Did comets help start life on Earth? A new study questions the idea and scientists are baffled

How often do you think about the start of life on Earth? Not much. But sometimes a kid may ask you that question or you see something strange in the sky. Watching a video or movie about aliens or news on life of other planets can take your thoughts there. You pick up your phone and scroll through multiple theories about how life could exist. Scientists have been trying hard to find out what really happened and take us much closer to reality.

Now there is one scientific theory that comets may carry chemicals towards Earth which sounds like a direct delivery from space and may have contributed to life on Earth. Scientists have long considered whether such deliveries helped life begin billions of years ago. But carrying something and delivering it safely are different things.

Imagine dropping a bag of eggs from a rooftop. The eggs reach the ground, but most will not arrive intact. According to a report by CNN, a new study has suggested that comets faced a similar problem. The force of their crashes may have destroyed chemicals that could otherwise have helped life on Earth get started.

Why did scientists think comets helped life begin?

Comets contain ice and dust. They also carry organic molecules, which are carbon-based chemicals. Some of those chemicals can take part in reactions that produce life’s building blocks. When scientists found them in comets it raised the possibility that may be space has sent the ingredients that early Earth needed. The new research asks whether enough of those ingredients could survive the delivery.

The study appeared in Scientific Reports on October 28. Richard Anslow led the research while working at the University of Cambridge’s Institute of Astronomy.

Which chemical did the researchers study?

The team focused on hydrogen cyanide, usually shortened to HCN. Although poisonous to humans, HCN interests scientists studying life’s beginnings. Under suitable conditions, it can help produce molecules needed for living things.

Scientists have detected HCN in comets. Its presence in those comets does not really mean that it contains life. Think of flour sitting in a kitchen. Flour can help make bread, but it is not bread. Similarly, a chemical ingredient is not a living organism.

What happens when a comet crashes into Earth?

A fast-moving comet hits with enormous force and then the crash creates intense heat and pressure. Those conditions can break apart the chemicals inside it. Researchers used computer models to examine the journey through Earth’s atmosphere and the crash itself. They considered whether enough HCN could remain intact.

A successful delivery needed the comet to arrive at a suitable speed and angle. Most did not meet the necessary conditions. Surviving the crash was not enough, either. The chemical had to be collected somewhere useful. In an ocean, it could spread through too much water to support the required reactions.

What did the computer simulations find?

The team ran 100,000 simulations of possible comet bombardment histories. In 54% of those runs, no crash successfully delivered the required HCN. Comets could still strike Earth without making a successful chemical delivery.

A few lucky deliveries remained possible. They would also need to happen somewhere with the other ingredients required for life-building chemistry. The researchers therefore describe the process as unlikely. They have not proved it never happened.

Does that mean comets played no role?

No. Other scientists say the question remains open. Earth scientist Queenie Chan told CNN that chemicals might react inside a comet before it reaches Earth. Some resulting compounds could survive a crash more easily.

The study also leaves other explanations worth exploring. Important chemicals may have formed on Earth itself. Asteroids could have contributed material too.

Mars offers another question. Comets can hit it more slowly, potentially giving fragile chemicals a better chance of surviving. None of these possibilities tells us exactly how life began.