Shock melting and vaporization of lunar rocks and minerals

Ahrens, Thomas J.; O’Keefe, J. D.

doi:10.1007/bf00562927

Cited by 188 publications

(160 citation statements)

References 24 publications

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“…With this, the whole p s − T s curve can be computed and the result is represented in Figure 3. Note that this curve is consistent with the results of Ahrens and O'Keefe (1972). An explicit relation between ρ s and T s can now be computed if one considers the ideal gas law:…”

Section: Thermochemical Relationssupporting

confidence: 86%

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Theoretical peak performance and optical constraints for the deflection of an S-type asteroid with a continuous wave laser

Thiry

Vasile

2017

Advances in Space Research

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This paper presents a theoretical model to evaluate the thrust generated by a continuous wave (CW) laser, operating at moderate intensity(<100GW/m 2 ), ablating an S-type asteroid made of Forsterite. The key metric to assess the performance of the laser system is the thrust coupling coefficient which is given by the ratio between thrust and associated optical power. Three different models are developed in the paper: a one dimensional steady state model, a full 3D steady state model and a one dimensional model accounting for transient effects resulting from the tumbling motion of the asteroid. The results obtained with these models are used to derive key requirements and constraints on the laser system that allow approaching the ideal performance in a realistic case.

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Section: Thermochemical Relationssupporting

confidence: 86%

“…In a layer of Fosterite, various reactions and sub-reactions occur during the vaporization process. A common assumption made by Ahrens and O'Keefe (1972) and Kahle et al (2006) is that the following reaction dominates during the vaporisation of Fosterite:…”

Section: Thermochemical Relationsmentioning

confidence: 99%

Theoretical peak performance and optical constraints for the deflection of an S-type asteroid with a continuous wave laser

Thiry

Vasile

2017

Advances in Space Research

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“…24 These competing processes were: ͑1͒ an increase in the production of entropy ͑heat production͒ and ͑2͒ a decrease in the impedance matching as the porosity increases. According to Ahrens 24 and Ahrens and O'Keefe, 25 an optimal entropygenerating distention for a certain impact velocity was observed. We did not observe such an optimal distention in any of the materials studied in our calculations even though our calculations covered a much larger distention and compression range, but the flattening of the projectile velocity contours does suggest that the competing processes theory is still valid within the compression and distention range covered by this study.…”

Section: Resultsmentioning

confidence: 98%

“…Here, we explicitly require only a linear UsϪUp relation for nonporous solid materials and conduct thermodynamic modeling of the states of shocked porous materials upon projectile impact in the laboratory. We extended earlier calculations 24,25 to distentions up to five and we improved the previous calculations by directly solving a modified Mie-GrXneisen equation of state for the porous material. Special interest is placed on minerals containing carbonates, sulfates, and hydroxyl groups that are of relevance to planetary climate…”

Section: Introductionmentioning

confidence: 99%

Shock wave induced vaporization of porous solids

Shen

Ahrens

O’Keefe

2003

Journal of Applied Physics

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Strong shock waves generated by hypervelocity impact can induce vaporization in solid materials. To pursue knowledge of the chemical species in the shock-induced vapors, one needs to design experiments that will drive the system to such thermodynamic states that sufficient vapor can be generated for investigation. It is common to use porous media to reach high entropy, vaporized states in impact experiments. We extended calculations by Ahrens ͓J. Appl. Phys. 43, 2443 ͑1972͔͒ and Ahrens and O'Keefe ͓The Moon 4, 214 ͑1972͔͒ to higher distentions ͑up to five͒ and improved their method with a different impedance match calculation scheme and augmented their model with recent thermodynamic and Hugoniot data of metals, minerals, and polymers. Although we reconfirmed the competing effects reported in the previous studies: ͑1͒ increase of entropy production and ͑2͒ decrease of impedance match, when impacting materials with increasing distentions, our calculations did not exhibit optimal entropy-generating distention. For different materials, very different impact velocities are needed to initiate vaporization. For aluminum at distention (m)Ͻ2.2, a minimum impact velocity of 2.7 km/s is required using tungsten projectile. For ionic solids such as NaCl at distention Ͻ2.2, 2.5 km/s is needed. For carbonate and sulfate minerals, the minimum impact velocities are much lower, ranging from less than 1 to 1.5 km/s.

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“…The surface temperature of the Earth was probably around 2800 K, which corresponds to the surface temperature of mantle silicate on an adiabat in equilibrium with the fully molten mantle liquidus [21]. As the partial pressure for olivine (a proxy for the mantle) at approximately 3300 K is only 1 bar [22], and that for tektites (a proxy for continental crust (CC)) is only approximately 3 bar at 3350 K and 0.1 bar at 1640 K [23], silicates would have been minor atmospheric components.…”

Section: (B) Initial Atmospheric Compositionmentioning

confidence: 99%

Terrestrial aftermath of the Moon-forming impact

Sleep

Zahnle

Lupu

2014

Phil. Trans. R. Soc. A.

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Much of the Earth's mantle was melted in the Moon-forming impact. Gases that were not partially soluble in the melt, such as water and CO 2 , formed a thick, deep atmosphere surrounding the post-impact Earth. This atmosphere was opaque to thermal radiation, allowing heat to escape to space only at the runaway greenhouse threshold of approximately 100 W m −2 . The duration of this runaway greenhouse stage was limited to approximately 10 Myr by the internal energy and tidal heating, ending with a partially crystalline uppermost mantle and a solid deep mantle. At this point, the crust was able to cool efficiently and solidified at the surface. After the condensation of the water ocean, approximately 100 bar of CO 2 remained in the atmosphere, creating a solar-heated greenhouse, while the surface cooled to approximately 500 K. Almost all this CO 2 had to be sequestered by subduction into the mantle by 3.8 Ga, when the geological record indicates the presence of life and hence a habitable environment. The deep CO 2 sequestration into the mantle could be explained by a rapid subduction of the old oceanic crust, such that the top of the crust would remain cold and retain its CO 2 . Kinematically, these episodes would be required to have both fast subduction (and hence seafloor spreading) and old crust. Hadean oceanic crust that formed from hot mantle would have been thicker than modern crust, and therefore only old crust underlain by cool mantle lithosphere could subduct. Once subduction started, the basaltic crust would turn into dense eclogite, increasing the rate of subduction. The rapid subduction would stop when the young partially frozen crust from the rapidly spreading ridge entered the subduction zone.

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Shock melting and vaporization of lunar rocks and minerals

Cited by 188 publications

References 24 publications

Theoretical peak performance and optical constraints for the deflection of an S-type asteroid with a continuous wave laser

Theoretical peak performance and optical constraints for the deflection of an S-type asteroid with a continuous wave laser

Shock wave induced vaporization of porous solids

Terrestrial aftermath of the Moon-forming impact

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