Which describes our understanding of flowing water on Mars? (a) It was never important. (b) It was important once, but no longer. (c) It is a major process on the Martian surface today.
How many of the five terrestrial worlds are considered “geologically dead”? (a) none (b) two (c) four
The correct answer and explanation is:
The correct answer for the understanding of flowing water on Mars is (b) It was important once, but no longer.
Explanation:
Flowing Water on Mars: Our understanding of Mars suggests that flowing water was important once but is not currently a major process on the Martian surface today. Evidence gathered from various missions, such as the Mars rovers and orbiters, has provided strong indications that liquid water existed on Mars billions of years ago. Features like ancient river valleys, lakebeds, and minerals that form in the presence of water strongly suggest a wetter and warmer past on Mars. This implies that flowing water played a significant role in shaping Mars’ surface during its earlier history. However, due to changes in Mars’ climate and atmosphere over time, liquid water is not stable on the surface today. The current environment on Mars is extremely cold and dry, with any liquid water likely existing temporarily as brines under specific conditions or as ice.
The presence of intermittent water flows or seeps has been detected in recent years, suggesting that some liquid water processes might still occur, albeit on a very limited and transient basis. These findings are important for understanding the potential habitability of Mars and its geological evolution over time.
Geologically Dead Terrestrial Worlds: The correct answer is (b) two.
Explanation:
In the context of the five terrestrial worlds in our solar system—Mercury, Venus, Earth, the Moon, and Mars—geologically dead refers to worlds that no longer exhibit active geological processes like volcanic activity or tectonic movement.
- Mercury: Mercury is considered geologically dead in the sense that its interior has likely cooled and solidified long ago, resulting in the cessation of volcanic activity and tectonic processes. Surface features suggest past volcanism and impacts, but no active geological processes are currently observed.
- Mars: Mars is also generally regarded as geologically dormant or dead. While evidence of past geological activity, such as volcanoes and ancient river valleys, is abundant, there is no active volcanic or tectonic activity observed today. The surface is primarily shaped by impact cratering and weathering processes rather than internal geological forces.
The other three terrestrial worlds—Venus, Earth, and the Moon—still exhibit active geological processes:
- Venus: Venus shows signs of ongoing volcanic activity and tectonic processes, including surface deformations and volcanic eruptions.
- Earth: Earth is geologically active with ongoing volcanic activity, tectonic plate movements, earthquakes, and erosion processes constantly reshaping its surface.
- Moon: Although less active than Earth, the Moon still experiences moonquakes and some minor volcanic activity, indicating residual geological processes.
Understanding which terrestrial worlds are geologically active or dead provides insights into the evolution of planetary bodies and their current states, influencing our understanding of planetary geology and potential habitability.