As they approached ninety degrees longitude, Aisha looked back at the Earth suspended above the horizon. Whatever the idiots had done, she doubted that they’d managed to render the whole blue world uninhabitable. Maybe they’d lost the means to send a radio signal—let alone a rocket—to their nearest neighbor, but that had been true for most of human history. So long as the air was still breathable and crops could still grow, to return would be worth the struggle.
“Why doesn’t the skyhook come lower?” Aisha had asked Yong. A gap of six kilometers above the base seemed excessively cautious.
“Because if it came much lower here,” he’d explained, “it would strike the ground at other points in its orbit. There are six locations where one hook or the other comes swinging down; the orbit needs to be high enough that all of them have some clearance.”
Six months later, when Aisha and Jingyi had been gestating the plan, they’d contemplated tweaking the skyhook’s orbit into an ellipse that came in low over the base while still avoiding the highlands of the farside. But the hub’s ion engine would take months to execute the change—and in just two weeks the farside and nearside would rotate into each other’s former locations.
So instead of making the orbit eccentric, they’d kept it circular but shrunk it as much as the safety margins hard-coded into the hub’s navigation system allowed. At the point on the farside opposite Medii, the bottom of the cable would come within ten meters of the ground.
When the buggy reached its destination, Aisha looked up into the star-filled sky, trying not to cower into her seat at the thought of the thousand-kilometer-long whip tumbling toward her.
Nuri woke and started crying. “I know,” Aisha commiserated. “Your mother stinks, and you’re tired of staring at her chin.”
She climbed out of the buggy and walked around for a few minutes, just to let her muscles know that their enforced idleness was over, then she unhooked the trailer and set to work.
She detached the roll cage from the buggy, undoing all the bolts and lifting off the tubular frame. Then she took the sheet of woven silica from the trailer and maneuvered it into the buggy, carefully positioning the loops of the connecting cords around the holes where the cage would reattach.
She took twelve of the struts from the trailer and assembled them into a rectangular tower half a meter high, fitted two extra bars across the top, then had the buggy drive up onto it. If she hadn’t practiced the whole thing a dozen times back at the base she would have been panicking already, but by now this part seemed as unremarkable as automatic parallel parking.
Nuri redoubled her wails. “Shh, my darling, it’s going to be fine,” Aisha promised. “Just think of it as monster trucks meets Lego.”
She attached a second tower to the first, and made it a full meter tall. The buggy crossed over without complaint; it knew its own abilities well enough to assess her request and decide it was achievable. The integrity of the tower, though, was outside its domain of expertise; it was up to the builder to ensure that the structure was sound.
Level by level, she raised the scaffolding, and the buggy followed. When the tower was seven and a half meters high, she climbed down and stepped back to inspect it. Jingyi had seen her get this far in the rehearsals, but apparently that hadn’t been enough to convince her to come along for the ride.
Aisha went to the trailer and fetched the magic box Jingyi had found in Yong’s workshop. She woke it from its sleep and checked the status of the skyhook. It was due to make its next pass over the site in about twenty minutes.
If the lunar GPS was still accurate and both she and the skyhook were employing the same coordinates, the magnetic hook at the bottom of the cable would descend directly over the buggy, stop half a meter above the top of the roll cage, then ascend again. With the magnet switched off, the buggy wouldn’t move a millimeter, but she had to be sure that the encounter really played out that way. She climbed the tower again, and turned the dash cam on the buggy up toward the sky.
As the time approached, Aisha lay flat on the ground. The hook could not be coming down so low here as to strike the rock; the effect on the whole cable would have been unmissable. But if the real safety margin turned out to be less than advertised, she might be none the wiser until the proof smacked her in the head.
Nuri turned her face toward her, though they couldn’t make eye contact. “You’re my beautiful girl,” Aisha declared soothingly. “You know you are.”
She waited a few minutes, in case the timing was off, then rose to her feet; the suit did its best to help.
The tower remained standing, the buggy undisturbed. Aisha had the suit access the dash cam and play back the footage in slow motion.
Her faceplate went opaque, then filled with stars. “Skip forward until something changes,” she said.
A circular silhouette moved toward her, growing, blocking out the stars. It slowed as it approached, as if she were looking down at a very large Frisbee tossed into the air, approaching the top of its arc.
She froze the image when the silhouette began to retreat. From the apparent size, the height was close to what she’d expected, but the thing was off-center by about six meters. She’d have to take the tower apart and rebuild it in the right location.
She took her time, instead of rushing to try to get the job finished in one orbit; if the tower collapsed and flipped the buggy, that would be the end. She hummed to Nuri as she worked; singing would have been nicer, but it made her throat dry.
Five hours later she was done, strapped into the buggy, perched high above the rock. She told the hub to power up the hook’s electromagnet, and programmed the switch-off time to the millisecond. Now the whole process was out of her hands.
Nuri was asleep. “We’re going to see your grandfather,” Aisha whispered. “Very soon.”
She sat watching the countdown projected in red onto her faceplate. At T-minus two, she was ready to believe that nothing would happen and she’d stay stranded forever. By T-plus two, the feeling of half her Earth weight pressing her into the seat had already gone from a shock to a kind of ecstasy. The landscape was falling away around her ever faster, but the buggy hadn’t yet tipped by any perceptible angle; the hub was still an unimaginable distance above her.
Nuri woke, but she did not seem troubled. Perhaps she found the greater pressure against her mother’s skin more comforting. Perhaps she’d always known that she needed more weight, more force, more friction if she was ever to thrive.
Aisha talked to her, explaining what was happening, then hummed for a while as she fed. Ten minutes into the upswing, the ground lay to her left, a sheer wall of gray rock like a distant cliff face. But down was still down in the buggy; the centrifugal force overwhelmed mere lunar gravity. And as the cliff slowly receded and tilted into an impossible roof above the dark slab of the magnet, she finally perceived the whole world of her prison as a mere disk in the sky again. Whatever happened now, at least she was free of it.
A few degrees past upside down, the magnet switched off and the buggy fell away into the void. Aisha grabbed at the seat, at the dashboard, but then the weightlessness lost its sense of danger, and once the magnet was out of sight there was nothing to tell her she was moving.
Nuri grizzled half-heartedly, then went quiet and contemplated the change. “We’re astronauts now!” Aisha told her. “How cool is that?”
They’d left the Moon traveling faster than most rockets, and the blue world grew more rapidly than it had diminished on the journey out. The buggy rotated slowly, taking hours to complete a turn, and each time the Earth rose over the dashboard Aisha could gauge its increased width against the instruments below.