Cosmic dust fluxes in the atmospheres of Earth, Mars, and Venus

The Meteoric Ni Layer in the Upper Atmosphere

“…This might indicate a high Ni enrichment in cosmic dust particles, but that contradicts the analysis of meteoritic fragments in our laboratory (Bones et al, 2019), and the Fe:Ni ratio measured in cosmic dust particles which survived atmospheric entry (Arndt et al, 1996). The CABMOD‐ZoDy ratio is a factor of ~0.42 times smaller than the Kühlungsborn lidar‐measured ratio of 38:1 (Gerding et al, 2019), which may suggest that Ni is converted to long‐term atmospheric sinks more efficiently than Fe (Carrillo‐Sánchez et al, 2020). In comparison, the Fe + :Ni + ratio measured between 85 and 100 km, measured during eight rocket flights, is , which is close to the ratio of the Fe and Ni MIFs (Carrillo‐Sánchez et al, 2020).…”

“…Here, the rate coefficients k 18‐20 are set to 7 × 10 −8 cm 3 s −1 , which is around 80 times larger than a typical dipole–dipole capture rate for these metallic molecules. This factor allows for Ni reservoir species polymerizing with other metal‐containing molecules of meteoric origin (e.g., FeOH, Mg (OH) 2 , and NaHCO 3 ), whose concentration will be around 80 times higher because the elemental ablation ratio of Ni atoms to the sum of Na, Fe, Mg, Si, Al, and K atoms is ~1/80 (Carrillo‐Sánchez et al, 2020). For comparison, in the case of two other minor meteoric metals, Ca and K, the dipole‐dipole capture rate was increased by factors of 100 (Plane et al, 2018) and 270 (Plane et al, 2014), respectively.…”

“…The peak density was 1.6 × 10 4 cm −3 at 87 km, with a column abundance of 2.7 × 10 10 cm −2 . Compared with Fe, another transition metal that should be injected through meteoric ablation over a similar height range (Carrillo‐Sánchez et al, 2020), the Fe:Ni column abundance ratio was only 1.2:1, which is much smaller than the carbonaceous Ivuna (CI) chondritic ratio of 18:1 (Asplund et al, 2009) (the CI ratio is regarded as the closest in composition to interplanetary dust; Jessberger et al, 2001).…”

“…Recently, we investigated the ablation of Ni from meteoritic fragments using the Meteoric Ablation Simulator (MASI): the evaporation of Ni and Na were measured by laser‐induced fluorescence (LIF) as size‐selected fragments were heated at rates that simulated atmospheric entry (Bones et al, 2019). The experimental results were then used to produce a new version of the Leeds Chemical ABLation MODel (CABMOD‐3), where the Ni is treated as being in Ni‐Fe‐S grains, which are separated from the bulk Fe‐Mg‐SiO 4 phase (Carrillo‐Sánchez et al, 2020). Both the MASI data and CABMOD‐3 simulations show that the ablation of Ni (as well as metallic or sulfide Fe) occurs rapidly at a relatively low temperature of ~2200 K, before the bulk silicate phase of Fe has ablated.…”

RETRACTED ARTICLE: Life on Venus and the interplanetary transfer of biota from Earth

“…In support of the solar-galactic-wind microbe-laden-dust hypothesis is evidence of an interplanetary (Misconi and Weinberg 1978) circumsolar ring of dust (Krasnopolsky and Krysko 1979) which appears to follow (Leinert and Moster 2007) and to have possibly originated external to the orbit of Venus (Altobelli et al 2003;Jones et al 2013;Leinert and Moster 2007;Russell and Vaisberg 1983) penetrates the planet's atmosphere (Carrillo-Sánchez et al 2020). As to dust originating from Earth, it is probable that microbes may be adhering to some of these particles (Arrhenius 1908(Arrhenius , 1918.…”