Extraterrestrial ice with emphasis on aggregation/interaction with organic matter
Recent planetary explorations found a lot of icy bodies in the solar system and many glacial structures on the planetary surfaces. It is proposed by the theoretical studies and astronomical observations that the materials that construct the solar system bodies came from molecular clouds. In the mole...
Gespeichert in:
1. Verfasser: | |
---|---|
Format: | Tagungsbericht |
Sprache: | eng ; ger |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | Recent planetary explorations found a lot of icy bodies in the solar system and many glacial structures on the planetary surfaces. It is proposed by the theoretical studies and astronomical observations that the materials that construct the solar system bodies came from molecular clouds. In the molecular cloud, we can observe water ice and other ices, which are solid of highly volatile molecules: e.g. CO, CH sub(4), CO sub(2) etc., and organic matters are also believed to exist [1]. These ices are formed to be sub-micron sized dusts. These sub-micron dusts are supposed to aggregate each other to grow icy bodies in the evolution of the molecular cloud toward the solar nebula [2]. The aggregation of the dusts in the nebula occurs by collision, so that the physical condition of the collisional growth on the dusts and the aggregates are important to clarify the formation process of icy bodies. Comets are fossils of the material in the primitive solar nebula evolved from the molecular cloud, so that there are a lot of observations finding highly volatile molecules and organic molecules in the comets [1,2]. Recent observations by planetary explorations revealed the densities and the surface structures of the comet nucleus. Thus, we recognize that it is a highly porous body having a surface layer composed of dusts and aggregates [3]. These properties are the same as that of icy planetesimals. Therefore, we can imagine that the comet-like bodies collided each other to become larger icy bodies in the solar nebula. Impact experiments on the icy materials have been conducted to clarify the accumulation condition of the icy bodies and the formation process of icy satellites [4,5]. The impact strength of ice aggregates with the various porosities was obtained as a result of laboratory experiments: the strength of pure ice aggregates increases with the increase of the porosity from 0 to 40%. However, the impact strength of porous ice-rock mixture has the opposite dependence on the porosity compared to pure ice aggregates: the strength of the mixture decreases with increasing the porosity. According to the theoretical consideration based on the above results, we can obtain the accumulation condition of porous icy bodies and discuss the effect of rock contents on the formation of icy satellites. |
---|---|
ISSN: | 1618-3193 |