Study On Characteristics Of Ionospheric Changes In Low And Middle Latitude Triggered By Spacecraft Launch

Human activities related to the launch of space vehicles?such as rockets,ballistic missiles,etc.?significantly change the ionospheric electron density,which can affect the normal operation of ground short-wave communication and GNSS?Global Navigation Satellite System?,and bring inconvenience to people's daily life and social production.With the rapid development in space technology and the increase of space activity,more and more spacecrafts are sent into the space by rockets,which has caused a certain impact on ionospheric environment and now has become a research hotspot.In order to study the influence of the launch of rocket in low and middle latitude ionosphere,the main work of this paper are as follows.According to the 58 rocket launch cases from December 2013 to December 2019published on the website of United Launch Alliance and the 71 rocket launch cases from December 2013 to December 2019 published on the website of Space X?a total of 129 rocket launch cases,of which 75 rocket launch cases at night and 54 rocket launch cases in daytime?,we used Swarm satellites observation data?2 Hz Langmuir probe observation data and 16Hz electron density observation data?provided by the European Space Agency and DMSP?Defense Meteorological Satellite Program?satellites observation data?ionospheric electron density,electron temperature,ion composition and ion drift velocity data?provided by Madrigal database to analyze the ionospheric abnormal phenomenon in low and middle latitude ionosphere caused by the launch of rocket and observed by Swarm and DMSP satellites.Then,for all the ionospheric abnormal phenomenon observed by Swarm and?or?DMSP satellites in low and middle latitude ionosphere caused by the launch of rocket,we used the global ionospheric VTEC?Vertical Total Electron Content?data provided by Madrigal database to analyze the variation characteristics of ionospheric VTEC after the launch of rocket.It is found that the launch of rocket at night will not cause significant abnormal changes in ionosphere,but the launch of rocket during daytime will cause significant changes in ionosphere.The main work and research results are summarized as follows.First,the Swarm satellites observation data after each rocket launch were analyzed one by one for all the 129 rocket launch cases,and we found ionospheric abnormal phenomenon in low and middle latitude ionosphere caused by the launch of rocket in 12 rocket launch cases,and the rocket launch time of these 12 cases were in daytime.The ionospheric characteristics in the area caused by the launch of rocket in these 12 cases were analyzed by using Swarm 2 Hz Langmuir probe observation data and 16 Hz electron density observation data,the results are as follows.1.Two hours after the launch of rocket,the latitude distribution range of ionospheric electron density depletion caused by rocket exhaust is about 1000 km.During the daytime?i.e.,in the case of photoionization?,the latitude distribution range of electron density depletion gradually decreased with the passage of time after the launch of rocket,and decreased to about 300 km five hours after the launch of rocket.2.In the daytime,five hours after the launch of rocket,the electron density at the center of the depletion area is still 0.1×10¹¹ m^-3–0.3×10¹¹ m^-3 lower than that in the background?i.e.,about 10%lower?.3.After analyzed the Swarm satellites 16 Hz electron density observation data,it is found that in the ionospheric electron density depletion area caused by rocket exhaust,the curve of electron density with latitude is very smooth,and there is no electron density substructure with a horizontal scale greater than 1 km.4.Compared with the background electron temperature,the ionospheric electron temperature increased significantly in the ionospheric electron density depletion area caused by rocket exhaust.5.After analyzed the Swarm satellites 2 Hz electron temperature observation data,it is found that in the ionospheric electron temperature rise area caused by rocket exhaust,the curve of electron temperature with latitude change is very smooth,and there is no substructure with a horizontal scale greater than 8 km.6.Two hours after the launch of rocket,the electron temperature at the center of the ionospheric abnormal phenomenon area caused by the launch of rocket is 0.2×10³ K–0.4×10³ K?i.e.,10%?higher than that in the background,and the electron temperature recover to the same temperature as the background 3–4 hours after the launch of rocket.Second,the DMSP satellites observation data after each rock launch were analyzed one by one for all the 129 rocket launch cases,and found ionospheric