For the last five decades, scientists have been finding elements of the building blocks of life in meteorites -- space rocks formed when two asteroids collide -- but earthly contamination was always a potential explanation against extraterrestrial origin. Until now.
Scientists have confirmed that nucleobases, the building blocks of DNA and RNA, found in meteorites are in fact from space.
Here's the evidence scientists at NASA and the Carnegie Institution for Science believe confirms the extraterrestrial origin of these nucleobases:
- Nucleobase analogs were found in meteorites. These analogs are structurally similar to the nucleobases found in biology but these analogs are rare and often not found on Earth.
- Terrestrial soil and ice samples collected in Antartica and Australia where some of these metorites hit, did not show the same distribution of these nucleobases and no nucleobase analogs were present.
- In the lab, scientists studied the reactions of hydrogen cyanide, the products from which include nucleobases. The nucleobases from these lab reactions are similar to those found in the meteorites. Hydrogen cyanide is dispersed everywhere in space and is likely to cause reactions in the meteorite.
The video below explains the evidence supporting this finding:
[youtube http://www.youtube.com/v/1g7AKVZ3HC4?version=3&hl=en_US expand=1]
Scientists studied 12 meteorites and found nucleobases in 11 of them. Fox News has more details on the evidence:
"At the start of this project, it looked like the nucleobases in these meteorites were terrestrial contamination — these results were a very big surprise for me," study lead author Michael Callahan, an analytical chemist and astrobiologist at NASA Goddard Space Flight Center, told SPACE.com.
Lab experiments showed that chemical reactions of ammonia and cyanide, compounds that are common in space, could generate nucleobases and nucleobase analogs very similar to those found in the carbonaceous chondrites. However, the relative abundances of these molecules between the experiments and the meteorites differed, which might be due to further chemical and thermal influences from space.
This findings reveal that meteorites may have been molecular tool kits, providing the essential building blocks for life on Earth, said study co-author Jim Cleaves, a chemist at the Carnegie Institution of Washington.
"All this has implications for the origins of life on Earth and potentially elsewhere," Callahan said. "Are these building blocks of life transferred to other places where they might be useful? Can alternative building blocks be used to build other things?"
Previous research has revealed amino acids, the building blocks of proteins, in meteorites. Coupled with this more recent finding that the building blocks of genetic material are found extraterrestrially, it supports some scientists' theory that these materials could have contributed to the origin of life on Earth (for more on the creation debate, see our story here).
This news comes around the same time scientists have identified what they think is the potential for rare flowing water on Mars.
In the last 15 years, scientists believe they have enough evidence to support historical water on Mars as well as frozen water. Recent observations from NASA's Mars Reconnaissance Orbiter revealed what scientists think may be flowing water on the planet.
Since all life on Earth needs water to survive, the potential of liquid water on Mars is a "big deal."
"Yeah it's a big deal," said Robert Zubrin, president and founder of the Mars Society. "The idea that there's liquid water on Mars today at the surface means that there could be life on Mars today at the surface."
The orbiter made observations of seasonal changes of slopes carved into the planet's surface. Scientists hypothesize that the streaks they're seeing change in images could be briny water that comes and goes with the seasons.