Title:
Laboratory Measurements of the Millimeter Wavelength Opacity of Phosphine (PH3) and Ammonia (NH3) Under Simulated Conditions for the Cassini-Saturn Encounter

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dc.contributor.advisor Steffes, Paul G.
dc.contributor.author Mohammed, Priscilla Naseem en_US
dc.contributor.committeeMember Aaron Lanterman
dc.contributor.committeeMember Andrew F. Peterson
dc.contributor.committeeMember Judith A. Curry
dc.contributor.committeeMember Waymond R. Scott
dc.contributor.department Electrical and Computer Engineering en_US
dc.date.accessioned 2005-07-28T18:02:10Z
dc.date.available 2005-07-28T18:02:10Z
dc.date.issued 2005-04-18 en_US
dc.description.abstract The molecular compositions of the atmospheres of the giant planets (Jupiter, Saturn, Uranus and Neptune) are fundamental to understanding the processes which formed these planets and the solar system as a whole. Microwave observations of these planets probe regions in their atmospheres from approximately 0.1 to several bars, a process otherwise unachievable by visible and infrared means. Many gases and various cloud layers influence the millimeter wave spectra of the outer planets; however phosphine and ammonia are the main microwave absorbers at Saturn at pressures less than two bars. Understanding the pressure induced absorption of both constituents at observational frequencies is therefore vital to the analysis of any observational data. Laboratory measurements have been conducted to measure the microwave absorptivity and refractivity of phosphine and ammonia at Ka-band (32-40 GHz) and W-band (94 GHz), under conditions characteristic of the atmosphere of Saturn. The results were used to verify the accuracy of the phosphine formalism created by Hoffman et. al (2001) for use at millimeter wavelengths. Based on the laboratory measurements conducted, new formalisms were also created to express the opacity of ammonia at the measured frequencies. An important method for the study of planetary atmospheres is the radio occultation experiment ??method that uses radio links between Earth, and the spacecraft which passes behind the planet. The Cassini mission to Saturn, which will be conducting such experiments at Ka-band as well as S (2.3 GHz) and X (8.4 GHz) bands, has prompted the development of a radio occultation simulator used to calculate excess Doppler shifts and attenuation profiles for Saturn, utilizing the newest formalisms for phosphine and ammonia. The results indicate that there will be unambiguous detection and profiling of phosphine and ammonia, and predictions are made for the pressures at which loss of signal is anticipated. en_US
dc.description.degree Ph.D. en_US
dc.format.extent 1354460 bytes
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/6927
dc.language.iso en_US
dc.publisher Georgia Institute of Technology en_US
dc.subject Microwave remote sensing en_US
dc.subject Radio occultation
dc.subject Millimeter wave measurements
dc.subject.lcsh Phosphine Optical properties en_US
dc.subject.lcsh Ammonia Optical properties en_US
dc.subject.lcsh Microwave remote sensing en_US
dc.subject.lcsh Millimeter waves Measurement en_US
dc.subject.lcsh Opacity (Optics) en_US
dc.subject.lcsh Planets Atmospheres en_US
dc.title Laboratory Measurements of the Millimeter Wavelength Opacity of Phosphine (PH3) and Ammonia (NH3) Under Simulated Conditions for the Cassini-Saturn Encounter en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Steffes, Paul G.
local.contributor.corporatename School of Electrical and Computer Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication c3d19a17-5d56-4df3-a89a-d5d07477b568
relation.isOrgUnitOfPublication 5b7adef2-447c-4270-b9fc-846bd76f80f2
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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