Authors: Edward M. Lerner
“Who is to say it didn't?”
The gravity tractor wasn't launched until Phoebe was discovered by NASA.
“Understood. But the
Verne
probe was.”
*Â Â Â *Â Â Â *
In a remote corner of the twenty-four-hour cafeteria, over desperately needed coffee, Valerie explained things as clearly as she could. This was
important,
damn it.
No matter that the implications terrified her.
Either she was too fried to explain or Pope was not buying, because he said, “This is not the time to commit astronomy. Everyone on Phoebe needs to focus on getting
down
. Before⦔
Before the missiles launch. No one would tell her how soon that would happen. Neither she nor Ellen had any security clearance, let alone clearances at that level. Her impression was that once some international coordination finishedâa missile salvo could so easily be misconstruedâthe missiles
would
launch.
“It's not astronomy, damn it,” Valerie said. “It's ⦠an option.”
Pope sighed. “Okay, try it again. With fewer, smaller words, please.”
“Forget astronomy and think history,” Ellen said. “In 2014, the Crudetastrophe. In 2018, Phoebe is captured, a permanent base established on it, and the PS-1 project begins. A busy four years, no?
“Back to October 2014 and the Crudetastrophe. All we knew at first was: We're screwed. But a year later, an ongoing NASA survey, watching for space rocks that could endanger Earth, spots something that ought not to exist, not in that orbit. However tough things have become, suddenly there's hope.
“Then, in round numbers: a year, at crash priority, to build a gravity tractor; a year to fly the intercept mission; and a year of infinitesimally weak gravitational nudging. End to end, from the Crudetastrophe to the reconfiguring of Phoebe's orbit, four years.”
“I still don't seeâ”
Valerie cut him off. “In October 2014,
Verne
had just reached the outer asteroid belt. Right where objects like Phoebe belong. A month after the Crudetastrophe,
Verne
went missing. A year before NASA spotted Phoebe on its inexplicable Earth-threatening orbit. Do the math, Tyler.”
Pope rubbed his chin thoughtfully. “Long enoughâby analogy, anywayâfor
Verne
to have changed Phoebe's orbit. You're saying that Burkhalter
threw
Phoebe at Earth?”
Valerie's eyes misted up. “I'm saying Patrick threw us a lifeline.”
“Give me a second.” Pope's eyes narrowed with concentration. “Burkhalter's note referred to his âlast mistake.' You're guessing that mistake was bringing Phoebe, and so the construction of PS-1, and so making possible the attacks from PS-1. That whatever he was doing with the Green Bank Telescope was trying to somehow make things right.”
“It fits, doesn't it?” Ellen said.
Pope said, “When he spotted Phoebe, why didn't he just tell JPL or NASAâ”
While
Verne
continued on its planned course deeper into the asteroid belt. While Phoebe and Earth diverged on their very different orbits. While an energy-starved civilization fell into pieces, and committeesâand nations?âdebated.
While the laws of physics dictated now or never.
Patrick would not have waited. Marcus wouldn't, either.
But Pope wanted it short. Valerie said, “Patrick saw the opportunity and he took it, because that was who he was. After that, would
you
want anyone to know?”
“I suppose not.” Pope glanced at his wristwatch. “But how can this matter now?”
“I'm getting to that.” Valerie swallowed hard. “
This
part is so sensitive none of us dared speak openly on the link. Suppose we're right. Then the big question becomes, where is the
Verne
probe now?”
“Why would I
care
?” Pope asked. He glanced again at his watch.
Valerie said, “Because there is a good chance
Verne
is on Phoebe. Ableâif we can find it, if it's in decent conditionâto ferry a few people to PS-1. If, by then, there is still a PS-1 to reach.”
Pope grabbed for his phone.
Â
Sunday, predawn, October 1
A synthesized representation of Phoebe, slowly spinning, floated above the base command center's main console.
If Marcus squinted hard enough to perceive Phoebe as a sphere, its radius was little more than a half mile. A true sphere of that radius had a surface area approaching five square miles. Double the area to account for hills and valleys? Ten square miles seemed far beyond what he could search in a few hours. But did the entire area require searching? This little moon had been inhabited continuously for five years.
