9.1 Graveyard orbits and re-orbiting techniques
3 min read•august 7, 2024
Graveyard orbits and re-orbiting techniques are crucial for managing space debris. These strategies involve moving defunct satellites to higher orbits, reducing collision risks with active satellites. It's a balancing act between fuel reserves, orbital mechanics, and long-term stability.
Re-orbiting requires careful planning and execution. Satellites need enough fuel for end-of-life maneuvers, and operators must consider factors like timing, collision risks, and international guidelines. It's all about responsible satellite disposal to keep space safe and usable.
Graveyard Orbits
Definition and Characteristics
Top images from around the web for Definition and Characteristics
Weltraummüll: die aktuelle Lage - globalmagazin View original
Is this image relevant?
Spacecraft cemetery - Wikipedia View original
Is this image relevant?
Herschel Telescope Archives - Universe Today View original
Is this image relevant?
Weltraummüll: die aktuelle Lage - globalmagazin View original
Is this image relevant?
Spacecraft cemetery - Wikipedia View original
Is this image relevant?
1 of 3
Top images from around the web for Definition and Characteristics
Weltraummüll: die aktuelle Lage - globalmagazin View original
Is this image relevant?
Spacecraft cemetery - Wikipedia View original
Is this image relevant?
Herschel Telescope Archives - Universe Today View original
Is this image relevant?
Weltraummüll: die aktuelle Lage - globalmagazin View original
Is this image relevant?
Spacecraft cemetery - Wikipedia View original
Is this image relevant?
1 of 3
- Graveyard orbit refers to a disposal orbit where defunct satellites are placed at the end of their operational life to reduce the risk of collisions with active satellites
- Super-synchronous orbit is an orbit above the geostationary orbit (GEO) altitude of 35,786 km, typically used for graveyard orbits
- Orbital stability is a crucial factor in selecting graveyard orbits to ensure long-term containment of disposed satellites and minimize the risk of their re-entry into the protected regions
- Long-term evolution of graveyard orbits is influenced by various perturbations such as solar radiation pressure, third-body effects (lunar and solar gravity), and the Earth's oblateness
Advantages and Challenges
- Graveyard orbits provide a safe disposal option for satellites at the end of their operational life, reducing the probability of collisions with active satellites in the geostationary orbit region
- Placing satellites in graveyard orbits requires additional fuel reserves and careful planning of end-of-life operations to ensure successful re-orbiting maneuvers
- The selection of appropriate graveyard orbits involves considering factors such as the satellite's mass, area-to-mass ratio, and the desired long-term stability of the disposal orbit
- Challenges associated with graveyard orbits include the need for accurate orbit determination and control, as well as the potential for long-term orbit instability due to perturbations
Re-Orbiting Techniques
Maneuvers and Requirements
- Re-orbiting maneuvers involve raising the satellite's altitude to a graveyard orbit at the end of its operational life
- Delta-v requirements for re-orbiting depend on the satellite's initial orbit, mass, and the desired graveyard orbit altitude
- Fuel reserves must be allocated and managed throughout the satellite's mission to ensure sufficient propellant is available for end-of-life re-orbiting maneuvers
- End-of-life operations include planning and executing the necessary maneuvers to raise the satellite's orbit, as well as deactivating and passivating the spacecraft to minimize the risk of explosions or fragmentation
Strategies and Considerations
- Re-orbiting strategies may involve a single burn or a series of smaller maneuvers to gradually raise the satellite's altitude over time
- The timing and sequence of re-orbiting maneuvers are critical to minimize the risk of collisions with other satellites during the disposal process
- Spacecraft design considerations for re-orbiting include the placement and sizing of propulsion systems, as well as the optimization of fuel consumption throughout the mission
- International guidelines and best practices, such as the recommendations, provide guidance on re-orbiting altitudes and post-mission disposal procedures
Risk Assessment
Collision Probability and Mitigation
- Collision risk assessment involves evaluating the probability of collisions between the disposed satellite and other objects in the geostationary orbit region
- Factors influencing collision risk include the satellite's size, shape, and altitude, as well as the population of objects in the surrounding orbital environment
- Mitigation measures to reduce collision risk include selecting appropriate graveyard orbit altitudes, minimizing the satellite's cross-sectional area, and ensuring the spacecraft is passivated and stabilized after disposal
- Regular tracking and monitoring of disposed satellites in graveyard orbits are essential to assess their long-term evolution and identify any potential risks or instabilities
Long-Term Orbit Evolution and Stability
- Long-term orbit evolution of disposed satellites in graveyard orbits is influenced by various perturbations, such as solar radiation pressure, gravitational effects, and the Earth's oblateness
- Assessing the long-term stability of graveyard orbits is crucial to ensure that disposed satellites remain confined within the designated disposal region and do not pose a risk to active satellites
- Numerical simulations and analytical models are used to predict the long-term behavior of disposed satellites and evaluate the effectiveness of graveyard orbit selection
- Regular updates and refinements to collision risk assessment methods are necessary to incorporate new data, improved models, and changes in the orbital environment over time
Key Terms to Review (16)
Active Debris Removal: Active debris removal refers to the set of technologies and missions designed to remove space debris from Earth's orbit actively. This process involves using various methods, such as robotic arms, nets, or harpoons, to capture and deorbit defunct satellites and fragments, thereby reducing the risk of collisions and ensuring the long-term sustainability of space activities.
