Mars rocks keep colliding with Earth, but something doesn’t add up

Thousands of years ago, Earth was bombarded by Martian rocks, sent through space after being ejected from their home world by violent impacts or volcanic processes. But as we collect these small samples, scientists are starting to learn something interesting: The age of these Martian rocks doesn’t line up with what we know about the age of Mars as a whole. They are much younger.

Mars is really old. Scientists believe that the planet finished its formation about 4.56 billion years ago, that is, about 90 million years before our planet. Furthermore, evidence suggests that much of Mars’ surface is ancient. So, why do pieces of Martian rock appear so young?

They say the answer most likely lies in the constant bombardment of the surface of Mars with meteorites and asteroids. With nearly 200 bombardments creating 4-meter-deep craters each year, the surface of Mars is constantly spitting more rocks into space, some of which find their way to Earth. The reason the age of Martian rocks does not appear to be proportional is that younger rocks replace older rocks as they are ejected from the planet.

This means that younger rocks from beneath the surface, still being replenished by volcanic activity, are eventually exposed to the surface and thus become the projectiles that meteorites send into space. This is what a group of scientists explained in a research published in Earth and planetary sciences letters, It could help us understand why Mars rocks found on Earth appeared so early.

Understanding how Mars is changing — inside and out — is important as NASA and others prepare for the first manned missions to Mars. Furthermore, scientists are constantly looking for new ways to understand how planets formed within our solar system, and how this can teach us more about the evolution of the universe as a whole.