Thermal analysis of the LLR optical telescope tube assembly based in Hartebeesthoek Radio Astronomy Observatory

dc.contributor.authorTsela, Philemon Lehlohonolo
dc.contributor.authorCombrinck, Ludwig
dc.contributor.authorBotha, R.
dc.contributor.authorNgcobo, B.
dc.contributor.emailphilemon.tsela@up.ac.zaen_ZA
dc.date.accessioned2016-12-19T08:26:56Z
dc.date.issued2016-09
dc.description.abstractThe Hartebeesthoek Radio Astronomy Observatory of South Africa is currently developing a lunar laser ranger (LLR) system based on a one metre aperture telescope in collaboration with National Aeronautics and Space Administration and the Observatoire de la Côte d’Azur. This LLR will be an addition to a limited list of operating LLR stations globally and it is expected to achieve sub-centimetre range precision to the Moon. Key to this expectation including the overall telescope operational performance is thermal analysis of the telescope structure, based on the thermal properties of component materials and their interaction with the environment through conventional heat transfer mechanisms. This paper presents transient thermal simulation results of the telescope’s optical tube and one metre primary mirror in terms of thermal variations and consequent structural deformations. The results indicate that on a non-windy, cloud-free and winter day, the temperature gradients on the structure could be within 1 °C with respect to the temporal ambient air temperatures at the site when these are between 9 and 23 °C. Furthermore, these gradients were coupled with thermally-induced total deformations that vary between 2.9 and 40.7 μm of the assembled telescope components. In overall, these findings suggest that both the tube and especially the mirror may respond very slowly to ambient temperatures; however, correcting for structural thermal variations is imperative in maximizing the pointing accuracy of the telescope thereby increasing the chance being on-target with the retroreflectors located on the Moon surface.en_ZA
dc.description.departmentGeography, Geoinformatics and Meteorologyen_ZA
dc.description.embargo2017-09-30
dc.description.librarianhb2016en_ZA
dc.description.sponsorshipP. L. Tsela hereby acknowledges research support in part by the National Research Foundation of South Africa for the grant, Unique Grant No. 93952.en_ZA
dc.description.urihttp://link.springer.com/journal/40328en_ZA
dc.identifier.citationTsela, P., Combrinck, L., Botha, R. & Ngcobo, B. Thermal analysis of the LLR optical telescope tube assembly based in Hartebeesthoek Radio Astronomy Observatory. Acta Geodaetica et Geophysica (2016) 51: 393-403. doi:10.1007/s40328-015-0132-6.en_ZA
dc.identifier.issn2213-5812 (print)
dc.identifier.issn2213-5820 (online)
dc.identifier.other10.1007/s40328-015-0132-6
dc.identifier.urihttp://hdl.handle.net/2263/58427
dc.language.isoenen_ZA
dc.publisherSpringeren_ZA
dc.rights© Akadémiai Kiadó 2015. The original publication is available at : http://link.springer.comjournal/40328.en_ZA
dc.subjectThermal variationen_ZA
dc.subjectDeformationen_ZA
dc.subjectOptical tubeen_ZA
dc.subjectPrimary mirroren_ZA
dc.subjectTelescope pointingen_ZA
dc.subjectHartebeesthoek Radio Astronomy Observatory of South Africaen_ZA
dc.subjectLunar laser ranger (LLR)en_ZA
dc.titleThermal analysis of the LLR optical telescope tube assembly based in Hartebeesthoek Radio Astronomy Observatoryen_ZA
dc.typePostprint Articleen_ZA

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