Gigantic Circular Shock Acoustic Waves in the Ionosphere Triggered by the Launch of FORMOSAT‐5 Satellite

Abstract

The launch of SpaceX Falcon 9 rocket delivered Taiwan's FORMOSAT‐5 satellite to orbit from Vandenberg Air Force Base in California at 18:51:00 UT on 24 August 2017. To facilitate the delivery of FORMOSAT‐5 to its mission orbit altitude of ~720 km, the Falcon 9 made a steep initial ascent. During the launch, the supersonic rocket induced gigantic circular shock acoustic waves (SAWs) in total electron content (TEC) over the western United States beginning approximately 5 min after the liftoff. The circular SAWs emanated outward with ~20 min duration, horizontal phase velocities of ~629–726 m/s, horizontal wavelengths of ~390–450 km, and period of ~10.28 ± 1 min. This is the largest rocket‐induced circular SAWs on record, extending approximately 114–128°W in longitude and 26–39°N in latitude (~1,500 km in diameter), and was due to the unique, nearly vertical attitude of the rocket during orbit insertion. The rocket‐exhaust plume subsequently created a large‐scale ionospheric plasma hole (~900 km in diameter) with 10–70% TEC depletions in comparison with the reference days. While the circular SAWs, with a relatively small amplitude of TEC fluctuations, likely did not introduce range errors into the Global Navigation Satellite Systems navigation and positioning system, the subsequent ionospheric plasma hole, on the other hand, could have caused spatial gradients in the ionospheric plasma potentially leading to a range error of ~1 m.

Ionospheric Disturbances Triggered by SpaceX Falcon Heavy

“…The initial parameters at 15:00 UT of the second day are then used to initialize the SAMI3/ESF. Nevertheless, these impulsive waves displaying a nonlinear wave pattern (N-shape) in vertical TEC profiles (not shown) are likely associated with the shock waves (e.g., Astafyeva et al, 2013;Zettergren et al, 2017), which are commonly observed during the rocket ascending (e.g., Afraimovich et al, 2002;Chou et al, 2018;Ding et al, 2014;Kakinami et al, 2013;Lin et al, 2014;. The longitude is limited to 6°with periodic boundary conditions for computing the potential and is centered at 3°so the universal time and local time are the same.…”

“…In Figure 3 the ionospheric plasma hole has a TEC reduction of~2 TECU (Figures 3b and 3c), approximately 17% of the background TEC (~12 TECU, Figure 3a), and last for over 1 hr without recovery owing to small production rate during the evening. Chou et al, 2018), partly because the flight altitudes of Falcon Heavy (below 200 km) are below ionospheric F region. The value of TEC depletion is small (cf.…”

“…The value of TEC depletion is small (cf. Chou et al, 2018), partly because the flight altitudes of Falcon Heavy (below 200 km) are below ionospheric F region. Note that the subionospheric point altitude is set to 300 km because the ionosphere has a peak electron density around that altitude.…”

“…It is widely recognized that rocket launches can be an anthropogenic source to trigger traveling ionospheric disturbances (TIDs) by generating acoustic-gravity waves (Afraimovich et al, 2002;Arendt, 1971;Bowling et al, 2013;Calais & Minster, 1996;Chou et al, 2018;Ding et al, 2014;Kakinami et al, 2013;Li et al, 1994;Lin et al, 2014;Lin, Shen, et al, 2017;Noble, 1990). The rocket-induced long-distance propagating TIDs associated with shock/ducted gravity waves and internal gravity waves were observed by using Arecibo incoherent scatter radar (Noble, 1990) and ground-based Global Positioning System total electron content (TEC) observations (Calais & Minster, 1996).…”

Advantages of Geostationary Satellites for Ionospheric Anomaly Studies: Ionospheric Plasma Depletion Following a Rocket Launch

“…In a recent publication, Chou et al [20] analyzed the ionospheric response to the 24 August 2017 Falcon 9 rocket launch from the Vandenberg Air Force Base in California. The fact that the second-stage engine continued burning throughout the 84-721 km altitude range allowed for a unique opportunity to study the interaction between the ionosphere and the rocket plume.…”