The cost of orbital debris can be measured in different ways. For example, spacecraft replacement cost is one measure of the economic harm caused by a catastrophic debris impact.2 This measure assumes that a spacecraft can be readily replaced, but replacement may be difficult because of lack of funding, launch window limitations, or other constraints. In addition, replacement cost alone underestimates the full cost to society of debris impact, because the debris generated by an impact has the potential to harm other spacecraft, thus posing additional costs for society beyond those incurred simply in spacecraft replacement.
The costs of orbital debris also take other forms. Shielding, debris avoidance maneuvers, and other efforts to avoid debris impact increase the cost of spacecraft design and operation. Similarly, actions taken to avoid generation of debris, such as the use of lanyards, venting of residual fuel, and moving spacecraft into graveyard orbits, also impose design and operating costs that are usually expressed in terms of mass, fuel, and lifetime penalties. Additional costs are borne in the form of debris surveillance, tracking, and reporting. The economic consequences of debris impacting a government-owned or government-operated spacecraft are borne by taxpayers because the government “self insures” its activities. These consequences take myriad forms: degradation of the services provided by debris-impacted spacecraft or loss of a mission altogether. The costs may not be reported directly and may be contained within the mission agency’s budget, but the costs are real nonetheless. Additional costs come in the form of any long-lived debris that may pose future harm to spacecraft, and are not measured at present.
The committee requested but received little information about the effect on space mission budgets of the need to shield, maneuver, move to a graveyard orbit, or take other protection measures against orbital debris. In the information received, one estimate was that 0 to 10 percent of mission cost was required to implement shielding and avoidance maneuvers; in another case, it was 5 to 10 percent of mission cost. Some reported incorporating collision avoidance into regularly scheduled maneuvers. Generally speaking, the information provided to the committee suggested that few experts see addressing orbital debris as imposing a large financial burden at present. Such a conclusion hardly supports the need to worry about debris, making the case seem weak to enhance space debris monitoring, modeling, and data collection or to consider investment in active debris removal. The committee emphasizes, however, that data is lacking on the economic cost of the future orbital debris population. If the cost were expected to be large, the economic case could be stronger for investment in improved debris models, monitoring, and removal.
In the case of commercially owned and operated spacecraft, companies insure their operations against loss of service, including loss of service due to debris impact. At present, insurers report that of the overall insurance premiums for spacecraft, the portion attributable to the possibility of a debris impact is quite small—less than 1 percent. They point out that debris impact is currently seen as a low-probability event.3 In terms of debris-related harm that might be created for other operating spacecraft if an insured spacecraft is damaged by a debris impact, insurers reported that they assume that the companies owning insured spacecraft operate as “good citizens.” In other words, insurers do not take account of whether an insured spacecraft will be a source of debris, and thus a potential harm to others. They insure only against harm to the insured spacecraft.
Going forward, NASA, other space operational agencies, and the commercial space industry could consider keeping better track of debris-related costs. Agencies should combine projections of the future debris population with estimates of potential economic damage. The absence of more transparent cost reporting can lead to underestimation of future debris-related problems. If costs were routinely inventoried and reported, they could provide a benchmark on the economic importance of managing debris. Such a benchmark would demonstrate the value of debris mitigation guidelines and help to inform when to tighten them, if costs were to grow. In addition to the many purposes it could serve, a cost benchmark can also help decision makers to assess the value of possible future investment in active debris removal technology.
2 Ailor, W., J. Womack, G. Peterson, and E. Murrell, “Space Debris and the Cost of Space Operations,” presented at the 4th International Association for the Advancement of Space Safety Conference, Huntsville, Alabama, May 19-21, 2010.
3 Kunstadter, C., “Space Insurance and NASA’s MMOD Program,” presented at the NRC Workshop to Identify Gaps and Possible Directions for NASA’s MMOD Programs, Fairfax, VA, March 10, 2011. See also: Swiss Re, Space Debris: On Collision Course for Insurers? Swiss Re, Zurich, Switzerland, 2011.