Did Life Begin from Space?

Can Life Survive Space?

One of the critical features of all panspermia theories is that they are dependent on the ability of complex organic molecules—or even microbial life itself—to survive transmission through space.  Interplanetary and interstellar space are extremely harsh environments. These environments are not just cold at near-absolute zero temperatures, but also filled with life-killing radiation.  Radiation is deadly to life because it breaks chemical bonds, causing complex organic molecules to fall apart, damages cells to the point of death, and alters DNA generating mutations, very few of which result in viable forms.  This raises the serious issue of whether organic molecules, DNA/RNA, and microbial life forms can survive in space for the millions of years required for panspermia to take place.

Is there evidence that meteorites that derive from ejecta of other planets may hold life or at least complex organic chemicals that are precursors to life? As it happens, scientific evidence does exist for meteorites as transports for life.

In August, 2011, NASA announced that definitive proof had been found that a certain class of meteorites, called carbonaceous chondrites, carry amino acids (the starting point for proteins and DNA) to the Earth’s surface.  This has been known since the 1960s. Unfortunately, proving that DNA discovered on these meteorites was not derived from contamination from DNA in the soils where the meteorite was discovered or from the handling of those who discovered the molecule has been very challenging (NASA, 10 August 2011).   

Analysis of one of the most pristine meteors, found in Tagish Lake in northern British Columbia, confirmed that the early solar system, when the asteroid belt between Mars and Jupiter, was formed, already contained a rich mixture of complex organic compounds. This mixture included amino acids, the building blocks of proteins, and monocarboxylic acid, another compound essential to life.  Since this asteroid is considered to be billions of years old, it is clear that these complex organic compounds can survive in space for extremely long periods depending on how the meteorite’s geology formed (University of Alberta, 09 June 2011; Herd, et al., 2011). 
In the case of this particular meteorite, scientists realized that the asteroid was created with both the organic compounds at the time of early solar system formation, and with ice, also present in the early solar system.  As the ice accumulated, it also warmed and melted. The liquid water became the medium that transformed the organic molecules into the pre-biotic complex compounds of amino acids.  The asteroid orbited the sun for billions of years, and finally impacted on Earth in January 2011. It was collected from a snow-covered frozen lake under the guidance of experts, and thus is considered uncontaminated by Earthly organic material (University of Alberta, 09 June 2011; Herd, et al., 2011).

This month, as this report is written, the extraterrestrial origin of the precursor molecules of life has been demonstrated conclusively.  Carnegie Institute’s Geophysical Laboratory carefully analyzed carbonaceous chondrites and discovered that they carried a complex mixture of nucleobases and nucleobase analogs (organic compounds that are very similar to the nucleobases that form DNA and RNA molecules).  Not only are those nucleobase analogs very rare on Earth, the surrounding material (ice and dirt from where the meteorite landed) held no such mixture of either the nucleobases or the nucleobase analogs.  Furthermore, the scientists attempted to construct the nucleobase analogs by combining ammonia and cyanide, both of which are common in space. They discovered that these nucleobase analogues concocted in their laboratory were similar to those in the meteorite. (Cody et al., 2011; Carnegie Institution, 04 April 2011).

Not only that, further analyses demonstrated that of the twelve meteorites studied, eleven of them had the life precursor molecules. It has now been shown that meteorites contain a wide variety of the compounds required for life including adenine, purine (DNA bases), and pyruvic acid and citric acid (chemicals required for a cell’s citric acid cycle, a requirement for life) (Cody, 2011; Witze, 10 August 2011; Carnegie Institution, 04 April 2011).