Ionospheric Disturbances Triggered by SpaceX Falcon Heavy

SpaceX launched its Falcon Heavy demonstration mission at 20:45 UT on 6 February 2018 at NASA Kennedy Space Center in Florida. Short-period northward propagating traveling ionospheric disturbances (TIDs) were observed following the shock waves in the ionospheric total electron content over East Florida-Atlantic region. These TIDs have the periods of similar to 6-8min, amplitude of similar to 0.05 total electron content unit, horizontal phase velocities of similar to 420-488 m/s, and horizontal wavelengths of similar to 164-240 km. They lasted for similar to 100 min and propagated a long distance of about 1,450 km, exhibiting a nearly coherent wave pattern and near-constant phase velocity. The theoretical dispersion relation suggests that the short-period TIDs were likely associated with the ducted gravity waves which became evanescent at altitudes around 170 km. Additional simulations were conducted in the Naval Research Laboratory SAMI3/ESF model using analytical expressions to approximate these gravity waves. Simulations reveal that modulations of the ionospheric electric fields through gravity wave wind dynamo perturbation can lead to weak ionospheric disturbances as observed. Plain Language Summary SpaceX launched its Falcon Heavy demonstration mission at 20:45 UT on 6 February 2018 at NASA Kennedy Space Center in Florida. The most powerful operational rocket consists of three Falcon-9 nine-engine cores in the first stage, however, produced relative weak traveling ionosphere disturbances in comparison with other Falcon-9 launches. The weak traveling ionospheric disturbances had the short period but could travel a long distance of similar to 1,450 km (from off coast Florida to Lake Ontario). These characteristics suggest that the rocket induced atmospheric gravity waves that were guided along the lower thermosphere similar to 115-170 km altitude. The guided gravity waves may not affect the ionospheric plasma directly, but on the other hand, created electrodynamic perturbations in the ionosphere. Numerical simulations confirm that the electrodynamic perturbations could transmit to the upper part of ionosphere or even the opposite hemisphere.