Vanessa can hear the breathlessness in Joan’s voice, and she wants to reach through the microphone and hold her and apologize. She wants to tell her that given the choice, she would deny herself the joy of having met Joan, just to keep Joan safe from what she has to do now.

She wants to say, “I’m sorry, honey,” in between hyperventilating sobs. “I’m so sorry.”

But she cannot do that.

What Vanessa is about to do will end her NASA career, if it does not end her life. But Joan’s life will go on. And Joan is great as CAPCOM. She can’t ruin that for Joan now.

So instead, she says, “Houston, I deeply regret any pain that will be caused by what I must do.”

There is no immediate response, so she keeps going: “But I could not live with myself if I didn’t try to get Lydia home in time to save her.”

If she has secured the payload bay doors just enough, she can save them both. If she keeps trying, she can only save herself.

“Navigator,” Joan says. Her voice sounds strong, but Vanessa can sense that it is cracking at the edges. “We are asking you to please continue to work on the payload bay doors in the hopes that we can at least get you home. That is what Jack is commanding right now. Do you read, Vanessa Ford? This is Jack’s command.”

Vanessa nods to herself and closes her eyes.

The way Joan says it reverberates in her mind.

This is Jack’s command.

Vanessa begins gathering the tools and securing them in the tool kit. “Roger that, Houston. Understood,” she says. “But I believe that trying to land the shuttle with the doors as they are now is Lydia’s best chance of survival.”

“Navigator, the entire—”

“Tell NASA to do whatever they have to do to me if I survive,” Vanessa says. “Censure me, fire me, arrest me. I do not care. I’m going back into the flight deck, and I’m starting deorbit procedures.”

“Navigator, you do not have the approval—”

“Everybody down there, listen to me. It’s not a discussion,” Vanessa says.

She needs to make Joan understand that there is no way to change her mind, or else Joan will blame herself for everything that happens today. She will replay it in her head for the rest of her life to see if there was anything she could have said to convince Vanessa otherwise. Vanessa cannot allow that to happen.

Vanessa needs Joan to understand that this was always inevitable.

From the moment Vanessa was born, this moment has been inevitable.