by Douglas Messier
In its waning days, the Trump Administration released the National Orbital Debris Research and Development Plan, which is designed to guide federal R&D efforts aimed at limiting, tracking, characterizing and remediating debris in Earth orbit.
The plan is the product of an interagency working group established by the National Science & Technology Council. The council is part of the White House’s Office of Science and Technology Policy.
The document lists 14 priority areas for future R&D work, which are shown below.
- Limit debris generation by design. Deliberate spacecraft design choices can limit the generation of new debris.
R&D priorities for element 1:
• Reduce debris during launch
• Improve resilience of spacecraft surfaces
• Improve shielding and impact resistance
• Develop designs that will reduce or limit fragmentation processes
• Improve maneuverability capabilities
• Incorporate end-of-mission approaches to minimize debris into spacecraft and mission design
- Track and characterize debris. Debris tracking and characterization are critical to enabling effective mitigation measures and safe spaceflight operations.
R&D priorities for element 2:
• Characterize orbital debris and the space environment
• Develop technologies to improve orbital debris tracking and characterization
• Reduce uncertainties of debris data in orbit propagation and prediction
• Improve data processing, sharing, and filtering of debris catalogs
• Transition research on debris tracking and characterization into operational capabilities
- Remediate or repurpose debris. Remediation activities, also called active debris removal, could in the long-term substantially reduce the risk of debris impact in key orbital regimes. Repurposing may also contribute to reducing risk and removing debris.
R&D priorities for element 3:
• Develop remediation and repurposing technologies and techniques for large-debris objects
• Develop remediation technologies and techniques for small-debris objects
• Develop models for risk and cost-benefit analyses
The report said orbital debris “poses a significant and growing hazard for safe spaceflight operations” as Earth orbit becomes increasingly congested.
“There are currently approximately 23,000 debris objects 10 centimeters in size (about the size of a softball) or larger that are cataloged and tracked for purposes of collision avoidance,” the document said. “However, there are estimated to be roughly 500,000 objects 1 centimeter in size or larger, and upwards of 100 million debris objects at least 1 millimeter in size. Objects less than 5 centimeters in size are difficult to track individually even if they are in low Earth orbit (LEO); therefore, these population size estimates rely heavily on statistical sampling and modeling techniques.
“While orbital debris is present throughout the space environment surrounding the planet, it is concentrated around the most widely used orbits,” the report added. “The highest concentration of cataloged objects is located in LEO—defined as the region below approximately 2,000 kilometers in altitude. The LEO region also contains the highest estimated mass of debris, at about 3,000 metric tons.3 Collectively, there are over 8,000 metric tons of orbital debris from LEO to geosynchronous orbit (GSO), which is around 35,800 kilometers in altitude.”
The report notes that satellite manufacturers and operators lack common orbital debris standards and best practices for satellite and mission design. Many spacecraft are not designed to be deorbited at the end of their lifetimes due to the high costs of doing so.
“Satellites can break up and generate debris during operation. Some of these are older satellites launched when debris considerations received less emphasis, but events involving newer satellites continue despite design improvements. Fragmentation debris objects dominate the tracked debris population,” the report said.
Launch vehicle upper stages and payload deployment systems are contributing to the debris problem. The report said many launch providers have not developed approaches to prevent new debris.
There is also a great deal of uncertainty about what debris is up there and exactly where it is located.
“Less than 1 percent of the debris objects that could cause mission-ending damage are currently tracked,” the report said. “Debris is insufficiently characterized for accurate and reliable risk assessments. An object’s size, shape, mass, and velocity all affect how much and what kind of damage occurs upon impact.
“The uncertainties are high in tracking objects and propagating orbits. The uncertainty tends to grow with time due to the compounding effects of atmospheric drag, space weather, and other nongravitational perturbations that may be difficult to predict,” the document added.
The report identified a number of challenges in active debris removal, including:
- higher costs relative to other methods of reducing debris
- costs and benefits are not well characterized
- a small market resulting from a lack of defined responsibility for removing debris
- risk of inadvertently creating even more debris
- difficulty in scaling the technology to capture multiple pieces of debris, and
- risk of reducing the near-term risk of collisions without addressing long-term sustainability of orbital space.
The document assigned responsibilities to NASA and the departments of Commerce, Defense, Transportation, State and the Interior.