The Upperside or Upper Edge is a location in Isaac Asimov's Foundation series and Second Foundation trilogy.
Description[]
The Upper Edge was the highest accessible level of Trantor's planetary city, existing beneath the artificial atmospheric containment field that separated the ecumenopolis from space. This critical zone served as Trantor's environmental interface, where advanced technology and carefully managed ecosystems maintained the planet's life support systems. The area featured vast platforms of reinforced durasteel supporting meteorological stations, energy collectors, and ecological preserves, all protected by partial domes and energy shielding that filtered radiation and maintained atmospheric integrity.
In Prelude to Foundation, Dr. Jenarr Leggen's meteorological expedition brought Hari Seldon to the Upper Edge, where research assistant Clowzia demonstrated the intricate ecological systems. She showed him the microforests of silver-leafed oxygen trees, capillary mosses that filtered atmospheric pollutants, and flowering vines that replenished essential nutrients. The carefully engineered fauna included atmospheric plankton that formed the base of the recycling ecosystem and nectar-sipping avian species that pollinated the vegetation. These systems worked in concert with technology to maintain Trantor's habitability.
Foundation's Fear by Gregory Benford expanded on these descriptions, revealing how the Upper Edge's algal vats produced approximately 15% of Trantor's nutrient supply through genetically modified algae strains that converted sunlight and carbon dioxide into proteins. The novel detailed the sophisticated symbiosis between biological systems and mechanical processors that regulated atmospheric composition.
The short story Trantor Falls by Harry Turtledove depicted the catastrophic failure of these systems during the Great Sack. The collapse began with the failure of containment fields, leading to the rapid deterioration of the microforests and contamination of the algal vats. As maintenance systems failed, the carefully balanced ecosystems perished, with plant species withering from atmospheric leaks and animal life succumbing to radiation exposure. This ecological collapse accelerated Trantor's descent into uninhabitability, symbolizing the final breakdown of Imperial infrastructure.
Throughout these accounts, the Upper Edge's biological systems represented both the Empire's technological achievement and its ultimate vulnerability. The flora and fauna, specifically designed for their environmental roles, could not survive without the constant maintenance and protection provided by Trantor's infrastructure. Their demise during the Great Sack demonstrated how even the most advanced artificial ecosystems depended entirely on the social and technological structures that created them.
Trivia[]
Asimov used the Upper Edge to critique humanity’s reliance on technology while acknowledging the enduring need for natural ecosystems, even in a fully urbanized galaxy as explained in his interviews