Thinning of the Earth's lithosphere by heat advected to its base is a possible mechanism for continental rifting and continental and oceanic mid-plate volcanism. It might also account for continental rifting-like processes and volcanism on Venus and Mars. Earth's continental lithosphere can be thinned to the crust in a few tens of million years by heat advected at a rate of 5 to 10 times the normal basal heat flux. This much heat is easily carried to the lithosphere by mantle plumes. The...
Topics: NASA Technical Reports Server (NTRS), ADVECTION, EARTH CRUST, EARTH MANTLE, GEOLOGICAL FAULTS,...
Temperatures recorded during two KOSI comet nucleus simulation experiments strongly suggest that heat transport by vapor flow into the interior of the sample is very important. Two comet nucleus simulation experiments have been done by the KOSI team in a big space simulator. The thermal evolution of the sample during insolation and the results of simplified thermal evolution calculations are discussed. The observed thermal histories cannot be explained by a simple model with heat transferred by...
Topics: NASA Technical Reports Server (NTRS), COMET NUCLEI, HEAT TRANSFER, MASS TRANSFER, SIMULATION, SPACE...
An active comet like comet Halley loses by sublimation a surface layer of the order of 1 m thickness per perihelion passage. In situ measurements show that water ice is the main constituent which contributes to the gas emission although even more volatile species (CO, NH3, CH4, CO2 etc.) have been identified. Dust particles which were embedded in the ices are carried by the sublimating gases. Measurements of the chemical composition of cometary grains indicate that they are composed of...
Topics: NASA Technical Reports Server (NTRS), CHEMICAL COMPOSITION, COMETS, ICE, SIMULATION, SUBLIMATION,...
