The process of water molecules becoming trapped in asteroid minerals and surviving an impact on Earth is still a topic of active scientific research, but I can provide you with some current understanding and theories.
Water is believed to have been present in the early solar system in the form of ice, primarily in regions beyond the frost line where temperatures were low enough for water to freeze. Asteroids that formed in these regions, such as in the outer regions of the asteroid belt or in the Kuiper Belt, could have contained significant amounts of water ice.
There are a few mechanisms through which water molecules could have become trapped in asteroid minerals. One possibility is through a process called adsorption, where water molecules adhere to the surfaces of minerals. Another mechanism is the incorporation of water molecules during the formation of minerals themselves. For example, certain minerals, like clays and hydrated silicates, have a structure that allows them to hold water within their crystal lattice.
When an asteroid containing water-bearing minerals impacts the Earth, several factors contribute to the survival of the water molecules. The size of the impacting asteroid plays a crucial role. Small asteroids, upon impact, may be vaporized or destroyed, leading to the release of the trapped water molecules into the atmosphere. However, larger asteroids have more mass and can penetrate deeper into the Earth's crust, preserving some of the water-bearing minerals from the extreme temperatures and pressures associated with the impact.
Additionally, the location and angle of impact can influence the survival of water-bearing minerals. Impact events that occur in regions with shallow water tables or in areas with porous rocks can facilitate the preservation of water molecules. The impact-generated shock waves can also cause fracturing and melting of surrounding rocks, creating temporary pockets where water can be preserved.
It's important to note that the specific mechanisms and the extent to which water molecules survive an impact are still being studied. Scientists use various methods to investigate these processes, including laboratory experiments, computer simulations, and analyzing samples from meteorites that have fallen to Earth. These studies contribute to our understanding of the origins of water on Earth and its potential role in the emergence of life.