Oral presentations and abstracts

Lunar Xenon from Ancient Earth-Wind

 The apparent secular variability of the Xe/Kr abundance ratio in the solar wind implanted in grains of the lunar regolith is a long-standing problem (Wieler, 2016): Recently irradiated soils (<100 Ma ago) show Xe/Kr ratios comparable to the ratio found in solar wind targets of the Genesis mission (Meshik et al. 2014, Vogel et al. 2011), while lunar samples exposed billions of years ago to the solar wind exhibit a Xe/Kr ratio about twice as high. 

It has been argued that this observation is the consequence of the variability of the solar wind composition. More recently it has also been suggested that, over time, cometary impacts have contributed significantly to the inventory of noble gases and other volatiles of the lunar regolith.

From our understanding of the development of typical G-stars, such as the Sun, we consider it unlikely that such a strong variation could have occurred several 100 My after the lunar regolith had started to build up. Today, variations of this ratio even in very different solar wind regimes are marginally distinguishable (Vogel et al. 2019). On the other hand, it seems also unlikely that early cometary impacts could have implanted sufficient amounts of Xe to noticeably modify the Xe/Kr inventory in the regolith with the correct isotopic compositions.

While we are currently unable to clearly outrule any of the above hypotheses, we here propose an alternative explanation: The ancient lunar regolith has been exposed to a xenon-rich Earth-Wind. An ancient Earth-Wind has been invoked previously (e.g., Geiss and Bochsler, 1991, Ozima et al. 2005) in order to explain the secular variability of the isotopic composition of nitrogen in the lunar regolith.

The apparent secular depletion of light isotopes of atmospheric xenon combined with the presumed large deficit of Xe in the atmosphere (Avice et al. 2018) recently led Zahnle et al. (2019) to postulate a loss of Xe ions over the first 3 Gy from the upper atmosphere, concomitant with the hydrogen escape and the oxygenation of the atmosphere. The loss mechanism devised by Zahnle and co-authors selectively involves Xe without affecting the other noble gases. It operates through resonant charge exchange of H⁺ with Xe, leading to a low-lying excited state of Xe⁺.

We believe that escaping terrestrial Xe ions will undoubtedly be incorporated into the flow of the magnetotail of the Earth and impact the lunar surface, whenever the Moon crosses the tail directed away from the Sun. From the present cross section of the magnetotail near the orbit of the Moon and the amount of xenon lost from the terrestrial atmosphere over the first few Gy, we conclude that the Xe-fluence of the Earth-Wind could be sufficient to account for the apparent secular variation of the lunar Xe/Kr ratio. Since we expect Earth-Wind-xenon to be strongly fractionated in favour of light isotopes, we expect its isotopic composition to deviate significantly from the present-day terrestrial atmosphere, approaching the composition of the solar wind. Unfortunately, given the experimental uncertainties of the isotopic composition of xenon in ancient lunar soil, it is difficult to obtain conclusive evidence in favour or against the Earth-Wind hypothesis from isotopic abundances.

In a simple box model as outlined in Figure 1, we investigate the potential contribution of the Earth-Wind to the lunar regolith using the compilation of data on the isotopic composition of Xe in the ancient atmosphere of Avice et al. (2018) and the abundance of Xe in the mantle to determine free parameters. Our first results indicate that the Earth-Wind is a viable alternative to explain the apparent secular decrease of the Xe/Kr ratio in the lunar regolith, even if the solar wind has decreased in intensity over the life-time of the Sun.

The Earth-Wind hypothesis could be tested by investigation of ancient lunar regolith samples with present-day state-of-the-art mass spectrometry and by analysis of lunar samples at different lunar longitudes, particularly from the lunar backside, which at least at present, is mostly shielded from the ion-flow in the geotail.     

References:

Avice G. et al. (2018) Geochimica et Cosmochimica Acta  232, 82-100.

Geiss J., and Bochsler P. (1991) In: The Sun in Time, The University of Arizona Press, 98-117.

Meshik A. et al. (2014) Geochimica et Cosmochimica Acta 127, 326-347.

Ozima M. et al. (2005) Nature 436, 655-659.

Vogel N. et al. (2011) Geochimica et Cosmochimica Acta 75, 3057-3071.

Vogel N. et al. (2019) Geochimica et Cosmochimica Acta 263, 182-194.

