International Space Station

Definition

The International Space Station (ISS) is a large spacecraft in low Earth orbit, serving as a microgravity and space environment research laboratory. It orbits Earth at an average altitude of approximately 400 km.

5 Must Know Facts For Your Next Test

1. The ISS orbits the Earth approximately once every 90 minutes, traveling at a speed of about 28,000 km/h.
2. Its orbital period allows it to experience multiple sunrises and sunsets each day, providing unique opportunities for astronomical observations.
3. The gravitational force experienced on the ISS is about 90% of that on Earth's surface, but the station remains in continuous freefall, creating a microgravity environment.
4. Energy for the ISS is primarily supplied by its solar arrays, which convert sunlight into electrical power.
5. Maintaining the ISS's orbit requires periodic boosts from visiting spacecraft or onboard thrusters to counteract atmospheric drag.

Review Questions

• What is the approximate altitude at which the ISS orbits Earth?
• Why does the ISS experience microgravity despite being within Earth's gravitational influence?
• How frequently does the ISS complete one orbit around Earth?

Related terms

Orbital Period: The time taken for a satellite to complete one full orbit around its primary body.

Microgravity: A condition in which objects appear to be weightless and experience very small accelerations due to gravity.

Atmospheric Drag: The resistance force exerted by Earth's atmosphere on objects moving through it, such as satellites and spacecraft.