Page 20 of Artemis

“Yeah.” He picked up a wrench and threw it into the air. It lofted toward the ceiling.

“Then they…what? Dump their load and go back to Moltke?”

“After they recharge.”

; I ran my hand along the sleek, reflective metal of the basin. “How big’s the battery?”

“Two point four megawatt hours.”

“Wow!” I turned to him. “I could arc-weld with that kind of juice.”

He shrugged. “Hauling a hundred tons of rock takes energy.”

I climbed under the harvester. “How does it deal with heat rejection? Wax state-change material?”

“No idea.”

When you’re in a vacuum, getting rid of heat is a problem. There’s no air to carry it away. And when you have electric power, every Joule of energy ultimately becomes heat. It might be from electrical resistance, friction in moving parts, or chemical reactions in the battery that release the energy in the first place. But ultimately it all ends up as heat.

Artemis has a complex coolant system that conveys the heat to thermal panels near the reactor complex. They sit in the shade and slowly radiate the energy away as infrared light. But the harvesters had to be self-contained.

After some searching, I found what I was looking for. The heat-rejection system valve. I recognized the type immediately—Dad and I had attached many of these in the past while repairing rovers.

“Yeah. It’s wax,” I said.

I saw Trond’s feet approach. “What’s that mean?” he asked.

“The battery and motor housings are encased in a solid wax reservoir. Melting the wax takes a lot of energy, so that’s where the heat goes. The wax lines are surrounded by coolant pipes. When the harvester comes home to recharge, they pump cold water into those pipes to re-chill the wax, then pull the newly heated water back out. Then they cool the water off at their leisure while the harvester gets back to work.”

“So can you make the harvesters overheat?” he asked. “Is that your plan?”

“It’s not that simple. There are safeties to prevent overheating. The harvesters would just shut down until they cooled off. Sanchez’s engineers would fix the problem right away. I have a different idea.”

I wriggled out from under the harvester, stood, and stretched my back. Then I climbed the side and dropped into the basin. My voice echoed as I spoke. “Can any of its cameras see in here?”

“Why?” he asked. “Oh! You’re going to ride a harvester to the Moltke Foothills!”

“Trond, can the cameras see in here?”

“No. Their purpose is navigation. They point outward. Hey, how will you get out of the city? You don’t have airlock privileges.”

“Don’t worry about it.” I climbed out of the basin and dropped four meters to the ground. I pulled a chair toward me, spun it around, and straddled it. I rested my chin on my palm and got lost in thought.

Trond sidled over. “So?”

“Thinking,” I said.

“Do women know how sexy they look when they sit like that?”

“Of course.”

“I knew it!”

“Trying to concentrate.”

“Sorry.”