Noachian

The Noachian refers to an early geologic system and time period on Mars, marked by frequent meteorite and asteroid impacts, and the possible presence of abundant surface water. This period likely occurred around 4100 to 3700 million years ago, a time when large impact basins formed on both the Moon and Mars. Scientists believe that during the Noachian, Mars had a denser atmosphere and a climate that may have been warm enough at times to allow rainfall.

Noachian-aged areas on Mars are considered excellent landing sites for spacecraft searching for fossil evidence of life. During this time, large lakes and rivers existed in the southern hemisphere, and an ocean may have covered the northern plains. Extensive volcanism built up the Tharsis region, releasing gases into the atmosphere and producing clay minerals that formed under conditions that could support microbial life.

Today, Mars is a cold, dry desert, making the Noachian period especially interesting for scientists studying the planet's past climate. While there is strong evidence for water on early Mars, exactly how and when this water existed remains a topic of debate. Some researchers think the climate was mostly cold and icy with brief warm periods, while others suggest there were occasional rainy periods warmed by special atmospheric conditions. Regardless, it seems the Noachian climate was not uniformly warm and wet, with much of the river and lake activity happening toward the end of this period.

Description and name origin

The Noachian System and Period is named after Noachis Terra, which means "Land of Noah". This is a heavily cratered area west of the Hellas basin on Mars. The Noachian surfaces are very hilly and rugged, looking similar to the lunar highlands. These areas have many old craters and are covered with materials thrown out by impacts. Large impact basins also uplifted parts of the ground, creating mountainous areas.

Noachian-aged units cover about 45% of Mars, mostly in the southern highlands but also in places like Tempe and Xanthe Terrae, Acheron Fossae, and near the Isidis basin (Libya Montes). This period had many large impacts, making the surface very cratered.

Noachian chronology and stratigraphy

Martian time periods are determined by studying the planet's surface using images from spacecraft. Scientists look at features like texture, color, and landforms to group areas into different units. These units help experts figure out the order of events in Mars' history.

The Noachian is one of these time periods on Mars. It is known for many impacts from space rocks and possibly lots of water on the surface a long time ago. Experts aren't exactly sure when the Noachian happened, but it was likely between 4100 to 3700 million years ago. This was a busy time for impacts, creating many big craters and basins on Mars.

Mars during the Noachian Period

The Noachian Period on Mars was a time of great change, marked by frequent impacts from space, erosion, and the possible presence of water. This period is known for its high rates of meteorite and asteroid impacts, which shaped the planet's surface. These impacts may have fractured the planet's crust and created deep layers of broken rock, allowing water to seep deep underground.

During this time, Mars also experienced significant erosion and the formation of valleys. Many areas show signs of valleys that look like river systems on Earth, suggesting that water may have flowed across the planet’s surface. These valleys are most common in older areas, hinting that Mars might have had a wetter and possibly warmer climate long ago. There is also evidence that large lakes and possibly oceans existed, especially in low-lying areas, adding to the idea that Mars could have been a place where water was more common than it is today.