abnormal phenomenon in low and middle latitude ionosphere caused by the launch of rocket in seven rocket launch cases,and the rocket launch time of the seven cases were in daytime.Four cases were observed by DMSP and Swarm satellites at different altitudes,and other three cases were observed by DMSP satellites.Then,the ionospheric electron density,electron temperature,ion composition,and ion drift velocity data observed by DMSP satellites along the satellite's orbit were used to analyze the ionospheric characteristics caused by the launch of rocket in these seven cases,the results are as follows.1.After analyzed the ionospheric abnormal phenomenon in low and middle latitude ionosphere caused by the same launch of rocke in four rocket launch cases,which were observed by DMSP and Swarm satellites at different altitudes,it was found that the electron density'descended amplitude(about 0.03×10¹¹ m^-3–0.05×10¹¹ m^-3)observed by DMSP satellites at the central position of ionospheric abnormal phenomenon area caused by rocket exhaust was one order of magnitude lower than that observed by Swarm satellites(about0.2×10¹¹ m^-3–0.5×10¹¹ m^-3).2.At the orbital altitude of DMSP satellites?i.e.,850 km from the ground?,in the ionospheric abnormal phenomenon area,the decrease of O⁺ion density account for more than 98%of the descended amplitude of total ion density,which indicated that the main ion is O⁺ion in the ionosphere at an altitude of 850 km.3.At the orbital altitude of DMSP satellites,50–60 minutes after the launch of rocket,DMSP satellites observed that the ionospheric vertical ion drift velocity increased downward by 30–40 m/s?i.e.,an increased of 60%–80%?compared with the background ionospheric vertical ion drift velocity in the ionospheric abnormal phenomenon area,but no significant changes in ionospheric horizontal ion drift velocity.4.At the orbital altitude of DMSP satellites,two hours after the launch of rocket,DMSP satellites observed that the ionospheric vertical ion drift velocity recovered to the same value as that in the background ionosphere in the ionospheric abnormal phenomenon area.Third,the global ionospheric VTEC data after each rocket launch were analyzed one by one for all the ionospheric abnormal phenomenon rocket launch cases observed by Swarm and DMSP satellites?a total of 15 cases?,and we found the ionospheric VTEC depletion caused by the launch of rocket in four rocket launch cases,and the rocket trajectories of these four cases were relative closely to the land.For these four cases,the impact of each rocket launch on the ionospheric VTEC was analyzed by using the global ionospheric VTEC data,and the results are as follows.1.About 10 minutes after the launch of rocket,along the trajectory of the rocket,the ionospheric VTEC near launch site firstly appeared obviously depletion phenomenon,and the space scale of the ionospheric VTEC depletion area caused by the launch of rocket in the horizontal direction is about 150–300 km,and the descended amplitude of ionospheric VTEC is about 1 TECU?i.e.,a decrease of 5%?compared with the background.2.About 20–30 minutes after the launch of rocket,the horizontal distribution range and the descended amplitude of the ionospheric VTEC depletion area reached the maximum value.On the center of the rocket trajectory,the horizontal spatial scale of the VTEC depletion area is 700–1000 km,and compared with the background the descended amplitude of VTEC is 4–6 TECU?i.e.,a decrease of 20%–30%?.3.In the daytime,the ionospheric VTEC depletion caused by the launch of rocket start to recover gradually under the action of photoionization after maintaining the maximum descended amplitude for a period of time?about 30–50 minutes?.Within two hours after the launch of rocket,the ionospheric VTEC in the area caused by the launch of rocket is 2–8TECU lower than the ionospheric VTEC in surrounding region.4.In the daytime,about two hours after the launch of rocket,the ionospheric VTEC depletion caused by the launch of rocket recovered to the level before the launch of rocket.5.In the daytime,about three hours after the launch of rocket,the ionospheric VTEC depletion caused by the launch of rocket recovered to the same level as the surrounding region ionospheric VTEC.The research results in this paper reveal that during the daytime?i.e.,in the case of photoionization?,within two hours after the launch of rocket,the ionospheric VTEC depletion?its horizontal spatial scale is about 700–1000 km?caused by the launch of rocket is 2–8 TECU lower than that in the surrounding region.Therefore,the pseudorange measurement error of GNSS single frequency positioning users will increase 0.3–2.3 m in the ionospheric VTEC depletion area caused by the launch of rocket.