) has continued her secret communications with Russian counterpart Sergei, feeding him American-made solutions to Russian space hurdles and vice versa. The partnership, now relegated to a payphone outside a record shop, isn’t all that secret in Russia, where Sergei is getting pressure from his bosses to reap nuclear details from Margo.

“It’s not going to go well,” Moore said, with the hint of a laugh. “In the premiere, Margo is unaware of just how dangerous a game she is playing. She knows she’s doing things she probably shouldn’t do, but you feel like she has it under control, and she’s very capable. It is going to turn on her, and there are going to be choices and consequences for Margo that I don’t think she could have possibly anticipated at the beginning of the season.”

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Sonya Walger as Molly.

With the mission to Mars on the line, the premiere teases other clashes likely to heat up in the coming episodes. Margo locks horns with Molly (Sonya Walger), whose radiation-induced glaucoma hasn’t stopped her from ascending to the head of the Astronaut Office. Elsewhere, the ever-competitive Ed and Danielle playfully spar — at least for now — about who’s going to lead the Mars mission.

All of it is poised to escalate the stakes even higher as “For All Mankind” continues to rewrite history, something Moore admitted is even more challenging with Mars in focus. The first season began after Russia had already won the race to the moon, the catalyst for the show’s entire alternative history timeline. Now the series’ creative team get the chance to follow the race toward what Moore calls a “compelling and unexpected” finish line.

“Once we sort of zeroed in on the idea and concept of it being a race again, that gave us the focus that this is going to be a different kind of story for us,” he said. “But we didn’t want the season to be completely defined by the race, so there is more at stake than just who wins.”

If the series has taught its audience anything, it’s to expect that not everyone will get to put their footprint on Mars.

“Space travel is inherently dangerous; our show has always made that point clear,” Moore said. “People will be lost along the way.”

“For All Mankind” airs new episodes Fridays on Apple TV+.