Asteroid 'time capsules' may help explain how life started on Earth

February 17, 2018, Georgia Institute of Technology
Nicolas Hud, director of the NSF-NASA Center for Chemical Evolution at the Georgia Institute of Technology. Hud will be a panelist at a press briefing "Asteroids for Research, Discovery, and Commerce" at 1 p.m. Central Time on Feb. 17 at the 2018 annual meeting of the American Association for the Advancement of Science (AAAS). Credit: Fitrah Hamid, Georgia Tech

In popular culture, asteroids play the role of apocalyptic threat, get blamed for wiping out the dinosaurs - and offer an extraterrestrial source for mineral mining.

But for researcher Nicholas Hud, asteroids play an entirely different role: that of time capsules showing what originally existed in our solar system. Having that information gives scientists the starting point they need to reconstruct the complex pathway that got started on Earth.

Director of the NSF-NASA Center for Chemical Evolution at the Georgia Institute of Technology, Hud says finding molecules in asteroids provides the strongest evidence that such compounds were present on the Earth before life formed. Knowing what molecules were present helps establish the initial conditions that led to the formation of amino acids and related compounds that, in turn, came together to form peptides, small protein-like molecules that may have kicked off life on this planet.

"We can look to the asteroids to help us understand what chemistry is possible in the universe," said Hud. "It's important for us to study materials from asteroids and meteorites, the smaller versions of asteroids that fall to Earth, to test the validity of our models for how molecules in them could have helped give rise to life. We also need to catalog the molecules from asteroids and meteorites because there might be compounds there that we had not even considered important for starting life."

Hud will be a panelist at a press briefing "Asteroids for Research, Discovery, and Commerce" on February 17 at the 2018 annual meeting of the American Association for the Advancement of Science (AAAS) in Austin, Texas. He will also be part of a session on February 18 on the topic, "Seeking the Identity and Origins of the First Polymers of Life."

NASA scientists have been analyzing compounds found in asteroids and meteorites for decades, and their work provides a solid understanding for what might have been present when the Earth itself was formed, Hud says.

"If you model a prebiotic chemical reaction in the laboratory, scientists can argue about whether or not you had the right starting materials," said Hud. "Detection of a molecule in an or meteorite is about the only evidence everyone will accept for that molecule being prebiotic. It's something we can really lean on."

The Miller-Urey experiment, conducted in 1952 to simulate conditions believed to have existed on the early Earth, produced more than 20 different amino acids, organic compounds that are the building blocks for peptides. The experiment was kicked off by sparks inside a flask containing water, methane, ammonia and hydrogen, all materials believed to have existed in the atmosphere when the Earth was very young.

Since the Miller-Urey experiment, scientists have demonstrated the feasibility of other chemical pathways to amino acids and compounds necessary for life. In Hud's laboratory, for instance, researchers used cycles of alternating wet and dry conditions to create over time. Under such conditions, amino acids and hydroxy acids, compounds that differ chemically by just a single atom, could have formed short peptides that led to the formation of larger and more - ultimately exhibiting properties that we now associate with .

"We now have a really good way to synthesize peptides with amino acids and hydroxy acids working together that could have been common on the early Earth," he said. "Even today, hydroxy acids are found with in living organisms - and in some meteorite samples that have been examined."

Hud believes there are many possible ways that the molecules of life could have formed. Life could have gotten started with molecules that are less sophisticated and less efficient than what we see today. Like life itself, these molecules could have evolved over time.

"What we find is that these compounds can form molecules that look a lot like modern peptides, except in the backbone that is holding the units together," said Hud. "The overall structure can be very similar and would be easier to make, though it doesn't have the ability to fold into as complex structures as modern proteins. There is a tradeoff between the simplicity of forming these molecules and how close these molecules are to those found in contemporary life."

Geologists believe the Earth was very different billions of years ago. Instead of continents, there were islands protruding from the oceans. Even the sun was different, producing less light but more cosmic rays - which could have helped power the protein-forming chemical reactions.

"The islands could have been potential incubators for life, with molecules raining down from the atmosphere," Hud said. "We think the key process that would have allowed these molecules to go to the next stage is a wet-dry cycling like what we are doing in the lab. That would have been perfect for an island out in the ocean."

Rather than a single spark of life, the molecules could have evolved slowly over time in gradual progression that may have taken place at different rates in different locations, perhaps simultaneously. Different components of cells, for example, may have developed separately where conditions favored them before they ultimately came together.

"There is something very special about peptides, nucleic acids, polysaccharides and lipids and their ability to work together to do something they couldn't have done separately," he said. "And there could have been any number of chemical processes on the early Earth that never led to life."

Knowing what conditions were like on the early Earth therefore gives scientists a stronger foundation for hypothesizing what could have taken place, and could offer hints to other pathways that may not have been considered yet.

