“Sounds like a temperature roller coaster for the pilot,” said Fatani.
“It takes some getting used to,” admitted Shenzu. “Sweltering heat one moment, teeth-chattering cold the next.”
“I’ve been doing this for months,” said the pilot, “and I’m still not used to it. But it’s a such a ride, I’d dig all day if they’d let me.”
“You said it had hyperfast mode?” asked Mazer.
“Speed is relative,” said Shenzu. “We consider it fast for a drill sledge.”
“How fast?” asked Mazer.
“We’ve topped them out at twenty-four kilometers per hour.”
“Through rock?” Mazer was stunned.
“Oh yes. When it’s gophering along, going normal speed, it runs about half that. But if you hit rock and punch it, if you go hot, she burns a hole through the ground.”
“So rock is faster?” asked Patu.
“More propulsion,” said Shenzu.
“What about communication?” asked Fatani. “Radio doesn’t go through dirt.”
“Infrasound,” said the pilot. “Elephant speech. It’s slower than regular speech, so the receiver speeds it up so you can hear it. There’s a time lag, though, as if you were talking to someone on the moon. Rocks carry the infrasound digitally, but you can’t receive anything when you’re going hot. Gophering you can hear. But when you punch it, you’re on your own.”
Shenzu waved over a Chinese soldier. The man approached carrying a helmet atop a neatly folded cool-suit. Shenzu took them both and handed them to Mazer. “We took the liberty of pulling your sizes from your files and making you each a suit. As the commanding officer of your team, Captain Rackham, we thought you’d like the honor of going first.”
“Now?” said Mazer. “I have no idea how to drive it yet.”
“This drill sledge fits two,” said Shenzu. “Not comfortably, I’m afraid, but it’s how we train our pilots. Lieutenant Wong here will take you for your first dig.”
“Relieve your bladder first,” said Wong. “Once we start digging we can’t pull over, and you do not want to go in your suit. Nothing’s worse than ice crotch.”
Mazer changed in the bunker and returned a few minutes later. The suit was tight, and the coils felt awkward. The ones on his inner thighs kept rubbing against each other, so he waddled and stepped bowleggedly.
“How does the suit feel?” asked Shenzu.
“It’s not freezing yet,” said Mazer, “so I can’t complain.”
The drill sledge was now held up in the air at a fifty-degree angle by long spindly legs that extended from the sides of it like legs on a granddaddy long-leg spider. The drill bit was pointed down toward the earth, less than a meter off the ground.
“The legs get it into a diving position,” said Shenzu. “It can’t dig down when it’s horizontal on the surface unless it’s entering into the side of a mountain.”
A collapsible ladder extended down from the cockpit. Lieutenant Wong was already up in the forward seat waiting. Mazer ascended the ladder and awkwardly climbed into the narrow seat behind him, nearly kicking Wong in the head as he brought his foot around. It was extremely close quarters, with only Wong’s seatback between them. Mazer found the chest harness and buckled in as Wong retracted the ladder and closed the cockpit, cutting out all exterior light. The glow from the cockpit instrumentation bathed them both in red and green, and Mazer leaned as far as he could to the side to see the front. A small holo of the drill sledge appeared in the air above the console.
“How do you know what’s ahead of you?” asked Mazer.
“Depth gauges,” said Wong. “They measure the density of mass ahead.” He made an adjustment to the holofield, and a colorful cross section of the earth appeared. “The darker areas are thickest,” he said, gesturing at the holo. “Probably granite. Hit those and you go hot, really cruising. The brighter spots like these here and here are soft earth, such as clay.”
“What about those white lines that crisscross through the image?”
“Those are tunnels we’ve dug with the drill sledges in the past. They’re all over this valley. It’s like a man-sized anthill beneath us.”
“What happens if you hit water? Like an underground lake or spring?”
“Better to avoid those. We try not to screw up the water table, but sometimes it’s unavoidable. Hit a water source on a dive, and the water chases you down the hole, like pulling the plug in the bathtub. Water isn’t much of a propulsion, either. It all goes to steam. So hitting water is like hitting the brakes. That’s why you always want to aim for rock. You ready?”
“Go easy on me.”
“There’s nothing easy about these babies.”
He made a few hand gestures in the holofield, and the drill bit roared to life, spinning quickly almost immediately and getting up to a screaming whine in less than ten seconds. The cockpit vibrated. Mazer felt as if his bones were rattling.