Results 261 to 270 of about 722,187 (326)
Some of the next articles are maybe not open access.
A Photochemical Model of the Martian Atmosphere
Icarus, 1994The factors governing the amounts of CO, O2, and O3 in the martian atmosphere are investigated using a minimally constrained, one-dimensional photochemical model. We find that the incorporation of temperature-dependent CO2 absorption cross sections leads to an enhancement in the water photolysis rate, increasing the abundance of OH radicals to the ...
Nair, Hari +4 more
openaire +4 more sources
Helium in the Martian atmosphere
Journal of Geophysical Research: Planets, 1993A simple two‐reservoir degassing model for the Earth decribes rather well the current degassing rate of 4He which is equal to (3±1)×106 cm −2s−1 according to data for the helium polar wind and the measured 3He/4He ratio. This value of the helium degassing and loss rate provides an important constraint in modeling of noble gases, and some recent models ...
Supriya Chakrabarti +2 more
openaire +2 more sources
Photochemistry of HCl in the martian atmosphere
Icarus, 2022The recent discovery of HCl on Mars (Korablev et al. 2021, Olsen et al. 2021) indicates its strong seasonal variations and correlation with dust. To study this idea, we develop photochemical models for summer midlatitudes at aphelion and perihelion. We assume that HCl is formed in heterogeneous reactions of FeCl3 and/or NaCl in the dust with H, and the
openaire +2 more sources
Isotopic Composition of the Martian Atmosphere
Science, 1976Results from the neutral mass spectrometer carried on the aeroshell of Viking 1 show evidence for NO in the upper atmosphere of Mars and indicate that the isotopic composition of carbon and oxygen is similar to that of Earth. Mars is enriched in 15 N relative to Earth by about 75 percent, a consequence of escape ...
Nier, Alfred O. +2 more
openaire +4 more sources
Photochemistry of the Martian atmosphere
Icarus, 1977A critical analysis is carried out for models which may be fine tuned to give agreement with observational constraints for O2, CO, and O3 in the Martian lower atmosphere and which are in accord also with upper atmospheric data for O and CO. The models have a number of features in common: dynamic mixing must be exceedingly rapid at heights above 90 km ...
Ten Ying Kong, Michael B. McElroy
openaire +2 more sources
Martian Atmospheric Erosion Rates
Science, 2007Mars was once wet but is now dry, and the fate of its ancient carbon dioxide atmosphere is one of the biggest puzzles in martian planetology. We have measured the current loss rate due to the solar wind interaction for different species: Q(O + ) = 1.6·10 23 per second = 4 grams per second (g ...
Rickard Lundin +3 more
openaire +3 more sources
Icarus, 1966
Abstract The Martian atmosphere in its average condition is inactive and transparent to long-wave radiation. It is activated when moisture is supplied by the evaporation of the polar cap in spring time. As typical examples, the great yellow cloud in 1956, the Neith-Casius cloud, and the Propontis cloud are described.
openaire +2 more sources
Abstract The Martian atmosphere in its average condition is inactive and transparent to long-wave radiation. It is activated when moisture is supplied by the evaporation of the polar cap in spring time. As typical examples, the great yellow cloud in 1956, the Neith-Casius cloud, and the Propontis cloud are described.
openaire +2 more sources
Composition of the Martian atmosphere
Space Science Reviews, 1991Data on the composition of the Martian atmosphere obtained by instruments aboard the Viking spacecraft are not of sufficient accuracy to address important questions regarding the composition and history of Mars. Laboratory analyses of gases trapped in glassy phases of shergottite meteorite EETA 79001 yield precise data, but it remains to be ascertained
openaire +2 more sources
Variability of D and H in the Martian upper atmosphere observed with the MAVEN IUVS echelle channel
Journal of Geophysical Research: Space Physics, 2017 A Stiepen, D Bhattacharyya, G M Holsclaw
exaly +2 more sources
Clues to the Martian Atmosphere
Science, 2001Some 30 years ago, it was discovered that the main constituent of the thin martian atmosphere is carbon dioxide (CO) but that it only contained trace amounts of carbon monoxide and molecular oxygen, the photodissociation products of CO. Chemical reaction cycles involving water and hydrogen species have been developed to explain these observations, but ...
openaire +2 more sources