I folded my arms. “Well, there’s two kinds, really. High-energy particles emitted by the sun, and GCRs that are just kind of everywhere.”

“Start with the solar particles,” she said.

“Sure. Solar particles are just hydrogen atoms emitted by the sun. Sometimes a magnetic storm on the sun can cause it to spit out a whole bunch of them. Other times it’s relatively quiet. And lately, the Astrophage infection has been robbing so much energy from the sun that magnetic storms are less common.”

“Horrifying,” she said.

“I know. Did you hear that global warming has been almost undone?”

She nodded. “Humanity’s recklessness with our environment accidentally bought us an extra month of time by pre-heating the planet.”

“We fell in poop and came out smelling like roses,” I said.

She laughed. “I have not heard that one. We don’t have that expression in Norwegian.”

“You do now.” I smiled.

She looked down at the hull plan—a little faster than I think was necessary, but whatever.

“How fast do these solar particles travel?” she asked.

“About four hundred kilometers per second.”

“Good. We can ignore them.” She scribbled a note to herself on the paper. “The Hail Mary will be going away faster than that within eight hours. They won’t be able to catch up, let alone do any damage.”

I whistled. “It’s really amazing what we’re doing. I mean… jeez. Astrophage would be the best thing ever if it weren’t, you know, destroying the sun.”

“I know,” she said. “Now, tell me about GCRs.”

“Those are trickier,” I said. “It stands for—”

“Galactic cosmic rays,” she said. “And they’re not cosmic rays, right?”

“Right. They’re just hydrogen ions—protons. But they’re going a lot faster. They’re going near the speed of light.”

“Why are they called cosmic rays if they’re not even electromagnetic emissions?”

“People used to think they were. The name stuck.”

“Do they come from some common source?”

“No, they’re omnidirectional. They’re made by supernovas, which have happened all over the place. We’re just kind of constantly awash with GCRs in all directions. And they’re a huge problem for space travel. But not anymore!”

I leaned forward to look at her schematic again. It was a cross-section of a hull. There was a 1-millimeter void between two walls. “Are you going to fill that area with Astrophage?”

“That’s the plan.”

I pondered the schematic. “You want to fill the hull with fuel? Isn’t that dangerous?”

“Only if we let it see CO⁠2-band light. If it doesn’t see CO⁠2, it won’t do anything. And it’ll be in the dark between the hulls. Dimitri plans to make a fuel slurry out of Astrophage and low-viscosity oil to make it easier to transport to the engines. I want to line the hull with that stuff.”