“Nikolai to Yankee.”

The radio crackled to life.

“What is it, Commie?”

A loud BLOOP indicated that a third party—mission control—had begun to broadcast on the channel.

“Use your callsigns, you two.”

“да.” “Yes sir.”

“And keep it English on transmissions.”

“Got it.” “Roger.”

They both knew that it was only appropriate to refer to each other by their first names or their callsigns. But this was their twelfth hour of spacewalk training, and just the hour before, they had been informed that their mission timetable was to be accelerated in order to support the mission that was already on the Martian surface. And with that accelerated timetable came, inexplicably, a refreshed set of ridiculous training callsigns (Tundra and Bullfrog), promptly forgotten.

“Nikolai to Yankee.”

When she realized a second BLOOP was not forthcoming, Sam laughed.

“Yankee here. Go on, Red.”

“Suit pressure check? Feeling lightheaded.”

“Thirty-two kPa. All indicators normal. Any other symptoms?”

“Bah.”

Silence.

“Yankee to Red, repeat. Any other symptoms?”

“I read you, Yankee. Am trying to read own pressure. Suspect instrument failure on your end.”

Nikolai didn’t have any pressure gauge on his suit.

“Yankee to Red. Excuse me?”

“I Repeat. Am trying to read own pressure.”

Sam looked up from the instrument panel and leaned over to see out the porthole into the pool where Nikolai was suspended for his mock spacewalk. Nikolai had partially disassembled one of his pneumatic tools and fed a pressure line into a breach in his pressurized suit. He was fiddling with his oxygen apparatus while he did this—apparently, he knew what pressure the tool operated at, and he was trying to deduce the original pressure of the suit by equalizing the suit pressure with the tool pressure and then factoring in the adjustments he had made to get there.

“Yankee to Red. Did you puncture the suit lining to do that?”

“Can be fixed.”

“Red, any other symptoms to report? I see elevated heart rate now.”

“Heart rate up, yes. Gloves tight, hands likely swelling. I know what the low oxygen symptoms are!”

“You probably know CO posioning symptoms, too, but tell me anyway. Feeling chest pain?”

The bulky white spaceman in the pool turned a little bit, almost as if annoyed. Nikolai removed the tool’s pressure feed to the suit and closed a glove over the suit puncture to keep the water out.

“Ah ha, you just have lower tolerances, friend. A little poisoning makes a man stronger. Chest pain subsiding. I think your pressure gauge has failed, I have twenty kPa. Will adjust.”

“Good. Cease activity and report if you feel additional CO symptoms. Actually, cease activity anyway, we should fix the gauge and your suit before control gets down here.”