Impact of meteors and space debris on Leo satellites

Keywords

Meteors; Space debris; Space vehicles -- Meteoroid protection; Leo satellites

Abstract

This Thesis focuses on the impact analysis of the meteors, micrometeorites and space debris on the Florida Space Institute's (FSI) Photon micro satellite structure. These impacts can occur at various energy levels. A detailed study of the impact of such foreign particles is carried out. Determining the best way to find out the probability of impact was specially challenging, as outer space is a vast expanse and little information is available on the density of the sparsely distributed potential impactors. During the ballistic penetration and perforation, penetrators and target plates are subjected to equal and opposite forces and impulses that are transmitted through contact interfaces. Waves propagate from the interfaces, transforming stress and strain states within the colliding bodies and inducing changes in the motion of the body of the satellite. The foreign object is going to lose the velocity, may tumble or gyrate (change attitude), may deform, may lose mass due to shock erosion, extrusion, shear, fracture and I or shatter processes and may drive materials from the plates in the form of single plate -plugs or multiple cloud of particles. Since the periphery of the satellite is surrounded by the solar panels, which are attached to the aluminum honeycomb, so the impactor shall strike these solar panels first before deflected or penetrating the satellite body depending on the kinetic energy of the impactor. The aluminum honeycomb has been designed as the thin plate of finite elements and so are the solar panels.

For multiyear missions, the assumption is made that the micrometeorites are coming towards the satellite in all possible directions. Most of the impacts on the satellites are at oblique angles, with orbital debris, approximately 1/1 Qth to 1/20th of the number of particles hit the trailing edge compared to the leading edge surfaces. The debris environment is increasing with time, with the small population increasing faster (at a compared rate of ,__,2% per year), than the population of much larger trackable particle (which increases at a linear rate of,__, 5% per year). The emphasis has been laid on finding the probability of the impact to the satellite, because of the meteorite activity and the ever-increasing space debris population. A novel approach was used to evaluate the probability in case of intense meteorite activity, avoiding the presence of the satellite in that area during that period of time shall help prevent the potential hazards to the satellite. Aluminum honeycomb material defines the periphery of the satellite, so it was decided to make an impact on the individual honeycomb all the peripheral nodes are constrained in all six degrees of freedom and then impact is made on the aluminum honeycomb, It has been assumed that the mass of the impactor remains the same (5 grams), while three velocity vectors of varying magnitude were analyzed, viz, 5, 7.5 and 10 km / sec. This shall provide us with three different energy levels of the impactor, with these energy levels, the reaction of the satellite body and computer are considered and then compared with the acceptance limits to determine the extent of damage caused to the satellite from each of them. Displacement and acceleration of the impacted node is presented in the form of graphs and colored contours, while the stress developed in the honeycomb plate is presented for the entire plate material. Comparison is then made with he ultimate stress values of the material, which is provided by the manufacturer of luminum honeycomb. It has been found that the stresses are within the acceptable limits. Analysis for impact on the complete satellite was performed, and for that case an impact was made on the center of gravity of the satellite, then another impact was made on the top surface, third case was made in which two impactors strike the satellite at the same time, this is the worst case scenario and if the displacement, acceleration and stress values remain within the limits as defined by military specifications, then the satellite is likely to survive in the outer space without losing its operationability. The military specification (with whom the results are compared) requires that the acceleration of the vital components (like computer, batteries) should not exceed a certain limit. The results obtained from the analysis for side impact are compared with this specification and it was found that the acceleration of the computer is just within the limiting requirements. Any particle of higher mass or greater velocity can easily either disorient the system or make the computer useless for future usage. For the top impact, the values of displacement and acceleration for the satellite and computer are relatively lesser than the side impact, but hey are also on the edge of the limit. However, for the third test that was carried out where a double impact takes place, both the impacting vectors are orthogonal to each other, the energy imparted to the system is 353553.39 Joules, with this energy level the analysis reveals that the computer exceeds the acceleration limits set up by military specifications, hence if the vital part is rendered useless because of the impact then the communication is ceased and satellite is reduced to another piece of space junk.

Notes

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Pages 23, 24, 25, 35, and 36 missing.

Graduation Date

2003

Advisor

Johnson, Roger

Degree

Master of Science (M.S.)

College

College of Engineering

Department

Mechanical, Materials, and Aerospace Engineering

Degree Program

Mechanical Engineering

Format

PDF

Pages

113 p.

Language

English

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Identifier

DP0029122

Subjects

Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic

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