Sky Nest

The Sky Nest is a hydrogen airship built by the spiders of Seven Trees. It carries Portia and her crew towards the top of their world’s atmosphere, and it is the mothership of the smaller Star Nest.

Description

The Sky Nest is a gasbag of silk and hydrogen with a long, slender crew cabin hanging beneath it. When Fabian first sees it over Seven Trees, the silvery envelope is three hundred metres long and dwarfs the cabin. At the height it was designed for, the gasbag has expanded to half a kilometre, and its leading edge has reshaped itself for streamlining. The profile of the whole vessel is fluid, set moment to moment by the tensioned cords of its internal structure. Gasbag and cabin are skinned with a silvery, glittering thread, an organic material that scatters and reflects sunlight. The crew compartment is cylindrical, built with two hulls and a layer of air between the sheets of silk for insulation. The spiders look out through the faintest shimmer at the ground.

Engines and brain

Apart from a small crew and a handful of engines, the ship is almost weightless: a cloud of silk and wood and hydrogen. Its propellers are worked by the god engines, named for an idea taken from the Messenger. Before that idea was dictated, nobody had considered rotary motion. Bioelectric fields spin the light metal propellers and steadily separate the ship from the ground.

The airship thinks for itself. Bianca designed it to, because the calculations needed to lift an object of gossamer and hydrogen to the upper atmosphere would challenge even her. An ant colony runs the vessel, workers of two centimetres at most, bred to receive complex conditioning and writing much of it themselves. Cultured tissue links the far parts of the colony, so the ants send impulses through the ship’s nerves instead of walking, and the impulses become chemical instructions at the other ends. Bianca wondered whether the thing she had made might one day cross the line between a calculation and a mind.

In the bows sit the radio and the main terminal, a lectern with paired pits. Viola places her palps in the pits and the ship tells her how each of its parts is holding up, by touch and by scent. Talking to the Sky Nest feels to her much the way speaking to the Messenger felt.

Flight

Portia and her crew of twelve, led by Viola, gather on farmland beyond the last buildings of Seven Trees. Two earlier attempts have been put off for bad weather. The Sky Nest floats over the city, drops lines a hundred metres to the ground, and the skeleton flight crew hands the ship over and abseils down its own lines.

The climb starts as the easy stage of the journey. The onboard colony reports to Bianca on its own radio frequency, and three distant transmitters triangulate the ship’s position. The work goes more slowly than expected and the cold discomforts the crew, though it stays within tolerance.

Higher up, the ship needs help from outside. Ants cannot regulate their own temperature and cannot work far beyond the core of the vessel, so the spiders put on suits of silk and crawl over the hull, weaving pressure doors and taking them apart again so temporary airlocks come and go. Some come back bound to the backs of their comrades, overcome by the cold despite the silk layers and the chemical heaters slung beneath their bellies.

At its ceiling the Sky Nest finds equilibrium in the upper air. The Star Nest has been clinging to the top of the gasbag, and now the ship’s ants cut the host of tiny lines holding it. The smaller craft floats free and climbs higher than the more robust Sky Nest can follow.

Role in the story

The project exists because the spiders have only a limited ability to build rockets that burn fuel, since life on their planet is too young to have laid down fossil fuels. Viola stays in the long crew compartment and radios instructions to Portia and Fabian as they separate. The first picture Bianca sends to the Messenger is a view of the Sky Nest lifting away from the city, and the Messenger’s language turns out to have a word for airship already. Portia returns to consciousness aboard the ship, gorged and damaged, having lost one rear leg, two sections of another limb and one of her secondary eyes.

Unanswered questions

• How long the climb to the operational ceiling took.
• How many ants serve aboard.
• What became of the Sky Nest after the Star Nest was released.

Trivia

• The chapter in which the Sky Nest first appears, 6.1, is titled “The Balloon Goes Up”.