Small bodies are unique in the Solar System, as they have escaped planetary accretion and have best preserved the composition of the matter initially present in the solar nebula. Cosmic dust originates from these small bodies, asteroids and comets. Interplanetary and cometary dust can be collected on Earth in regions where there is a low accumulation rate of terrestrial dust, like the polar caps or the stratosphere. Interplanetary dust particles (IDPs) have been collected in the stratosphere by NASA for a few decades. A fraction of IDPs (at least) are proposed to be of cometary origin. Cosmic dust collection from the polar caps have yielded larger dust particles than from the stratosphere, and are called micrometeorites. The Concordia micrometeorite collection performed since 2000 at Dome C, near the Concordia station in Antarctica contain very pristine samples, including particles of very probable cometary origin. Spatial missions like Stardust (NASA), Hayabusa (JAXA) and Rosetta (ESA) also gave access to the structure and composition of asteroidal and cometary dust. Stardust brought dust particles from comet 81P/Wild 2 to Earth, but the collection occurred at high relative velocity (6 km/s) and the samples were altered during the collection. The Rosetta mission collected dust particles from comet 67P/Churyumov-Gerasimenko at much lower velocity (1-10 m/s), but the dust analyses had to be performed in situ by the dust instruments (GIADA, COSIMA, MIDAS) onboard the Rosetta orbiter. The Hayabusa mission returned samples from asteroid Itokawa, which is an asteroid related to ordinary chondrite meteorites. At least two future spatial missions are bound to bring back samples from carbonaceous asteroids: Hayabusa 2 (JAXA, asteroid Ryugu) et OSIRIS-REx (NASA, asteroid Bennu). The CAESAR mission is also currently under study to bring back a sample from comet 67P/Churyumov-Gerasimenko.

The presentation will summarize the present knowledge on the composition of interplanetary and cometary dust, based on the results of laboratory analysis of dust particles collected on Earth, and of spatial missions.