Wieler R. (2016) Chemie der Erde - Geochemistry 76, 463-480.

Zahnle K.J., Gacesa M., and Catling D.C. (2019), Geochimica et Cosmochimica Acta 244, 56-85.

How to cite: Bochsler, P. and Rainer, W.: Lunar Xenon from Ancient Earth-Wind, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-177, https://doi.org/10.5194/epsc2020-177, 2020.

Sinuous collapse chains and skylights in Lunar and Martian volcanic regions have often been interpreted as collapsed lava tubes (also known as pyroducts, [1]). This hypothesis has fostered a forty years debate among planetary geologists trying to define if analogue volcano-speleogenetic processes acting on Earth could have created similar subsurface linear voids in extra-terrestrial volcanoes. On Earth lava tubes are well known thanks to speleological exploration and mapping in several shield volcanoes, with examples showing different genetic processes (inflation and overcrusting [1, 2, 3]) and morphometric characters. On the Moon subsurface cavities have been inferred from several skylights in maria smooth plains [4], and corroborated using gravimetry and radar sounder [5, 6] while on Mars several deep skylights have been identified on lava flows with striking similarities with terrestrial cases [7]. Nonetheless, a clear understanding of the potential morphologies and dimensions of martian and lunar lava tubes remains elusive.

Although it is still impossible to gather direct information on the interior of martian and lunar lava tube candidates, scientists have the possibility to investigate their surface expression through the analysis of collapses and skylight morphology, morphometry and their arrangement, and compare these findings with terrestrial analogues. In this work we performed a morphological and morphometric comparison with lava tube candidate collapse chains on Mars and the Moon.

By comparing literature and speleological data from terrestrial analogues and measuring lunar and martian collapse chains on satellite images and digital terrain models (DTMs), this review sheds light on tube size, depth from surface, eccentricity and several other morphometric parameters among the three different planetary bodies. The dataset here presented indicates that martian and lunar tubes are 1 to 3 orders of magnitude more voluminous than on Earth and suggests that the same processes of inflation and overcrusting were active on Mars, while deep inflation and thermal entrenchment was the predominant mechanism of emplacement on the Moon. Even with these outstanding dimensions (with total volumes exceeding 1 billion of m³), lunar tubes remain well within the roof stability threshold. The analysis shows that aside of collapses triggered by impacts/tectonics, most of the lunar tubes could be intact, making the Moon an extraordinary target for subsurface exploration and potential settlement in the wide protected and stable environments of lava tubes.

References

[1] Kempe, S., 2019. Volcanic rock caves, Encyclopedia of Caves (Third edition). Academic Press, pp. 1118-1127

[2] Calvari, S. and Pinkerton, H., 1999. Lava tube morphology on Etna and evidence for lava flow emplacement mechanisms. Journal of Volcanology and Geothermal Research, 90(3-4): 263-280.

[3] Sauro, F., Pozzobon, R., Santagata, T., Tomasi, I., Tonello, M., Martínez-Frías, J., Smets, L.M.J., Gómez, G.D.S. and Massironi, M., 2019. Volcanic Caves of Lanzarote: A Natural Laboratory for Understanding Volcano-Speleogenetic Processes and Planetary Caves, Lanzarote and Chinijo Islands Geopark: From Earth to Space. Springer, pp. 125-142.

[4] Haruyama, J., Morota, T., Kobayashi, S., Sawai, S., Lucey, P.G., Shirao, M. and Nishino, M.N., 2012. Lunar holes and lava tubes as resources for lunar science and exploration, Moon. Springer, pp. 139-163.

[5] Chappaz, L., Sood, R., Melosh, H.J., Howell, K.C., Blair, D.M., Milbury, C. and Zuber, M.T., 2017. Evidence of large empty lava tubes on the Moon using GRAIL gravity. Geophysical Research Letters, 44(1): 105-112

[6] Kaku, T., Haruyama, J., Miyake, W., Kumamoto, A., Ishiyama, K., Nishibori, T., Yamamoto, K., Crites, S.T., Michikami, T. and Yokota, Y., 2017. Detection of intact lava tubes at marius hills on the moon by selene (kaguya) lunar radar sounder. Geophysical Research Letters, 44(20).

