life on Earth – astroengine.com

Let The Planet Seeding Begin! Comets Have Amino Acids Too…

comet_tempel

Yesterday, NASA announced exciting news about a discovery made by a NASA mission that did a cosmic dance with comet Wild 2 back in 2004. The Stardust mission managed to scoop an amino acid called glycine from the comets dusty tail, thereby proving it’s not just asteroids that contain this critical ingredient for life.

“It’s not a particularly unexpected discovery that glycine is in a comet — we’ve found amino acids in meteorites before — but it does show that comets are another way that amino acids could have come to Earth,” lead researcher Jamie Elsila, with NASA’s Goddard Space Flight Center, told Irene Klotz from Discovery News.

Elsila and colleagues are responsible for developing a technique to extract and study the deposits of glycine from the aluminium foil that lined the probe’s collection plates. They confirmed the glycine was in fact of extraterrestrial origin (rather than contamination here on Earth), as the carbon atoms in the glycine molecules had an extra neutron in the nucleus. This means the glycine was formed in space.

“We see in this comet that amino acids were forming at the earliest time in our solar system,” Mike Zolensky, a comet dust researcher from NASA’s Johnson Space Center in Houston, said.

Zolensky suspects that heat from the radioactive decay of short-lived particles melted a piece of comet ice laced with organic compounds and water. This may have allowed the cosmic amino acid to form.

Now that an amino acid has been scraped off the collection plate of the Stardust mission, it would appear the building blocks for life are widely available throughout the Solar System (assuming comet Wild 2 isn’t a special case). Asteroids contain amino acids, as do meteorites, now it looks as if comets carry the building blocks for life too. This means early-Earth certainly had plenty of opportunities to acquire extra-terrestrial sources of amino acids…

Source: Irene Klotz, Discovery News Space Correspondent

Laboratory Ice Links Comets with Life On Earth

Artist impression of the nucleus of Comet Tempel (NASA)

It is an established theory that comets may have, in some way, seeded life on Earth. Some extreme ideas support the panspermia concept (where bacterial organisms hitched a ride on comets, asteroids or some other planetary debris, spreading life throughout the Solar System), while others suggest comets may have contributed the chemical building blocks essential for life to form 4 billion years ago. We know these icy bodies are also awash with organic compounds, so it’s not a huge leap of the imagination to think comets may have donated life-making material to the early Earth.

In an effort to study cometary material and its possible influence for nurturing early life on Earth, Prof. Akiva Bar-Nun of the Department of Geophysics and Planetary Sciences at Tel Aviv University has been creating his own comets in the laboratory. By doing this, Bar-Nun is hoping to gain a better perspective on how comets acquired their composition of the noble gases Argon, Krypton and Xenon.

The proportion of these elements are found in the Earth’s atmosphere, but are not thought to have originated from the rocky material our planet consists of. By understanding the proportions of these elements that formed in the icy laboratory environment, if the proportions match that of what we’ve measured on Earth, it goes to some way in explaining how comets formed in space and how they delivered organic compounds to the surface.

“Now if we look at these elements in the atmosphere of the Earth and in meteorites, we see that neither is identical to the ratio in the sun’s composition,” said Bar-Nun. “Moreover, the ratios in the atmosphere are vastly different than the ratios in meteorites which make up the bulk of the Earth.”

“So we need another source of noble gases which, when added to these meteorites or asteroid influx, could change the ratio. And this came from comets.”

Prof. Bar-Nun and his team carried out the research using a comet-making machine unique to Tel Aviv University, and although the original press release is light on the details, it is assumed the chemical composition of the early Solar System was recreated and then deep-frozen.

Comets bombarded the Earth 4 billion years ago. Organic chemicals were therefore deposited, possibly kick-starting life (NASA)

Comets formed some distance from the Sun (and a vast number of them populate the Oort Cloud), water vapour would have condensed and frozen, in temperatures as low as -250°C, trapping a primordial collection of chemicals inside their dusty, icy interiors. Some time after, these comets may have fallen into the inner Solar System, many impacting the Earth. Amino acids may have been introduced to the surface and oceans, or vital chemical components from the comets combined with chemicals already on Earth and life was sparked. When this happened, these comets would have left a chemical fingerprint.

Bar-Nun’s team were successful in creating their own synthetic comet, freezing water vapour, creating a natural ratio between the three elements. Then a link could be made, from the laboratory comet, with the very definite noble gas proportions, and the proportions of these gases found in the atmosphere.

“The pattern of trapping of noble gases in the ice gives a certain ratio of Argon to Krypton to Xenon, and this ratio — together with the ratio of gases that come from rocky bodies — gives us the ratio that we observe in the atmosphere of the Earth,” added Bar-Nun.

Judging by the information available (the paper is published in the journal Icarus), Bar-Nun’s research has provided evidence that comets left a unique ratio of stable noble gases in the atmosphere, a ratio of necessary materials for life to eventually form.

Source: Tel Aviv University, EurekAlert via @Avinio

Could Extraterrestrial Genes Be Like Ours?

DNA and amino acids. Not just a terrestrial thing? (©CG4TV)

This is probably one of the biggest questions that hang over science fiction story lines: Will extraterrestrials have any resemblance to Life As We Know It™? To be honest, to toy with the thought of anything other than carbon-based life is pure conjecture, just because there might be some other form of life (such as silicon-based creatures), doesn’t mean there is (doesn’t mean there isn’t, either). So, here we are with the only form of life we know and understand, carbon-based life that was somehow spawned via a crazy mix of amino acids and some astronomical or terrestrial event that sparked the formation of prokaryotes (a.k.a. the simplest single-celled speck of life) some 4 billion years ago.

So we have an understanding of what formed life on Earth, perhaps if we look for the traces of evidence that evolved into Life As We Know It™ we can gauge whether extraterrestrial life has-formed/is-forming/will-form elsewhere in the observable Universe. From simulations of Earth evolution, scientists have predicted that 10 types of amino acids should form with the planet. These 10 amino acids are found inside the proteins of all living things on Earth. The same 10 amino acids have been found inside meteorites. Therefore, we already have a connection with the amino acids we find here on Earth and amino acids found in chunks of rock from elsewhere in the Solar System.

Now, a group of Canadian researchers have found that the same 10 amino acids are readily available elsewhere in the cosmos. Does this mean the components for life are common, not only on Earth, in the Solar System, but also in the Milky Way (and beyond)? It looks like it…
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