The findings of this study, published in the peer-reviewed academic journal ACS Central Science, features a first-of-its-kind experiment that looked at how the building blocks of life are formed.
The result was that the seeds that would sprout into life could very well have been created thanks to gamma rays.
Amino acids: The building blocks of life
Amino acids are basic organic compounds that come in a wide variety of forms. To most, the most important type is the alpha-amino acids, which help make up proteins.
However, as an early organic compound, it is thought that amino acids may play a key role in the origin of life on Earth alongside the other important building blocks of life such as carbohydrates, lipids and nucleic acids, alongside the role of important materials like carbon and water.
However, amino acids in particular stand out as being incredibly important. This is because they can be synthesized from inorganic compounds, provided the conditions are correct.
And as the famous 1952 Millery-Urey experiment proved, the conditions of early Earth may have been able to do just that – create amino acids out of wholly inorganic matter.
This was done through external sources of energy, and any number of possible things could have done it. It could have been lighting, bubble implosions, meteor entries or just radiation.
But that's just for Earth. What about elsewhere? Specifically, what about amino acids found on carbonaceous chondrite meteors and on asteroids?
We know that amino acids can be found on asteroids. In fact, some scientists have speculated that it was space rocks that may have brought amino acids in the first place, though we have never been sure.
Still, the question remains: How did amino acids get on these meteors and asteroids in the first place?
That is where this study comes in.
Led by Yokohama National University astrobiologist Yoko Kebukawa, this study built off the team's previous research that definitively identified two inorganic compounds common in asteroids that could synthesize into amino acids if the conditions were right: Ammonia and formaldehyde. In that prior research, they figured out that two things were needed for this transformation to take place: heat and liquid water. And they would need to come from somewhere.
The water part was very easy to figure out – all carbonaceous chondrites have water as well as ammonia and formaldehyde. But what about the heat? That would have been the catalyst for it all, but what was its source?
This new study presented the idea of gamma rays. How would gamma rays have gotten there? The answer is radioactive decay.
Certain atoms are radioactive, specifically isotopes. As it decays, it can create gamma rays, which would have essentially cooked the ingredients of ammonia, formaldehyde and water into amino acids.
In order to test this, Kebukawa and her fellow researchers decided to make gamma rays through the decay of radioactive cobalt isotopes and had the rays hit ammonia and formaldehyde.
Ultimately, a number of compounds were created, including amino acids.
The researchers further calculated how long it would take for amino acids to become incredibly abundant in a given meteor, and the answer was less than 100,000 years – and on a cosmic scale, that's a very short time. This, in turn, means that it is likely that amino acids were very common on these space rocks a long time ago.So, can amino acids be created by gamma rays emitted by decaying radioactive isotopes within asteroids in meteorites? Yes, it certainly seems that way. And it is possible, though unknown, that these amino acids could have arrived on Earth through these space rocks, thus planting the seeds of the living world we live in.
But all of this raises another big question: Why Earth? Why couldn't this have happened in other places in the solar system?
Certainly it is possible. In fact, who is to say it didn't happen in the past?
Speaking to Motherboard, Kubekawa specifically cited Mars and icy moons like Saturn's moon Enceladus as such places where this could have happened. However, it would have had to have been a long time ago, within the solar system's first few million years of life. After that, the gamma rays would have been depleted and it wouldn't have been possible.
But there are many other questions that can be asked as well. For example, amino acids are the building blocks of life but they aren't the only things. How did they form? Could gamma rays possibly help them form too?
Either way, future studies certainly have a lot to build on going forward.