[7] Cushing, G.E., 2012. Candidate cave entrances on Mars. Journal of Cave and Karst Studies, 74(1): 33-47

How to cite: Sauro, F., Pozzobon, R., Massironi, M., De Bernardinis, P., Santagata, T., and De Waele, J.: Lava tubes on Earth, Moon and Mars: a review on their size and morphology revealed by comparative planetology, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-1021, https://doi.org/10.5194/epsc2020-1021, 2020.

Among the variety of earth analogues, what surely stand out are lava tubes.

A lava tube is a type of lava cave formed by a low-viscosity lava flow that can develop 1) forming a continuous and hard crust, which forms a roof above the still flowing lava stream (over-crusting), or 2) slipping between pre-existing lava flows (inflation). The resulting structure constitutes among the most efficient thermal structures on Earth, because of their capacity of thermal insulation isolated lava flows can travel over long distances across lava fields.

Lava tubes, which on Earth are typical features of lava fields encountered in intracontinental plateaus and volcanic-shield islands (slopes <2°, e.g. Hawaii and Canaries), have also been recognised on the surface of other rocky bodies of the Solar System such as Mars and the Moon [1]. Due to the similar characteristics of basaltic volcanism on rocky bodies, it is expected that lava tubes have similar morphologies and origin among them. Only recently it has been possible to perform comparisons between lava tubes on different planetary bodies with implications on the study of planetary volcanology, habitability and astrobiology [2].

Indeed, in the last decade, high-resolution orbital images on planetary bodies like Mars and the Moon offer the possibility of studying the morphology of these structures, detecting them from the recurrent collapses in the pyroduct’s roof, that shows the presence and the path of the pyroduct itself. The pit chains show characteristics similar to those on Earth: elongated with minor axis representing the width of the tube and with major axis along the flow direction.

The differences in gravity between Earth and the other planetary bodies and its concurrent influence on the effusion rates result in a significant difference in lava tube dimensions, indeed, terrestrial pyroducts tend to generally have a smaller width (10–30 m) than those on Mars (250–400 m) and the Moon (500–1100 m) [3].

In the post-cooling phases, lava tubes are characterized by a near-constant inner temperature and, on other planetary bodies, they might offer natural protection against micrometeorites and solar and cosmic radiations making them ideal locations for future planetary explorations.

Within this framework, studying the largest lava tubes on Earth is of interest as they could represent the best planetary analogues.

In order to employ lava tubes as locations for future explorations, it is important to understand exactly how they form and develop not only during the active phase (flow-phase) but also and more importantly during the post-cooling phase.

Alongside the NW African continental margin (Morocco), is located the Canary Island Seamount Province (CISP), a magmatic province generated by the extremely slow transit (~8–10 mm/yr) of the African plate over a hotspot during more than the last 133 Ma [5] and hence represents both long-term and spatially focused volcanic activity over a poorly mobile tectonic plate. For this reason, it constitutes one of the best terrestrial analogues of the Martian one-shell plate volcanism [6]. In the NE region of Lanzarote (Canary Islands) stands La Corona lava tube system that, with its 7.6 km length and an average width of 30 m [4], is one of the largest volcanic cave complexes on Earth. 

Therefore, the occurrence of volcanism on an almost stationary plate and the impressive dimensions of La Corona lava tube make it one of the most suitable lava tubes for interplanetary analogies.

Different field surveys were conducted over the last two years in order to explore its three-dimensional geometry using 3D laser-scan. These data allowed to place constraints on the tube origin (inflation process rather than over-crusting), the involvement of thermal erosional processes (inferred from characteristic morphologies) and to identify a weak pyroclastic level within the tube which might have favoured the inflated tube inception. Also, the presence of an important amount of secondary mineralisation inside the tube has been very significant in understanding the evolution of the pyroduct in the cooling and post-cooling phases. These secondary mineralisation (mainly sulphates) show an interesting contribution from the Aeolian and marine environment in the latest evolutionary stages of this lava tube.

Studying this exceptional example of terrestrial lava tube will allow to improve our understanding of the formation and evolutional processes giving rise to analogue features on other planetary bodies of the Solar System.

