25. May 2013
The scientific study of the Martian atmosphere is particularly interesting because this planet is similar to Earth in many respects. Martian geomorphology shows in a spectacular way the probable existence, at least in the past, of large quantities of liquid water on the Martian surface or in the subsurface layers. Surface features resembling massive outflow channels provide evidence that the Martian crust contained the equivalent of a planet wide reservoir of water several hundred meters deep. The Magnetometer / Electron Reflectometer (MAG/ER) experiment on board of Mars Global Surveyor has detected surface magnetic anomalies of up to 1500 nT during its low aerobreaking passes, resulting from remanent crustal magnetism. These magnetic anomalies strongly indicate the existence of a strong ancient intrinsic Martian magnetic moment which corresponded to a magnetic field strength of 10% - 100% of present Earth's. Such an ancient intrinsic magnetic field had significant consequences for the evolution of the Martian atmosphere, especially by reducing the amount of certain atmospheric constituents lost to space.
The evolution of the Martian atmosphere, with regard to water, is influenced by non-thermal atmospheric loss processes of heavy atmospheric constituents and will be investigated by Mars Express. Since Mars does not have an appreciable intrinsic magnetic field at present and a comparatively small gravitational acceleration, all known atmospheric loss processes work and several important atmospheric constituents, namely H, H2, N, O, C, CO, O2 and CO2 are lost from the atmosphere. The escape rates of atmospheric constituents over time, including the loss of H2O from Mars indicate that the red planet could have lost an atmosphere of at least 1 bar to space during the past 3.5 billion years.
The second important effect of an ancient intrinsic magnetic field and a much denser atmosphere is the shielding of the Martian surface from cosmic rays, soft X-rays and UV radiation. By investigating the surface protection during the history of the Martian atmosphere one can see that the atmospheric conditions on Mars were comparable to Earth, 3.7 billion years in the past. As life on Earth may be as old as 3.8 billion years, similar life forms may have developed on Mars under those more favorable atmospheric conditions.
| |
| 1. |
Kulikov et al.:
A comparative study of the influence of the active young Sun on the early atmospheres of Earth, Venus and Mars,
Space Sci. Rev.,
129,
207-243, doi 10.1007/s11214-007-9192-4,
2007.
|
| |
| |
| 2. |
Kolb et al.:
The chemical variability at the surface of Mars: Implication for sediment
formation and rock weathering,
Icarus,
183,
10-29,
2006.
|
| |
| |
| 3. |
Lammer et al.:
Thermospheric X-ray and EUV heating by the young Sun on early Venus and Mars,
Space Sci. Rev.,
122,
189-196,
2006.
|
| |
| |
| 4. |
Terada et al.:
Simulation of the total ion loss evolution on Mars with a global hybrid model: Implications for the planet's hydrosphere,
submitted to Icarus,
2006.
|
| |
| |
| 5. |
Kolb et al.:
An ultraviolet simulator for the incident Martian surface radiation and its applications,
Astrobiol.,
4,
241-249,
2005.
|
| |
| |
| 6. |
Penz et al.:
A comparison of magnetohydrodynamic instabilities at the Martian ionopause,
Adv. Space Res.,
36,
2049-2056,
2005.
|
| |
| |
| 7. |
Lichtenegger et al.:
Possible temperature effects of energetic neutral hydrogen atoms on the Martian exosphere,
Adv. Space Res.,
33,
140–144,
2004.
|
| |
| |
| 8. |
Meishan-Goh, G., B. Kazeminejad
:
Mars through the looking glass: An interdisciplinary analysis of forward and backward contamination,
Space Policy,
20,
217-225,
2004.
|
| |
| |
| 9. |
Patel et al.:
Annual solar UV exposure and biological effective dose rates on the Martian surface,
Adv. Space Res.,
33,
1247–1252,
2004.
|
| |
| |
| 10. |
Penz et al.:
Ion loss on Mars caused by the Kelvin–Helmholtz instability,
Planet. Space Sci.,
52,
1157–1167,
2004.
|
| |
| |
| 11. |
Becker et al.:
Isotopic Signatures of Volatiles in Terrestrial Planets,
Space Sci. Rev.,
106,
377-410,
2003.
|
| |
| |
| 12. |
Ellery et al.:
Astrobiological Instrumentation for Mars - The Only Way is Down,
Astrobiol.,
1,
365-380,
2003.
|
| |
| |
| 13. |
Lammer et al.:
Estimation of the past and present Martian water-ice reservoirs by isotopic constraints on exchange between the atmosphere and the surface,
Astrobiol.,
2,
195-202,
2003.
|
| |
| |
| 14. |
Lammer et al.:
Loss of water from Mars: Implications for the oxidation of the soil,
Icarus,
165,
9-25,
2003.
|
| |
| |
| 15. |
Lammer, H., S.J. Bauer:
Isotopic fractionation by gravitational escape,
Space Sci. Rev.,
106,
281-291,
2003.
|
| |
| |
| 16. |
Patel et al.:
Seasonal and diurnal variations in Martian surface UV irradiation: Biological and chemical implications for the Martian regolith,
Astrobiol.,
2,
21-34,
2003.
|
| |
| |
| 17. |
Rontó et al.:
Solar UV irradiation conditions on the surface of Mars,
Photochem. Photobiol.,
77,
34-40,
2003.
|
| |
| |
| 18. |
Lichtenegger et al.:
Energetic neutral atoms at Mars III: Flux and energy distributions of planetary energetic H atoms,
J. Geophys. Res.,
107,
1279, 10.1029/2001JA000322,
2002.
|
| |
