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Mission Concept and Trade-Off Study
Published in Shen-En Qian, Hyperspectral Satellites and System Design, 2020
Low Earth orbits are those whose maximum altitudes are less than approximately 2000 km and have the shortest orbital periods, on the order of an hour and a half. Some of these orbits are circular, while others may be somewhat elliptical. The degree of eccentricity is limited by the fact that the orbit is not much larger than the Earth plane, whose diameter is approximately 12,760 km.
Low-Gravity Environment
Published in Basil N. Antar, Vappu S. Nuotio-Antar, Fundamentals of Low Gravity Fluid Dynamics and Heat Transfer, 2019
Basil N. Antar, Vappu S. Nuotio-Antar
An object released motionless relative to the spacecraft at some distance from the center of mass along the radial vector from the center of the Earth will have an orbit slightly different from that of the spacecraft. Since the velocity required to maintain a circular orbit varies inversely with the square root of the distance from the center of the Earth, this object will have a slightly different velocity which will put it into an elliptical orbit with a different period. This trajectory will cause the object to slowly drift away from its initial position as the spacecraft describes its orbit around the Earth. The accelerations required to continuously alter the trajectories of such interior objects to keep them in the same relative configuration are of the order 10–7g0 for each meter of radial displacement from the spacecraft’s center of mass.
Orbits and trajectories
Published in Jonathan Allday, Apollo in Perspective, 2019
Figure 4.7 shows three possible paths around a planet. A satellite placed in an equatorial orbit circles around the planet's equator and will be visible directly overhead by people living at this latitude. A geostationary orbit is an equatorial orbit in which a satellite turns about the Earth in the same time period that the Earth requires to turn about its axis.
Relative equilibria, stability and bifurcations in Hamiltonian galactic tidal models
Published in Dynamical Systems, 2021
J. L. Zapata, F. Crespo, S. Ferrer
Our analysis hinges in the possible values of H for every fixed L. We distinguish between equilibria that exit for every value of the parameters and others that appear in a particular range, these two categories are dubbed as permanent and non-permanent equilibria. The set of permanent equilibria is formed by and . The relative equilibrium is generically associated with an elliptic orbit, which becomes rectilinear for H = 0 and circular for . Precisely, for H = 0 the equilibrium corresponds to the equatorial rectilinear orbits and for we have equatorial circular orbits. Notice that the rectilinear orbits are parametrized by a whole circle, while there are only two circular orbits. For we have a circular orbit whose inclination is determined by H and G. Further details on the inclination and eccentricity for each value of H are provided in Table 2.
A Review of Morton Effect: From Theory to Industrial Practice
Published in Tribology Transactions, 2018
Therefore, the larger the orbit size, the higher the differential temperature between the two points, as concluded in Bradley (7), Murphy and Lorenz (8), and Gomiciaga and Keogh (24). Gomiciaga and Keogh (24) found a similar trend via a CFD study, in which a general elliptic orbit was decomposed into a forward circular orbit and a backward circular orbit. Their results, well noted in the literature, revealed a nonlinear relationship, with a decreasing slope along the curve of versus orbit sizes (Gomiciaga and Keogh (24)).
Distributed optimal formation algorithm for multi-satellites system with time-varying performance function
Published in International Journal of Control, 2020
Note that the LVLH frame is attached to the chief satellite. Thus, in the following we will mainly analyse the influence of the motion of the chief satellite to the LVLH frame. Suppose that the chief satellite moves around the Earth in a desired elliptic orbit that can be expressed by the six orbit elements uniquely. Once the orbit of the chief satellite is settled, the angular velocities and the angular accelerations of the chief satellite are expressed as following