[1] Haruyama, J. et al. (2012) Trans. JAPAN Soc. Aeronaut. Sp. Sci. Aerosp. Technol. JAPAN 10

[2] Tettamanti C. (2019) Analysis of skylights and lava tubes on Mars, Department of Physics and Astronomy “Galileo Galilei", Univerisy of Padova (Italy)

[3] Sauro, F., et al. (2018) 49th Lunar Planet. Sci. Conf. 2018

[4] Carracedo, J. C. et al. (2003) Estud. Geol. 59

[5] van den Bogaard, P. (2013). Sci. Rep. 3

[6] Meyzen, C. M., et al. (2015) Geol. Soc. London, Spec. Publ. 401

How to cite: Tomasi, I., Massironi, M., Meyzen, C., Pozzobon, R., Sauro, F., Penasa, L., Martínez-Frías, J., and Mateo Medero, E.: The importance of the evolutional processes in the study of lava tube analogues: the case of La Corona tube (Lanzarote), Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-554, https://doi.org/10.5194/epsc2020-554, 2020.

Inverted channels with polygonal fractures and layered mounds from the Ntwetwe pan in the Makgadikgadi Basin (central Botswana) have been herein investigated. These morphologies are from an evaporitic basin (the Makgadikgadi Basin) that is the remnant of an ancient Plio-Pleistocene lake and is currently part of the world’s largest evaporitic system.

The mounds in the Ntwetwe pan are characterized by a layered structure and low relief (max. 5 m above the pan floor) and can be in excess of 2 km wide. The mounds consist mainly of loose (non-lithified) sand and silt with high moisture contents, even during the dry season. Geophysical investigations have shown that groundwater processes, particularly those related to the capillary fringe that rises and conveys moisture through the mounds, are factors that make mound sediments resistant to wind erosion.

The inverted channels, identified in the southern part of the Ntwetwe pan, are characterized by gentle reliefs and depressions, which depend upon the distribution of calcretes and indurated sediments. Large scale (up to 100 m wide) polygonal fractures localized at the front of the fan, disappear at the transition with the present-day pan floor.

We consider that these particularmounds, withinthe Ntwetwe pan, are remnants of the strandline of the paleo-Makgadikgadi Lake, and that the inverted channels representdistributary channels of a relict fan delta,formed by an ephemeral river, most likelythe paleo-Boteti River, during a Lake Paleo-Makgadikgadihighstand stage. We consider that largescale (up to 100 m wide) polygonal fractures, located on thechannel-mouth lobes, representlarge-scale desiccation cracks formed byrapid water evaporation from deltadeposits.

The results of this investigation highlight the importance of the paleo-drainage system and itsinteractions with thewater table and wind-deflation as main geomorphological factors within salt pan environments. The mounds in the Makgadikgadi pans also show strong geomorphic similarities to spring mounds on the surface of Mars, localized in equatorial layered deposits (ELDs). These ELDs mounds are considered to result from cyclical groundwater upwelling, evaporation and wind deflation. The geological processes that resulted in the formation of mounds within the Makgadikgadi may, therefore, help to explain how similar layered deposits formed on Mars and confirm existing theories.

How to cite: Franchi, F., MacKay, R., Selepeng, A., and Barbieri, R.: Inverted channels, polygonal fractures and layered mounds from the Makgadikgadi Pan of Botswana: possible analogues for Martian morphologies, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-579, https://doi.org/10.5194/epsc2020-579, 2020.

Abstract: We model nitrogen (N) partitioning in the magma ocean stage and cycling between the surface and mantle through Earth's history, and suggest that N in the present-day mantle may be set by subduction before the development of the modern N cycle.

Introduction: On present-day Earth, N cycling between the surface and mantle is largely controlled by biological N fixation and aerobic biological processing. Biological N fixation brings the majority of inorganic N into the modern N cycle. In the oceans, dissolved nitrate is the main form of nitrogen available for life, and dissimilatory denitrification leads to residual nitrate being kinetically enriched in ¹⁵N by ~6‰. The isotopically enriched nitrate is then reduced to ammonium and finally trapped in sediments (e.g., Stüeken al. 2016). 

Though secular subduction of ¹⁵N-rich sediments should cause ¹⁵N enrichment in the mantle, the mantle N sampled from mid-ocean ridge basalt (MORB) is rather depleted in  ¹⁵N (~-5‰), which is known as the N isotopic disequilibrium. Previous studies hypothesized that N in the mantle is a primordial component (Cartingy & Marty, 2013; Labidi et al. 2020). In the primordial origin scenario, the isotopic disequilibrium is attributed to atmospheric escape, which enriched the atmosphere with ¹⁵N. Another study proposed a recycling origin scenario in which the N isotopic composition of sediments has changed over time (Marty & Dauphas, 2003). Neither of these scenarios has been modeled quantitatively. Here we test the different scenarios by using numerical models coupled with N isotopes.