"There are probably a lot more clues in the asteroids about what molecules were really there," said Hud. "We may not even know what we should be looking for in these asteroids, but by looking at what molecules we find, we can ask different and more questions about how they could have helped get life started."

Explore further: Could interstellar ice provide the answer to birth of DNA?

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22 comments

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someone11235813
1 / 5 (1) Feb 17, 2018
...small protein-like molecules that may have kicked off life on this planet...


I can't see a connection between some random amino acids and the formation of life. I do not see any reference to DNA or even RNA.
jonesdave
2 / 5 (4) Feb 17, 2018
My understanding of the Miller-Urey experiment is that it vastly overestimated the level of H in the atmosphere. I believe current thinking is that it was dominated by CO2. & N. The experiment was re-run a few times, with the currently accepted early atmospheric make up:

https://www.scien...epeated/
Rational_Thinker
1 / 5 (1) Feb 18, 2018
So let me get this straight, Hud has made some complex molecule in a precisely designed bit of lab kit, indicating that they are is easily damaged.

Presumably this can't happen at Cryogenic temperatures so must of happened on another planet etc. This planet explodes, propelling bits of rock through cryogenically cold space, flies through our atmosphere at 40 000 miles per hour or so, reaching a re-entry temperature of maybe 2 000 degree C and is an RNA ready component.

I'd sooner sign up to the idea the moon is made of cheese.
Rational_Thinker
1 / 5 (1) Feb 18, 2018
I'm going to go with the conclusion of someone11235813. he's having a laugh.
tblakely1357
not rated yet Feb 19, 2018
How does our sun produce 'cosmic rays'? Did they mean a greater solar wind?
Rational_Thinker
1 / 5 (2) Feb 19, 2018
@ mackita. This theory of Hud's is based on the idea that there hasn't been enough time for complex RNA molecules to form, so they arrived by "catching a lift" on Asteroids aka interstellar transport. various people (Google Fred Hoyle) have concluded life must have evolved in space because it couldn't have managed it on earth.

Sure, hydrocarbons are on Titan. The analogy of the step from methane to life is thinking that an Airbus 380 aeroplane can be designed and built from scratch by a boy knowing how to fold a up paper airplane.
Rational_Thinker
1 / 5 (1) Feb 19, 2018
@ mackita. Fair point about the panspermia hypothesis: it does just shift the problem back, but as the possibility of even molecules to life is put at 1x10^300. That is, 1 with 300 zero's after it, it leaves me with a problem.

Since their are just 1x10^80 atoms in the universe, the calculated probability is so far fetched we should simply say it can't happen........ which leaves bit of a dilemma because were writing this.
jonesdave
1 / 5 (3) Feb 19, 2018
@ mackita. Fair point about the panspermia hypothesis: it does just shift the problem back, but as the possibility of even molecules to life is put at 1x10^300. That is, 1 with 300 zero's after it, it leaves me with a problem.

Since their are just 1x10^80 atoms in the universe, the calculated probability is so far fetched we should simply say it can't happen........ which leaves bit of a dilemma because were writing this.


I haven't checked the figures, but it seems there is only one option; it isn't as difficult a process as may be being painted. There is no other possibility. ID? Nope, a rather silly idea that is just creationism in disguise. I'm not aware of anything else.
rrwillsj
1 / 5 (2) Feb 19, 2018
Panspermia? Really? You guys still flogging that stinking pile of manure?

If you really wanted to consider how life originated on Earth? You have to comprehend the span of time and how paper-thin the environment is for life.

I think the best way to do that is to consider the lowly stromatolite. No magic wands, no BEMs or LGM needed. Just the simplicity of endurance. Across aeons of time by slowly evolving organisms.

If the chemistry works, biology is possible even when improbable.

However, as the researchers on Antarctica's desert have discovered. There is a definite limit to how extreme an environment can sustain life.

Wishing and wanting and fantasizing are fun but not a description of reality!
Rational_Thinker
1 / 5 (1) Feb 19, 2018
@ jonesdave: the figures do checkout. Several people have published similar ones varying from 1x10^100 to 1x10^300. Given that they are leading experts in their respective fields, they are probably going to be right.

@ rrwillsj Wishing and wanting and fantasizing are fun but not a description of reality!...I think you have hit the nail on the head.
jonesdave
2.6 / 5 (5) Feb 19, 2018
@ jonesdave: the figures do checkout. Several people have published similar ones varying from 1x10^100 to 1x10^300. Given that they are leading experts in their respective fields, they are probably going to be right.


And yet it happened, by definition! I'd be interested to see the links for the papers where these figures were published.

Rational_Thinker
1 / 5 (1) Feb 20, 2018
@jonesdave - I was looking for these and saw I got the number wrong ... Sorry.

Fred Hoyle and N. Chandra Wickramasinghe calculated it 1 in 10 to the 40,000power.

..... I'm ok with this, Dr Grebe is obviously not as good as us all in Wishing thinking and fantasizing.

