International Space Station

The ISS is the most expensive object ever built — estimated at $150 to $160 billion. It is a geopolitical artifact as much as an engineering one: the result of a 1993 decision to invite Russia into the partnership, partly to redirect Russian aerospace engineers from arms proliferation. The first module — Zarya — launched November 20, 1998. The American Unity node followed seventeen days later. Assembly continued for twelve years across 42 flights. At completion the station was 109 meters across, 73 meters long, 30 meters high. Expedition 1 arrived November 2, 2000. The station has been continuously inhabited since. As of 2026, humans have spent more than 23 continuous years aboard it. The medical findings on bone density loss, fluid redistribution, vision impairment, and radiation exposure are the foundation of everything we know about what long-duration spaceflight does to a human body. Reports of UAP proximity to the ISS have been made by multiple crew members over the program's history. Some are easily explained. Not all of them are.