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Schism on Aggregate vs. Per-Satellite

Space Operators Tar Object-Years Approach on Orbital Debris as 'Simplistic'

The commercial space industry widely objects to the FCC's proposed "object-years" approach for space safety, with numerous operators in comments last week calling it ineffective and more than one deriding it as "simplistic" (docket 18-313). Those comments were part of a record refresh in the FCC's orbital debris mitigation docket (see 2405020048). The FCC's object-years proposal would cap at 100 the number of years failed satellites in a constellation could remain in orbit. It has placed 100 object-years conditions on several non-geostationary orbit (NGSO) constellations in the past year (see 2406120006).

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The object-years approach “is overly simplistic and fails to adequately account for the multiple factors that drive collision risk” for NGSOs, the Satellite Industry Association said. It added the approach doesn’t calculate and manage risk well because it doesn’t accurately reflect risk levels that can come from NGSO operations at lower altitudes, while also being too restrictive when applied to systems at higher altitudes. SIA and a variety of satellite operators argued that an object-years standard could essentially require 100% deorbit reliability, which is impossible to guarantee.

Object-years “is both an insufficient proxy for measuring risk profiles of NGSO constellations and an inappropriate performance metric to apply on a ‘one-size-fits-all’ basis,” Astroscale said. Operators that take risk-reduction steps, such as reducing mass or operating with smaller cross-sections, wouldn’t see those efforts reflected in an object-years approach, it said. Viasat filed a 21-page white paper critical of the object-years approach. Also critical of the object-years approach, Amazon’s Kuiper urged that the FCC use NASA recommendations for collision risk thresholds. SES/O3b and Telesat also criticized the object-years approach.

The 100-year cap is a bad stand-in for the actual problem -- the potential for collision risk due to failed satellites -- and could allow large numbers of failed satellites in what's an already-crowded low earth orbit while penalizing satellites in higher LEO altitudes that may have a substantially lower collision risk, said Eutelsat/OneWeb. A cap other than 100 years doesn't fix that problem, it added. Varda Space Industries said it's unclear what research the 100 object-year metric is based on.

Backing the object-years approach, SpaceX reiterated its argument that conditions the FCC put on its second-generation satellites -- including semi-annual reports on collision avoidance maneuvers and the 100 object-years cap -- also apply to other constellations (see 2405240045).

There was less agreement among space operators and space interests on whether the FCC should gauge satellite collision risk on an individual satellite basis or in the aggregate across an entire satellite system.

Per-spacecraft collision risk metrics better align incentives across satellite operators, the National Space Society said. Aggregate metrics create uneven rules with safety requirements varying depending on who operates an individual satellite, it noted. Telesat argued for evaluating collision risks on an individual satellite basis. It said any aggregate system approach will unnecessarily affect constellation design. Eutelsat/OneWeb backed an aggregate approach and said a per-satellite approach ignores the number and frequency of high- and low-risk events across an operator’s fleet. Also backing an aggregate approach, Astroscale said the agency should consider positive action operators take to mitigate those risks.

Viasat said an aggregate limit would reduce the risks any particular NGSO system presents while giving operators flexibility to design their systems. Evaluating collision risk on a per-satellite basis allows more precise risk assessment and mitigation strategies tailored to individual satellites, said the Commercial Smallsat Spectrum Management Association. CSSMA also argued the FCC should avoid prescribing a particular technology, such as propulsion, for maneuverability, when there are potential alternatives such as differential drag and deployable sails. Eutelsat/OneWeb and Kuiper also urged the FCC to mandate that satellites have maneuverability in orbits higher than 400 km.

TechFreedom questioned the FCC's orbital debris regulatory authority. The agency's reliance on the public interest standard is "a “wafer-thin reed” that’s unlikely to withstand judicial scrutiny," it said. TechFreedom has also questioned FAA orbital debris regulatory authority 2312260009). The Commercial Spaceflight Federation also questioned FCC authority. "Continued deference to agencies with technical expertise and adherence to a limited role in orbital debris and space safety should guide the Commission’s rulemaking," CSF said.

There is a lack of good tools for assessing the system risk of large constellations, Lynk said. Until they arrive, the FCC's best approach is via demonstration missions at lower altitudes that show reliability, it said.