What does orbital decay refer to?

• A. The sudden increase of altitude of a satellite
• B. The decrease of a satellite's orbit due to drag
• C. The maintenance of a stable orbit over time
• D. The preservation of a satellite's equipment

Answer: (B)

Orbital decay refers to the process where a satellite's orbit gradually decreases in altitude over time, primarily due to atmospheric drag. As satellites orbit the Earth, they encounter residual atmospheric particles, even at high altitudes. These particles create drag which slows down the satellite's velocity, resulting in a lower orbit. Over time, this reduction in altitude can lead to re-entry into the Earth’s atmosphere and potential destruction of the satellite.

This phenomenon is particularly relevant for low Earth orbit (LEO) satellites, where the atmosphere, although thin, can still exert a significant drag force. Understanding orbital decay is crucial for mission planning and ensuring that satellites are operated in a manner that considers their eventual end of life, whether through controlled re-entry or natural decay.