Cornelius was grinning. “Isn’t it beautiful? You see, there are resonances between Cruithne’s orbit and Earth’s. When it comes closest, Earth’s gravity tweaks Cruithne’s path. That makes Cruithne’s year slightly longer than Earth’s, instead of shorter, as it is now. So Earth starts to outstrip the kidney bean.” He ran the animation forward. “And when it has spiraled all the way back again to where it started—” Another reversal. “ — Earth tweaks again, and makes Cruithne’s year shorter again — and the bean starts to spiral back.”
He accelerated the time scale further, until the kidney-bean ellipses arced back and forth around the sun.
“It’s quite stable,” Cornelius said. “For a few thousand years at least. Remember a single kidney bean takes around a year to be traced out. So it’s a long time between reversals. The last were in 1515 and 1900; the next will be in 2285 and 2680—”
“It’s like a dance,” said Malenfant. “A choreography.”
“That’s exactly what it is.”
Although Cruithne crossed Earth’s orbit, its inclination and the tweaking effect kept it from coming closer than forty times the distance from Earth to Moon. Right now, Malenfant learned, the asteroid was a hundred times the Earth-Moon distance away.
After a time Malenfant’s attention began to wander. He felt obscurely disappointed. “So we have an orbital curiosity. I don’t see why it’s so important you’d send a message back in time.”
Cornelius rolled up his softscreen. “Malenfant, NEOs — near-Earth objects — don’t last forever. The planets pull them this way and that, perturbing their orbits. Maybe they hit a planet, Earth or Venus or even Mars. Even if not, a given asteroid will be slingshot out of the Solar System in a few million years.”
“And so—”
“And so we have plausible mechanisms for how Cruithne could have been formed, how it could have got into an orbit close to Earth’s. But this orbit, so finely tuned to Earth’s, is unlikely. We don’t know how Cruithne could have gotten there, Malenfant. It’s a real needle-threader.”
Malenfant grinned. “And so maybe somebody put it there.”
Cornelius smiled. “We should have known. We shouldn’t have needed a signal from the downstreamers, Malenfant. That Earth-locked orbit is a red flag. Something is waiting for us, out there on Cruithne.”
“What?”
“I have absolutely no idea.”
“So now what?”
“Now, we send a probe there.”
Malenfant called back George Hench. The engineer prowled around the office like a caged animal.
“We can’t fly to this piece of shit, Cruithne. Even if we could reach it, which we can’t, Cruithne is a ball of frozen mud.”
“Umm,” Cornelius said. “More to it than that. We’re looking at a billion tons of water, silicates, metals, and complex organics — aminos, nitrogen bases. Even Mars isn’t as rich as this, pound for pound. It’s the primordial matter, the stuff they made the Solar System out of. Maybe you should have planned to fire the probe at a C-type in the first place.”
“George, it’s true,” Malenfant said evenly. “We can easily make an economic case for Cruithne—”
“Malenfant, Reinmuth is made of steel. My God, it gleams. And you want to risk all that for a wild-goose chase with your la-la buddy?”
Malenfant let George run on, patiently. Then he said, “Tell me why we can’t get to Cruithne. It’s just another NEO. I thought the NEOs were easier to reach than the Moon, and we got there forty years ago.”
George sighed, but Malenfant could see his brain switching to a different mode. “Yeah. That’s why the space junkies have been campaigning for the NEOs for years. But most of them don’t figure the correct energy economics. Yes, if you look at it solely in terms of delta-vee, if you just add up the energy you need to spend to get out of Earth’s gravity well, there are a lot of places easier to get to than the Moon. But you need to go a chart deeper than that. Your NEO’s orbit has to be very close to Earth’s: in the same plane, nearly circular, and with almost the same radius. Now, Reinmuth’s orbit is close to Earth’s. Of course it means that Reinmuth doesn’t line up for low-energy missions very often; the orbits are like two clocks running slightly adrift of each other…”
“So tell me,” Malenfant said heavily, “why Cruithne is so much more difficult.”
George ticked the problems off on his fingers. “Cruithne is twenty degrees out of the plane of the ecliptic. Plane changes are very energy-expensive. That’s why the Apollo guys landed close to the Moon’s equator. Two: Cruithne’s orbit is highly eccentric, so we can’t use the low-energy Hohmann trajectories we employ to transfer from one circular orbit to another, for instance in traveling from Earth to Mars. Changes to elliptic orbits are also energy-expensive. Three…”
Malenfant listened a while longer.
“So you’ve stated the problem,” Malenfant said patiently. “Now tell me how we do it.”
There was more bluster and bullshit and claims of impossibility, which Malenfant weathered.
And then it began.
George produced mass statements for the BOB and its payload, began to figure the velocity changes he would need to reach Cruithne, how much less maneuvering capability he would have, how much less payload he could carry there compared to Reinmuth. Then he began calling in an array of technicians, all of whom started just as skeptical as himself, and most of whom, in the end, were able to figure a reply. They called up Dan Ystebo at Key Largo to ask him how little living room his pet squid really, truly could survive in. Dan was furious, but he came back with answers.
It took most of the day. Slowly, painfully, a new mission design converged. Malenfant only had to sit there and let it happen, as he knew it would.
But there was a problem.
The present spacecraft design packed enough life support to take Sheena 5 to Reinmuth, support her work there, and bring her home again: she was supposed to come sailing into Earth’s atmosphere behind a giant aeroshell of asteroid slag.
But there was no way a comparable mission to Cruithne could be achieved.
There was a way to meet the mission’s main objectives, however. In fact it would be possible to get Sheena to Cruithne much more rapidly.
By cutting her life support, and burning everything up on the way out.
For Sheena, a Cruithne voyage would be one way.
Emma Stoney:
From Emma’s perspective, sitting in her office in Vegas, every-
thing was starting to fall apart.
The legalistic vultures were hovering over Malenfant and his toy spaceships, and meanwhile the investors, made distrustful by rumors of Malenfant’s growing involvement with bizarre fu-turian types, were starting to desert.
If Malenfant had made himself more available, more visible to shore up confidence, it might have made a difference. But he didn’t. Right through Christmas and into the New Year Malenfant remained locked away with Cornelius Taine, or holed up at his rocket test site.
It seemed to Emma events were approaching a climax. But still Malenfant wouldn’t listen to her.
So Emma went to the Mojave.
Emma stayed the night in a motel in the town of Mojave itself.
She was profoundly uncomfortable, and slept little.
Her transport arrived before dawn. It was an army bus. When she climbed aboard, George Bench was waiting for her. He had a flask of coffee and a bagel. “Breakfast,” he said. She accepted gratefully; the coffee was industrial strength, bat welcome.
The other passengers were young engineers trying to sleep with their heads jammed in corners by the windows.
The drive out to the BOB test site was dull but easy. The sun had risen, the heat climbing, by the time they hit the thirty-mile road to Malenfant’s BOB launch complex — or launch simplex, as he liked to call it.