Research Article
Attitude Estimation of H2A Rocket Body from Light Curve Measurements
Alessandro Vananti,
Yao Lu,
Thomas Schildknecht
Issue:
Volume 11, Issue 2, June 2023
Pages:
15-22
Received:
18 September 2023
Accepted:
12 October 2023
Published:
28 October 2023
Abstract: The knowledge of the attitude motion of space debris is relevant for active debris removal missions. One possibility to characterize the attitude of space objects consists in the acquisition of photometric measurements over time, called light curves. The observed object is illuminated by the Sun and the variation of its apparent brightness gives information about its attitude state, e.g. whether the object is tumbling or not. If the light curve indicates a clear periodic variation it can be assumed that the object is rotating around its own axis with approximately constant angular velocity. However, often the orientation of the spin axis in body-fixed and inertial frame is unknown and its determination is challenging. Depending on the observed object and the information available about its shape, surface, components, a limited number of methods exists to determine the spin axis orientation. In this article we focus the attitude analysis on the Japanese H2A upper stage. Several light curves of this type of rocket body exhibit specific peaks, which can be exploited to extract attitude information. We assume that the peaks are related to the specular reflection occurring on the conical part of the upper stage. We present a novel method to estimate the direction of the rotation axis from the position of these peaks.
Abstract: The knowledge of the attitude motion of space debris is relevant for active debris removal missions. One possibility to characterize the attitude of space objects consists in the acquisition of photometric measurements over time, called light curves. The observed object is illuminated by the Sun and the variation of its apparent brightness gives in...
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Research Article
Protoplanetary Disk Formation in a Self-gravitating Molecular Cloud
Gemechu Muleta Kumssa*,
Solomon Belay Tessema
Issue:
Volume 11, Issue 2, June 2023
Pages:
23-37
Received:
19 October 2023
Accepted:
2 November 2023
Published:
30 November 2023
Abstract: The formation of the protoplanetary disc is a crucial step in planetary system formation. The study of protoplanetary disk formation is important for understanding the origins of our solar system as well as planets orbiting other stars. Many studies of protoplanetary disc formation focus on the initial properties of the planetary disc, such as mass, radius, and density, rather than the parent cloud properties. As a result, we’re looking into the formation of the protoplanetary disc in the context of the central star-forming core and the parent cloud parameters. Thus we derive numerical results from the theoretical model using boundary conditions, confirming the presence of a correct link between the features of the developing disk, parent cloud, and central core. In theory, we model the disc’s mass, density, and temperature in terms of the parent cloud and the center core’s attributes. In addition, using the mass-momentum transfer method in conjunction with the newly formulated disc mass and the associated host star, we determine the masses of the disk and core. We also explain how the magnetic field affects disc formation by formulating the mass of the disc formed from a magnetized cloud. The findings reveal that the properties of the parental cloud and the host star have a significant impact on the formation of a protoplanetary disc and its essential dynamic parameters, such as mass, surface density, and mass density.
Abstract: The formation of the protoplanetary disc is a crucial step in planetary system formation. The study of protoplanetary disk formation is important for understanding the origins of our solar system as well as planets orbiting other stars. Many studies of protoplanetary disc formation focus on the initial properties of the planetary disc, such as mass...
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