The Red Planet
An article on Mars.
Martian Breath and Surface
- The temperature of Mars (and of Earth) falls with respect to the altitude. Average temperature is about -63 degrees cenlcius.
- Mars lacks a properly built magnetosphere, and so it is exposed to charged solar rays, ripping apart any molecules along the way. This is one of the reasons that Mars is unable to form a stable Ozone layer
- Unlike the Earth, there's no Greenhouse effect on Mars, and therefore no warming of the atmosphere, because of the lack of Ozone (negligible). But 60 - 120kms up, CO2 absorbs solar radiation of near IR wavelengths, making the molecules jiggle faster and emit more heat. Above 120km, both in Earth and Mars, the temperature of the atmosphere is very warm.
- Martian air is about 95% CO2.
- Mars lacks of Greenhouse effect because of its very thin atmosphere, it wouldn't hold onto sun's radiation (the number of CO2 molecules are too low in Martian atmosphere)
- Pressure in Martian atmosphere is lesser than 1% of sea-level atmospheric pressure on Earth (because of thin atmosphere in Mars). Therefore, the astronomers would need pressurized suits.
- Due to lesser presence of oxygen forms (O2 and O3) and exposed atmosphere to solar winds, an Ozone layer is unable to be formed in Mars, and thus it is vulnerable to hazardous solar rays coming from the sun.
- If Mars is vulnerable to solar radiation, all the CO2, in Mars' atmosphere should be converted into CO and O2, but it hasn't been the case. It is suggested that due to the trace amount of water vapor in Mars produce OH, which acts as an agent in converting back CO and O2 to CO2, in a reverse reaction.
- 30% of these CO2 is trapped in polar ice caps, due to a condensation-sublimation phenomenon. Mars is so cold that it rains CO2 "snowflakes".
- Earth's observatories detected trace amounts of Methane (CH4), to everyone's surprise, since the source of Methane in Mars is currently unknown. On Earth, the primary sources of Methane are human-activities and livestock, mixed with natural sources such as wetlands. Is there a Martian agriculture we never knew about?
How is atmosphere lost to space?
An atmosphere can be lost due to two reasons.
- The atmosphere can turn into solid forms.
- Or, it can just dissappear into space.
Methods of losing the atmosphere:
- Jean's Escape: Atoms/molecules reaching the escape velocity due to temperature variations.
- Photochemical Loss: Products which are produced by photochemical activities (e.g O2+ irons) can combine with each other and perform exothermic reactions. These reactions may give the atoms/molecules the escape velocity to leave the atmosphere.
- Iron Loss: Ionized molecules, in presence of a magnetic field can flow into atmosphere(called iron outflow). Even there is no magnetic dipole (e.g. Venus), the solar wind can carry them out to space. In Mars, where there is some strong crustal magnetic fields in some positions of the planet, both of these scenarios are possible. Nevertheless, we don't have much data to prove Iron Loss occuring on Mars.
- Sputtering: In cases of nobel gases such as Ar, the irons flowing with the solar wind can "knock" the atoms of Ar into space.
- The young Sun had a lot of ultraviolet radiation and solar winds.
- Mars displays a moderate amount of sputtering of atmospheric molecules into space.
Winds of Mars
The swift winds of Mars are mainly due to thermal differences in different areas. When air gets warm, they expand and flows upward (like a baloon). This leads to lower pressure at altitude, and these warmer air pockets are pushed by force towards low pressure regions which are cooler.
- The landscape of the Martian surface is lagely sculpted by the winds.
- However, even though there are swift winds in Mars, the air is very thin. How does this thin airflow carve such amazing sand dunes we observe in Mars?
- Micrometer-sized sand particles are swifted away by the winds.
- Thousands of years of winds make these carvings that we see today.
- Saltation: — "The sand particles are first lifted off from the surface and accelerated downwind, next colliding with the ground and ejecting new particles (6–12)—which is responsible, among other things, for the appearance of sand dunes and ripples such as those recently imaged at Meridiani Planum on Mars." (Ref: Giant saltation on Mars)
- Mars grains saltate x100 higher and longer trajectories and reach 5-10 times higher velocities than Earth grains do (Ref: Giant saltation on Mars).
