The Jupiter Theft

Jameson watched the pictures change on the black surface. Ruiz had painstakingly drawn a four-step animated diagram showing the multiple orbits. The moon jumped in its circle around the Jovian planet, moving counterclockwise. The rosette of dots jumped in its egg-shaped orbit around the moon, moving clockwise.

“The orbit of the ships around the moon has the same period as the moon’s orbit around the planet,” Ruiz went on. “Doubtless the ships’ orbits are continuously adjusted to keep them synchronized as the planet shrinks and the moon’s orbit changes. But as you can see, the ships are always sheltered from the radiation caused by collision with interstellar hydrogen.”

“Beautiful, beautiful,” Mike murmured.

“Commander Jameson thinks—and I agree with him—that a significant portion of that impacting hydrogen also becomes grist for the Cygnans’ mill. After all, it’s already been ionized. It becomes an energy bonus to partially offset the inefficiency inherent in the Cygnan method of travel.”

“Can I quit?” Jameson said. “My thumb’s getting tired.” He passed the lightpad back to Ruiz.

“It seems kinda complicated,” the Giff said, being a bad boy again.

“It wasn’t complicated for the Cygnans,” Ruiz said. “Don’t forget, they started with the components of the system already in place. That moon they use for a shield was the world they evolved on … I wonder how they feel about traveling with its corpse. The gas giant they used for fuel was the primary that their world revolved around. It would have been natural for them to start building their fleet in orbit around their world. They had a whole population to transfer, a shipboard ecology to establish, a technology to develop. It might have taken millennia. They had the time. Perhaps they didn’t develop the technology for that Einsteinian siphon of theirs until the work was well under way. They might not have traveled at relativistic speeds for the first few centuries, while they completed the shakedown for those synchronized orbits. It wouldn’t have happened all at once.”

Jameson was the first to pick up on it. “You said … they had the time. What do you mean?”

Ruiz was fiddling with his lightpad. He had more of his day’s work stored there. He looked up, almost absently.

“One of their suns was going to go supernova. And they had half a million years to get ready for it.”

The crowd around Ruiz had grown. Word had gotten about that something lively was going on. Jameson could see Liz Becque nestled against Omar, her arm around his thick waist, her post at the punchbowl deserted. Even Klein had joined the group. He was at the fringes of the crowd, his knotted arms folded, standing next to Yeh and Chia, so intent on the discussion that he’d forgotten his aversion to his Chinese shipmates.

“The Cygnans are the children of a binary system that now consists of a black hole and a blue supergiant,” Ruiz said. “They spent twenty thousand years watching one of their suns swallow the other.”

Beside Ruiz, Captain Boyle nodded gravely. “We can begin to understand something about the Cygnans’ motives now. We knew that they came from the direction of the X-ray source known as Cygnus X-l, about ten thousand light-years away. What Commander Jameson managed to see on the Cygnan computer display confirmed that it was their origin, incredible as that seems.”

Mike Berry was itchy with questions. “Twenty thousand years. That’s longer than all of human history. You sure of that figure?”

Ruiz swung his narrow beak toward him. “We can calculate the timetable for the evolution of an X-ray binary system from the mass of its components. And we get that from their dynamical behavior.”

Jameson spoke up. “The Cygnan commentary got eloquent about a ‘Great Mother’ that swallows her … not ‘children’… maybe something like ‘little brother.’ I assumed it had something to do with eclipses in a double-star system. I saw some spectacular ones.”

“It was more literal than that,” Ruiz said. “One of their suns was swallowing the other. And the mass exchange took place fast enough to be noticeable over the generations. It must have been a key part of the Cygnan race consciousness since they first crawled out of the ooze and became civilized beings.”

Liz Becque, shuddered and drew closer to Omar. “You mean they actually would have seen one of their suns getting bigger and the other getting smaller?”

“As their suns evolved, yes.”

“Think of it!” Dmitri blurted. “To live under such a sky! When you think of the burden of myth and theology we humans have invented from our own simple sunrises and sunsets and seasons…”

“The myths would have turned into scientific knowledge,” Ruiz said dryly. “When they got to the point where they knew what we know about close binaries and mass exchange, they would have known exactly what the fate of their suns would be. And exactly when it would happen.”