Thesis (MEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Throughout its lifetime in space, a spacecraft is exposed to risk of collision with orbital
debris or operational satellites. This risk is especially high within the Low Earth Orbit
(LEO) region where the highest density of space debris is accumulated.
This study investigates orbital decay of some LEO micro-satellites and accelerating orbit
decay by using a deorbitsail. The Semi-Analytical Liu Theory (SALT) and the Satellite
Toolkit was employed to determine the mean elements and expressions for the time rates
of change. Test cases of observed decayed satellites (Iridium-85 and Starshine-1) are used
to evaluate the predicted theory. Results for the test cases indicated that the theory tted
observational data well within acceptable limits.
Orbit decay progress of the SUNSAT micro-satellite was analysed using relevant orbital
parameters derived from historic Two Line Element (TLE) sets and comparing with decay
and lifetime prediction models. The study also explored the deorbit date and time for a
1U CubeSat (ZACUBE-01).
A proposed orbital debris solution or technology known as deorbitsail was also investigated
to gain insight in sail technology to reduce the orbit life of spacecraft with regards to de-
orbiting using aerodynamic drag. The deorbitsail technique signi cantly increases the
e ective cross-sectional area of a satellite, subsequently increasing atmospheric drag and
accelerating orbit decay. The concept proposed in this work introduces a very useful
technique of orbit decay as well as deorbiting of spacecraft. / AFRIKAANSE OPSOMMING: Gedurende sy leeftyd in die ruimte word 'n ruimtetuig blootgestel aan die risiko van 'n
botsing met ruimterommel of met funksionele satelliete. Hierdie risiko is veral hoog in die
lae-aardbaan gebied waar die hoogste digtheid ruimterommel voorkom.
Hierdie studie ondersoek die wentelbaanverval van sommige Lae-aardbaan mikrosatelliete
asook die versnelde baanverval wanneer van 'n deorbitaal meganisme gebruik gemaak word.
Die Semi-Analitiese Liu Teorie en die Satellite Toolkit sagtewarepakket is gebruik om die
gemiddelde baan-elemente en uitdrukkings vir hul tyd-afhanlike tempo van verandering
te bepaal. Toetsgevalle van waargenome vervalde satelliete (Iridium-85 en Starshine-1) is
gebruik om die verloop van die voorspelde teoretiese verval te evalueer. Resultate vir die
toetsgevalle toon dat die teorie binne aanvaarbare perke met die waarnemings ooreenstem.
Die verloop van die SUNSAT mikrosatelliet se wentelbaanverval is ook ontleed deur gebruik
te maak van historiese Tweelyn Elemente datastelle en dit te vergelyk met voorspelde baan-
elemente. Die studie het ook ondersoek ingestel na die voorspelde baan-verbyval van 'n
1-eenheid cubesat (ZACUBE-01).
Die impak op wentelbaanverval deur 'n voorgestelde oplossing vir die beperking van
ruimterommel, 'n deorbitaalseil, is ook ondersoek. So seil verkort 'n satelliet se ruimte-
leeftyd deur sy e ektiewe deursnee-area te vergroot en dan van verhoogde atmosferiese
sleur en sonstralingsdruk gebruik te maak om die vervalproses te versnel. Hierdie voorgestelde
konsep is 'n moontlike nuttige tegniek vir versnelde baanverval en beheerde deorbitalering
van ruimtetuie om ruimterommel te verminder.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/85862 |
| Date | 12 1900 |
| Creators | Afful, Michael Andoh |
| Contributors | Steyn, W. H., Opperman, B. D. L., Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | xiv, 118 p. : ill. |
| Rights | Stellenbosch University |
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