scholarly journals Accuracy of Symmetric Multi-Step Methods for the Numerical Modelling of Satellite Motion

2020 ◽  
pp. 781-791
Author(s):  
Evgenia D. Karepova ◽  
Iliya R. Adaev ◽  
Yury V. Shan’ko
Keyword(s):  
Absolute Stability ◽  
3D Model ◽  
Model Problem ◽  
Kepler Problem ◽  
Satellite System ◽  
Satellite Motion ◽  
Symmetric Methods ◽  
The Earth ◽  
One Year ◽  
Multi Step Methods

Stability of high-order linear multistep St¨ormer-Cowell and symmetric methods are discussed in detail in this paper. Efficient algorithms for obtaining intervals of absolute stability and periodicity are given for these methods. To demonstrate the accuracy of numerical integration of the orbit over an interval about one year two model problems are considered. First problem is the 3D Kepler problem. Second one is a specially designed 3D model problem that has the exact solution and simulates the Earth-Moon-satellite system

Preliminary monthly gravity field models from kinematic orbits of SWARM Satellites

2021 ◽  
Author(s):  
Xingfu Zhang ◽  
Qiujie Chen ◽  
Yunzhong Shen
Keyword(s):  
Gravity Field ◽  
Large Scale ◽  
Earth System ◽  
The Earth ◽  
Swarm Satellites ◽  
Variable Gravity ◽  
Data Gap ◽  
One Year ◽  
Gravity Recovery ◽  
Gravity Field Models

<p>      Although the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE FO) satellite missions play an important role in monitoring global mass changes within the Earth system, there is a data gap of about one year spanning July 2017 to May 2018, which leads to discontinuous gravity observations for monitoring global mass changes. As an alternative mission, the SWARM satellites can provide gravity observations to close this data gap. In this paper, we are dedicated to developing alternative monthly time-variable gravity field solutions from SWARM data. Using kinematic orbits of SWARM from ITSG for the period January 2015 to September 2020, we have generated a preliminary time series of monthly gravity field models named Tongji-Swarm2019 up to degree and order 60. The comparisons between Tongji-Swarm2019 and GRACE/GRACE-FO monthly solutions show that Tongji-Swarm2019 solutions agree with GRACE/GRACE-FO models in terms of large-scale mass change signals over amazon, Greenland and other regions. We can conclude that Tongji-Swarm2019 monthly gravity field models are able to close the gap between GRACE and GRACE FO.</p>

scholarly journals COASTAL APPLICATIONS OF THE ERTS-A SATELLITE

1972 ◽  
Vol 1 (13) ◽  
pp. 113
Author(s):  
Orville T. Magoon ◽  
Douglas M. Pirie ◽  
John W. Jarman
Keyword(s):  
Multispectral Images ◽  
Precise Location ◽  
Multispectral Data ◽  
Topographic Features ◽  
Efficient Management ◽  
The Earth ◽  
Maximum Utility ◽  
Data Output ◽  
Constant Observation ◽  
One Year

This paper describes the Earth Resources Technology Satellite (ERTS) placed in orbit in July 1972 and the ERTS simulation high altitude aircraft flights which have been flown for approximately one year. The ERTS satellite and simulation programs conducted by the National Aeronautics and Space Administration (NASA) have been developed to demonstrate the techniques for efficient management of the earth's resources. To achieve this objective the ERTS-A satellite provides for the repetitive acquisition of high resolution multispectral data of the earth's surface on a global basis. Two sensor systems have been selected for this purpose: a fourchannel multispectral scanner (MSS) subsystem for ERTS-A and a threecamera return beam vidicon (RBV) system. Systematic repeating earth coverage under nearly constant observation conditions is provided for maximum utility of the multispectral images collected by the ERTS satellite, which operates in a circular sun synchronous nearly polar orbit at an altitude of 494 nautical miles. It circles the earth every 103 minutes completing 14 orbits per day and views the entire earth in 18 days. The orbit has been selected so that the satellite ground trace repeats its earth coverage at the same local time every 18-day period within 20 nautical miles. A number of data output products are available from this satellite which include 70 mm products for precise location of topographic features, 9.5 inch positive or paper prints and also computer compatible tapes or punched cards. Also described are the results of the ERTS-A simulation flights flown at an altitude of 65,000 feet as related to coastal studies. Simulations of both the RBV and MSS in coastal areas are presented.

