Megascale engineering is the construction, operation, and maintenance of structures large enough to be best measured in megameters. Terraforming, large geoengineering projects, and stellar husbandry may be considered megascale engineering.
One megameter is 1,000,000 meters (621.371 miles).
- More than 4x the length of Lake Kariba, the world's largest manmade lake (223 kilometers).
- Approximately 37x the circumference of the Large Hadron Collider (27 kilometers).
- The Earth's circumference is 40.07 megameters at the equator, and 39.93 megameters pole-to-pole. Its diameter is about 12.74 megameters.
Terraforming and Geoengineering
The Great Green Wall project aims to create a series of artificial landscapes 7.7 megameters long to combat desertification and climate change effects in Northern Africa. As of 2019 the project reports approximately 15% completion, with a goal of contributing to the 2030 global agenda of the UN Sustainable Development Goals.
A space elevator would require an anchor mass in geosynchronous orbit, about 35.79 megameters from the Earth's surface. Several other methods of tether propulsion for surface-to-orbit launch systems have been proposed, including skyhooks and rotovators.
An orbital ring is a ring-shaped stable station centered around a planet or other celestial body, usable as a habitat, shipyard, solar power collection facility, and/or tether support for surface-to-orbit propulsion. Such a structure around Earth's equator would, at minimum, exceed 81 megameters in circumference.
Construction and use of a stellar engine marks the transition to a Type II civilization on the Kardashev scale.