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Experiments on Micrometeoroid Ablati...

DeLuca, Michael Donald.

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Experiments on Micrometeoroid Ablation in Planetary Atmospheres.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Experiments on Micrometeoroid Ablation in Planetary Atmospheres./
作者:	DeLuca, Michael Donald.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2020,
面頁冊數:	186 p.
附註:	Source: Dissertations Abstracts International, Volume: 81-11, Section: B.
Contained By:	Dissertations Abstracts International81-11B.
標題:	Aerospace engineering. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=27834535
ISBN:	9798645452148

Experiments on Micrometeoroid Ablation in Planetary Atmospheres.
DeLuca, Michael Donald.

Experiments on Micrometeoroid Ablation in Planetary Atmospheres. - Ann Arbor : ProQuest Dissertations & Theses, 2020 - 186 p.

Source: Dissertations Abstracts International, Volume: 81-11, Section: B.

Thesis (Ph.D.)--University of Colorado at Boulder, 2020.

This item must not be sold to any third party vendors.

Cosmic dust and micrometeoroids provide a constant influx of material into planetary atmospheres. Understanding how these particles ablate during atmospheric entry is critical to determining the detectability of meteors to constrain the inner Solar System's particle environment and to determine how these particles deliver their material to planets. I will discuss a set of laboratory measurements that reveal the basic physical processes that occur during meteor ablation in free molecular flow, the flow condition in which most of the mass flux to Earth ablates. Using a dust accelerator and gas target facility to simulate meteor ablation in the laboratory, I measured the ionization efficiency, drag/heating, and differential ablation of simulated micrometeoroids. First, I present measurements of the ionization efficiency of Al and Fe particles in air across the entire meteoric speed range. The measurements indicate that the ionization efficiency may be slightly higher at low speeds than previously thought, and an updated semi-empirical function is presented that matches the data at both low and high speeds. Next, I present measurements of the drag coefficient of Al particles in air, Ar, CO2, and N2. The measured drag coefficient in all 4 gases is about 1.3, which is slightly higher than previously thought and corresponds to a heating coefficient of about 0.6 assuming the gas molecules reflect diffusely. Finally, I present observations of the differential ablation of organics from the surfaces of organic-coated olivine particles shot into the gas target. The observations show that volatile materials such as organics can differentially ablate from the surfaces of micrometeoroids. The organics appear to survive in a complex form, which provides a potential route by which meteors may have injected organics into Earth's atmosphere prior to the origin of life. The implications of these different measurements are then discussed, including the effects that they may have on the ablation and radar detectability of actual meteors in the atmosphere. Taken together, these measurements provide a more complete understanding of meteor ablation.

ISBN: 9798645452148Subjects--Topical Terms:

1002622
Aerospace engineering.
Subjects--Index Terms:

Ablation

Experiments on Micrometeoroid Ablation in Planetary Atmospheres.
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100 1 $a DeLuca, Michael Donald. $3 3544215
245 1 0 $a Experiments on Micrometeoroid Ablation in Planetary Atmospheres.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2020
300 $a 186 p.
500 $a Source: Dissertations Abstracts International, Volume: 81-11, Section: B.
500 $a Advisor: Sternovsky, Zoltan.
502 $a Thesis (Ph.D.)--University of Colorado at Boulder, 2020.
506 $a This item must not be sold to any third party vendors.
520 $a Cosmic dust and micrometeoroids provide a constant influx of material into planetary atmospheres. Understanding how these particles ablate during atmospheric entry is critical to determining the detectability of meteors to constrain the inner Solar System's particle environment and to determine how these particles deliver their material to planets. I will discuss a set of laboratory measurements that reveal the basic physical processes that occur during meteor ablation in free molecular flow, the flow condition in which most of the mass flux to Earth ablates. Using a dust accelerator and gas target facility to simulate meteor ablation in the laboratory, I measured the ionization efficiency, drag/heating, and differential ablation of simulated micrometeoroids. First, I present measurements of the ionization efficiency of Al and Fe particles in air across the entire meteoric speed range. The measurements indicate that the ionization efficiency may be slightly higher at low speeds than previously thought, and an updated semi-empirical function is presented that matches the data at both low and high speeds. Next, I present measurements of the drag coefficient of Al particles in air, Ar, CO2, and N2. The measured drag coefficient in all 4 gases is about 1.3, which is slightly higher than previously thought and corresponds to a heating coefficient of about 0.6 assuming the gas molecules reflect diffusely. Finally, I present observations of the differential ablation of organics from the surfaces of organic-coated olivine particles shot into the gas target. The observations show that volatile materials such as organics can differentially ablate from the surfaces of micrometeoroids. The organics appear to survive in a complex form, which provides a potential route by which meteors may have injected organics into Earth's atmosphere prior to the origin of life. The implications of these different measurements are then discussed, including the effects that they may have on the ablation and radar detectability of actual meteors in the atmosphere. Taken together, these measurements provide a more complete understanding of meteor ablation.
590 $a School code: 0051.
650 4 $a Aerospace engineering. $3 1002622
650 4 $a Astrophysics. $3 535904
653 $a Ablation
653 $a Cosmic dust
653 $a Meteors
653 $a Micrometeoroids
690 $a 0538
690 $a 0596
710 2 $a University of Colorado at Boulder. $b Aerospace Engineering. $3 1030473
773 0 $t Dissertations Abstracts International $g 81-11B.
790 $a 0051
791 $a Ph.D.
792 $a 2020
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=27834535