scholarly journals Statistical Reliability Analysis of Interplanetary Spacecraft Operating at Different Interplanetary Extremity

2021 ◽  
Author(s):  
Malaya Kumar Biswal M
Keyword(s):  
Reliability Analysis ◽  
Parametric Analysis ◽  
Interplanetary Space ◽  
Success Probability ◽  
Space Environment ◽  
Integration Testing ◽  
Spacecraft Design ◽  
Statistical Reliability ◽  
The Earth ◽  
The Difference

Reliability of the spacecraft determines the extent of success probability and mission accomplishment. Despite effective testing and integration, the complexity of the space environment affects reliability. In this paper, we investigate the reliability behaviour of interplanetary spacecraft operating at different interplanetary extremities. So, our investigation assesses spacecraft inhered in interplanetary space with the context of the interplanetary boundary (between distinct planetary orbit or within the bounds of heliopause). From the perspective of spacecraft reliability in interplanetary space, we have excluded planetary landers, atmospheric probes, and satellites maneuvering earth orbit. Thus, we have identified 131 spacecraft (includes 82 probes within the bounds of Sun and the Earth, and 49 within the bounds of Earth and Heliopause) along with their gross mass at launch and lifespan. Based on acquired data, we first conduct a non-parametric analysis of spacecraft reliability to obtain two reliability curves for distinct interplanetary extremity. We then perform a parametric fit (Weibull Distribution) over the data to show the analogy of reliability behaviour. Results showed that the spacecraft operating beyond the extremity of the Earth and the Mars exhibits increased reliability than any other interplanetary extremity. In addition to this, we execute reliability analysis over spacecraft of various mass categories (Small-Medium-Large) to testify the reliability effect interpreted by Dubos in 2010. Finally, we discuss the possible factors and causes accountable for the difference in reliability behaviour concerning the spacecraft design and integration, testing, and constraints in considering spacecraft mass.

scholarly journals Modelling and Analysis of Emitter Geolocation using Satellite Tool Kit

2020 ◽  
Vol 70 (4) ◽  
pp. 440-447
Author(s):  
Suman Agrawal ◽  
Anupam Sharma ◽  
Charul Bhatnagar ◽  
D.S. Chauhan
Keyword(s):  
Radio Frequency ◽  
Multiple Antennas ◽  
Signal Strength ◽  
Received Signal Strength ◽  
Geostationary Satellite ◽  
Space Environment ◽  
The Earth ◽  
The Difference ◽  
Geolocation Accuracy

This paper considers geolocation of a stationary radio frequency emitter which is being steered by multiple antennas installed on a geostationary satellite using received signal strength metric. The difference in the signal strengths is measured by the antennas and subsequently plotted as lines of position on the surface of the earth. Intersection of these two or more lines of position indicates the location of the terrestrial radio frequency transmitters. This problem is appropriately modelled using a satellite tool kit that simulates the space environment involving satellites, antennas, emitters, etc in a realistic and integrated manner. Accuracy and size of the geolocation area depend on the distance between emitters and the receiver and also on the contour widths geometry. Results of geolocation accuracy are compared by installing the radio frequency emitter at increasing latitudes and at varying contour widths. It is observed that the emitters placed at lower latitudes and having smaller contour widths provided higher accuracy in geolocation that validates the proposed formulation.

The Origin of the Moon

1962 ◽  
Vol 14 ◽  
pp. 149-155 ◽  
Author(s):  
E. L. Ruskol
Keyword(s):  
Chemical Composition ◽  
Solar System ◽  
The Moon ◽  
The Earth ◽  
The Difference ◽  
Origin Of The Moon

The difference between average densities of the Moon and Earth was interpreted in the preceding report by Professor H. Urey as indicating a difference in their chemical composition. Therefore, Urey assumes the Moon's formation to have taken place far away from the Earth, under conditions differing substantially from the conditions of Earth's formation. In such a case, the Earth should have captured the Moon. As is admitted by Professor Urey himself, such a capture is a very improbable event. In addition, an assumption that the “lunar” dimensions were representative of protoplanetary bodies in the entire solar system encounters great difficulties.

scholarly journals A review of the SCOSTEP’s 5-year scientific program VarSITI—Variability of the Sun and Its Terrestrial Impact

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Kazuo Shiokawa ◽  
Katya Georgieva
Keyword(s):  
Solar Wind ◽  
Interplanetary Space ◽  
Solar Wind Plasma ◽  
The Sun ◽  
Scientific Program ◽  
Solar Cycles ◽  
Grand Minimum ◽  
The Earth ◽  
Earth Connection ◽  
Near Future

