What Happens to Satellites When They Run Out of Fuel: The Orbits, Decay, and Residual Liveliness

Satellites Atmospheric Drag Dynamics

At Low Altitudes: In low Earth orbit (LEO), satellites, like any other objects in space, are subject to atmospheric drag. As stated, “Jenius!” we should not be surprised by this phenomenon since it is a well-established fact. In low Earth orbit, the extremely thin atmosphere exerts a minute but persistent frictional force on the satellite. The friction causes the satellite to lose velocity gradually, resulting in a gradual descent. However, if the satellite is equipped with fuel, it can use its thrusters to counteract this drag, maintaining its altitude and orbital speed. Once the fuel is depleted, the satellite no longer has the capability to compensate, and it continues to lose altitude. Eventually, it enters a denser part of the atmosphere, where it further slows down and is consumed by atmospheric friction, leading to a burn-up and disintegration.

High Altitudes and Space Trash: In contrast, satellites in higher orbits experience much less atmospheric drag. The atmosphere at these altitudes is so thin that its influence on the satellite is negligible, and the satellite can maintain its orbit indefinitely without fuel. However, these satellites do not escape completely unscathed. They still experience a very minor deceleration due to other factors such as radiation pressure and the gravitational pull of other celestial bodies. This deceleration, although extremely slow, can lead to an eventual decay over decades, centuries, or even millennia. Some notable examples include the Vanguard 1, a satellite launched in 1958, which continues to orbit the Earth even today, and the Moon, which has been in orbit for billions of years without the need for fuel.

Historical Context and Newton’s Laws: Historically, the behavior of satellites can be explained through Newton's laws of motion and his theory of gravity. Isaac Newton famously stated, “Satellites don’t need no stinking fuel,” which is a paraphrase of his third law of motion, which essentially states that every action has an equal and opposite reaction. While Newton’s laws might seem straightforward in theory, they have held true in practice for centuries, ensuring that satellites maintain their orbits without the continuous expenditure of fuel. The Moon, with its billions of years of uninterrupted orbit, stands as a testament to this principle. Modern satellites, like the Vanguard 1, demonstrate the interplay between orbital decay and the effects of atmospheric drag, while high-altitude satellites exemplify sustained orbits without reliance on fuel.

Orbit Decay in Various Altitudes: For satellites in higher orbits, orbital decay is a slow, drawn-out process. These satellites are not immune to orbital changes, but the atmospheric drag is minimal, making the decay extremely gradual. This means that even if a satellite is not equipped with fuel, it can remain in orbit for a very long time, potentially hundreds or even thousands of years. However, the agricultural predictions of long-term orbital stability eventually lead to a point where the satellite will either burn up in the atmosphere or crash into the Earth if it is large enough to survive the re-entry process.

Conclusion on Satellites and Fuel: While satellites in LEO require continuous fuel to maintain their orbits, those in higher orbits can function without any propulsion for extended periods. Satellites like the Vanguard 1 and the Moon prove that orbits can be sustained without the need for fuel, at least for the purpose of maintaining a stable orbit. The interplay between atmospheric drag and orbital mechanics continues to be a fascinating area of study, with much still to be learned and understood about the long-term behavior of satellites in space.