Apogee and Perigee Adjustments: Apogee and perigee adjustments refer to the maneuvers made by satellites to change their orbits, specifically the points at which they are farthest (apogee) and closest (perigee) to the Earth. These adjustments are crucial for maintaining a satellite's operational orbit, ensuring its functionality, and managing space debris by positioning defunct satellites in graveyard orbits away from operational ones.
Collision avoidance: Collision avoidance refers to the strategies and techniques used to prevent spacecraft from colliding with space debris or other satellites. This concept is crucial for ensuring the safety and sustainability of space operations, as even small debris can cause significant damage. Effective collision avoidance incorporates tracking space objects, predicting their trajectories, and executing maneuvers to avoid potential collisions.
Demise: In the context of space debris and orbital mechanics, 'demise' refers to the process by which an object in space is destroyed or disintegrated during re-entry into the Earth's atmosphere. This concept is critical for ensuring that defunct satellites and other space debris do not pose risks to people or property on the ground. Understanding demise is key to designing spacecraft that can effectively minimize risks associated with space debris.
Deorbit devices: Deorbit devices are technologies designed to facilitate the controlled re-entry of satellites and space debris into Earth's atmosphere, ensuring that they safely burn up upon re-entry or fall into designated areas, such as oceans. These devices help mitigate the risks associated with space debris by actively promoting the removal of defunct satellites from orbit, thereby addressing the growing concern of overcrowded space environments and potential collisions.
Disposal trajectory: A disposal trajectory refers to the planned path or orbit that a satellite or space debris follows when it is intentionally decommissioned and removed from operational use. This trajectory is crucial in managing the end-of-life phase of spacecraft to minimize the risk of collisions and space debris generation, particularly by guiding defunct satellites into graveyard orbits or deorbiting them safely into the Earth's atmosphere.
End-of-life disposal: End-of-life disposal refers to the processes and methods used to manage spacecraft and satellite systems when they reach the end of their operational lifespan. This includes strategies to ensure that defunct satellites do not contribute to space debris, which can pose risks to active spacecraft and the sustainability of space activities.
Geostationary Orbit Graveyard: The geostationary orbit graveyard is a designated area in space located approximately 300 kilometers above the geostationary orbit (GEO), where defunct satellites are moved to prevent interference with operational satellites. This area serves as a critical part of space debris mitigation strategies by providing a safe zone for decommissioned satellites, thus reducing the risk of collisions in the densely populated GEO region. The practice of relocating satellites to this orbit is essential for maintaining the long-term sustainability of space operations.
Inter-Agency Space Debris Coordination Committee (IADC): The Inter-Agency Space Debris Coordination Committee (IADC) is an international forum for space agencies to coordinate efforts in the area of space debris mitigation and research. It facilitates collaboration among member organizations to develop guidelines and strategies aimed at minimizing space debris, ensuring safe operations in space, and promoting sustainable practices in outer space activities.
Low Earth Orbit Graveyard: A low earth orbit graveyard refers to a designated orbital region where defunct satellites and space debris are intentionally placed at the end of their operational lives. This practice helps reduce the risk of collision with active satellites and ensures that the primary operational orbits remain clear for future missions.
Orbital inclination: Orbital inclination is the angle between the orbital plane of an object in space and the reference plane, typically the equatorial plane of the celestial body it orbits. This angle is crucial in determining the characteristics of an orbit, as it influences factors such as ground track, coverage, and potential collisions with other objects in space. Understanding orbital inclination is essential for managing the placement of satellites and ensuring effective communication while minimizing the risks associated with space debris.
Passive deorbiting: Passive deorbiting refers to the natural process by which a satellite or space object re-enters the Earth's atmosphere and eventually burns up due to atmospheric drag, without the need for active propulsion systems. This method is particularly important in the management of space debris, as it helps ensure that defunct satellites and other objects do not contribute to the growing problem of orbital congestion and collision risks. Passive deorbiting is often employed in conjunction with techniques such as using lower altitude graveyard orbits to facilitate a controlled descent over time.
Propulsive maneuvers: Propulsive maneuvers are deliberate adjustments made to a spacecraft's trajectory or orbit by using onboard propulsion systems. These maneuvers are essential for maintaining or changing the position of a spacecraft, especially when addressing space debris concerns and ensuring compliance with mitigation guidelines. They play a critical role in the operational life of satellites, helping to either re-orbit decommissioned satellites to graveyard orbits or maneuver active ones to avoid collisions with debris.
Space surveillance networks: Space surveillance networks refer to systems and technologies used to detect, track, and monitor objects in Earth's orbit, including satellites and space debris. These networks are crucial for maintaining safe operations in space by providing data that helps prevent collisions and manage the increasing amount of space debris. The effectiveness of these networks is essential for innovative approaches to large-scale debris removal and the management of graveyard orbits.
Tracking telescopes: Tracking telescopes are specialized instruments designed to monitor and follow the movement of objects in space, particularly satellites and space debris. These telescopes utilize advanced tracking systems to accurately maintain focus on their targets, allowing for detailed observation and data collection necessary for tracking the trajectory and behavior of these objects.
United Nations Space Debris Mitigation Guidelines: The United Nations Space Debris Mitigation Guidelines are a set of voluntary guidelines established to promote the long-term sustainability of outer space activities by minimizing space debris and its harmful effects. These guidelines provide recommendations for space-faring nations and organizations to follow, ensuring responsible behavior in space operations and addressing the growing issue of orbital debris that poses risks to both active satellites and crewed missions.