Graveyard Orbits: Final Resting Place for Satellites
Graveyard orbits are designated zones where inactive satellites are moved to minimise space debris. Discover their importance and function.
A graveyard orbit is a region in space where defunct satellites are moved at the end of their operational life to reduce the risk of collision with active satellites. Typically situated several hundred kilometres above geostationary orbit (GEO), these orbits are used to safely dispose of satellites that can no longer be controlled. This practice helps to manage the growing problem of space debris, which includes over 28,923 tracked objects according to current data.
How Do Graveyard Orbits Work?
Graveyard orbits function by relocating satellites from their operational orbits to a higher altitude, where they pose less risk to active satellites. For GEO satellites, this involves moving them approximately 300 km above their operational orbit. This process requires the satellite to retain enough fuel to perform a final manoeuvre. The NORAD ID system tracks these satellites to ensure they remain in their designated graveyard orbit, contributing to the safety of the space environment.
Why Are Graveyard Orbits Important?
Graveyard orbits are crucial for mitigating the risks associated with space debris. With over 18,180 active satellites and an estimated 15,800 tonnes of orbital mass, the potential for collisions is significant. By transferring defunct satellites to graveyard orbits, space agencies can reduce the probability of collisions that would generate additional debris. This is particularly important for maintaining the safety and sustainability of the geostationary belt, which is vital for communication and weather satellites.
Graveyard Orbit vs. Deorbiting
While graveyard orbits are used for satellites in higher orbits, deorbiting is the preferred method for those in low Earth orbit (LEO). Deorbiting involves guiding the satellite back into Earth's atmosphere, where it burns up upon re-entry. This method is not feasible for GEO satellites due to the vast amount of energy required to lower their orbits. The choice between graveyard orbiting and deorbiting depends on the satellite's altitude, remaining fuel, and mission design.
The Process of Moving to a Graveyard Orbit
The transition to a graveyard orbit involves a series of precise manoeuvres. A satellite must first increase its altitude using its onboard propulsion system. This requires careful planning to ensure the satellite has enough fuel remaining at the end of its mission. Once in the graveyard orbit, the satellite's systems are typically shut down to prevent interference with other spacecraft. The Orbital Radar glossary provides detailed definitions of terms related to this process.
Key Takeaways
Graveyard orbits play a vital role in space sustainability by reducing collision risks and managing debris. With over 28,923 objects tracked in orbit, effective satellite disposal strategies are essential. By moving defunct satellites to graveyard orbits, space agencies help preserve the operational integrity of critical orbital zones. The Orbital Radar debris map offers insights into the current space debris environment.
