𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Mass and Energy Balance in the Near-Surface Layers of a Cometary Nucleus

✍ Scribed by Yu.V. Skorov; N.I. Kömle; W.J. Markiewicz; H.U. Keller

Publisher
Elsevier Science
Year
1999
Tongue
English
Weight
422 KB
Volume
140
Category
Article
ISSN
0019-1035

No coin nor oath required. For personal study only.

✦ Synopsis

In the near future, several space missions are scheduled, which will closely investigate short-period comets. Some of these (e.g., ROSETTA) will also deliver landing probes for in situ investigations of the nucleus' surface. Therefore there is now renewed interest in the structure and behavior of cometary surface layers.

In this paper we discuss in detail some basic features that may constitute the "landscape" of a comet nucleus: gas outflow from gaps and holes is considered, based on a fundamental kinetic approach and previous work. Both the gas emission from icedominated walls and the outflow through "dusty" channels with a sublimating icy bottom are calculated. We attribute special emphasis to the influence of recondensation on the energy balance. It is found that-assuming realistic temperature profiles as a function of depth-there exist areas of net recondensation along the walls of ice channels, which might act as interior heat sources. Furthermore, our Monte Carlo model is applied to interpret some results obtained in various comet simulation (KOSI) experiments, which were performed in the years 1989-1993 with porous ice samples irradiated in the space simulator at DLR Cologne/Germany. It was found that when using the measured temperature profile inside the ice sample Monte Carlo calculations predict that the recondensation region coincides with the region of the steepest temperature gradient.

Another result relevant for the understanding of cometary surface phenomena is that at least in first order the temperature difference between a sublimating ice front and the surface temperature of an overlying porous dust mantle or nonvolatile cohesive residuum is almost independent of the thickness of the nonvolatile layer.

📜 SIMILAR VOLUMES

A Model of Heat and Mass Transfer in a P
A Model of Heat and Mass Transfer in a Porous Cometary Nucleus Based on a Kinetic Treatment of Mass Flow
✍ Yu.V. Skorov; N.I. Kömle; H.U. Keller; G. Kargl; W.J. Markiewicz 📂 Article 📅 2001 🏛 Elsevier Science 🌐 English ⚖ 325 KB

The main aspect of this paper is to provide a synthesis between two major lines of development in the understanding of mass and heat transfer in a volatile porous medium. The first one is a macroscopic approach, where the medium is considered as a continuum, and heat and mass transfer equations are

The role of clouds in the surface energy
The role of clouds in the surface energy balance over the Amazon forest
✍ Eltahir, Elfatih A. B.; Humphries, E. James 📂 Article 📅 1998 🏛 John Wiley and Sons 🌐 English ⚖ 186 KB 👁 1 views

Deforestation in the Amazon region will initially impact the energy balance at the land surface through changes in land cover and surface hydrology. However, continuation of this human activity will eventually lead to atmospheric feedbacks, including changes in cloudiness which may play an important

Spatio–temporal variation in microclimat
Spatio–temporal variation in microclimate, the surface energy balance and ablation over a cirque glacier
✍ David M. Hannah; Angela M. Gurnell; Glenn R. Mcgregor 📂 Article 📅 2000 🏛 John Wiley and Sons 🌐 English ⚖ 892 KB

Climatic processes, operating at a range of scales, drive energy fluxes at the glacier surface which control meltwater generation and ultimately runoff. Nevertheless, to date, most glacier microclimate research has been both temporally (short-term) and spatially (single station) restricted. This pap