FCC Showing Interest in Object-Years, but Some See Flaws in Approach
The FCC is increasingly leaning toward an "object-years" regulatory approach to space safety, experts say. But some warn of flaws in the approach. The agency is seeking input, due June 27, on its orbital debris open proceeding about using a 100 object-years benchmark -- a cap on the total cumulative time to deorbit failed satellites -- for assessing the risk of a constellation's derelict satellites (see 2405240005).
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The FCC is taking a novel approach, tying persistence on orbit to space safety and authorization. Few if any other countries link how long a satellite remains on orbit with its safety and thus regulatory status, Constellation Advisory President Patricia Cooper told us. Still to be determined is whether 100 object-years is a reasonable metric, she said. Also unknown is whether satellite systems typically can meet it, she said.
The 100 object-years discussion, and the FCC's five-year deorbit rule adopted almost two years ago (see 2209290017), are different approaches to the same fundamental issue of limiting the amount of inactive objects in space, said Marlon Sorge, executive director-Center for Orbital and Reentry Debris Studies, Aerospace Corp. Using 100 object-years as a benchmark is "definitely complicated," as the amount of material and its mass are important, not just how long an object will be in orbit, Sorge said.
The agency has applied object-years conditions on a handful of non-geostationary orbit constellations, often at the urging of SpaceX, whose second-generation constellation approval included an object-years condition (see 2301040007). The Space Bureau in its August approval of Iceye's second tranche of satellites called the 100 object-years condition -- which SpaceX had sought on Iceye -- "relevant." It said the same about the object-years condition put on a Planet Labs license modification, also granted in August. The 100 object-years conditions were also imposed this year on a HawkEye 360 license modification, as well as approvals last month for Planet Labs (see 2405130045) and Tomorrow Companies (see 2405200049).
In a public notice soliciting feedback on the object-years approach, the FCC Space Bureau said it "has used a 100 object-years metric in some licenses as a trigger for cases in which disposal failures would warrant additional Commission review of the execution of debris mitigation measures, and it seeks comment on whether this approach should be utilized more or less widely, and in which types of cases."
The federal Orbital Debris Mitigation Standard Practices policy lays out a 100 object-years expectation. "For all planned released debris larger than 5 mm in any dimension, the total debris object-time product in low Earth orbit (LEO) should be less than 100 object-years per upper stage or per spacecraft. The total object-time product in LEO is the sum, over all planned released objects, of the orbit dwell time in LEO," it said.
"Mass matters," Darren McKnight, LeoLabs senior technical fellow, wrote in an email. He said that while he suggested a 100 object-years approach to the FCC, it was part of the development of his actual proposed metric of object-kilogram-years. "Leaving a 100 kg object is worse than leaving a 1 kg object in orbit" because the larger-mass object can result in more fragments if it collides with something and more mass generally means the object has a larger collision cross-section, he said. That greater mass also typically means a smaller area-to-mass ratio, so it will linger in orbit longer, he said.
McKnight said the FCC apparently is "embracing the original theme that inspired me to propose this metric -- simplicity." He said whether using object-years or object-kg-years, a public vetting of the correct numerical value remains necessary -- whether it's 100 or something else. "The public comment process provides a fine way for the FCC to say 'we are using object-kg-years' and then ask for public dialogue on the right numerical threshold before issuing a finding," he said.
NASA emailed it "is working to provide feedback" to the FCC on the object-years proposal, but didn't comment further.
Aerospace's Sorge said while the object-years metric addresses the issue of failed satellites, in terms of sheer numbers, mega constellations' defunct satellites that are deorbiting can be a bigger space sustainability concern than failed satellites. He said that if the FCC codifies object-years in its rules, other nations surely would consider the approach. But some space regulators are being more aggressive on orbital debris than the FCC. For instance, the European Space Agency's Zero Debris recommendation aims at not leaving objects in orbit for any length of time after a satellite's mission is complete.