Year: 2021
Type: article
Abstract: NASA should design missions to Mars for the purpose of generating "Aha!" discoveries to jolt scientists contemplating the molecular origins of life.These missions should be designed with an understanding of the privileged chemistry that likely created RNA prebiotically on Earth, and universal chemical principles that constrain the structure of Darwinian molecules generally. BackgroundResearch to understand the origin of life is central to the NASA mission, and has been recognized as such for a half century.However, as many have noted, because of the antiquity of that event, laboratory research is poorly constrained by hard data.As a result, the field is characterized by the pursuit of idées fixes, half-hypotheses, and scripted reaction sequences, often for decades.Before his untimely death, Robert Shapiro likened such sequences to "a golfer who had successfully played a golf ball around an 18 hole course, [assuming] that the ball could then play the same course by itself, through a combination of the wind and other natural forces." 1 Further, scientists working on "origins" do not have easy access to "Aha!" discoveries that might productively jolt them from established lines of thinking.Such jolts are, of course, extremely useful in all other sciences.In particular, laboratory research for how life originated in the Solar System lacks strong constraints concerning the relevant environments at the relevant times on the relevant planet.If that planet is Earth, the oldest physical records come as zircons ~4.35 billion years old.These may entrap elements (e.g.Ce 3+ / Ce 4+ ) that indicate the redox states of fluids that they crystallized from, 2 trace elements (e.g.boron) that are proposed to constrain maturation of carbohydrates possibly relevant to RNA-first models for the origin of life, 3 and carbon, whose 12 C/ 13 C ratio might provide hints of a biosphere.4 Most of the rest of the physical record on earth before 4+ Ga has been destroyed by plate tectonics.This physical record is "not nothing".Further, it has been possible to integrate the scarce terran physical record with models for Solar System evolution, histories of planetary bombardment, 5 and models for planetary evolution late in accretion.To this is added analysis of late arriving materials in meteorites and limited samples from the Moon and other Solar System bodies.From this, we can arrive at privileged chemistry that almost certainly occurred in the redoxneutral atmosphere that most likely dominated in the Hadean.This included formaldehyde (perhaps 3 x 10 8 molecules formed per cm 2 every second in the Hadean atmosphere) 6 , and trace amounts of glycolaldehyde (perhaps one part per million of formaldehyde) 7 .These materials could not help have matured by well-known chemistry, 8 especially if the reactive aldehydes were
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W3082447039