Persistent Link:
http://hdl.handle.net/10150/291518
Title:
The detectability of lunar impacts in the near infrared
Author:
Clark, Richard Dean
Issue Date:
1996
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Impact crater scaling laws are used to predict the diameter and amount of melt produced in impacts on quartz sand of projectiles with mass from 100 gm to 100 kg and velocity from 20-40 km/sec. A one dimensional cooling model incorporating conduction, change of phase, and radiation is used to predict the cooling history of the crater. Several possible initial distributions (exposed to surface, shallow or moderate burial by cooler material) of the impact melt are considered. Infrared spectra are calculated for the modeled surface temperature distribution at several times during the cooling. The impact IR signature is prominent in the wavelength range 1.5-6 μ against the lunar nightside background. The optimum wavelength for detecting the smallest accessible impact is between 3 and 4 μ. It is found that the maximum signal strength is dependent on the initial distribution of melt as well as impact energy. The duration of the signal above a minimum detectability threshold is proportional to impact energy with only modest dependence on the initial melt distribution. Basic design requirements and capabilities for sensors to detect the impact signature from lunar orbit and earth orbit are considered. The lunar orbiting sensor can detect impacts as small as ∼50 gm. With a field of view covering ∼640000 km² a rate of approximately 2 events per week might be expected. An earth orbiting sensor could detect impacts of ∼100 gm at the sub earth point. Larger impacts could be detected closer to the lunar limb. Monitoring a large fraction of the nighttime hemisphere visible from earth orbit the observable event rate is similar to that from the lunar orbiter. Ground based observation at wavelengths between 2 and 2.4 μ could detect ∼2 kg impacts with an event rate estimated at 1 per 400 hours observing time.
Type:
text; Thesis-Reproduction (electronic)
Keywords:
Physics, Astronomy and Astrophysics.
Degree Name:
M.S.
Degree Level:
masters
Degree Program:
Graduate College; Planetary Sciences
Degree Grantor:
University of Arizona
Advisor:
Drake, Michael J.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleThe detectability of lunar impacts in the near infrareden_US
dc.creatorClark, Richard Deanen_US
dc.contributor.authorClark, Richard Deanen_US
dc.date.issued1996en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractImpact crater scaling laws are used to predict the diameter and amount of melt produced in impacts on quartz sand of projectiles with mass from 100 gm to 100 kg and velocity from 20-40 km/sec. A one dimensional cooling model incorporating conduction, change of phase, and radiation is used to predict the cooling history of the crater. Several possible initial distributions (exposed to surface, shallow or moderate burial by cooler material) of the impact melt are considered. Infrared spectra are calculated for the modeled surface temperature distribution at several times during the cooling. The impact IR signature is prominent in the wavelength range 1.5-6 μ against the lunar nightside background. The optimum wavelength for detecting the smallest accessible impact is between 3 and 4 μ. It is found that the maximum signal strength is dependent on the initial distribution of melt as well as impact energy. The duration of the signal above a minimum detectability threshold is proportional to impact energy with only modest dependence on the initial melt distribution. Basic design requirements and capabilities for sensors to detect the impact signature from lunar orbit and earth orbit are considered. The lunar orbiting sensor can detect impacts as small as ∼50 gm. With a field of view covering ∼640000 km² a rate of approximately 2 events per week might be expected. An earth orbiting sensor could detect impacts of ∼100 gm at the sub earth point. Larger impacts could be detected closer to the lunar limb. Monitoring a large fraction of the nighttime hemisphere visible from earth orbit the observable event rate is similar to that from the lunar orbiter. Ground based observation at wavelengths between 2 and 2.4 μ could detect ∼2 kg impacts with an event rate estimated at 1 per 400 hours observing time.en_US
dc.typetexten_US
dc.typeThesis-Reproduction (electronic)en_US
dc.subjectPhysics, Astronomy and Astrophysics.en_US
thesis.degree.nameM.S.en_US
thesis.degree.levelmastersen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePlanetary Sciencesen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorDrake, Michael J.en_US
dc.identifier.proquest1383560en_US
dc.identifier.bibrecord.b34525397en_US
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