The Thermosphere Is a Drag: The 2022 Starlink Incident and the Threat of Geomagnetic Storms to Low Earth Orbit Space Operations

Abstract

SpaceX launched 49 Starlink broadband communications satellites into a 210 × 350 km staging orbit for on-orbit assessments prior to raising the satellites to their operational circular 550 km orbits. The launch took place during the recovery phase of a minor geomagnetic storm rated G1 on the NOAA Space Weather Prediction Center G-scale. According to SpaceX, "atmospheric drag [increases] up to 50% higher than during previous launches" was experienced in the staging orbit. The increased drag on the Starlink vehicles led operators to command them into a low-drag configuration in an attempt to decrease altitude loss rates. Despite this mitigation, 38 of the 49 satellites could not be recovered from the low-drag configuration for orbit raising and subsequently re-entered the atmosphere and burned up on or about 07 February 2022.The loss of the Starlink satellites was noteworthy for several reasons. Most notably, this is the first public record of a simultaneous loss of a large number of operational satellites in low Earth orbit (LEO) due solely to atmospheric

The Daytime Variations of Thermospheric Temperature and Neutral Density Over Beijing During Minor Geomagnetic Storm on 3–4 February 2022

“…However, it is worth noting that the air drag during this event was reported to be up to 50% higher than that during previous launches (SpaceX, 2022). Furthermore, this minor storm is the first public record of satellites loss in low Earth orbit (LEO) with air drag thought to be the primary factor contributing to the loss of satellites (Berger et al, 2023).…”

“…The maxima of 3-hourly Kp and Ap indices in this storm were 5 + and 56 nT, respectively, thus this storm was classified as a minor storm (G1) according to the NOAA SWPC's Space Weather Scale (https://www.swpc.noaa.gov/noaa-scales-explanation). Different from severe geomagnetic storms, which can cause neutral density enhancement of ∼200% or even higher, impacts from minor geomagnetic storms are expected to be limited to small perturbations in satellites' orbits, and could not cause such serious consequences as the loss of the satellites (Berger et al, 2023;Bruinsma et al, 2006;Lei et al, 2010). However, it is worth noting that the air drag during this event was reported to be up to 50% higher than that during previous launches (SpaceX, 2022).…”

Space Weather Effects on Satellites

“…Based on an alternative geomagnetic indices, the first storm reached Dst= −66 nT (11 UT; the exact values of Dst in 2022 may be subject to change, https://wdc.kugi.kyoto-u.ac.jp/dst_realtime/, accessed on 17 August 2023) and Kp of 5+ on 2022-02-03 and followed by another GS with Dst= −61 nT (21 UT) and Kp = 5+ on 2022-02-04, respectively. Despite the modest strength of the GSs, it was noted that the launch took place at the time when the thermosheric neutral density had reached its maximum increase [59]. This was the first time for a Starlink constellation to experience an enhanced level of atmospheric drag (reported by the operator as 50% higher than previous launches) that ultimately led to the loss of most spacecraft by 2022-02-07.…”

Thermospheric Wind Response to March 2023 Storm: Largest Wind Ever Observed With a Fabry‐Perot Interferometer in Tromsø, Norway Since 2009

“…In terms of the molecular‐rich air originating in the heated thermosphere at high latitudes, we might have attempted to understand the generation mechanism by assuming thermospheric expansion and successive upwelling air. Owing to air drag observations by low‐earth orbit satellites, thermospheric density increases during geomagnetic storms are unquestionable (Berger et al., 2023; Bruinsma et al., 2006; Burke et al., 2007; Dang et al., 2022; Fang et al., 2022; Forbes et al., 2005; Kataoka et al., 2022; Knipp et al., 2013; Lin et al., 2022; Liu et al., 2010; Liu & Lühr, 2005; Sutton et al., 2005). However, we should note that the upwelling stream is hardly generated by buoyancy in the thermosphere because the heating rate per mass peaks in the upper thermosphere, and heavier cooler air is located under lighter hotter air (Burns et al., 2021).…”