Low Earth Orbit
Low Earth Orbit
Low Earth Orbit (usually abbreviated LEO) refers to the region of space extending from roughly 160 to 2,000 kilometers above Earth's surface. By 2158 it is the busiest volume of space in human history, serving as the principal gateway between Earth and the rest of the Solar System.
Most atmospheric spacecraft entering orbit rendezvous somewhere within LEO before transferring passengers or cargo to larger orbital vehicles. Hundreds of stations, hotels, shipyards, fuel depots, warehouses, research facilities and manufacturing complexes occupy a wide variety of orbital altitudes and inclinations. Some remain in service for decades, while others are assembled, expanded, relocated or dismantled as commercial needs change.
Unlike the open expanses of deep space, LEO is tightly managed. Spacecraft follow assigned traffic corridors and approach procedures coordinated by a combination of human controllers and AI traffic management systems. Unauthorized maneuvers are treated seriously, not only because of collision risks but because even small debris can remain in orbit for years.
The largest destination in Low Earth Orbit is Goddard Transfer Station, the primary interchange between atmospheric spacecraft and orbital transport. Travelers arriving from Earth aboard Shenlong-class spaceplanes normally transfer there to chemical orbital vehicles or Nuclear Thermal Rocket (NTR) spacecraft bound for Luna, the Lagrange colonies or destinations farther out in the Solar System.
For most people working in space, Low Earth Orbit becomes routine surprisingly quickly. Veterans joke that "you haven't really left Earth until you've left LEO." Despite the enormous number of spacecraft operating there, much of the traffic is invisible from any single station. Radar, optical tracking systems and AI coordination maintain a constantly changing picture of tens of thousands of active objects, from crewed spacecraft to maintenance drones.
Although launch costs have fallen dramatically since the early twenty-first century, reaching orbit remains one of the most energy-intensive parts of any journey. As a result, large interplanetary spacecraft are rarely built on Earth's surface. Instead, components are launched separately and assembled in orbit by construction robots, autonomous cranes and human crews working in vacc suits.