The footprint of cometary dust analogues: II. Morphology as a tracer of tensile strength and application to dust collection by the Rosetta spacecraft. (arXiv:1904.07543v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ellerbroek_L/0/1/0/all/0/1">L.E. Ellerbroek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gundlach_B/0/1/0/all/0/1">B. Gundlach</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Landeck_A/0/1/0/all/0/1">A. Landeck</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dominik_C/0/1/0/all/0/1">C. Dominik</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Blum_J/0/1/0/all/0/1">J. Blum</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Merouane_S/0/1/0/all/0/1">S. Merouane</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hilchenbach_M/0/1/0/all/0/1">M. Hilchenbach</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+John_H/0/1/0/all/0/1">H. John</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Veen_H/0/1/0/all/0/1">H. A. van Veen</a>
The structure of cometary dust is a tracer of growth processes in the
formation of planetesimals. Instrumentation on board the Rosetta mission to
comet 67P/Churyumov- Gerasimenko captured dust particles and analysed them in
situ. However, these deposits are a product of a collision within the
instrument. We conducted laboratory experiments with cometary dust analogues,
simulating the collection process by Rosetta instruments (specifically COSIMA,
MIDAS). In Paper I we reported that velocity is a key driver in determining the
appearance of deposits. Here in Paper II we use materials with different
monomer sizes, and study the effect of tensile strength on the appearance of
deposits. We find that mass transfer efficiency increases from $sim$1 up to
$sim$10% with increasing monomer diameter from 0.3 $mu$m to 1.5 $mu$m (i.e.
tensile strength decreasing from $sim$12 to $sim$3 kPa), and velocities
increasing from 0.5 to 6 m/s. Also, the relative abundance of small fragments
after impact is higher for material with higher tensile strength. The
degeneracy between the effects of velocity and material strength may be lifted
by performing a closer study of the deposits. This experimental method makes it
possible to estimate the mass transfer efficiency in the COSIMA instrument.
Extrapolating these results implies that more than half of the dust collected
during the Rosetta mission has not been imaged. We analysed two COSIMA targets
containing deposits from single collisions. The collision that occurred closest
to perihelion passage led to more small fragments on the target.
The structure of cometary dust is a tracer of growth processes in the
formation of planetesimals. Instrumentation on board the Rosetta mission to
comet 67P/Churyumov- Gerasimenko captured dust particles and analysed them in
situ. However, these deposits are a product of a collision within the
instrument. We conducted laboratory experiments with cometary dust analogues,
simulating the collection process by Rosetta instruments (specifically COSIMA,
MIDAS). In Paper I we reported that velocity is a key driver in determining the
appearance of deposits. Here in Paper II we use materials with different
monomer sizes, and study the effect of tensile strength on the appearance of
deposits. We find that mass transfer efficiency increases from $sim$1 up to
$sim$10% with increasing monomer diameter from 0.3 $mu$m to 1.5 $mu$m (i.e.
tensile strength decreasing from $sim$12 to $sim$3 kPa), and velocities
increasing from 0.5 to 6 m/s. Also, the relative abundance of small fragments
after impact is higher for material with higher tensile strength. The
degeneracy between the effects of velocity and material strength may be lifted
by performing a closer study of the deposits. This experimental method makes it
possible to estimate the mass transfer efficiency in the COSIMA instrument.
Extrapolating these results implies that more than half of the dust collected
during the Rosetta mission has not been imaged. We analysed two COSIMA targets
containing deposits from single collisions. The collision that occurred closest
to perihelion passage led to more small fragments on the target.
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