The LATE HEAVY BOMBARDMENT Stage in the Hadean Eon

Late Heavy Bombardment Stage

Last Updated: Aug 13, 2018

Space debris pelted Earth in the late heavy bombardment stage (LHB)

About 4 billion years ago, the Earth was in the late heavy bombardment stage.

Asteroids, comets and space debris pelted our young planet Earth.

Despite the harsh conditions, scientists believe the late heavy bombardment was responsible for supplying the Earth with water.

Also, these impacts may have given the boost it needed for the origin of life to start on Earth.

Evidence of the late heavy bombardment stage

You won’t find evidence of the impacts left behind from the late heavy bombardment stage on Earth.

This is because Earth recycles rocks through plate tectonics. In addition, it has undergone significant weathering and volcanism in this time span.

So this means these processes have erased any evidence of the late heavy bombardment here on Earth.

But we know the heavy bombardment stage in fact did happen because we can observe our solar system.

For example, we can see large craters on the moon which are scars from the late heavy bombardment. We also see impact evidence on other bodies in the solar system like Mercury.

Late heavy bombardment supplied water to Earth

The Earth was a violent place in its early stages of formation. Not only was Earth being pummeled by space debris, but heat flow was nearly 3 times as high as it is today.

Water may have existed early at this time. But any water would have evaporated quickly into space because of the intense heat.

In order for ice-rich comets to strike Earth and pool into oceans, cooling was a necessary step. Eventually, Earth did cool down at the start of the Archean Eon.

When Earth cooled down, water could condense. Instead of water evaporating into space, water had a chance to form oceans.

This is why scientists suggest that ice-rich comets were responsible for transporting water during the late bombardment stage.

The spark for the building blocks of life

What was the spark that built the chemical building blocks for life? Scientists believe the late heavy bombardment stage generated the boost for early life to emerge.

Scientists once believed the excessive heat in this eon sterilized Earth’s surface. In other words, microbes could not survive the harsh conditions on Earth at the time.

But the impacts from the late heavy bombardment could have created subsurface and underwater environments.

Within these hydrothermal vent habitats, any existing microbial life on Earth could have found refuge.

Scientists are trying to recreate these conditions and collisions that took place to reconstruct the origin of life.

This is because these first chains of DNA were the necessary building blocks for more complex life to form on Earth.

The late heavy bombardment stage (LHB)

About 4 billion years ago, asteroids, comets and space debris pelted our young planet Earth. It was a catastrophic period for early Earth

We have observed these impacts all around the solar system including our moon.

Scientists believe the late heavy bombardment stage supplied water to Earth.

In addition, these impacts were the spark needed to generate early life on Earth.

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