“The nearest stars aren’t that far from here,” Barbie said, carefully.  “Surely we could just make our way to them without using the tramlines ...”

“No,” James said, crossly.  “Let me see.”

He ticked off points on his fingers as he spoke.  “The closest star system to us that isn't New Russia is three light years away,” he said.  He knew he sounded disdainful, he just didn't care.  “Placed in context, that means it takes three years for light to reach it.  Assuming we work the drive to the bone, we should be able to make a third of light speed, if we don’t mind the risk of burning out the system in the middle of the interstellar desert.  It will take us roughly nine years to reach this star.”

Barbie’s face twisted, but James wasn't finished.  “There's nothing to slow us down in interplanetary space,” he added, “so we would just keep going if the drive burnt out.  That would send us rocketing through the system at a sizable rate, making it impossible for us to stop.  Nor could anyone catch up with us long enough to offload the crew.  If we didn't run into the star, we'd just fly through and carry on to the next star system.

“All of this assumes, of course, that the  food supplies don’t run out.  We produce only a limited amount of supplies in the hydroponic bays, as we tore half of them out to store weapons and spare parts.  I estimate that we would run out of foodstuffs within two years, at the very latest.  In order to get part of the crew through the voyage, the remainder would have to be eliminated, their bodies fed into the recycling system to nourish the rest of us.”

Barbie blanched.  “You’d have us eating human flesh?”

“Oh, it would be the only way to survive,” James assured her.  The fact that the food processors could turn human flesh into something safe to eat was a closely-guarded secret, one devised by bureaucrats intent on ensuring that the crews always had something to keep them going.  So far, no one had ever had to use the systems.  “But I’m afraid that’s not the end of it.

“Nine years.  Think about it.  Nine years.  The aliens could win the war by then; we might arrive at our destination only to discover an alien fleet waiting for us.  Or perhaps humanity would have won the war.  The universe would have moved on and we would be hopelessly out of date.”

“That’s enough,” Yang said, sharply.

James smiled, then shrugged.  “We will do our very best to get you all home,” he said, wondering just how much of his lecture would make it into the final reports.  Somehow, he suspected the detail about potential cannibalism would be erased by the censors before it was broadcast to the British public.  “And I suggest that you relax and let us work.”