An Assessment of CYGNSS Ocean Wind Speed Products

2021 ◽  
Author(s):  
Matthew Hammond ◽  
Giuseppe Foti ◽  
Christine Gommenginger ◽  
Meric Srokosz ◽  
Nicolas Floury
Keyword(s):  
Remote Sensing ◽  
Wind Speed ◽  
Satellite System ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
The Earth ◽  
L1 Data ◽  
Global Navigation ◽  
Global Navigation Satellite ◽  
Ocean Wind

<p>Global Navigation Satellite System-Reflectometry (GNSS-R) is an innovative and rapidly developing approach to Earth Observation that makes use of signals of opportunity from Global Navigation Satellite Systems, which have been reflected off the Earth’s surface. CYGNSS is a constellation of 8 satellites launched in 2016 which use GNSS-R technology for the remote sensing of ocean wind speed. The ESA ECOLOGY project aims to evaluate CYGNSS data which has recently undergone a series of improvements in the calibration approach. Using CYGNSS collections above the ocean surface, an assessment of Level-1 calibration is presented, alongside a performance evaluation of Level-2 wind speed products. L1 data collected by the individual satellites are shown to be generally well inter-calibrated and remarkably stable over time, a significant improvement over previous versions. However, some geographical biases are found, which appear to be linked to a number of factors including the transmitter-receiver pair considered, viewing geometry, and surface elevation. These findings provide a basis for further improvement of CYGNSS products and have wider applicability to improving calibration of GNSS-R sensors for remote sensing of the Earth.</p>

Construction of correspondences between the sky we see and the heliocentric model: problem-based learning in 7th grade of elementary school

2019 ◽  
Vol 15 (S367) ◽  
pp. 444-445
Author(s):  
Fernando Ariel Karaseur ◽  
Alejandro Gangui
Keyword(s):  
Elementary School ◽  
Solar System ◽  
Model Problem ◽  
Point Of View ◽  
School Students ◽  
Moon Phases ◽  
The Earth ◽  
External Point ◽  
Local Point ◽  
Specific Material

AbstractWe present the results of the implementation of a didactic sequence based on the formulation and resolution of astronomical problems by seventh grade elementary school students from the Autonomous City of Buenos Aires, Argentina. Its objective is to generate a meaningful understanding of the heliocentric model of the Solar System from the systematization of topocentric observations of the sky, either direct or mediated by resources such as diagrams, Stellarium software and tables, which we correlate with the parallel globe, other models with specific material and the Solar System Scope software. Throughout the sequence we address topics such as the diurnal and annual movement of the Sun, the night sky, astronomical ephemeris, Moon phases and eclipses. These are developed in parallel to the sphericity of the Earth and the concept of motion in science. For each of these topics we start from its recognition. We then implement strategies to guide students towards a possible description from the local point of view, and then extend it to other locations on the surface of the Earth. We encourage them to explain their ideas about the possible links between these topocentric observations and the corresponding relative positions of the celestial objects as seen from an external point of view to the Earth. These ideas are then contrasted with geocentric and heliocentric models. Here we highlight the integrative instances in which the students formulated problems in small groups and shared them for their resolution. Thus, motivated and challenged by the collaboration between peers, they became the protagonists of their learning.

Theories of Polar Motion from Tisserand to Poincaré (1890 – 1910)

2000 ◽  
Vol 178 ◽  
pp. 41-66 ◽  
Author(s):  
P. Melchior
Keyword(s):  
Polar Motion ◽  
Scientific Community ◽  
Circular Motion ◽  
Computing Power ◽  
The Earth ◽  
Fixed Pole ◽  
One Year ◽  
Elliptical Motion ◽  
The Impact ◽  
Chandler Period

