Liz looked up at him, her eyes widening. “Cantrell knew we’d run out of reactant, didn’t he?”
“He figured we’d be forced to return to the ship.”
“Only now we can’t return.”
Tobias nodded grimly.
“So how long will the oxygen last?” Liz asked.
“Oh, the oxygen will last quite a while,” he said, frowning. “That’s not the problem.”
“It isn’t?”
He shook his head. “Sniff.”
She sniffed. “Rotten eggs,” she said.
“The earthquake damaged the airlock,” he said. “I also found a crack in the duroplast, back along the wall behind those cabinets.” He pointed toward a row of storage cabinets lining the rear wall of the igloo. “Without the scrubbers, we’re going to get a buildup of hydrogen sulfide. We can’t even refill the tanks in our survival suits.”
“How much time do we have?” she asked.
He frowned, thinking. “I don’t know. Two hours, maybe three. Hydrogen sulfide isn’t like carbon dioxide. It’s more like hydrogen cyanide. It binds with the iron in your hemoglobin. Once it reaches your cells, it shuts down energy production in your mitochondria. Your metabolism grinds to a halt.”
“Does it hurt?”
Tobias thought for a moment, then shrugged. “Not for long.”
“We have a plan,” Advocate Lassiter announced as soon as they reached him over the igloo’s com-link. The interference had worsened, and he had to shout to make himself heard over the static. “We’re going to modify a probe and send down a canister of ferric chloride for the scrubbers. Superintendent Cantrell is personally supervising the work.” His soft jowls glistened with perspiration as he peered nervously out at them through the snow on the monitor.
“Oh, so you weren’t actually planning to kill us,” Tobias shouted back. “That’s reassuring.”
Lassiter winced, not looking either of them in the eye. “No one thought we’d need a second shuttle. We never thought there’d be any reason to go down to the surface.”
“How long does Cantrell think it’s going to take?” Liz asked.
“He’s down in the maintenance bay right now,” Lassiter answered. He glanced away, as though he might actually be able to see the superintendent through the multiple bulkheads separating him from the maintenance bay. “None of this was supposed to happen.”
“I understand that,” Liz said. She clenched her fists in her lap, forcing herself to remain calm. “But we need an answer. How long is it going to take? We only have two hours.”
She knew that wasn’t quite true, of course. They had another two hours before the hydrogen sulfide in the igloo reached lethal levels, but after that they would have two or three more hours of air in the tanks of their survival suits.
“We didn’t plan on any of this,” Lassiter rattled on. As he spoke, the transmission began to break up. “It never occurred to anyone that we could lose the shuttle in an earthquake. It was all just a terrible combination of misfortunes.”
“How long?” Tobias shouted, no longer able to contain his anger. “Just answer the question!”
“Two hours,” Lassiter blurted as his image all but dissolved in the snow on the monitor. “Superintendent Cantrell says he can have the probe down to you in two hours.”
While they waited, Liz and Tobias worked—as much to keep their minds off what was happening as to learn more about the worms.
“I can’t believe the worms’ DNA,” Tobias said after he’d finished his initial analysis. “They now have more genes than we do. More than a hundred thousand. It’s like the genes for a whole new species have been added into their genome. The genes for the old species, the organism that metabolized hydrogen sulfide, are still there, but its genes have been turned off.”
“Then the Anunnaki really were trying to lift them out of their old environment.”
“Someone was. It looks like the whole ecosystem has been reengineered. Maybe not to the extent that we would have modified it if we wanted people to live here, but enough for the worms to survive with an oxygen metabolism.”
“But why?” Liz asked.
Tobias shook his head. “I have no idea. Like I said, organisms that metabolize oxygen produce more energy than chemotrophs, but why the Anunnaki would care is beyond me. All we can do is look at more worms, see if we can figure out which other characteristics were turned off and which were added.”
They had just put another dozen samples into the gene analyzer when Advocate Lassiter notified them that Cantrell had launched the probe with two backup canisters of reactant for the scrubbers. Snapping their faceplates shut, Liz and Tobias hurried outside to wait.
“There it is,” Tobias shouted, pointing up through the wisps of orange mist.
The probe’s exhaust plume guttered like a burning arrow against the dark mass of the gas giant above them. The small craft slid slowly across the sky, then, when it was nearly overhead, the exhaust plume winked out.
“That’s it,” Liz said, peering down at the mission assistant wrapped around her forearm. “The probe has deployed its parachute. Now it’s all up to the computers.”
Looking up into the darkness, she saw a momentary stab of white light as the probe briefly fired one of its steering thrusters. The onboard navigational computer had been programmed to bring it down on a level area of rock about a hundred yards away. One or another of the steering jets fired several more times as the small craft descended toward their position.
“Everything looks fine,” Liz said, studying the readout on her assistant. “It should be down in another thirty seconds.”
Suddenly a blast of wind gusted down from the ice sheet behind them, buffeting Liz with bits of rock and sand. If the probe had been lower, the wind wouldn’t have carried it as far as the fissure. If it had been higher, it might have had time to correct its descent. But the gust came at exactly the wrong moment, and Liz and Tobias could only watch as the small craft was carried out over the abyss, its steering jets firing a constant blast of white flame as it dropped into the cauldron of iron-rich magma below.
“We don’t have another probe,” Advocate Lassiter shouted over the static when they reached him on the igloo’s com-link. The interference was now so bad that they could barely make out his face through the snow. “We need time to figure out another solution.”
“In case you haven’t noticed, we’re running out of time,” Tobias shouted back. “The hydrogen sulfide levels are now above five hundred parts per million. We can’t even take off our helmets.”
In the brief moments that the transmission cleared, Liz could see that Lassiter’s eyes were damp with anguish, his lips trembling. “If there were anything we could do, anything at all…” he said.
“How long until the mining ships get here?” Liz asked. She could feel the fear clutching like gnarled fingers at her chest.
“They’re at maximum acceleration,” Cantrell said. He paced behind Lassiter, little more than a shadow on the snow filled monitor. “This is costing us an arm and a leg.” He stopped, his face coming into focus as he leaned toward them. “But money’s no object, okay? We’ll spend whatever it takes.”
“How long?” Tobias repeated.
The superintendent straightened, shoving his hands into the pocket of his tunic. “Seventy-three hours.”
Tobias glanced down at his own mission assistant, then up at Cantrell. “Perfect,” he said. “You’re only going to miss by three days.”
“I don’t know what to say,” Advocate Lassiter shouted. “We never planned on any of this.”
“That’s the problem,” Tobias said as he reached out to break the connection. “You never planned on anything.”