THE WORLD HAS CHANGED. It’s not just the triple alliance among the Atlantic Union, the Caspians, and the Pac Alliance.

My world has changed.

Emma is that world. We’ve been orbiting around each other like two planets, both unsure about the gravity between us. That gravity, and the distance separating us, has now collapsed. We have collided, the mass of our attraction suddenly too great to keep us apart. I don’t know what comes next for us, but I’ve never been this excited in my whole life.

In the aftermath of the collision, we lie in bed, her head on my shoulder. “How was the trip?” she asks softly.

“Piece of cake.” “Liar.”

“All’s well that ends well.” “They’re going to help us?” “Looks that way.”

“How soon can we launch?”

“I’m not sure. When we were planning before, we didn’t know what kind of resources we had at our disposal. Whether the mission would be the Atlantic Union alone or us with the help of one or two allies. And we didn’t know the state of their space assets.”

“Have they told you?”

“Not yet, but Fowler and I have met with each nation’s space program and military. We’ve created a working group among the three nations. We’ll probably know what we have to work with by the end of next week. My

guess is, we can be ready to launch in a few months. Three or four at the most. We need to be. I’m not sure how much more time we have.”

She pushes up from the bed and looks at me, chewing her lip the way she does when she’s nervous about something.

“What?”

“Nothing,” she mutters.

I doubt it’s nothing. There’s something she wants to say to me, but whatever it is, she decides now isn’t the moment to do it.

WHEN EMMA and I get up, we don’t talk about what happens next. Or what we are. It’s as if we’re both on autopilot. We move the pertinent items from my bedroom to her bedroom. There’s no decision to be made there—my room is a pigsty, hers looks like something out of a furniture catalog.

In fact, apart from my bedroom and my office, the rest of the house is spotless—cleaner than the day we moved in. I feel like I’m walking around some sort of CDC biocontainment room. She’s been tidying up. A lot.

“What do you want to do with the other bedroom?” she asks. “I’m not sure.”

She grins. “I’ve got an idea.” I raise an eyebrow.

“Drone workshop.” “Just like the Pax?”

“But with more gravity.” “Perfect.”

WE HAVE dinner for everyone that night: Fowler and his family, Madison and her family, Abby and the kids. It’s crowded, and it’s kind of perfect that way.

Emma and I sit next to each other, and when dinner is over I put my arm around her and she leans closer to me, something we’ve never done before, at least in front of everyone.

Madison fixes Emma with a curious gaze that I can’t read. Something between the sisters. I’m a good scientist and a capable investigator, but I’ll never crack that code.

Jack and Sarah and Adeline and Owen play together; the four of them have become fast friends. Fowler’s children are older, and they mostly study their tablets while the younger kids run around in circles and play with the robotic dog, which they’ve named Marco (I believe because he responds Polo to the name, which they feel is hilarious).

The scene reminds me of Christmas at my parents’ house. My father had a brother and two sisters, and everyone always spent Christmas together. It was a full house. It was a chaotic and joyous event and at times contentious. It was perfect. And so is this, with one glaring exception: Alex. It seems that’s a bridge too far. One with too much water under it. One that might be washed away forever.

THAT NIGHT, Emma and I are lying in bed, both reading, when she turns to me.

“I need to talk to you about something.”

She’s using the tone you see in a movie, when the girl breaks up with the boy or tells him she’s pregnant or breaks some kind of news that shatters their world. It’s nerve-racking. I’m instantly on the defensive. I just want her to spit it out so I can know what I’m dealing with.

I set the tablet aside. “Sure.” The word comes out like the sound of a sword chopping the air.

“I’m going on the mission.” “What mission?”

“The mission.”

“To Ceres? To the harvester?” “Yes, that mission.”

“Emma—”

“No. Don’t. I know you don’t want me to go. I know you’re worried about my health. But I’m worried about you too. It was agonizing when you were gone. Agonizing. I can’t do it for months at a time, wondering if

you’re hurt or if something has gone wrong out there. I can’t stay here and wait and hope that you come back. I’m going with you. I have to.”

My mind races like a computer doing a dictionary assault on a password

—running through combinations trying to find a key to unlock this argument, to convince her to stay on Earth. The harvester mission is a true long shot. Longer odds than the first contact mission. Much longer. It’s a Hail Mary. I can’t take the woman I love up there.

I decide to pursue the most logical approach.

“Emma, you’ve already lost too much bone density. You simply can’t go on another mission.”

“My bone density won’t matter if I’m dead. And it won’t matter if you’re dead.” She swallows hard and inhales. “Just listen to me for a minute, okay? Really listen.”

“Okay.”

“Here on Earth, I’m broken. I’ll never be the woman I was before. I’ll never regain the strength I had before I left for the ISS. Down here I’m weak. Up there, I’m whole again. Strong. And I have a role to play. I can help you. And if it’s your fate to die up there, then it’ll be my fate too. I’m going, James. I’m going.”

I know when I’m beaten. She needs to go. And, deep down, I want her there. So she’s going.

I nod slowly, and she puts her arms around my neck, and the decision is made. We’re going back into space. Together. Possibly for the last time.