
A large spacecraft in low Earth orbit that serves as a microgravity and space environment research laboratory.The International Space Station (ISS) is a modular space station in low Earth orbit, serving as a microgravity and space environment research laboratory. It is a collaborative project among five space agencies: NASA (United States), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). The ISS has been continuously inhabited since November 2000, providing a unique platform for experiments in biology, physics, astronomy, and materials science that cannot be performed on Earth.
The first module, Zarya, was launched in November 1998, followed by the Unity module in December 1998. The station has been continuously crewed since Expedition 1 arrived in November 2000.
The ISS orbits Earth at an average altitude of about 420 kilometers, completing roughly 16 orbits per day. It maintains a microgravity environment (about 10^-6 g) by continuously free-falling around Earth. The station's systems include solar arrays for power, thermal control radiators, life support for crew, and docking ports for visiting spacecraft. Experiments are conducted in onboard laboratories, with results transmitted to Earth or returned via cargo capsules.
The ISS supports research in protein crystallization, combustion science, fluid dynamics, and human physiology, with applications ranging from drug development to understanding bone loss in osteoporosis.
The ISS is visible from Earth with the naked eye and is the largest human-made object in space, spanning about the size of a football field.









