Longitudinal Variation of Thermospheric Density during Low Solar Activity from APOD Observations

Chen, Guangming; Xie, Lihua; He, Maosheng; Liu, Shushi; Man, Haijun; Gao, Hong; Li, Yongping

doi:10.3390/atmos14010155

Cited by 3 publications

(2 citation statements)

References 31 publications

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“…Figure 2a illustrates variations in the atmospheric density measured by the satellite, and Figure 2b shows the density map for the specific month. Significantly different maps were obtained for other seasons [13]. The SuLPOs are elliptical orbits with high apogee and low perigee where satellites dip very close to the Earth's surface, e.g., for ultra-high-resolution imaging, and they then leave low altitudes for the remainder of the orbital path.…”

Section: Introductionmentioning

confidence: 86%

Carbon Nanocomposites in Aerospace Technology: A Way to Protect Low-Orbit Satellites

et al. 2023

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Recent advancements in space technology and reduced launching cost led companies, defence and government organisations to turn their attention to low Earth orbit (LEO) and very low Earth orbit (VLEO) satellites, for they offer significant advantages over other types of spacecraft and present an attractive solution for observation, communication and other tasks. However, keeping satellites in LEO and VLEO presents a unique set of challenges, in addition to those typically associated with exposure to space environment such as damage from space debris, thermal fluctuations, radiation and thermal management in vacuum. The structural and functional elements of LEO and especially VLEO satellites are significantly affected by residual atmosphere and, in particular, atomic oxygen (AO). At VLEO, the remaining atmosphere is dense enough to create significant drag and quicky de-orbit satellites; thus, thrusters are needed to keep them on a stable orbit. Atomic oxygen-induced material erosion is another key challenge to overcome during the design phase of LEO and VLEO spacecraft. This review covered the corrosion interactions between the satellites and the low orbit environment, and how it can be minimised through the use of carbon-based nanomaterials and their composites. The review also discussed key mechanisms and challenges underpinning material design and fabrication, and it outlined the current research in this area.

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Section: Introductionmentioning

confidence: 86%

Carbon Nanocomposites in Aerospace Technology: A Way to Protect Low-Orbit Satellites

et al. 2023

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“…We chose the average value along the terminator because terminator orbits are chosen for ABEP spacecraft, which will be discussed later in Section 2.2. It should be noted that the atmospheric density of the VLEO region varies (generally not more than 40%) with time and position (latitude and longitude), which is mainly caused by the insolation angle and the local low-level atmospheric flow [31,32]. Since this variation is hard to predict, and there is a cumulative effect of the long-term orbital flight, the atmospheric density is considered to be the orbital average value at each altitude.…”

Section: Abep Flight Scheme Analysis 21 Vleo Space Environment and Ab...mentioning

confidence: 99%

Elliptical Orbit Design Based on Air-Breathing Electric Propulsion Technology in Very-Low Earth Orbit Space

Yue,

Geng,

Feng

et al. 2023

Aerospace

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Very-low Earth orbit (VLEO) space below 200 km is essential for high-quality communications and near-Earth space environment detection. Due to the significant atmospheric drag, orbital maintenance is required for spacecraft staying here. Based on air-breathing electric propulsion (ABEP) technology, this paper analyzed the orbital boundary conditions of the spacecraft under the constraints of parameters including slenderness ratio, thrust-to-power ratio, drag coefficient, and effective specific impulse. The energy balance is the key constraint for low VLEO orbits, which is determined by the drag coefficient, slenderness ratio, and thrust-to-power ratio. Under the existing technical conditions, the lowest circular orbit (along the terminator) is about 170 km. An elliptical orbital flight scheme is also analyzed to reach a 150 km perigee. A half-period control method was proposed based on the on–off control method for the elliptical orbit, which could enable the spacecraft to maintain a stable 150–250 km elliptical orbit.

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Study on the Hemispheric Asymmetry of Thermospheric Density Based on In-Situ Measurements from APOD Satellite

Zhang

et al. 2023

Atmosphere

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In this article, high spatiotemporal resolution data obtained by the atmospheric density detector carried by China’s APOD satellite are used to study the hemispheric asymmetry of thermospheric density. A detailed analysis is first performed on the dual magnetic storm event that occurred near the autumnal equinox on 8 September 2017. The results show that the enhancement ratio of atmospheric density in the southern polar region (SPR) on the duskside was approximately 1.33–1.65 times that of the northern polar region (NPR), demonstrating a strong hemispheric asymmetry of thermospheric atmospheric density response during the magnetic storm. However, the asymmetry response was smaller on the dawnside, suggesting that the hemispheric density response asymmetry is related to local time (LT). The energy injection in high-latitude regions increases local atmospheric density and forms traveling atmospheric disturbances (TADs). TADs can propagate to low-latitude regions over several hours and affect the global distribution of thermospheric atmospheric density. Similarly, the geomagnetic index fitting slope of SPR relative density difference is greater than that of NPR. The SuperDARN convection pattern indicates that the plasma convection velocity of SPR is significantly greater than that of NPR, indicating that joule heating caused by neutral friction of ions in the Southern Hemisphere may be stronger. Subsequently, an analysis of annual solar activity and seasons was carried out on the thermospheric NPR, SPR atmospheric density, and their differences from December 2015 to December 2020. The results show that thermospheric atmospheric density decreases overall as the number of sunspots decreases. The differences between the NPR and SPR atmospheric densities in the thermosphere exhibits a noticeable annual periodicity. The NPR and SPR atmospheric densities appear to have different distribution characteristics in different seasons. The NPR density peak is mainly in March or April. In particular, the “double-peak” phenomenon occurred in 2017, with peaks in March and September, while the most obvious feature of SPR atmospheric density is that its minimum value occurs in the summer months of June and July. This paper reveals the annual, seasonal, and magnetic storm response characteristics of the hemispheric asymmetry of thermospheric atmospheric density, which has significant implications for the study of multilayer energy coupling of the magnetosphere–ionosphere–thermosphere.

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Longitudinal Variation of Thermospheric Density during Low Solar Activity from APOD Observations

Cited by 3 publications

References 31 publications

Carbon Nanocomposites in Aerospace Technology: A Way to Protect Low-Orbit Satellites

Carbon Nanocomposites in Aerospace Technology: A Way to Protect Low-Orbit Satellites

Elliptical Orbit Design Based on Air-Breathing Electric Propulsion Technology in Very-Low Earth Orbit Space

Study on the Hemispheric Asymmetry of Thermospheric Density Based on In-Situ Measurements from APOD Satellite

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