Low Earth Orbit

Definition

Low Earth orbit (LEO) refers to the region of space surrounding the Earth where satellites and spacecraft orbit at altitudes below 2,000 kilometers (1,200 miles) above the Earth's surface. This orbital regime is characterized by a relatively short orbital period and close proximity to the Earth's atmosphere.

5 Must Know Facts For Your Next Test

1. Satellites in low Earth orbit typically complete an orbit around the Earth in less than 2 hours.
2. The International Space Station (ISS) is located in low Earth orbit, at an altitude of approximately 400 kilometers (250 miles).
3. Due to atmospheric drag, satellites in low Earth orbit have a limited lifespan and require periodic boosts to maintain their altitude.
4. Many Earth observation and remote sensing satellites are placed in low Earth orbit to take advantage of the close proximity to the planet's surface.
5. Microgravity conditions in low Earth orbit enable unique scientific experiments and research on the effects of weightlessness on various biological and physical processes.

Review Questions

• Explain the key characteristics of low Earth orbit and how they differ from higher orbits.
  • Low Earth orbit is defined by its relatively low altitude, typically below 2,000 kilometers above the Earth's surface. This proximity to the Earth results in a shorter orbital period, with satellites completing an orbit in less than 2 hours. Additionally, low Earth orbit is affected by atmospheric drag, which can slow down and eventually cause satellites to re-enter the atmosphere, requiring periodic boosts to maintain their altitude. In contrast, higher orbits, such as geostationary orbit, are located much farther from the Earth and have longer orbital periods, as well as reduced atmospheric effects.
• Describe the significance of low Earth orbit for scientific research and space exploration.
  • Low Earth orbit provides a unique environment for scientific research and experimentation, particularly in the field of microgravity science. The reduced gravity conditions in low Earth orbit enable the study of various biological and physical processes that are influenced by the effects of weightlessness, such as the behavior of fluids, the growth of crystals, and the physiological changes in living organisms. Additionally, many Earth observation and remote sensing satellites are placed in low Earth orbit to take advantage of their close proximity to the planet's surface, allowing for high-resolution imaging and data collection.
• Analyze the challenges and considerations involved in maintaining satellites and spacecraft in low Earth orbit.
  • Maintaining satellites and spacecraft in low Earth orbit presents several challenges. The primary challenge is the effect of atmospheric drag, which can slow down and eventually cause objects to re-enter the Earth's atmosphere. To counteract this, satellites require periodic boosts to maintain their altitude, which consumes valuable fuel and resources. Additionally, the high-speed orbital velocity in low Earth orbit, combined with the potential for collisions with space debris, necessitates careful tracking and maneuvering to avoid potential impacts. Factors such as the radiation environment and the effects of microgravity on the spacecraft's systems and components must also be carefully considered and mitigated to ensure the long-term viability of missions in low Earth orbit.

Related terms

Orbital Period:

The time it takes for a satellite or spacecraft to complete one full revolution around the Earth in its orbit.

Atmospheric Drag: The force exerted by the Earth's atmosphere on an object in low Earth orbit, which can slow down and eventually cause the object to re-enter the atmosphere.

Microgravity: The condition of near-weightlessness experienced by objects and astronauts in low Earth orbit, where the force of gravity is significantly reduced compared to the Earth's surface.