AbstractThe Sun is a variable active-dynamo star, emitting radiation in all wavelengths and solar-wind plasma to the interplanetary space. The Earth is immersed in this radiation and solar wind, showing various responses in geospace and atmosphere. This Sun–Earth connection variates in time scales from milli-seconds to millennia and beyond. The solar activity, which has a ~11-year periodicity, is gradually declining in recent three solar cycles, suggesting a possibility of a grand minimum in near future. VarSITI—variability of the Sun and its terrestrial impact—was the 5-year program of the scientific committee on solar-terrestrial physics (SCOSTEP) in 2014–2018, focusing on this variability of the Sun and its consequences on the Earth. This paper reviews some background of SCOSTEP and its past programs, achievements of the 5-year VarSITI program, and remaining outstanding questions after VarSITI.

III. On the figure, dimensions, and mean specific gravity of the Earth, as derived from the ordnance trigonometrical survey of Great Britain and Ireland

1857 ◽  
Vol 8 ◽  
pp. 111-116 ◽  
Keyword(s):  
United Kingdom ◽  
Great Britain ◽  
Specific Gravity ◽  
Royal Society ◽  
The United Kingdom ◽  
The Earth ◽  
The Difference ◽  
The Government

The Trigonometrical Survey of the United Kingdom commenced in the year 1784, under the immediate auspices of the Royal Society; the first base was traced by General Roy on the 16th of April of that year, on Hounslow Heath, in presence of Sir Joseph Banks, then President of the Society, and some of its most distinguished Fellows. The principal object which the Government had then in view, was the connexion of the Observatories of Paris and Greenwich by means of a triangulation, for the purpose of determining the difference of longitude between the two observatories.

Data Fusion of Total Solar Irradiance Composite Time Series Using 40 years of Satellite Measurements: First Results 

2021 ◽  
Author(s):  
Jean-Philippe Montillet ◽  
Wolfgang Finsterle ◽  
Werner Schmutz ◽  
Margit Haberreiter ◽  
Rok Sikonja
Keyword(s):  
Time Series ◽  
Data Fusion ◽  
Solar Irradiance ◽  
Total Solar Irradiance ◽  
Maunder Minimum ◽  
The Sun ◽  
Climate Reconstructions ◽  
The Earth ◽  
First Results ◽  
The Difference

<p><span>Since the late 70’s, successive satellite missions have been monitoring the sun’s activity, recording total solar irradiance observations. These measurements are important to estimate the Earth’s energy imbalance, </span><span>i.e. the difference of energy absorbed and emitted by our planet. Climate modelers need the solar forcing time series in their models in order to study the influence of the Sun on the Earth’s climate. With this amount of TSI data, solar irradiance reconstruction models  can be better validated which can also improve studies looking at past climate reconstructions (e.g., Maunder minimum). V</span><span>arious algorithms have been proposed in the last decade to merge the various TSI measurements over the 40 years of recording period. We have developed a new statistical algorithm based on data fusion.  The stochastic noise processes of the measurements are modeled via a dual kernel including white and coloured noise.  We show our first results and compare it with previous releases (PMOD,ACRIM, ... ). </span></p>

INVESTIGATION OF THE ABSOLUTENESS OF TIME

2021 ◽  
pp. 51-54
Author(s):  
S. Tiguntsev
Keyword(s):  
High Precision ◽  
Gravitational Potential ◽  
High Speed ◽  
Relativistic Effect ◽  
Theoretical Research ◽  
Clock Frequency ◽  
Positioning Systems ◽  
The Earth ◽  
Flow Of Time ◽  
The Difference

In classical physics, time is considered absolute. It is believed that all processes, regardless of their complexity, do not affect the flow of time The theory of relativity determines that the flow of time for bodies depends both on the speed of movement of bodies and on the magnitude of the gravitational potential. It is believed that time in space orbit passes slower due to the high speed of the spacecraft, and faster due to the lower gravitational potential than on the surface of the Earth. Currently, the dependence of time on the magnitude of the gravitational potential and velocity (relativistic effect) is taken into account in global positioning systems. However, studying the relativistic effect, scientists have made a wrong interpretation of the difference between the clock frequency of an orbiting satellite and the clock frequency on the Earth's surface. All further studies to explain the relativistic effect were carried out according to a similar scenario, that is, only the difference in clock frequencies under conditions of different gravitational potentials was investigated. While conducting theoretical research, I found that the frequency of the signal changes along the way from the satellite to the receiver due to the influence of Earth's gravity. It was found that the readings of two high-precision clocks located at different heights will not differ after any period of time, that is, it is shown that the flow of time does not depend on the gravitational potential. It is proposed to conduct full-scale experiments, during which some high-precision clocks are sent aboard the space station, while others remain in the laboratory on the surface of the earth. It is expected that the readings of the satellite clock will be absolutely identical to the readings of the clock in the Earth laboratory.

