New NASA research suggests that creating the building blocks of life might not necessary be as hard as previously assumed. This research means that certain components of those building blocks could have been delivered to Earth in the form of comets and meteorites. The research also advocates the idea that these building blocks could be produced in different manners. This means that certain compounds can be made in either cold or hot environments.
While similar research has been published in years past with inconclusive results, time will tell if this team has gotten it right this time around. I have no doubt these findings will be heavily scrutinized (especially in terms of contamination) as with previous studies – the early Murchison meteorite research comes immediately to mind. For the time being, I’m hopeful but not yet convinced. Either way, this study has merit and is worthy of further examination.
Meteorites contain a large variety of nucleobases, an essential building block of DNA. Artist concept credit: NASA
The NASA Goddard Space Flight’s Astrobiology Analytical Laboratory analyzed a number of meteorite samples that had experienced high temperatures. These particular objects had compounds that were similar to amino acids. These acids are used to make proteins. Previously, it was understood that these compounds could only form at relatively low temperatures. Interestingly enough, the new class of reaction is similar to the type of chemical reaction that was used to process coal into gasoline to overcome fuel shortages during the Second World War.
The original experiments that showed a connection between Fischer Tropsch type reactions and amino acids were preformed a long time ago. Meteorites contain several types of nucleobases and the team eventually wants to search for amino acids in all of the known carbon-rich meteorite groups. They have actually expressed feelings that suggest it would be strange if they didn’t find any further amino acids.
“Although we’ve found amino acids in carbon-rich meteorites before, we weren’t expecting to find them in these specific groups, since the high temperatures they experienced tend to destroy amino acids,” said Dr. Aaron Burton, a researcher in NASA’s Postdoctoral Program stationed at NASA Goddard. “However, the kind of amino acids we discovered in these meteorites indicates that they were produced by a different, high-temperature process as their parent asteroids gradually cooled down.” Burton is lead author of a paper on this discovery that appeared March 9 in Meteoritics and Planetary Science (reference below).
The team believes the majority of the amino acids they found in the 14 meteorites were truly created in space, and not the result of contamination from terrestrial life, for a few reasons. First, the amino acids in life (and in contamination from industrial products) are frequently linked together in long chains, either as proteins in biology or polymers in industrial products. Most of the amino the amino acids discovered in the new research were not bound up in proteins or polymers. In addition, the most abundant amino acids found in biology are those that are found in proteins, but such “proteinogenic” amino acids represent only a small percentage of the amino acids found in the meteorites. Finally, the team analyzed a sample of ice taken from underneath one of the meteorites. This ice had only trace levels of amino acids suggesting the meteorites are relatively pristine.
The experiments showing FTT reactions produce amino acids were performed over 40 years ago. The products have not been analyzed with modern techniques, so the exact distributions of amino acid products have not been determined. The team wants to test FTT reactions in the laboratory using a variety of ingredients and conditions to see if any produce the types of amino acids with the abundances they found in the 14 meteorites.
What are your thoughts? Is it possible that life came about as a result of a meteorite bringing “alien compounds” to Earth?
BURTON, A., ELSILA, J., CALLAHAN, M., MARTIN, M., GLAVIN, D., JOHNSON, N., & DWORKIN, J. (2012). A propensity for n-ω-amino acids in thermally altered Antarctic meteorites Meteoritics & Planetary Science DOI: 10.1111/j.1945-5100.2012.01341.x
NASA – National Aeronautics and Space Administration. (2012, March 9). NASA. Retrieved March 15, 2012, from http://www.nasa.gov/topics/solarsystem/features/life-components.html