The Billion Dollar Surprise: How Solar Cycle 25 Cut Satellite Lifetimes in LEO

Engineering notes

Engineering notes will be added by the Power for Solar editorial team.

Chinese explanation / 中文解读

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Original abstract

Solar Cycle 25 has run far stronger than the 2019 consensus forecast issued by the NOAA/NASA/ISES prediction panel, with densities in low Earth orbit from 2022-2026 holding at 2-3x the predicted levels. The cumulative drag impulse experienced by LEO satellites reached 5-6 standard deviations beyond the forecast's stated uncertainty. This means that even operators who designed conservatively against the two-sigma worst case fell short of their drag budgets. This paper quantifies a lower bound on the economic cost of that misprediction. Starting from the 13,704 payloads on-orbit below 800 km during 2022-2026, we screen to the 1,597 payloads which we validated with high confidence to be both operational and in ballistic freefall. We estimate each satellite's ballistic coefficient and propagate its trajectory under the forecasted atmosphere versus the observed one. A probabilistic cost model assigns each satellite an annualized mission cost based on direct costs (amortized capital costs plus annual operations), stratified by size class, with bespoke estimates for high value missions. Survival and forward cost discounting is applied at a modal 11% per year. We combine the differences in lifetime with the cost model to estimate the total dollar impact. Against the forecast's two-sigma upper bound which we consider to be a standard engineering design target, these satellites lost 688 cumulative mission years valued at \$0.88 billion. Against the nominal forecast, they lost 2,472 mission years worth \$2.77 billion. These estimates are deliberate lower bounds which exclude propulsive satellites, revenue above direct cost, and downstream economic impact. The results give a quantitative case for the value of accurate decadal-scale space weather forecasting, and show that well-calibrated uncertainties are as valuable to a satellite operator end-user as the accuracy of the central prediction itself.

Links and sources

• Official / arXiv page
• PDF from original source

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