Methods: We developed two sets of models for the origin of observed mantle N isotopic composition: i) the primordial origin and ii) the recycling origin. The results are either accepted or rejected by the comparison to the amounts and isotopic compositions of N in contemporary surface reservoirs and mantle (Johnson & Goldblatt, 2015; Labidi et al. 2020).

For the primordial origin scenario, we calculate N partitioning between the atmosphere and mantle upon magma ocean solidification by using a melt-trapping model (Hier-Majumder & Hirschmann, 2017) and the partitioning coefficients between minerals, silicate melt, and the atmosphere (Li et al. 2013; Dalou et al. 2017). We consider the range of oxygen fugacity relevant to Earth's formation. We also estimate the ¹⁵N-enrichment effect due to EUV-driven escape (Watson et al. 1981) and solar-wind pick-up (Lichtenegger et al. 2010) to see how much atmospheric N should be removed to reproduce ~+5‰ difference between the atmosphere and mantle.

For the recycling origin scenario, we calculate secular N exchange between the surface reservoirs and mantle. Our model is based on that of Labidi et al. (2020). The isotopic fractionation between the atmosphere and subducting sediments is taken to be ~-9‰ and ~+6‰ before and after the Great Oxidation Event at 2.4 Ga, respectively, considering the change from abiotic fixation and anaerobic processing to biological fixation and aerobic processing. We fix the subduction and degassing fluxes on present-day Earth, and their power-law indices as a function of time as parameters. Bulk N partitioning and the isotopic difference between the reservoirs in the initial state are also treated as parameters.

Figure 1: Nitrogen partitioning between the atmosphere and mantle at the time of magma ocean solidification (PAN = present-day atmospheric nitrogen). The range of the modeled mantle N content reflects the uncertainty in the oxygen fugacity of the magma ocean.

Figure 2: Evolution of masses (left) and ¹⁵N/¹⁴N ratios (right) in the surface reservoirs (blue) and mantle (red). Curves show accepted models having different initial conditions and fluxes. Gray areas are the estimates for present-day surface reservoirs and mantle.

Results: Because N is relatively insoluble in silicate melts, it is mostly partitioned into the atmosphere even when trapping in interstitial melts is considered (Figure 1). Partitioning N into the mantle as much as present-day leads to 100 times excess in PAL N. We found that the excess amount of N can be removed neither by EUV- nor solar-wind-induced loss without excessive ¹⁵N enrichment in the atmosphere. Impact erosion by the late veneer bombardment removes atmospheric N without isotopic fractionation up to ~10 bar (Sakuraba et al. 2019), but it may not be sufficient to remove all excess N in the atmosphere.

Since the results of our partitioning model suggest that the primordial origin is unlikely, next we tested the recycling scenario in our N cycling model (Figure 2). In our successful runs, the mantle is initially depleted in N, and N in the present-day mantle is a result of higher net subduction flux on early Earth where sedimentary N is depleted in ¹⁵N due to abiotic N fixation and anaerobic N processing. The change to modern N cycle is visible in the kink in δ¹⁵N evolution, which may provide a way to test our model with evidence from geologic record.

Discussion: We suggest that N partitioning between the surface and deep Earth may be set by subduction driven by plate tectonics and partially by biology. This also suggests that the difference of atmospheric N contents between Venus and Earth, the former of which has three times more N in the atmosphere, is caused by their long-term evolution rather than early formation and differentiation processes.

Conclusions: We conclude that N in the present-day mantle may be set by subduction before the development of the modern N cycle. Further results for parameter survey and discussion on other geological and geochemical constraints will be shown in our presentation.

How to cite: Kurokawa, H., Laneuville, M., Li, Y., Zhang, N., Fujii, Y., Sakuraba, H., Houser, C., and Cleaves II, H. J.: Origin of nitrogen in Earth's mantle constrained by models for partitioning and cycling, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-206, https://doi.org/10.5194/epsc2020-206, 2020.

