Comets that crashed into Earth millions of years ago, might have originated amino acids, life's main ingredients, according to a research from Lawrence Livermore National Laboratory.

LLNL's Nir Goldman and his colleagues have found that molecules found in comets, like water, ammonia, methylene and carbon dioxide, might just be what started life on Earth, and published the discovery yesterday, in the online edition of Nature Chemistry.

What led them to this conclusion was their discovery that the sudden compression and heating of cometary ice crashing into Earth can cause complexes that resemble the amino acid glycine.

Scientists are looking for the origins of life on Earth for a long time and the latest theory that said amino acids formed from organic materials already present on the planet was contradicted by further research that established that the Earth's atmosphere contained mainly carbon dioxide, nitrogen and water.

Researchers carried out shock-heating experiments that proved that these three factors could not have created organic molecules for amino acid production.

Goldman said that “there is a possibility that the production or delivery of prebiotic molecules came from extraterrestrial sources.

“On early Earth, we know that there was a heavy bombardment of comets and asteroids delivering up to several orders of magnitude greater mass of organics than what likely was already here,” he added.

Comets can go from 1.6 to 56 kilometers in size and those that passed through the Earth's atmosphere heated up at the exterior but remained frozen on the inside, and on impact, the sudden compression generated a shock wave.

Shock waves cause very high pressures and temperatures, and so it was believed that life from the comet would not survive the blast.

Still, Goldman and his team found a way of proving that a collision could generate much lower temperatures.

“Under this situation, organic materials could potentially be synthesized within the comet’s interior during shock compression and survive the high pressures and temperatures,” he said.

“Once the compressed material expands, stable amino acids could survive interactions with the planet’s atmosphere or ocean.

“These processes could result in concentrations of prebiotic organic species ’shock-synthesized’ on Earth from materials that originated in the outer regions of space.”

The team made an experiment simulating a comet crashing into Earth, and concluded that as the material decompresses, there is a possibility that amino acids would form.

The research was funded by the Laboratory Directed Research and Development Program.