A new experiment simulating conditions in deep space reveals that the complex building blocks of life could have been created on icy interplanetary dust and then carried to Earth, providing raw materials for the organic chemistry needed for life.
The experimenters showed that conditions in space are capable of creating complex dipeptides – linked pairs of amino acids – that are essential building blocks shared by all living things. The discovery raises the possibility that these molecules were brought to Earth on a comet or possibly meteorites, catalyzing the formation of proteins (polypeptides), enzymes and even more complex molecules, such as sugars, that are necessary for life.
While scientists have discovered basic organic molecules, such as amino acids, in numerous meteorites that have fallen to Earth, they have been unable to find the more complex molecular structures that are prerequisites for our planet’s biology. As a result, scientists have always assumed that the really complicated chemistry of life must have originated in Earth’s early oceans.
In an ultra-high vacuum chamber chilled to 10 degrees above absolute zero (10 Kelvin), researchers simulated an icy snowball in space including carbon dioxide, ammonia and various hydrocarbons such as methane, ethane and propane. When zapped with high-energy electrons to simulate the cosmic rays in space, the chemicals reacted to form complex, organic compounds, specifically dipeptides. The organic residues were then analyzed with an instrument designed for ultrasensitive detection and identification of small organic molecules in the solar system. The analysis revealed the presence of complex molecules – nine different amino acids and at least two dipeptides – capable of catalyzing biological evolution on earth.