The Mysteries of the Moon. Park 5

The face of the Moon has long fascinated us with its alien pits and pockmarks. And with almost no atmosphere or water to alter their appearance, craters retain their original form for billions of years. Now, Japan’s Kaguya orbiter is finding new clues in this ancient landscape, clues that could change everything we know about the origins of life on Earth.

Dr. Junichi Haruyama said: “It’s now possible to study the number of craters in detail, providing us with information on when small celestial bodies hit the Moon, as well as their mass and quantity. Kaguya has helped us significantly boost such information”.

Scientists determine the age of a crater by analyzing its state of degradation compared with others around it. They then measure its width and depth. Charting the size and age of the craters reveals an interesting pattern, a spike in Moon impacts around 3.8 to 4 billion years ago. But what caused this sudden peak? Scientists once believed that comets crashing in from the outer solar system made most of the Moon’s craters. But that wouldn’t explain the spike in activity for billion years ago. Dr. Fumi Yoshida thinks she’ found the real culprits—asteroids. Most of these small planetary bodies orbit in a belt between Mars and Jupiter. And, they’ve been there since the Moon was formed, Dr. Yoshida uses a highly advanced telescope to measure more than a thousand of these asteroids. Then she compares them against the lunar craters formed 3.8 to 4 billion years ago. To her astonishment, the sizes match almost perfectly.

Dr. Fumi Yoshida said: “The size distribution of craters is like a fingerprint. And so is the size distribution of asteroids. Since the fingerprints matched, we can believe that numerous asteroids collided with the Moon some 3.8 billion to 4 billion years ago”.

But why the sudden spike in activity? Four billion years ago, Jupiter’s orbit shifts slightly. This unleashes thousands of asteroids from the belt and sends them hurtling toward the Moon…and the Earth, but with much different results. Dr. Takeshi Kakegawa sets up an experiment to simulate what might have happened when asteroids hit this planet. Asteroids are largely composed of iron, so Kakegawa’s team mixes that element carbon, water and nitrogen, very common substances on Earth 4 billion years ago. They’re sealed together in a container. Next, Kakegawa simulates the massive impact of an asteroid strike on Earth, by firing the container at almost 2000 miles an hour. The projectile unleashes a massive burst of energy on the chemicals inside. Dr. Kakegawa analyzes the chemicals and makes an amazing discovery. In addition to the original iron and nitrogen, a mysterious new substance forms. The team discovers that this material is an amino acid, one of the building blocks of life. This astounding revelation may finally explain one of the greatest mysteries facing science, the origins of life on this planet.

Dr. Takeshi Kakegawa said: “The Earth had all the necessary materials for the creation of life, such as carbon and nitrogen. But how were they combined? That was a question that puzzled us. But now we’ve come to believe that fragments from asteroids bursting on impact provided the massive energy necessary to merge the substances”.

Dr. Kakegawa comes up with a scenario for the evolution of life on Earth. 4 billion years ago, oceans rich in carbon and nitrogen cover most of the planet. When the asteroid storm strikes, the impact energy melts the iron and sparks a strong chemical reaction with the carbon and for life on earth, nitrogen. And suddenly, amino acids are born, the key ingredient for life on Earth, in all its evolving forms. The ancient Moon has no such oceans, so while the crashing asteroids dramatically shape the lunar landscape, they can never generate the spark of life. Indeed, this barren place hardly seems hospitable to human living conditions, but that’s all changing. After forty years, man is going back to the Moon, this time, to stay.