Assessing the survivability of biomarkers within terrestrial material impacting the lunar surface

Halim, Samuel; Crawford, Ian; Collins, G. S.; Joy, Katherine H.; Davison, T. M.

doi:10.1016/j.icarus.2020.114026

Cited by 5 publications

(4 citation statements)

References 84 publications

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“…These points are discussed, for example, in the work of Halim et al . ( 2021 ); however, their simulations still show biomarkers potentially surviving in terrestrial ejecta that impact the Moon.…”

Section: Discussionmentioning

confidence: 98%

“…Two qualifications, however, are required: (1) the degree of shock during ejection from Earth is also important, as is (2) the increase in temperature due to the shock impact. These points are discussed, for example, in the work of Halim et al (2021); however, their simulations still show biomarkers potentially surviving in terrestrial ejecta that impact the Moon.…”

Section: Terrestrial Ejecta Impacting the Moonmentioning

confidence: 99%

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Tardigrade Survival Limits in High-Speed Impacts—Implications for Panspermia and Collection of Samples from Plumes Emitted by Ice Worlds

Traspas

Burchell

2021

Astrobiology

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The ability of tardigrades to survive impact shocks in the kilometer per second and gigapascal range was investigated. When rocks impact planetary surfaces, the impact speeds and shock pressures are in the kilometer per second and gigapascal range. This investigation tested whether tardigrades can survive in impacts typical of those that occur naturally in the Solar System. We found that they can survive impacts up to 0.9 km s -1 , which is equivalent to 1.14 GPa shock pressure, but cannot survive impacts above this. This is significantly less than the static pressure limit and has implications for tardigrade survival in panspermia models. The potential survival of tardigrades in impacts of terrestrial impact ejecta on the Moon is shown to be impossible for the average lunar impact speed of such ejecta. However, a notable fraction (around 40%) of such ejecta impact at vertical speeds low enough to permit survival. Similarly, martian impact ejecta striking Phobos, for example, at a typical impact speed will not permit viable transfer of tardigrade-like organisms, but if a fraction of such material had a lower impact speed, survival may be possible. We also consider the implications of this for the collection of viable samples by spacecraft transiting the plumes of icy water worlds such as Europa and Enceladus. We have found the limit on survival of shocks to be around 1 GPa, which is instrumental in determining appropriate mission scenarios and collection methods for the acquisition of viable materials.

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Section: Discussionmentioning

confidence: 98%

Section: Terrestrial Ejecta Impacting the Moonmentioning

confidence: 99%

Tardigrade Survival Limits in High-Speed Impacts—Implications for Panspermia and Collection of Samples from Plumes Emitted by Ice Worlds

Traspas

Burchell

2021

Astrobiology

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“…Studies also constrain ejecta velocity (Melosh 1989), size (Grady & Kipp 1980), and number (Mileikowsky et al 2000). The Moon has been recognized as a means of archiving information from early Solar System (Crawford et al 2008;Halim et al 2019); this has brought attention to the flux of Earth material onto its surface (Armstrong et al 2002;Armstrong 2010), as well as the survivability of such ejecta (Burchell et al 2010;Crawford & Joy 2014;Joy et al 2016;Halim et al 2021).…”

Section: Numerical Integrationsmentioning

confidence: 99%

“…However, it has a much lower escape velocity and minimum impact speed of about 2.4 km s −1 , as well as a more porous surface. Several studies investigate the aftermath of an impact on the Moon, mainly in the context of Earthorigin fragments ejected during LHB, and potential of recovering information about the early state of Earth (Armstrong et al 2002;Crawford et al 2008;Bland et al 2008;Halim et al 2021). Oblique ( 45 • ) impacts at speeds 7 km s −1 avoid melting in nearly all cases (Bland et al 2008).…”

Section: Lunar Entry and Regolithmentioning

confidence: 99%

Lunar Exploration as a Probe of Ancient Venus

Laughlin¹

2020

Preprint

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An ancient Venusian rock could constrain that planet's history, and reveal the past existence of oceans. Such samples may persist on the Moon, which lacks an atmosphere and significant geological activity. We demonstrate that if Venus' atmosphere was at any point thin and similar to Earth's, then asteroid impacts transferred potentially detectable amounts of Venusian surface material to the Lunar regolith. Venus experiences an enhanced flux relative to Earth of asteroid collisions that eject lightly-shocked ( 40 GPa) surface material. Initial launch conditions plus closeencounters and resonances with Venus evolve ejecta trajectories into Earth-crossing orbits. Using analytic models for crater ejecta and N -body simulations, we find more than 0.07% of the ejecta lands on the Moon. The Lunar regolith will contain up to 0.2 ppm Venusian material if Venus lost its water in the last 3.5 Gyr. If water was lost more than 4 Gyr ago, 0.3 ppm of the deep megaregolith is of Venusian origin. About half of collisions between ejecta and the Moon occur at 6 km s −1 , which hydrodynamical simulations have indicated is sufficient to avoid significant shock alteration. Therefore, recovery and isotopic analyses of Venusian surface samples would determine with high confidence both whether and when Venus harbored liquid oceans and/or a lower-mass atmosphere. Tests on brecciated clasts in existing Lunar samples from Apollo missions may provide an immediate resolution. Alternatively, regolith characterization by upcoming Lunar missions may provide answers to these fundamental questions surrounding Venus' evolution.

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