AbstractThe discovery by Seth C. Chandler (1891) that the motion of the pole (the reality of which had been established by K.F. Küstner and by the simultaneous latitude observations at Honolulu and Berlin by German astronomers) resulted from two components i.e. a free circular motion with a period of 427 days and a forced elliptical motion with a period of 365.25 days, raised considerable interest in the scientific community of astronomers and geophysicists.The celebrated Mécanique Céleste of Tisserand (1890) had been published just one year before at a time when doubts still persisted and arguments could be presented in favor of the fixed pole. Starting with Tisserand’s arguments, we describe in this paper the impact of the successive contributions by A. Greenhill, S. Newcomb, Th. Sloudsky, S. Hough, G. Herglotz, A. Love, J. Larmor and H. Poincaré to the solution of the problems raised by the Chandler period.The lines of reasoning taken by these eminent scientists were rigorously correct so that, after about one hundred years, contemporary researchers, who benefit from a far better knowledge of the inner structure of the Earth and are able to take advantage of modern computing power, do not contradict any of their conclusions and instead refine them with an accuracy which was not imaginable one century ago.

scholarly journals VLBI studies of the nutations of the earth

1988 ◽  
Vol 129 ◽  
pp. 371-375
Author(s):  
T. A. Herring
Keyword(s):  
Truncation Error ◽  
Very Long Baseline Interferometry ◽  
Long Baseline ◽  
The Earth ◽  
Vlbi Data ◽  
One Year ◽  
Nutation Series ◽  
Theoretical Considerations ◽  
Active Investigation

The application of very–long–baseline interferometry (VLBI) to the study of the nutations of the earth has yielded unprecedented accuracy for the experimental determination of the coefficients of the nutation series. The analysis of six years of VLBI data has yielded corrections to the coefficients of the seven largest terms in the IAU 1980 nutation series with periods of one year or less, with accuracies approaching the truncation error of this nutation series (0.1 mas). The nutation series coefficients computed from the VLBI data, and those obtained from theoretical considerations (the IAU 1980 nutation series), are in excellent agreement. The largest corrections are to the coefficients of the retrograde annual nutation [2.0 ± 0.1 mas], the prograde semiannual nutation [(0.5 - ι 0.4) ±0.1 mas], and the prograde 13.7 day nutation [−0.4 ± 0.1 mas]. (The imaginary term for the semiannual nutation represents a term 90° out–of–phase with the arguments of the nutation series.) The geophysical implications of these results are currently under active investigation. We discuss the methods used to extract the nutation information from the VLBI data, the calculations of the uncertainties of the resultant corrections to the coefficients of the nutation series, and the current research into the nutations of the earth.

scholarly journals ANALYSIS OF THE VOLUME COMPARATION OF 3’S (TS, GNSS and TLS)

2019 ◽  
Vol 94 ◽  
pp. 01014
Author(s):  
Khomsin ◽  
Danar Guruh Pratomo ◽  
Ira Mutiara Anjasmara ◽  
Faizzuddin Ahmad
Keyword(s):  
3D Model ◽  
Laser Scanner ◽  
Satellite System ◽  
Navigation Satellite ◽  
Scanner Data ◽  
Total Station ◽  
Volume Calculation ◽  
Laser Scanners ◽  
Technological Developments ◽  
Global Navigation Satellite

Recently, technological developments in the field of surveys and mapping are growing very rapidly such as total station, navigation satellite (Global Navigation Satellite System), drones and laser scanners. One application of this technology is to measure a stockpile area quickly and accurately. This research will measure two stockpiles (coal warehouses) using total station (TS), GNSS and terrestrial laser scanner (TLS). This research will compare the results of volume calculations with the data generated by 3’S (TS, GNSS and TLS). Research is conducted at Coal Yard PT. Barkalin Surabaya in Benowo District, Surabaya, East City with geographically located at 112°39'11'’ E and 7°07’13‘' S. The first step is to make 3D model of Laser Scanner data by TLS Faro 3D 120 and to do regristrastion and filltering using Faro Scene. After that the data export to be 3D model from Faro Scene format to Recap 2016 (.rcp) to present and get coordinates. The next step is to compare the coordinates from TLS, TS and GNSS RTK. Finally, the accuracy of volume calculation from TS and GNSS RTK can be compared to TLS. The volume differences between TS and TLS data are -7.31 m3 (-0.45%) for the 1st location and -6.89 m3 (-0.24%) for the 2nd location. While the volume differences between GNSS RTK and TLS are -10.34 m3 (-0.63%) and -9.05 m3 (-0.31%) for the 1st location and the 2nd location respectively. Generally, the volume differences between TLS, TS and GNSS RTK are not significant. Therefore, 3’S can be used to measure a volume of stockpile.