- Red color: Our blood is red because of Iron Oxides. The same reason is for Mars. Its regolith oxidize with oxygen forms in the atmosphere and makes a reddish-orange color. How did iron get combined with oxygen in a oxygen-poor atmosphere?
- There are many debates. Some say that it was an earlier incident, when Mars was younger, it was abundant with water and oxygen. Others say that it was a gradual process, years of oxidization with smaller amounts of oxygen in the atmosphere. Some argue that it was due to the strong winds crumbling quartz crystals in the regolith and leaving their oxygen-rich surfaces exposed.
The planet's grandest volcanos are situated near Tharis. Tharsis is not the only Martian volcanic center. There's Elysium, Syrtis Major, and a cluster of low-profile volcanic structures near the Hellas impact basin, to name the larger volcanic areas alone. These volcanos are believed to be a source of CO2 present in the atmosphere, and it is believed that they heated the atmosphere as well.
- No active volcano today
- The outer crust of Mars is too thick for the molten metal in the core to be ejected out through a volcanic activity.
- The large size of the Martian volcanos is due to the absense of plate tectonics of the planet. In the absence of tectonics, it would form one huge volcano instead of producing a series of smaller ones.
Perhaps Martian volcanic activity has ended permanently. However, it's also possible that we are simply seeing Mars at a geologically quiet moment, and activity may resume any time.
Olympus Mons, the largest volcano in the solar system, is 600km in diameter, and 21km in height (nearly thrice the height of Mount Everest!).
Scientists argue that in the earlier epochs in Mars, it was lively with water and a steady atmosphere, with volcanic activity going on here and there.
Two kinds of craters exist.
- Volcanic craters: Created after a massive explotion of a volcano
- Impact craters: Created following a collision between the surface and a meteorite.
Mars consists of 635,000 impact craters wordwide. The largest crater observed being the Huygen's crater, named after Christian Huygens, the discoverer of Titan, the largest moon on Saturn. There are certain craters (volcanic) called Maar craters, which are formed by a violent reaction of volcanic magma with a steady region of groundwater. They look very much like impact craters, and it's difficult to discern. However, identifying Maar craters is a precursor for water beneath them.
Martian River Valleys
Looking from telescopes, we see river-like carvings in the Martian surface. What are they?
Scientists have found out that once in a lively epoch on Mars, water flowed through these great river valleys. Lava and liquid carbon dioxide were also thought of as candidates, but they were refuted by evidence.
The sources for water than ran on these river valleys are numerous. Hydrothermal sources, that are formed following some kind of an impact on a side of a volcano, and causes magma to rise. This heats water within the sub-surface, and forms convection springs of heated water. Another source might be due to rain.
Mars Reconnaissance Orbiter (MRO) used its spectrometer to find out traces of hydrated minerals on those narrow streaks inside the crater walls. These minerals (salts) can lower the freezing point of sub-surface luqids, including water.
Even on Earth, there are forms of life that can endure extreme environmental conditions like high pressures and high temperatures. They find their own ways to cope up with changing surroundings, either by shelter or adapting themselves to change.
If someone pushes a planetary scientist, to point out where to search for Life on Mars, without any doubt the scientist would answer "Look where the water is!". Water is an essential component to life as we know it. But that is for life as we know it. Can there be Sillicon-based beings, unknown to our imaginations, living beneath the rocks?
The current conditions on Mars do not permit life. Absence of a steady temperature, and the lack of hospitable atmosphere makes life a little implausible at a first glance. To terraform mars, we must:
- Create an atmosphere
- Mediate the temperature
- Harbour (or transport) the neccessary essentials for life.
- Creating the atmosphere would require to create sufficient greenhouse effect for plants to breath in CO2 and breath out O2, just like they did in primitive Earth.
- Temperature would be mediated if it is possible to create the aforementioned greenhouse effect, since the CO2, CH4 and H2O molecules trap the heat of solar radiation.
- Food and water are essential for life. We must find a way to either transport goods from Earth, or to manufacture/grow the requirements on Mars. Mars' soil is not rich for plants to grow, and thus, fertilizers and other requirements are needed to be artificially manufactured. If we can tap into the riches of underground water that scientists believe there exist today, this would help the process of terraforming.
