Noachian

Mars Cross Section

Lava flow and crater ejecta

Ridged Plains Overlying Noachian

AncientMars

Branched Channels from Viking

Eberswalde. Delta

Noachian refers to a geologic system and early time period on the planet Mars, characterized by high rates of meteorite and asteroid impacts and the presence of abundant surface water in the form of rivers, lakes, and possibly oceans. This period is named after Noachis Terra, a heavily cratered highland region on Mars, and is analogous to the Hadean and early Archean eons of Earth's geologic time scale. The Noachian period is estimated to have spanned from about 4.1 to 3.7 billion years ago, making it the oldest of the three broad periods of Martian geological time, followed by the Hesperian and Amazonian periods.

Overview

During the Noachian period, Mars is believed to have had a thicker atmosphere and warmer climate, which could have supported the presence of liquid water on its surface. Evidence for this includes the discovery of ancient river valleys, delta formations, and lake beds by various Mars missions. These features suggest that water was abundant and may have played a significant role in shaping the Martian landscape during this time.

The Noachian period is also significant for its implications for the potential for life on Mars. The presence of liquid water, a key ingredient for life as we know it, along with the discovery of minerals that form in the presence of water, suggests that Mars could have been habitable during the Noachian.

Geology

The geology of the Noachian period is marked by extensive cratering, indicating that Mars was subjected to heavy bombardment by meteorites and asteroids. This is similar to the Late Heavy Bombardment thought to have occurred in the inner Solar System, including Earth, around the same time. The Noachian terrain is characterized by its heavily cratered surfaces, large impact basins, and the presence of phyllosilicates, minerals that form in the presence of water.

Climate

The climate of Mars during the Noachian period was likely much different from the cold, arid conditions observed today. Models suggest that Mars had a thicker atmosphere, which would have provided greater insulation and possibly supported a greenhouse effect, warming the planet's surface. This would have allowed liquid water to exist, shaping the planet's surface through erosion and sediment deposition.

Implications for Astrobiology

The Noachian period is of particular interest to astrobiologists, who study the potential for life beyond Earth. The evidence of liquid water, along with the detection of organic molecules on Mars by missions such as Curiosity, suggests that the conditions during the Noachian may have been conducive to the emergence of life. However, whether life ever arose on Mars remains a subject of speculation and ongoing research.

Exploration

The exploration of Mars has provided much of the evidence for understanding the Noachian period. Missions such as the Mars Reconnaissance Orbiter (MRO) and Mars rovers have been instrumental in identifying features indicative of past water flow and analyzing mineral compositions that point to a warmer, wetter past. Future missions aim to further explore these ancient terrains, seeking more direct evidence of past life and further elucidating the climate and geology of early Mars.

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