“Twenty percent, Mrs. Chen.”

“Very good.”

Jessi leans halfway into Konstance’s lap. Into her ear she hisses, “Earth!”

Mrs. Chen glares in their direction and Jessi straightens and Konstance feels heat rush to her cheeks. The image of Beta Oph2 rotates above the Portal: black, green, black, green. The children sing:

You can be one,

Or you can be one hundred and two,

It takes everyone together,

Everyone together,

to get to Beta Oph2.

The Argos is an interstellar generation ship shaped like a disk. No windows, no stairs, no ramps, no elevators. Eighty-six people live inside. Sixty were born on board. Twenty-three of the others, including Konstance’s father, are old enough to remember Earth. New socks are issued every two mission years, new worksuits every four. Six two-kilo bags of flour come out of the provision vaults on the first of every month.

We are the lucky ones, the grown-ups say. We have clean water; we grow fresh food; we are never ill; we have Sybil; we have hope. If we allocate carefully, everything we have with us is everything we will ever need. Anything we cannot solve for ourselves, Sybil will solve for us.

Most of all, the grown-ups say, we must mind the walls. Beyond the walls waits oblivion: cosmic radiation, zero gravity, 2.73 Kelvin. In three seconds outside the walls, your hands and feet would double in size. The moisture on your tongue and eyeballs would boil away, and the nitrogen molecules in your blood would clump together. You’d suffocate. Then you’d freeze solid.

Konstance is six and a half when Mrs. Chen brings her, Ramón, and Jessi Ko to see Sybil in person for the first time. They arc down corridors, past the Biology Labs, past the doors to Compartments 24, 23, and 22, curling inward toward the center of the ship, and step through a door marked Vault One.

“It’s very important that we don’t bring in anything that might affect her,” says Mrs. Chen, “so the vestibule will clean us. Shut your eyes, please.”

Outer door sealed, announces Sybil. Beginning decontamination.

From somewhere deep inside the walls comes a sound like fans accumulating speed. Chilled air whooshes through Konstance’s worksuit and a bright light pulses three times on the other side of her eyelids and an inner door sighs open.

They step into a cylindrical vault fourteen feet across and sixteen feet high. At the center, Sybil hangs suspended inside her tube.

“So tall,” whispers Jessi Ko.

“Like a gatrillion golden hairs,” whispers Ramón.

“This vault,” says Mrs. Chen, “has autonomous thermal, mechanical, and filtration processes, independent of the rest of the Argos.”

Welcome, says Sybil, and pinpricks of amber go fluttering down her tendrils.

“You’re looking lovely today,” says Mrs. Chen.

I adore visitors, says Sybil.