Saturn Run

44.

The Celestial Odyssey’s trajectory was very tight and its speed was way too fast. The Chinese ship would hit closest approach at over fifty kilometers per second. The Chinese would have to kill more than half of that velocity to get into a circular orbit. Plus, their trajectory was still inclined fifteen degrees to the ring plane, and even if they achieved orbit, they’d need yet more delta-vee to turn their orbit into one that brought them into reasonable proximity with the alien depot.

The Nixon’s nav crew said the Celestial Odyssey’s approach would bring them through the ring system out of view of the Nixon on the first pivotal pass. At the Chinese ship’s velocity, the most critical part of the encounter was going to be over in less than an hour. The Nixon wouldn’t be able to see the ship again until well after it passed periapsis.

Joe Martinez had a fix for that. He and Sandy modified two recon shells, fabbing lens extenders for the standard camera lenses. Martinez launched his do-it-yourself reconnaissance satellites into polar orbits, a half an orbit out of phase. That way, at any moment, one satellite had a view above the ring plane and the other below. The solution wasn’t perfect: the two cameras gave them only ninety-five percent coverage, but it would have to do.

By that “night”—ship’s time—the Chinese ship was still in free fall, closing in on Saturn faster and faster when it should have been decelerating. The nuclear thermal engines, monstrous as they were, still only provided a fraction of a gee. With dozens of kilometers per second to shed, the Chinese ship’s burn should have started hours before.

“They don’t have the reaction mass,” Fang-Castro told Crow.

“I don’t think so. They’re not going to make orbit.”

The Celestial Odyssey finally began its retro burn. They were as far from Saturn as the moon from Earth, but at their velocity, that was nothing.

Navigation: “Admiral? They’re not correcting their trajectory. Periapsis is dropping. They’re barely going to clear Saturn’s atmosphere.”

“Mr. Crow,” asked Fang-Castro, “do you have any reports of trouble aboard the Celestial Odyssey?”

“No.” Crow amended himself. “At least, not as of two hours ago.”

“Comm, keep monitoring for a distress call,” Fang-Castro said.

Nav was losing her voice: “They’re still not correcting their periapsis! They’re going to hit the upper atmosphere!”

Martinez: “Oh hell. I’ve got it.” He looked bemused. “They’re crazy. They’re going to try aerobraking.”

Crow: “What?”

“They’re going to try to skim through the atmosphere deep enough that they can shed some velocity through friction. It’s been considered standard operating procedure on any Mars mission. But they’re nuts. Mars is one thing. Saturn’s another. Different atmosphere, different gravity profile, and, uh, three or four times the velocity? It’s nuts.”

Twenty minutes before close encounter, the Celestial Odyssey cut its main engines. Everyone looked at Martinez.

“Oh, yeah, that’s right. They’ve got to get the orientation and angle of attack absolutely perfect. Can’t come in tail-first, they’ll burn off their engines. Even if they get their attitude right, they can’t come in too shallow or they’ll skip along the top of the atmosphere like a stone on a lake. There wouldn’t be enough friction, and they won’t kill enough velocity. On the other hand, if they come in too steep, they’ll just be another meteor.”

The Chinese ship’s image on recon shell’s camera’s IR channel, a bare handful of pixels, had dimmed sharply when the engines cut out and dimmed even more as the engines cooled. Now it began to brighten again.

“Hope they tied down everything good. Aerobraking’s a bumpy ride,” Martinez said. “These boys have got some major balls, I can tell you that.”

Nav: “They are definitely slowing down. They’re shedding significant velocity.”

Fang-Castro: “Enough to put them in a closed orbit?”

“Nowhere near, but probably more than enough, before they’re done, to shed the excess velocity they piled on with that midcourse burn.”

Fang-Castro looked over at Crow, an unvoiced message going between them: Maybe we dodged a bullet.

“Uh-oh, that’s bad,” Martinez said. Fang-Castro and Crow looked back at the display. Trailing the IR blip of the Celestial Odyssey, there were sparkles. Bright pixels that quickly winked out.

“Something’s burned off. Nothing should be burning off,” Martinez said. “They wouldn’t have an expendable heat shield. They figured something wrong. They broke something.”

“Comm, any messages?”

“Nothing, ma’am.”

“Hope they didn’t burn off their comm antennas,” Martinez said.

A minute or so later, the IR image of the Celestial Odyssey started to dim, as it left Saturn’s atmosphere. “Navigation, what’s their trajectory?”

“Still open, ma’am. They don’t have orbit, yet.”

Fifteen minutes passed, then twenty. No call. Nothing. Fang-Castro waited for the Mayday call. Nothing.

The image of the Celestial Odyssey suddenly brightened; simultaneously, Martinez called out, “They’ve started retro burn, again!”

Cheers broke across the bridge.

“Let’s keep the discipline, people,” Fang-Castro said, though she felt like cheering herself. It was space: it made a family of everybody. The President doesn’t get that, she thought. She probably never would.