Have you ever pondered the possibility of extraterrestrial life? This question has plagued scientists and intellectuals for years, even centuries. Amid the numerous research endeavors directed toward space exploration and discovering signs of life beyond the bounds of our planet, breakthrough results were recently reported about organic material recovered from the Bennu asteroid, which orbits the sun.
Researchers came together from the U.S., the U.K., Australia, France, Germany, and Japan to collaborate in analyzing and identifying the material brought back from the asteroid Bennu by the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer mission, also known as the OSIRIS-REx. This mission succeeded in bringing back carbon-rich astromaterial with little to no contamination by Earth’s biosphere. As soon as NASA researchers could get their hands on the material, it was tightly secured and stored in unreactive nitrogen gas, to prevent Earth’s atmosphere from chemically altering the substances.
Carbon is the building block of life, so this is already a good indication of finding organic molecules typically present in biological material. Samples consisting of fine to intermediate-sized particles (100-500 µm) were characterized using elemental and stable isotopic analyses for the detection of carbon, nitrogen, and hydrogen. Further, tools like optical and ultraviolet fluorescence microscopy, which provide information on how a substance interacts with light, were used to study particles that were particularly bright and reflective. Lastly, the all-pervasive mass spectrometry technique provided valuable insight into the various organic molecules present in the Bennu samples.
“The mass spectra showed data corresponding to 16,000 kinds of organic molecules containing carbon, hydrogen, nitrogen, oxygen, sulfur, and magnesium.”
The mass spectra showed data corresponding to 16,000 kinds of organic molecules containing carbon, hydrogen, nitrogen, oxygen, sulfur, and magnesium. Further, 33 amino acids were identified in the samples. Fourteen of these amino acids are specific to Earth’s terrestrial biology. The other nineteen are considered rare and not present in any known proteins. An interesting implication of the presence of these amino acids is that all of the chiral ones were present in racemic or near-racemic mixtures. Chiral refers to molecules that are asymmetric and are not superimposable images of each other. These kinds of molecules can exist in mixtures of equal proportions, which is called a racemic mixture. On Earth, early life favored left-handed-based proteins or left-handed chirality. However, the amino acids from Bennu had no favored chirality; they were racemic, confirming the molecules’ extraterrestrial origin and their underdeveloped state of life.
Because Bennu is hypothesized as only a fragment of a larger, more primitive icy body, the organic material is theorized to have developed in room-temperature pockets inside of the larger “mother” body. So, when Bennu broke off 65 million years ago, the organic material went right along with it, abruptly halting the biotic development of the material. This snapshot of prebiotic life provides invaluable information about astrobiology and the emergence of life on Earth.
Bennu is just one asteroid we have been lucky enough to encounter, and these biotic developments are likely happening deep within other celestial bodies as well. In this way, there might even be some random pocket of organic material right now that is slowly growing into something we could one day recognize as life.