scholarly journals Evaluation of the GPS Precise Orbit and Clock Corrections from MADOCA Real-Time Products

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2580 ◽  
Author(s):  
Shaocheng Zhang ◽  
Shikang Du ◽  
Wei Li ◽  
Guangxing Wang
Keyword(s):  
Real Time ◽  
Satellite Orbit ◽  
Satellite System ◽  
Precise Orbit ◽  
Term Evaluation ◽  
Consistent Performance ◽  
One Year ◽  
Navigation Signals ◽  
Kinematic Ppp ◽  
The One

The Japanese Quasi-Zenith Satellite System (QZSS) is a regional navigation satellite system covering the entire Asia-Oceania region. Except for the standard satellite navigation signals, QZSS satellites also broadcast L6E augmentation signals with real time GNSS precise orbit every 30 s and clock messages every 1 s, which is very important and necessary for Real-Time precise point positioning (RTPPP) applications. In this paper, the MADOCA real-time services derived from L6E augmentation signals were evaluated for both accuracy and availability compared with IGS final products. To avoid the datum difference of GPS orbit between MADOCA real-time and IGS final products, the 7-parameters Helmert transformation was firstly used in this paper, and then the orbit was evaluated on radial, along, and cross-track directions. On the clock evaluation, the mean satellites clock errors were taken as reference clock error, and then the standard deviation (STD) was calculated for each satellite. Furthermore, the signal in space range errors (SISRE) were also summarized to evaluate the ranging-measurement accuracy. Seven-day evaluation results show that satellite orbit, clock errors, and the final SISRE errors range as being 1.8–3.9 cm, 0.04–0.15 ns (1.2–4.5 cm), and 5–10 cm, respectively. For the one-year long-term evaluation, daily SISRE errors in 2018 show consistent performance with that of seven days. Furthermore, the open source software RTKLIB was used to evaluate the kinematic PPP performance based on the MADOCA real-time products, and it shows that the daily positioning accuracy of the 20 globally distributed IGS stations can reach 4.9, 4.2, 11.7, and 12.1 cm in the east, north, up, and 3D directions, respectively. Hence, it is concluded that the current MADOCA real-time ephemeris products can provide orbit and clock products with SISRE on centimeters level with high interval, which could meet the demands of the RTPPP solution and serve real-time users who can access the MADOCA real-time products via L6E signal or internet.

Extreme TGF Imaging by ASIM

2020 ◽  
Author(s):  
Víctor Reglero ◽  
Paul Connell ◽  
Javier Navarro ◽  
Christopher Eyles ◽  
Nikolai Ostgaard ◽  
...  
Keyword(s):  
Convective Cell ◽  
Imaging Data ◽  
Source Imaging ◽  
Extended Source ◽  
The Earth ◽  
Operational Phase ◽  
One Year ◽  
Asymmetric Matter ◽  
Imaging Conditions ◽  
Accurate Imaging

<p>One year after the starting of ASIM operational phase, we have succeeded to perform accurate Imaging of 54 TGF.  Among them, some have been analysed at extreme imaging conditions in terms of TGF position at the MXGS partially coded field of view.  20 TGF events have angular distances larger than 40º respect to the MXGS FOV centre. Extreme cases at angular distances larger than 50º are presented. Validation of TGF position by WLN data is included in the discussion.</p><p>The canonical value of 32 LED cnts as the minimum fluency for TGF imaging defined during MXGS development was checked using low luminosity TGF.  At the present, we have succeeded to obtain imaging solution for 7 TGF with less than 20 cnts. A sample is presented with indication of position accuracy and S/N ratios.  </p><p>Last part of the presentation is the discussion of a TGF with a very large and asymmetric probability distribution at the MXGS FOV that suggest the TGF as an extended source. Imaging data projected to the Earth surface is compared with GOES data, showing that the TGF is at the edge of a large convective cell, close to the TGF imaging data map.  Therefore, we can conclude that for some bright TGF it is possible to estimate the TGF fireball dimensions generated by the iteration of TGF photons with local atmospheric asymmetric matter distributions. The presence of a large CZT tail is coherent with the size of the convective cell.</p>

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