On July 25, 2018, a meteoroid-associated airburst occurred near the Qaanaaq town, in Greenland, at approximately 22:00 UTC (20:00 local time). The event generated seismic waves that were recorded by two stations of the Danish Seismological Network (TULEG and NEEM) and the bolide trajectory was consequently calculated by the NASA Center for Near-Earth Object Studies (CNEOS). The total impact energy, calculated by CNEOS was 2.1 kT of TNT and the brightest point on its trajectory corresponds to an altitude of around 43 km, at a distance of about 50 km S of the Qaanaaq town and 50 km N of the TULEG station and the Thule Air Force Base [1].

An airburst occurring over the icy surface of Greenland is a rare terrestrial analog for regions of the Solar System, where both an atmosphere and an icy surface exist. In the past, a variety of works had indicated the presence of ice on Titan, the biggest moon of Saturn (e.g. [2] and more recently [3]) and more precisely, the icy composition of mountains which are formed by tectonic activity [4]. Titan has a relatively thick atmosphere, compared to those of other moons in the Solar System, composed mainly (94%) of nitrogen [5]. The characterization of atmospheric meteoroid-associated seismic sources for Titan has a particular interest, as it is found that, contrary to other moons of the solar system, the presence of craters on its surface is extremely low (only about 0.4% according to [3]). The reason for this low cratering of the surface is the presence of the thick atmosphere, into which many of the meteoroids are entirely ablated into dust. Therefore, a methodology for the characterization of airbursts as seismic sources and the modeling of the associated generated seismic waves is necessary for a future seismic experiment, as any recorded signal will either be a direct atmospheric wave (nonlinear shock wave, or linear acoustic wave) or a seismic wave generated through the coupling of the atmospheric and solid/ice part.
 
In the present study, our aim is to perform a seismic investigation of the Greenland ice shell with the use of the airburst-associated seismic source. The performed tasks into which this effort has been divided, include the application of a technique which approaches the bolide as an atmospheric seismic source, the calculation of the distance of shock wave propagation in the atmosphere, the description of the mechanism of generation of the seismic waves in the atmosphere and the solid-icy part.

When the bolides enter the atmosphere of the Earth or that of any other body, shock waves are generated along the trajectory of the meteoroid. These waves are characterized by the overpressure that they generate, which create a clear pressure discontinuity in the atmosphere, referred to as the nonlinear part of the shock wave propagation. The propagation distance of this nonlinear wave is associated to the ratio of the meteoroid speed to the ambient sound speed, also known as the Mach number, as well as the physical diameter of the meteoroid. In this work, we compute this distance for the Earth case and for the known trajectory of the detected and examined bolide [1][6].

The methodology developed in this study can serve the seismic investigation of structures covered by ice on planets or planetary bodies with a relatively thick atmosphere, where airbursts can occur due to the friction of the meteoroid with the ambient atmospheric material. An ideal example of this case are the icy mountains of Titan, which are known to be formed by tectonic activity on the Saturn’s moon [4]. The future Dragonfly mission to Titan will carry a seismometer as part of the DraGMet (Dragonfly Geophysics and Meteorology Package) payload [7]. Even if the primary goal of the mission is the characterization of the regolith properties, an eventual airburst and collection of seismic data near these mountainous icy structures, will be a great opportunity to investigate, through the identification of the associated waves and thus the investigation of the coupled seismic waves, the properties of this icy cover, its depth and composition.

References: [1] https://cneos.jpl.nasa.gov/fireballs/ [2] Sohl, F. et al. (1995) Icarus, 115, 278–294 [3] Lopes R.M.C. et al. (2019) Nat Astron, [4] Radebaugh J. et al. (2007) Icarus, 192, 77-91, [5] Niemann H.B. et al. (2005) Nature, 438, 779–784 [6] Schmerr, N. et al. (2018) Abstract P21E-3406, AGU Fall Meeting 2018, Washington DC [7] Lorenz R. et al. (2018) Johns Hop- kins APL Technical Digest, 34, 3

How to cite: Karakostas, F., Schmerr, N., Bailey, S. H., Dellagiustina, D., Habib, N., Bray, V., Pettit, E., Dahl, P., Quinn, T., Marusiak, A., Avenson, B., Wagner, N., and Brodbeck, J.: The Qaanaaq airburst as an analog of seismic source in extraterrestrial atmospheres: seismic and infrasound investigation , Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-480, https://doi.org/10.5194/epsc2020-480, 2020.