If
Verne
was on Phoebe, why hadn't someone, or some bot, spotted it?
He pondered the globe. He added overlays highlighting the little world's mines, factories, and various surveys. Any terrain NASA and its contractors and their bots had not crossed a million times, tourist bots must have explored.
What about beneath the surface? He retrieved surveys done with ground-penetrating radar. They only reminded him that Phoebe was not a world so much as a rubble pile, a loosely bound community of rocks, agglomerations of dust and hydrocarbons, seams of ice, and vacuum gaps. The Grand Chasm was impossible to ignore, but nothing else leapt out at him.
Three possibilities, Marcus enumerated, yawning, struggling to organize his thoughts. One:
Verne
is nowhere on Phoebe. It can't be found. Two:
Verne
is here, but Patrick hid it. Or three: It's here because Patrick lost control and it crashed.
Only Patrick could not have lost control. He didn't
have
direct control at the end, lacking access to a big radio transmitter. Presumably, Patrick had uploaded new commands to
Verne
via the Deep Space Network while he retained access as
Verne
's principal investigator. He erased the upload from the comm buffers to cover his tracks, not because he panicked. After that, the
Verne
probe, repurposed, had to watch out for itself.
“What did you do, Patrick?” Marcus asked a holo.
The holo volunteered no more than Patrick ever had.
Marcus leaned back in his seat, hands behind his head, fingers interlaced. Patrick had no control. The spacecraft was on its own.
Verne
pulled Phoebe, just as Phoebe pulled
Verne,
the gravitational attraction between two bodies simple to calculate. By maintaining a constant separation,
Verne
transferred the miniscule force of its thrusters to moving Phoebe. No impact or hard shoving to risk scattering the rubble. No landing to hazard.
Marcus stared at the most recent deep-radar survey. It stared back, hinting at something he was too tired or obtuse to see. Taunting him. A not-round, not-at-all-uniform rubble pile.
A nasty suspicion struck him. “Savannah Morgan,” he paged on the base intercom. “Come to the command center.”
Savvy showed up after a couple of minutes. She had dark bags under her eyes and darker smudges on her jumpsuit. “What's up?”
“I need a software engineer's insight.” He gestured at the Phoebe holo. “Autopilot for a gravity tractor. Easy or hard to program?”
“Balancing act, right?”
“Yeah. Thrusters offsetting gravitational attraction between the two bodies.”
“So the closer to Phoebe's surface the tractor hovers, the stronger the attraction. You would want to keep the probe in close.”
“As I understand it.”
Tipping her head this way and that, she examined the holo. “That being one of the bodies?”
“Yeah.”
“Tumbling?”
Like its much bigger sister moon, Phoebe had one face tidally locked to Earth. But in the depths of space, remote from any large mass, why wouldn't Phoebe have tumbled? “I assume so.”
She said, “Then, yes, a big deal. Because Phoebe was tumbling and is irregularly shaped, the force of gravity between it and the tractor would have varied continuously. Ditto because Phoebe's mass distribution is far from uniform. Obvious example: whether the Grand Chasm is near or far from the tractor.”
“So howâ?”
“How would I program such an autopilot? Adaptively. Using lidar or radarâ
Verne
has one of those, right?âto monitor real-time separation. Constantly fine-tuning thrust to maintain separation within a narrow range. And if I want the tractor to hover just over the surface to maximize attraction? That means very little time to react when some inhomogeneity pulls in the probe.
“Or maybe I'd put the tractor into orbit around Phoebe. Any thrust from the spacecraft insufficient to break orbit would nudge the bound system of
both
objects. I figure a close orbit in that case, rather than a close hover, so I could apply more thrust. The probe's orbit would be changing
constantly,
both from the engine thrusting and Phoebe's inhomogeneity. Again, very little time to react whenever real life trumps maneuver calculations.”
