Preliminarily study of Saturn’s upper atmosphere density by observing Cassini plunging via China’s deep space station

When the Cassini spacecraft finally plunged into the Saturnian atmosphere on 2017 September15,China’s deep space telescope pointed to Saturn to observe Cassini and study the Saturnian upper neutral atmosphere.In this first Chinese Saturnian radio science experiment,X band Doppler velocity radio science data between the deep space telescope and the Cassini spacecraft were obtained.After removing Saturnian and solar gravity effects,Earth rotation effect,the remaining Saturnian atmosphere drag information was retrieved in the Cassini final plunge progress.Saturn’s upper neutral atmosphere mass density profile is approximately estimated based on atmosphere mass density derived principally by real orbit measurement data.Saturn’s upper neutral atmosphere mass density from 76000 km to 1400 km is estimated from the orbit measurement data,the mass density results are about from 1.4×10^-15 kg cm^-3 to 2.5×10^-14 kg cm^-3.

CHANGES OF THE THERMOSPHERE DENSITY IN THE SUNSHINE AND SHADE AREA OBSERVED BY "SZ-2" ATMOSPHERIC DENSITY DETECTOR

In this paper,thermosphere density data of"SZ-2"Atmospheric Density Detec tor From February to April 2001 are used to study the changes of the thermo sphere density in the sunshine and shaded area during solar and geomagnetic activity.The results show that in the sunshine area,the peak value of atmo spheric density changes as F10.7 varies;during geomagnetic activity,the peak value of atmospheric density in the shaded area increases as Ap increases,and start off with higher latitude,therefore move to lower latitude.

Variations of Thermosphere Density Based on Joint Analysis of In-Situ Measurement Data From Shenzhou Spacecrafts

Based on the measurements made by Atmospheric Density Detectors(ADDs) onboard Chinese spacecraft Shenzhou 2-4,the variations of thermosphere density are revealed.During the quiet period,the density at spacecraft altitude of 330~410 km exhibited a dominant diurnal variation,with high value on dayside and low value on nightside.The ratio of the diurnal maximum density to the minimum ranged from 1.7 to 2.0.The ratio shows a positive correlation with the level of solar activity and a negative correlation with the level of geomagnetic activity.When a geomagnetic disturbance comes,the atmospheric density at the altitude of 330～410 km displayed a global enhancement.For a strong geomagnetic disturbance,the atmospheric density increased by about 56%,and reached its maximum about 6～7 hours after the geomagnetic disturbance peak. The density asymmetry was also observed both in the southern and northern hemisphere during the geomagnetic disturbance peak.

The Quantum Chromodynamics Gas Density Drop and the General Theory of Relativity Ether

β decay is one of the most fundamental and thoroughly studied nuclear decay. Surprisingly, the β decay rates were found to have a periodic time variability [1]. However, others argued that there is no evidence for such cyclic deviation from the exponential first order kinetics decay law [2]. Here we propose that the β decay is a pseudo-first order exchange reaction triggered by uddũexotic mesons and propose a QCD gas theory. In analogy to the atmospheric gas density, the proposed QCD gas density drops with elevation from the sun. Accordingly, we propose that the β decay rate periodic variability is due to the pseudo-first order exchange reaction kinetics and the QCD gas atmospheric density drop. The proposed QCD gas may be a possible candidate for Einstein’s general theory of relativity ether [3]. Our main results are the derived formulas for calculating the effective mass of the QCD gas and the cosmology perfect fluid equation of state dimensionless parameter, based on the measured ratio of the β decay rates at the earth trajectory aphelion and perihelion dates. .

Measurement of Electron Density and Ion Collision Frequency with Dual Assisted Grounded Electrode DBD in Atmospheric Pressure Helium Plasma Jet

The properties of a helium atmospheric-pressure plasma jet（APPJ）are diagnosed with a dual assisted grounded electrode dielectric barrier discharge device.In the glow discharge,we captured the current waveforms at the positions of the three grounded rings.From the current waveforms,the time delay between the adjacent positions of the rings is employed to calculate the plasma bullet velocity of the helium APPJ.Moreover,the electron density is deduced from a model combining with the time delay and current intensity,which is about 10^（11）cm^（-3）.In addition,The ion-neutral particles collision frequency in the radial direction is calculated from the current phase difference between two rings,which is on the order of 10~7 Hz.The results are helpful for understanding the basic properties of APPJs.

