When an active satellite fails, its fate depends on several factors, including its altitude, design, and any intervention measures taken. Here are some possible scenarios:
Low Earth Orbit (LEO): Satellites in LEO, typically below 2,000 kilometers (1,200 miles) altitude, are subject to atmospheric drag. When a satellite fails, it may experience a gradual decay in its orbit due to this drag. Over time, the satellite's orbit may deteriorate to the point where it re-enters Earth's atmosphere and burns up, posing minimal risk to people on the ground.
Geostationary Orbit (GEO): Satellites in GEO, located approximately 36,000 kilometers (22,000 miles) above the Earth's equator, operate at higher altitudes where atmospheric drag is negligible. If a GEO satellite fails, it will typically remain in its orbit for an extended period since there is no significant atmospheric drag to cause rapid decay. Depending on the satellite's design and remaining propellant, operators may try to maneuver it into a graveyard orbit, a higher orbit specifically designated for retired satellites. This practice helps to reduce the congestion of active satellite orbits.
Controlled Re-entry: In some cases, satellite operators may have the capability to control a satellite's re-entry process. By firing onboard thrusters or adjusting its trajectory, they can guide the satellite to safely re-enter Earth's atmosphere over an uninhabited area like an ocean. This controlled re-entry helps minimize the risks associated with uncontrolled satellite debris falling in populated regions.
Uncontrolled Re-entry: If a satellite is unable to be controlled or maneuvered, it will eventually re-enter the Earth's atmosphere on its own. Uncontrolled re-entry means that the satellite's path cannot be precisely predicted, making it challenging to determine where the debris may land. However, the vast majority of Earth's surface is covered by oceans, and the likelihood of satellite debris causing harm to individuals or property is very low.
It's important to note that satellite operators and international space agencies prioritize safe and responsible practices regarding satellite disposal to mitigate the risks of space debris and protect both people on Earth and other operational satellites in space.