Like a time capsule, the pristine asteroid that arrived on Earth on September 24 contained much more than just rocks and dust. It also contained water and carbon, which NASA on Thursday revealed are crucial ingredients for life. It’s the first time that such a large amount of these molecules have been found in an asteroid sample, NASA said during a press event. The samples, retrieved by the OSIRIS-REx mission, were “loaded with organics,” senior scientist Daniel Glavin said, calling the material an “astrobiologist’s dream.”
The space agency revealed that the asteroid 101955 Bennu is more than 4.5 billion years old and has changed little since its formation. The asteroid is about half a kilometer in diameter and contains many of the same materials that make up our solar system. Its low temperature, which is a result of its age and size, makes it easier to study the chemical reactions that led to the evolution of our planet.
Asteroid explorers were excited to discover that Bennu has the same chemical makeup as other asteroids and meteoroids collected by spacecraft. But the real discovery was that it is chock-full of carbon, essential for forming organic compounds—the building blocks of life.
Nasa says its early analysis has found that a sample of the asteroid contains 4.6 percent carbon by weight, more than the percentage in the Earth’s oceans and atmosphere. The asteroid is also rich in water, another key ingredient for creating organic molecules.
These discoveries are based on the first data received from the mission’s two science instruments, which have been in operation since December. After a seven-year roundtrip journey, the OSIRIS-REx spacecraft landed on Bennu to reach the asteroid and scoop up a sample with its robotic arm. The samples were then delivered to the Johnson Space Center in Houston, where scientists began analyzing them.
One of the most important things scientists will look for is the ratio of hydrogen to deuterium in the asteroid sample. This will tell them if the samples came from the same source as the water in the Earth’s oceans. The team is also looking for amino acids, the building blocks of proteins needed for life.
In addition to discovering traces of organic chemicals, scientists hope to learn more about the origin of our solar system, which was seeded with carbon by asteroids and then accreted into its current form by gravity. They will look for evidence of this in the asteroid sample by studying its structure and how it has changed over time. Scientists will also analyze the asteroid to determine whether it is made of pure rock or a clump of sand or gravel. This information is critical because it could help determine if Bennu is a “contact binary” asteroid—one that may one day collide with the Earth or one that will miss us.