Torsional oscillation of a homogeneous elastic spheroid

1962 ◽  
Vol 52 (3) ◽  
pp. 469-484 ◽  
Author(s):  
Tatsuo Usami ◽  
Yasuo Satô
Keyword(s):  
Fundamental Mode ◽  
Free Oscillation ◽  
Torsional Oscillation ◽  
Numerical Calculations ◽  
Higher Harmonics ◽  
Oblate Spheroidal ◽  
The Earth ◽  
Spectral Peaks ◽  
The Difference ◽  
Spheroidal Coordinates

abstract There are several causes for the observations of splitting of the spectral peaks determined from the free oscillation of the earth. In this paper, the splitting due to the ellipticity is studied assuming a homogeneous earth described by oblate spheroidal coordinates. Ellipticity causes the iTn mode to split into (n + 1) modes, while the earth's rotation causes it to split into (2n + 1) modes. 1/297.0 is adopted as the ellipticity of the earth. Numerical calculations are carried out for the fundamental mode (n = 2, 3, 4) and for the first higher harmonics (n = 1). The difference between the extreme frequencies for each value of n is 0.7% (n = 2), 0.5% (n = 3), and 0.4% (n = 4).

Address of the President, Sir Howard Florey, at the Anniversary Meeting, 30 November 1964

1965 ◽  
Vol 283 (1392) ◽  
Keyword(s):  
Interplanetary Space ◽  
Diurnal Variations ◽  
Kinetic Theory Of Gases ◽  
Tidal Effects ◽  
Subsequent Work ◽  
The Earth ◽  
Predominant Component ◽  
Wide Range ◽  
Magnetic Field Variations ◽  
Great Mass

The Copley Medal is awarded to Professor S. Chapman, F.R.S. Professor Chapman is distinguished for his contributions to many aspects of physics, astronomy and geophysics. His work on the kinetic theory of gases now forms the basis for much detailed study of gaseous phenomena, and over forty years ago his interest in these problems led him to consider the processes of diffusion and viscosity in stars. In addition to these important studies Chapman’s name has, for over half a century, been inseparably linked with problems in terrestrial magnetism and with a wide range of studies concerned with the high atmosphere, ionosphere and interplanetary space. From a statistical analysis of a great mass of data Chapman succeeded in demonstrating the existence of a small lunar component in the Earth’s quiet magnetic field variations, and he showed that the solar and lunar diurnal variations could be separated into a predominant component originating above the Earth’s surface and a subsidiary component within the Earth itself. From this standpoint he developed the general theory of the relation of the magnetic variations to the solar and lunar atmospheric tidal effects, a theory which has been fundamental to all subsequent work.

scholarly journals Reliability Analysis of a Filtering Reducer under the Discrete Space Environmental Shocks

2014 ◽  
Vol 6 ◽  
pp. 921720 ◽  
Author(s):  
Jing Lu ◽  
Zhonglai Wang ◽  
Wei Chen ◽  
Xuefei Zhang ◽  
Hao Liu
Keyword(s):  
Differential Equations ◽  
Dynamic System ◽  
Mechanism Design ◽  
Reliability Analysis ◽  
Dynamic Model ◽  
Space Environment ◽  
Newmark Method ◽  
Lumped Mass ◽  
Dynamic Reliability ◽  
Environmental Shocks

Dynamic reliability analysis of a filtering reducer is performed by accounting for discrete shocks from the space environment. Gears are considered as the lumped mass and meanwhile the meshing between different gears is equivalent to a dynamic system consisting of springs and dampers during construction of the dynamic model. The Newmark method is employed to resolve differential equations, and then the additional acceleration could be obtained, caused by shocks to the filtering reducer. Dynamic reliability analysis is conducted with the help of the Simulink tool for the outputs. The results are hopefully useful for spacecraft mechanism design.

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