Chemist Dr. Grebe: "That organic evolution could account for the complex forms of life in the past and the present has long since been abandoned by men who grasp the importance of the DNA genetic code."

Rational_Thinker
not rated yet Feb 20, 2018
@mackita " we need to start looking on Mars a bit harder ".
rrwillsj
1 / 5 (1) Feb 20, 2018
mack, please do not take this as a criticism. But... "
We Haven't Even Begun to Look for Mars Life" is an PRE-sumption that there is life to be found on Mars. Let's do the search first before announcing conclusions.

I would be surprised (pleasantly) if we will eventually dig deep enough and find fossilized remnants of archaic Mars life.

Pity those canali didn't work out. Helium didn't have enough Mick navvies to get the job done! Erin Go Ariean?
jonesdave
2 / 5 (4) Feb 20, 2018
Fred Hoyle and N. Chandra Wickramasinghe calculated it 1 in 10 to the 40,000power.


Well, if they're right (which I doubt), then that rules out panspermia as well. The Universe isn't old enough for life to have arisen in 13 Gyrs, be it on Earth or elsewhere at those odds. All that is left is creationist woo. And that is far more unlikely than anything else proposed.
Rational_Thinker
not rated yet Feb 20, 2018
@ jonesdave: The Universe isn't old enough for life to have arisen in 13 Gyrs, be it on Earth or elsewhere at those odds

@ jonesdave. Hmmm. I can see your point.

the figures do checkout. Several people have published similar ones varying from 1x10^100 to 1x10^300. Given that they are leading experts in their respective fields, they are probably going to be right.


And yet it happened, by definition! I'd be interested to see the links for the papers where these figures were published.


Rational_Thinker
1 / 5 (1) Feb 20, 2018
@ jonesdave: The Universe isn't old enough for life to have arisen in 13 Gyrs, be it on Earth or elsewhere at those odds

@ jonesdave. Hmmm. I can see your point.

the figures do checkout. Several people have published similar ones varying from 1x10^100 to 1x10^300. Given that they are leading experts in their respective fields, they are probably going to be right.

I've looked at this and the calculations seem very reasonable. The problem seems to be with probability theory. If two thing have a 1:4 chance of happening, then altogether, for them both to happen at once they need to be multiplied. So we get 1:16 chance. Multiplying lots of things with big numbers by other big numbers gives us big numbers.

Being a genius with my calculator it seems your 13 Gyrs = 65*10^15 seconds. So... if we have 1x10^285 goes per second at trying to arrange all the right stuff in a different ways, for the whole 13Gya, we'll get the one that works.
rrwillsj
1 / 5 (1) Feb 21, 2018
I fear that we had the misfortune to evolve at a very early stage of the Universe.

It's so lonely out there, we don't even hear crickets chirping.

It is my (unsubstantiated) opinion, that it will take tens of billions of years before there is even a thin scattering of Living Planets.

And not until after the entanglement of Our Milky Way with the Andromeda Galaxy. With the subsequent of new stars and planets during the restructuring. Perhaps multiplying the opportunity for Living Planets?

I doubt if it would be any sooner to expect the commonality of life as described in our fiction.

So? Figuring out how to achieve and survive relativistic time dilation, is looking better all the time?

Rational_Thinker
not rated yet Feb 21, 2018
@rrwillsj ....You have to comprehend the span of time and how paper-thin the environment is for life.

@ rrwillsj ....If the chemistry works, biology is possible even when improbable.

@ jonesdave The Universe isn't old enough for life to have arisen in 13 Gyrs, be it on Earth or elsewhere at those odds.

@ rrwillsj ........Wishing and wanting and fantasizing are fun but not a description of reality!

@ jonesdave ........There is no other possibility. ID? Nope, a rather silly idea that is just creationism in disguise. I'm not aware of anything else.

@ jonesdave All that is left is creationist woo. And that is far more unlikely than anything else proposed.



rrwillsj How does relativistic time dilation,work, looks like we need to give it a shot.
rrwillsj
1 / 5 (1) Feb 22, 2018
...." rrwillsj How does relativistic time dilation,work, looks like we need to give it a shot. "....

How about the good ship "Looking Glass"?

Run fast... No, run faster... No, no! Run faster than fast!

And if that fails? Go back in time to the first square and start over again.

And if that fails? We can blame Snowdrop and Kitty. I have always suspected them of being Schrodinger's cats.
Rational_Thinker
not rated yet Feb 25, 2018
Just imagine it can't you. The universe has a really bad day 'cos after thousands of millions of years it was feeling really pleased with itself from trying out a combo for protein which worked {didn't make life or nothing, but something vaguely useful} ..... and then the bottle of bleach fell over and destroyed the lot. @"&> I nearly had that working
Rational_Thinker
1 / 5 (1) Feb 25, 2018
I was looking about 'cos its quite thought provoking and seen this video https://www.youtu...BqYDBW5s all about this. It was called the programming of life.

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