From Rosetta to Museums: The very long journey of cometary dust particles within the zodiacal cloud
Résumé
Die Kometen-
Mission Rosetta
/ Symposium
am
12.
Juli
2018
4/9
KOMMISSION FÜR ASTRO
NOMIE
und
KOMMISSION FÜR GEOWI
SSENSCHAFTEN
in Kooperation mit dem
NATURHISTORISCHEN MU
SEUM
WIEN
From Rosetta to Museum
s
The very long journey of cometary dust particles within the zodiacal cloud
Prof. Dr. Anny
-Chantal
Levasseur
-Regourd
Universität Sorbonne
| LATMOS
-Institut,
Paris
https://www.latmos.ipsl.fr/index.php/en/annuaire?id=3735
Anny
-Chantal.Levasseur@aerov.jussieu.fr
The Rosetta rendezvous mission has established that dust particles in the coma of comet
67P/Churyumov
-Gerasimenko (thereafter 67P) are aggregates, with sizes mainly from tens to
hundreds of micrometers. They present a hierarchical structure, are built up from a large number of
subunits (at least down to tens of nanometers), and may be rather compact or quite fluffy. Rosetta has
also provided evidence for the dominance of organic matter in such particles. Their
porous structure
and carbonaceous composition, in agreement with results tentatively inferred from other comets, are
perfectly consistent with the results established for the nucleus of 67P.
Cometary dust particles, once released from a cometary nucleus,
are subjected to gravitational and
non
-gravitational forces, which scatter them along cometary dust tails and trails, and progressively
inject them into the zodiacal cloud (also called interplanetary dust cloud), where they may slowly spiral
inwards durin
g tens of thousands of years, before finally falling into the Sun. It has been recently
recognized that most of the interplanetary dust particles reaching the Earth’s environment originate
from comets on orbits comparable to that of 67P.
Some of these nu
merous dust particles entering the Earth’s atmosphere may survive their impact,
because of their relatively low velocities and their fluffy structure. They have indeed been collected
during the last decades, within the stratosphere, as CP-IDPS (Chondritic Porous Interplanetary Dust
particles), and from snow and ice of high
-altitude sites in Antarctica, as UCAMMs (Ultra Carbonaceous
Antarctica Micro Meteorites). They are presently carefully preserved and analyzed, as unique
remnants of the early solar system