The Flying Cities: Engineering the Pav Rescue

When Jacques came to me with the problem — "we need to move a city, Oliver, a flying city made of wood and hope, across interstellar distances" — I thought he was joking. He wasn't. The Pav had built their civilisation on gas giant floaters, using a primitive form of SURGE technology for lift. They had no spaceflight, no hulls, no radiation shielding. We had to wrap each city in a habitable bubble and fly it to a new star system.

📖 From the Books: The Pav flying cities were a marvel of alien engineering, described in All These Worlds (Book 3). They used SURGE coils — independently invented — for lift within their gas giant's atmosphere, but had never built anything capable of leaving the planet. The Bobs' engineering challenge was to enclose each city in an environmentally sealed bubble, provide artificial gravity (the Pav's native gravity was ~0.6 G), install life support, navigation, and propulsion — and do it without the Pav inside panicking and taking their chances with the gas giant. The project was one of the most complex engineering efforts in Bobiverse history.

The Cities

The Pav cities were extraordinary structures. Each one was built around a framework of woven organic fibre — something between wood and carbon composite — with living spaces suspended beneath a massive SURGE-driven lifting body. They were designed for atmospheric flight, not space. The entire city flexed and moved with the wind currents. Permanently mooring one to a propulsion system was like trying to strap a rocket to a cloud.

We built a framework of Heaven-4 structural members around each city — a geodesic cage that would hold its shape during acceleration and provide mounting points for the SURGE drives. The cage didn't touch the city itself; it was spaced about 50 metres from the outermost structures, so the Pav could see out and wouldn't feel enclosed. Jacques insisted on that. "They need to see the sky," he said. "Even if it's a different sky."

The Bubble

The life support system was the tricky part. The Pav breathe a slightly different gas mix than humans — higher CO₂ tolerance, lower oxygen — so we couldn't just pump in standard atmosphere. We built a closed-loop environmental system that matched their native air composition, temperature, and humidity. The bubble was transparent (they needed to see the stars, Jacques again) but polarised for radiation protection. It inflated around the cage, sealed, and pressurised. Two weeks of testing, then go.

The Transit

Fourteen months at 0.04c. The Pav had never left their atmosphere. They certainly had never experienced weightlessness. We spun the entire assembly at 0.6 G during transit so they could walk normally. The priests — and there were many priests — spent the first month in non-stop prayer. The children spent it pressing their faces against the bubble, watching the stars go by.

When we arrived at the destination system and lowered the cities into the new gas giant's atmosphere, the oldest Pav elder — Vesper — stepped onto the new surface and said: "The angels have kept their promise." I'm not religious. But I'll admit, I felt something.