Other
Scientific paper
Dec 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008agufm.p33d..03g&link_type=abstract
American Geophysical Union, Fall Meeting 2008, abstract #P33D-03
Other
0325 Evolution Of The Atmosphere (1610, 8125), 0343 Planetary Atmospheres (5210, 5405, 5704), 5455 Origin And Evolution, 5480 Volcanism (6063, 8148, 8450), 6225 Mars
Scientific paper
By using present-day observation and simple evolution models, we study the long term evolution of the Martian atmosphere influenced by volcanism degassing and atmospheric escape. Using a straightforward back integration based on the present state of the atmosphere, we show that even with the few data available we can propose a scenario for the evolution of the Martian atmosphere over the last three billion years. We focus on CO2 as the most likely main gas present in the atmosphere at that time and involved in large scale and long term processes. However we also apply our model to argon, nitrogen, sulphur and water. The model takes into account the effects of volcanic degassing, which constitutes an input of volatiles, and atmospheric escape into space. Atmospheric escape is assumed to have a major influence over planetary atmospheres. In the case of Mars in particular, where no evidence for carbonates has been found, escape seems to be the main mechanism for CO2 removal. Since hydrodynamic escape mostly takes place during the first few hundreds of million years, other processes for atmospheric escape have been considered in order to quantify the loss of volatiles during later periods. These processes are ionospheric outflow, ion pick-up, sputtering and dissociative recombination and are non-thermal. Their contributions are estimated by using data from ASPERA and Mars Express and several models such as those created by Leblanc (2001) or Chassefière, Leblanc and Langlais (2006). The input of gazes in the atmosphere is obtained by estimating the intensity of the volcanism over the history of Mars. Numerical models are used to quantify the melt production rate during the evolution of the planet. Here we used models from Breuer and Spohn (2006), Manga et al. (2006) and O'Neill et al. (2007). Depending on the volatile contents of the lavas, we have access to the amount of gazes released in the atmosphere. We show that with all our scenarios, the ancient primary atmosphere is efficiently lost around 3 billion years ago, leading in most of the cases to a time of thin atmosphere. The period of "high" CO2 pressures coincides with the formation of fluvial landforms (Mangold et al., 2004) and we show that the atmosphere at that time was probably able to sustain liquid water on the surface at least for short periods provided the surface temperature is high enough. However our model shows that over the past three billion years it is unlikely Mars could harbour a thick (>1 bar) atmosphere. The volcanism is then responsible for the preservation of what remains and, when the outgassing is sufficient, for the creation of a young secondary atmosphere. This implies that the present-day atmosphere might be recent rather than simply remnants of the primordial one, slowly eroded over 4.5 billion years. Our model shows this young atmosphere is likely to be 1 to 2 billion years old but might be even younger. We show that even with very low volcanic activity, the present-day Martian atmosphere is very likely composed of more than 50% to 70% of volcanic gazes.
Chassefiere Eric
Geenen Thomas
Gillmann Cédric
Lognonné Philippe
Moreira Manuel
No associations
LandOfFree
Mars: Volcanism and Young Atmosphere. does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Mars: Volcanism and Young Atmosphere., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mars: Volcanism and Young Atmosphere. will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1238064