What does air drag do to low satellites, and why do they fall?

"Artificial satellites in low Earth orbit have as main disturbance the atmospheric drag, which is a non-conservative disturbance that causes the satellite to lose orbital energy due to the friction with the air."

"Basically, the drag force is a function of the velocity, the local air density and the satellite’s constructive parameters."

"Another relevant effect of solar activity is the variation in the volume of the atmosphere and consequently in the value of the air density for a given altitude, longitude and latitude."

"However, they also experience significantly larger atmospheric drag that will quickly lead to orbital decay, due to the much denser atmosphere present in VLEO."

"The solar activity, a significant factor in modelling atmospheric density, is forecast based on observation data from past solar cycles."

"To maintain the satellite at its desired operational altitude, thrust is applied to counteract perturbations."

"for low Earth orbiting satellites, atmospheric drag is the dominant factor, causing a satellite to gradually lose altitude (orbital decay)"

"causing a satellite to gradually lose altitude (orbital decay) and eventually enterer the dense lower layers of the Earth's atmosphere, where is burned up."

"Even for fairly high altitudes, this decay can be fairly rapid."

"This effect can also be used for planned destruction of defunct satellites so as not to add to the space debris problem."

"It is found that for 2005year the simulated orbit altitude decay is consist with the real one best when the drag coefficient being as 2.91as large. ... Thus the resulted coefficients are much larger than the conventionally used value of 2.2."

"The simulated semi-major axis length shows a standard deviation in respect with observed ones as small as 81 m."

"However, their operational lifetimes are strongly influenced by orbital decay due to atmospheric drag."

"we explore how altitude, satellite mass, and cross-sectional area affect decay timescales."

"The results highlight the importance of accurate atmospheric density representation and solar activity in predicting satellite lifetimes"

"Atmospheric drag is the largest source of uncertainty for low-perigee RSOs."

"Geomagnetic storms inject significant energy into the upper atmosphere, increasing thermospheric temperature and density and, consequently, increase the atmospheric drag experienced by satellites in low Earth orbit (LEO)."

"An average unmodeled secular neutral density decrease of 1.7% per decade is detected."

"Modeling CD for an RSO requires knowledge of the gas-surface interaction (GSI) that defines the manner in which the atmospheric particles exchange momentum and energy with the surface."

"Results show that the decay rate increased from 73 m/day to 104 m/day in 2003, and from 155 m/day to 258 m/day in 2024"

"because the perigee will either rise to heights where the drag is obviously negligible, or will be forced down to a height where the satellite will decay."

"in general agreement with global cooling estimates determined from previous analyses of satellite orbital decay."

"demonstrating a significant i ncrease in drag on satellites which may affect their useful life."

"As a result, Swarm‐A orbital decay rate is increased from 79.43 to 96.28 m/day, and from 19.91 to 42.43 m/day during the AR4366 and AR3664 QHF events, respectively."

"Significant density enhancements up to 25%–30% and 50%–75% sustained for a few days, on both day and night sides, were observed at ∼460 km altitudes during QHF from AR4366 (February 2026) and AR3664 (May 2024), respectively."

"Repeated EUV heating at intervals shorter than the typical thermospheric relaxation time during QHF flares is responsible for sustained density enhancements and therefore needs to be considered one of the important drivers of satellite drag."

"This work considers only orbital perturbations due to aerodynamic forces, which spacecraft experience due to the presence of a rarefied atmosphere, causing tumbling motion and orbital decay."

"Space debris orbiting in space experiences orbital decay due to various orbital perturbations."

"Geomagnetic storms enhance thermospheric density and increase atmospheric drag on low-Earth-orbit (LEO) satellites, accelerating their orbital decay, as illustrated by the loss of 38 Starlink satellites following the modest February 2022 storm."

"because the mean free path of the gas molecules is large compared to the size of the satellite"

"as illustrated by the loss of 38 Starlink satellites following the modest February 2022 storm"

"Eleven values of density scale height have been determined from the decrease in perigee height, with a 2 per cent error"

"The satellite would also experience a spin decay due to the aerodynamic torque acting to slow the satellite spinning."

"Although the overall drop in inclination over the 16 days was only 0.02°"

"The effect of drag on a circular orbit can be shown to cause a decay in orbital radius per orbit"

"The polar orbit of Heos 2 second-stage rocket, 1972-05B, has been determined on each of the final 16 days before its decay in September 1978"