Summary of Jakosky et al.
The first two possibilities were investigated in a paper in 2018 by a research group led by Bruce M. Jakosky. The group considered the possibilities to harbour an environment that is habitable, by using the materials and resources available on Mars itself. They considered scenarios such as using the reservoires of CO2 in the polar ice caps, heating them and tapping into the CO2 to create a greenhouse effect. Furthermore, they investigated scenarios such as using carbon-bearing minerals and oxidizing them to produce the CO2 yield they required. Their conclusion was that using the contemporary technology that we possess today, and what we have observed in Mars upto date, we do not have enough resources and/or Mars do not possess enough materials to create the sufficient atmospheric conditions to suit for life. Either the materials which we can use to terraform Mars have not been observed, inaccessible or not there. Another possibility they considered was increasing the atmospheric density by outgassing juvenile gasses and creating a form of an artificial magnetic field making the atmosphere resistant to the solar wind. However, a natural outgassing mechanism (e.g. volcanos) operate at very low pace on Mars, and thus it would consume 10 million years to create the current atmospheric mass (which is very low) in Mars even with zero loss of atmosphere to space.
- Forget, F., Costard, F. and Lognonné, P., n.d. Planet Mars.
- Almeida, M., Parteli, E., Andrade, J. and Herrmann, H., 2008. Giant saltation on Mars. Proceedings of the National Academy of Sciences, 105(17), pp.6222-6226.
- Earthdata.nasa.gov. 2020. In Search Of Martian Craters | Earthdata. [online] Available at: https://earthdata.nasa.gov/learn/sensing-our-planet/in-search-of-martian-craters [Accessed 14 November 2020].
- Jakosky, B. and Edwards, C., 2018. Inventory of CO2 available for terraforming Mars. Nature Astronomy, 2(8), pp.634-639.
- LePan, N., 2020. Map Of Mars: The Geology Of The Red Planet. [online] Visual Capitalist. Available at: https://www.visualcapitalist.com/map-of-mars-the-geology-of-the-red-planet/ [Accessed 14 November 2020].
- Columbia.edu. 2020. MARS. [online] Available at: http://www.columbia.edu/dlc/garland/deweever/M/mars.htm [Accessed 14 November 2020].
- Airandspace.si.edu. 2020. Mars Volcanoes | Exploring The Planets | National Air And Space Museum. [online] Available at: https://airandspace.si.edu/exhibitions/exploring-the-planets/online/solar-system/mars/surface/volcanoes/ [Accessed 14 November 2020].
- NASA. 2020. NASA's MAVEN Reveals Most Of Mars' Atmosphere Was Lost To Space. [online] Available at: https://www.nasa.gov/press-release/nasas-maven-reveals-most-of-mars-atmosphere-was-lost-to-space [Accessed 14 November 2020].
- Russell, C. and Jakosky, B., 2015. Preface: The Mars Atmosphere and Volatile Evolution (MAVEN) Mission. Space Science Reviews, 195(1-4), pp.1-2.
- Staff, S., 2020. Mars Surface Scarred By 635,000 Big Impact Craters. [online] Space.com. Available at: https://www.space.com/16153-mars-impact-crater-map.html [Accessed 14 November 2020].
- Musiolik, G., Kruss, M., Demirci, T., Schrinski, B., Teiser, J., Daerden, F., Smith, M., Neary, L. and Wurm, G., 2018. Saltation under Martian gravity and its influence on the global dust distribution. Icarus, 306, pp.25-31.
- Nature.com. 2020. Mars Rover Detects ‘Excitingly Huge’ Methane Spike. [online] Available at: https://www.nature.com/articles/d41586-019-01981-2 [Accessed 14 November 2020].
- Nasa.gov. 2020. NASA - Robert Goddard: A Man And His Rocket. [online] Available at: https://www.nasa.gov/missions/research/f_goddard.html [Accessed 14 November 2020].
- Wall, M., 2020. Lunar Pit Stop? Mars-Bound Astronauts May Refuel Near Moon. [online] Space.com. Available at: https://www.space.com/30838-manned-mars-mission-moon-refueling.html [Accessed 14 November 2020].