Arklet 1, which had been sent up on Day 285, turned out to have a few teething problems with its maneuvering thrusters, and so the first bolo coupling in the history of the Cloud Ark took place between Arklet 2 and Arklet 3. Those had been launched on Days 296 and 300, respectively. These first three Arklets represented competing designs and so they all looked a little different. No matter; they were destined to be punched out in different factories and launched on different types of heavy-lift rockets from different spaceports, so minor variations in styling were to be expected. They all had the same general shape, though: a cylinder with domed end caps. That was for the ineluctable reason that they had to be pressurized in order to perform their basic function of keeping humans alive, and pressure sooner or later made everything round. Dinah thought that the pressure hulls looked like the big liquid propane tanks seen next to cabins and mobile homes in the rural mining camps where she had grown up. Others likened them to railway tanker cars, or stubby hot dogs.