She took a deep breath. “For many reasons, that's far from the type of software I would care to write on the fly, let alone have to sneak into an unauthorized upload and splice into code designed for another purpose.”
“A complex balancing act, then. And yet, it worked.”
“Yeah.” Savvy examined the holo some more. “Dollars to doughnuts, at some point it ended like most balancing acts.”
“In a crash?”
She nodded. “Just don't ask me where.”
*Â Â Â *Â Â Â *
It took two hours for another mystery to insinuate its way into Marcus's conscious ruminations.
“Someone awake down there?” he called over the surreptitious downlink.
Define awake.
“I need someone to dig through the rental records for tourist bots.”
I'll get Dr. Clayburn. One minute.
“Sure,” Marcus said.
Valerie here.
There was a pause Marcus read as, “You look terrible, but it won't help for me to point that out.”
What do you need?
“Suppose Patrick didn't just happen to develop a hobby driving Phoebe robots?”
Why would I suppose that?
“If
Verne
is on Phoebe, Patrick wouldn't want anyone to find the wreckage. Not after he had kept its hijacking secret all these years. He would want to hide
Verne
. Physically bury it.”
Yeah. I had wondered about that. Out of Body rental files show check-in and checkout times. Nothing about where a bot happens to wander.
“It was a thought.” He drummed fingers on the console counter. “Say, Val? Could you check the files for lost and stranded bots?” Because if you failed to return your bot to the corral before its batteries ran dry, you paid for its retrieval.
Just a sec.
After a minute, she wrote,
Good call. Patrick got billed to replace several bots. But the records don't indicate locations.
“Replace, not retrieve?”
Yeah. Why?
“Remember seeing any lost bots? On a very unorthodox first date?”
In landslides. In the Grand Chasm.
A long pause.
Could it be?
“Well, we know that
something
hit Phoebe.”
Â
Sunday morning, October 1
Finding
Verne,
knowing where to look, could have been easy. Peer into the Grand Chasm with a high-sensitivity IR sensor: the spacecraft's radioisotope thermoelectric generator, powered by the slow and steady radioactive decay of plutonium, would still be warm. Or survey the chasm from above, towing a metal detector behind a hopper.
If only the terrorists had left them with IR sensors or hoppers. Or if there had been some reason to stock metal detectors on a world devoid of metal.
Instead Marcus made do with the nine volunteers game to join him in the chasmâand twenty less adventuresome types willing to man safety tethers to pull people out as they got stuck. Everyone entering the chasm carried a quick-and-dirty homemade metal detector, little more than an ac oscillator, a couple wire coils, and a voltmeter. Each volunteer had a stretch of canyon about two hundred feet long to search.
Straightened out, the chasm would have run about a third of a mileâbeyond grand for a world not quite four miles in circumference. The rift varied in spots from a few feet in width to almost a hundred feet.
Marcus stepped into the abyss, his rate of descent at first scarcely perceptible. Weighing less than a pound, he easily arrested his fall with his gas pistol. Lateral motion was trickier; practicing, he almost crashed twice. The second time, his boot scraped a furrow along a shallow slope, setting off a slow-motion avalanche.
Verne
's arrival might have been like that: a slow, glancing, bouncing blow. He pictured rock and dust collapsing into subsurface voids. And he pictured something his boot could not imitate: plasma exhaust from
Verne
's thrusters flashing ice to steam. Newly coaxed sunward, much of Phoebe's subsurface ice would have been primed, cometlike, to explode.
Maybe the spacecraft had cartwheeled from one end to the other of what would become the Grand Chasm, triggering steam eruptions and setting off majestic collapses. A blast of steam might have blown
Verne
away. Or
Verne
might lie buried deep beneath the chasm floor, crushed and inaccessible. Or the long-lost spacecraft might be just below the surface, unharmed by the slow-motion rain of dust.
And in just such a shallow hiding place, one of the volunteers found it.
*Â Â Â *Â Â Â *
Six men carried the
Verne
spacecraft into the abandoned hopper garage. Three men on a side. Like pallbearers. The remainder of the work party, like mourners, lagged behind.