Of Molecules and Men
Atoms and molecules are tiny but can have a big influence on the habitability of planets and astrobiologists’ theories about them.
Hydroxyl ions (one oxygen and one hydrogen) are highly reactive ions formed by the breakdown of ozone by the sun. Science Daily reported that others are formed at night by a different process. This process was not observed till scientists at the University of Pennsylvania found a short-lived intermediate. Hydroxyl ions act as the “atmosphere’s detergent,” the article says, taking the initial steps in the breakdown of hydrocarbons and other pollutants.
Water is, of course, the ultimate prerequisite for life in the minds of most astrobiologists – so much so, that they think “life” whenever they find ice (see hydrobioscopy). The latest story being told about stars and our early solar system is that water is older than the sun. Scientists at the Carnegie Institute of Washington, reported Live Science, did not actually observe water before the sun. They just figured with their models that it had to be, or else the ratios of heavy water (containing deuterium instead of hydrogen) wouldn’t work.
“The implications of our study are that interstellar water-ice remarkably survived the incredibly violent process of stellar birth to then be incorporated into planetary bodies“study lead author Ilse Cleeves, an astronomy Ph.D. student at the University of Michigan, told Space.com….
“A significant fraction of Earth’s water is likely incredibly old, so old that it predates the Earth itself,” Cleeves said. “For me, uncovering these kinds of direct links between our daily experience and the galaxy at large is fascinating and puts a wonderful perspective on our place in the universe.“
Polonium-209 is an atomic isotope, not a molecule. It made news recently by getting a new age. The old half-life was 102 years. That has been increased by 25%, PhysOrg says, to 125.6 years. “The difficulty in measuring the particular Po-209 half-life arises from its scarcity in pure form, the long length of its half-life, and the specific types of radiation involved in its decay.” Po-209 has long been used as a tracer for geophysical processes. What effect might this change have? “Because sediment cores are used for determining human impact on the environment over the past century, the new measurement could impact these studies as well as other environmental measurements and biological assays.” The article did not discuss whether this revision would impact half-life measurements of longer-lived isotopes used in radiometric dating.
Cellulose is a molecule that is stronger, ounce-for-ounce, than steel, Science Daily says. It is also the most abundant organic compound on earth—a primary component of wood and plant stems that keeps plants upright. It is also indigestible except by bacteria. Purdue University scientists recently determined the structure of the enzyme, cellulose synthase, that makes cellulose. This knowledge might help bioengineers “make new kinds of natural products to replace those we now make from oil.”
Isopropyl cyanide has been found in space, Cornell University announced. What does that imply? It’s big news for astrobiologists, who feel that it shows that branched molecules can form naturally. Many amino acids have branching parts. “The branched carbon structure of isopropyl cyanide is a common feature in molecules that are needed for life — such as amino acids, which are the building blocks of proteins,” the press release says. “This new discovery lends weight to the idea that biologically crucial molecules, like amino acids that are commonly found in meteorites, are produced early in the process of star formation — even before planets such as Earth are formed.” The BBC News really pushed the life angle in its coverage.
Elementary, my star flotsam: How do stars make the elements? Arizona State wants to know. It has its own version of Genesis:
In the beginning, all was hydrogen – and helium, plus a bit of lithium. Three elements in all. Today’s universe, however, has nearly a hundred naturally occurring elements, with thousands of variants (isotopes), and more likely to come.
ASU will be joining with other universities to figure out how elements are made by supernovae and “chemical evolution” after the big bang (for problems with getting lithium from the big bang, see the 9/15/14 entry) . According to current theories of nucleosynthesis, stars “crank out carbon, nitrogen, oxygen and all those good things that make you and me.” This has been common thought for decades. “While the broad outline is clear, details are a lot murkier,” ASU astrophysicist Frank Timmes admits. We also don’t know how the first stars made of hydrogen and helium did it, because “all those stars are gone”. Our sun is made of elements that didn’t exist in the big bang, he explains, so our sun must be the end product of “many, many previous generations of stars”. How many?
Timmes explains, “A typical massive star, in round numbers, lives about a million years. The Big Bang occurred about 7 billion years before the sun formed. I need a thousand generations of massive stars to get us to a billion years, so I need on the order of 10,000 generations of massive stars to get one with the sun’s composition.”
The whole theory relies on models of supernovas. Those are observable, but the underlying mechanisms and the processes of nucleosynthesis are not. “In a loose, hand-waving sense, we know that stars explode, of course, but exactly how it happens isn’t well-known or understood.”
If you can keep your head with observable science when all the experts about you run are losing theirs with hand-waving models based on evolutionary assumptions leading to just-so stories, yours is the Earth and everything that’s in it, and—which is more—you’ll be a Man, my son!