Low Earth Orbit Decay: Understanding Atmospheric Drag and Reboost Strategies

What is Low Earth Orbit Decay?

Low Earth orbit (LEO) decay refers to the gradual decrease in a satellite's altitude due to atmospheric drag. As satellites move through the Earth’s atmosphere, they experience air resistance that slows them down and causes their orbits to shrink over time.

This phenomenon is particularly significant for objects in LEO, which typically range from 160 to 2,000 kilometers above the Earth's surface, where the density of the atmosphere is sufficient to exert a noticeable drag force.

Factors Influencing Orbital Decay

Several factors contribute to LEO decay. The primary factor is atmospheric drag, which increases with decreasing altitude and higher solar activity. Solar radiation heats the upper atmosphere, causing it to expand and increase the density of air at lower altitudes.

The ballistic coefficient (BC) of a satellite also plays a crucial role in determining its rate of decay. BC is a measure of how effectively an object can penetrate through the atmosphere; satellites with higher BC experience less drag.

Reboost Strategies and Propellant Budgets

To counteract LEO decay, satellite operators often plan reboost maneuvers. These involve using onboard propulsion systems to raise the orbit altitude, which can extend the operational lifetime of a spacecraft.

The success of these maneuvers depends on careful planning, as they require precise calculations of the necessary delta-v (change in velocity) and the associated propellant budget.

Real-World Applications

Understanding LEO decay is essential for mission planners and operators. By accurately modeling atmospheric drag and solar activity, they can predict when a satellite will need reboosts to maintain its operational orbit.

This knowledge also helps in designing more efficient satellites that require less frequent reboosts, thereby extending their useful life and reducing the amount of space debris generated by decommissioned spacecraft.

Frequently asked questions

Try it live

Everything above runs in your browser — open Low Earth Orbit Decay: Atmospheric Drag, Solar Cycle, Ballistic Coefficient and Reboost Budget Lab and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.