SMC-S-015 End-of-Life Disposal of Satellites at Geosynchronous Altitude

“Published by the U.S. Air Force Space Command’s Space and Missile Systems Center (SMC),The SMC-S-015 standard “End-of-life disposal of satellites at geosynchronous altitude” describes the requirements for the disposal of a satellite in earth orbit that has reached the end of its life.

Disposal of a satellite in Earth orbit at the end of its useful life means:

• To remove the satellite from the region of space where other satellites operate in a way that will not interfere with other users of space in the future.
• Ensuring that the disposed object is left in an inert state and does not cause an internally generated explosive event that could leave debris and threaten operating satellites.

For satellites operating in the geosynchronous belt, the most effective disposal method is to reposition the satellite into a supersynchronous orbit above the region of the operating spacecraft and the maneuvering corridor used to move operating satellites to new longitudinal mounts, followed by discharging the batteries, venting the thrusters, and other actions to eliminate the possibility of a debris-generating event.

This standard covers the following requirements:

• Planning the disposal of satellites operating at geosynchronous altitude and adequately characterizing the final disposal to ensure that sufficient propellant is retained for maneuvering.
• Selecting final disposal orbits where the satellite will not re-enter the operational region in the foreseeable future.
• Successful execution of the disposal manoeuvre
• Exhausting all energy resources on the vehicle before its lifespan is reached to minimize the possibility of a wreck-producing event

Techniques for planning and conducting space hardware disposal that reflect current internationally accepted guidelines and take into account current operational best practices are provided. This revision incorporates the results of recent technical studies by the Interagency Space Debris Coordination Committee to limit the initial eccentricity of the disposal orbit to ensure that the disposed satellite does not re-enter the zone of operational and maneuvering satellites for at least 100 years.

End of life is the point at which a satellite is permanently shut down or ground control of the satellite is no longer possible.

End of mission refers to the point in a satellite's life that:

• The point at which it can no longer perform its primary duties and is no longer required to operate at its rated operating altitude.
• The point at which remaining fuel, attitude control, or other functions critical to conducting a successful kill maneuver reach a level or capability where further delay makes completion of the kill maneuver unlikely.

The geosynchronous zone can be defined as a circular ring around the earth in the plane of the earth's equator. The average angular velocity of a space object moving along the ring is equal to or very close to the rotation speed of the earth, meaning that the satellite appears to be positioned over a fixed ground position.

In terms of disposal maneuver planning under the primary requirements, a mission end disposal plan shall be developed, maintained, and updated during all phases of mission and spacecraft design and operation. This standard shall include:

• Details of nominal mission orbit
• Details of the targeted disposal trajectory
• Estimates of fuel required for disposal
• Identification of systems and capabilities required for successful completion of disposal
• Criteria that, when met, dictate that disposal be initiated
• Identification of energy resources that must be consumed before reaching the end of their life
• A timeline for initiating and executing the disposal process
• A timeline for the depletion of remaining energy resources
• List of persons or organizations to be notified of the end of duty and disposal and a timetable for notification

The space system should be designed such that the probability of successful end-of-mission disposal, including exhaustion of energy resources, exceeds 0,90. The design details underlying the probability estimate should be included in the end-of-mission disposal plan.

Specific criteria for initiating disposal action should be developed, incorporated into the mission end disposal plan, and monitored throughout the mission life. Mission life projections based on these criteria should be performed as a regular part of mission status reviews throughout the mission life. The status of these criteria should be presented in periodic (at least annual) mission reviews.

Regardless of the success or failure of other aspects of the disposal action, a contingency plan must be developed to exhaust all energy resources and render the spacecraft safe before its eventual demise. The goal is to ensure that actions necessary to render the spacecraft safe are taken before critical systems are lost. The contingency plan should include criteria defining when security actions should be taken, a rationale for each criterion, and a schedule for security actions. The contingency plan should be included in the mission end disposal plan.

Planning activities for end-of-mission disposal should begin at mission design. Planning for the actual disposal action should begin at least six months prior to the date of re-orbit maneuvers. The following steps will be followed during all mission phases and should be documented in the end-of-mission disposal plan:

• Developing an accurate estimate of fuel reserves in the propulsion system
• Calculating the initial perigee increment (perigee is the point in a satellite's orbit closest to the center of the earth)
• Development of basic maneuvering requirements for stable disposal trajectory
• Validation of long-term (100-year) disposal trajectory characteristics
• Determining the maneuver order
• Developing a vehicle safety plan
• Developing an emergency plan

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the "SMC-S-015 End-of-life destruction of satellites at geosynchronous height" standard are also provided to businesses.