Atmospheric density determination using high-accuracy satellite GPS data

Atmospheric drag is the main source of error in the determination and prediction of the orbit of low Earth orbit （LEO） satellites; however, empirical models that are used to account for this often have density errors of around 15%-30%. Atmospheric density determination has thus become an important topic for researchers. Based on the relationship between file atmospheric drag force and the decay of the semi-major axis of the orbit, we derived atmospheric density along the trajectory of challenging mini-satellite payload （CHAMP） satellite with its rapid science orbit （RSO） data. Three primary parameters--the ratio of cross-sectional area to mass, the drag coefficient, and the decay of the semi-major axis caused by atmospheric drag--were calculated. We also analyse the source of the error and made a comparison between the GPS-derived and reference density. The result for December 2, 2008, showed that the mean error of the GPS-derived density could be decreased from 29.21% to 9.20%, if the time span adopted for the process of computation was increased from 10 min to 50 min. The result for the entire month of December indicated that a density precision of 10% could be achieved, when the time span meets the condition that the amplitude of the decay of the semi-major axis is much greater than its standard deviation.

Calibration of atmospheric density model using two-line element data

For satellites in orbits,most perturbations can be well modeled;however the inaccuracy of the atmospheric density model remains the biggest error source in orbit determination and prediction.The commonly used empirical atmospheric density models,such as Jacchia,NRLMSISE,DTM,and Russian GOST,still have a relative error of about 10%-30%.Because of the uncertainty in the atmospheric density distribution,high accuracy estimation of the atmospheric density cannot be achieved using a deterministic model.A better way to improve the accuracy is to calibrate the model with updated measurements.Twoline element(TLE)sets provide accessible orbital data,which can be used in the model calibration.In this paper,an algorithm for calibrating the atmospheric density model is developed.First,the density distribution of the atmosphere is represented by a power series expansion whose coefficients are denoted by the spherical harmonic expansions.Then,the useful historical TLE data are selected.The ballistic coefficients of the objects are estimated using the BSTAR data in TLEs,and the parameterized model is calibrated by solving a nonlinear least squares problem.Simulation results show that the prediction error is reduced using the proposed calibration algorithm.

Atmospheric environmental capacity and urban atmospheric load in China's Mainland

Daily and annual average atmospheric environmental capacity coefficient(A-value) sequences for China's Mainland are calculated from hourly data recorded at 378 ground stations over 1975–2014. A-values at different recurrence intervals are calculated by fitting the sequences to Pearson type III distribution curves. Based on these A-values and source-sink balance(reference concentration 100 μg m^(-3)), atmospheric environmental capacities at the recurrence intervals are calculated for all of China's Mainland and each provincial administrative region. The climate average atmospheric environmental capacity reference value for the entire mainland is 2.169×10~7 t yr^(-1). An urban atmospheric load index is defined for analyses of the impact of population density on the urban atmospheric environment. Analyses suggest that this index is also useful for differentiating whether air quality changes are attributable to varying meteorological conditions or variations of artificial emission rate.Equations guiding the control of unorganized emission sources are derived for preventing air quality deterioration during urban expansion and population concentration.

APOD mission status and preliminary results

On September 20 th, 2015, twenty satellites were successfully deployed into a near-polar circular orbit at 520 km altitude by the Chinese CZ-6 test rocket, which was launched from the Tai Yuan Satellite Launch Center. Among these satellites, a set of 4 Cube Sats conform the atmospheric density detection and precise orbit determination(APOD) mission, which is projected for atmospheric density estimation from in-situ detection and precise orbit products. The APOD satellites are manufactured by China Spacesat Co. Ltd. and the payload instruments include an atmospheric density detector(ADD), a dual-frequency dualmode global navigation satellite system(GNSS) receiver(GPS and Beidou), a satellite laser ranging(SLR) reflector, and an S/Xband very long baseline interferometry(VLBI) beacon. In this paper, we compare the GNSS precise orbit products with colocated SLR observations, and the 3 D orbit accuracy shows better than 10 cm RMS. These results reveal the great potential of the onboard micro-electro-mechanical system(MEMS) GNSS receiver. After calibrating ADD density estimates with precise orbit products, the accuracy of our density products can reach about 10% with respect to the background density. Density estimates from APOD are of a great importance for scientific studies on upper atmosphere variations and useful for model data assimilation.