NASA scientists want to solve a mystery: why does life “turn left?”

When POT He launched a spacecraft to an asteroid, the scientists patiently waited for their opportunity to see bits of the space Rock in a laboratory, hoping that he answers some of the most durable questions of humanity.

For Danny Glavin, a senior sample scientist, wanted amino acidsthe molecules that build proteins?

His moment came almost a decade later. Glavin and a team of researchers investigated the area of BennuA carbon rich asteroid freely linked rocksBut what they found threw a curved ball. Instead of supporting one of the leading hypotheses, which the early fuito voltaic system favored the left -handed variety and brought those ingredients to the primitive land, showed no favoritism at all.

“I have to admit that I was a little disappointed or disappointed,” Glavin said. “I felt that this invalidated 20 years of research in our laboratory and my career.”

Many amino acids, whether used in biology or not, come in two forms of mirror image. Each molecule has a central carbon atom with other groups of united atoms, oriented in one direction or on the back. This property, called chiralities as a left and right hand: they are similar, but if you stacked them, the thumbs would be of opposite crafts.

In life on Earth, amino acids are always “left -handed” and sugars, which partially form the backbone of DNA, they are always right -handed, which gives the double propeller its characteristic turn to the right. The homogeneity between them is especially confusing for scientists because the left and right -handed versions of all these molecules are equally available in chemical mixtures.

Speaking practically, if all biological molecules took the reverse form, that could work well. So, if life could have taken the other way, why not? Is “handbook” uniform a secret ingredient in the recipe of life, and more specifically did? have To turn left? Did bias towards left -handed amino acids started in the cosmos, or did it happen later on this planet?

“A Basic question for all of us is whether life had to be as it is,” said Iris Chen, a professor of chemical and biomolecular engineering in UCLA, who was not involved in the asteroid study. “Is the universe predisposed to our type of life, or is it our biology the result of accidents and chance?”

NASA chose the asteroid rich in bennu carbon to study the chemical origins of life.
Credit: NASA

The scientists knew at the beginning that they would use the material collected by the Osiris-Rex mission of $ 800 million of NASA, abbreviation for Origins, spectral interpretation, resource identification and security registration explorerto analyze the “hand” of individual amino acids. Bennu’s mineral fragments could be older than the 4600 million years photo. These Stardust grains could come from MORIBUNDAS STARS either Supernovas That finally led to the creation of The sun and planets.

To do their study, they developed a kind of “bennu tea”, boiling a small amount of rocks and powder in water and acids to extract organic compounds. Then they used mass spectrometry techniques to identify organic molecules, including 14 of the 20 amino acids that life uses to build proteins, which carry out genetic instructions. Some of The last findings They were published this week in the magazine Astronomy of Nature.

“I have to admit that I was a little disappointed or disappointed. I felt that this invalidated 20 years of research in our laboratory and my career. ”

In recent decades, researchers have found that Meteorites – Rocks that have traveled the space and ribbon On Earth, it has had a greater concentration of left -handed amino acids than the right -handed ones, in the neighborhood of 60 percent more. Perhaps the space rocks delivered the compounds that later suffered chemical reactions near Earth deep waters To form the first cells. The rest is evolution, perhaps.

These results, together with the knowledge that space rocks have bombarded the planet for eons, have led scientists to believe that old asteroids, time capsules of the photo voltaic system, also reveal more left -handed amino acids. If the photo voltaic system really houses more left -handed, perhaps the polarized light in the El Culpable period. A light favoritism in the environment could become a greater disparity over time.

Scientists think that meteorites and planetary collisions of the body may have delivered the origins of the chemistry of life to the early earth, including left -handed amino acids.
Credit: NASA Goddard Space Flight Center Illustration of Conceptual Laboratory of Conceptual Images

But Bennu’s researchers found the left -handed people who arrived equally. Now Glavin wonders if previous studies on meteorites are invalid, perhaps contaminated with proteins of the earth when they fell to the ground. Jason Dworkin, a project scientist for the Osiris-Rex missionThink that there may be a different reason for Bennu to be in the trend.

“Bennu is an example of a future meteorite type that is too fragile to survive landing on earth, so it is not really in our collections,” said Dworkin.

Perhaps the reality is that the design of life was determined by a currency change. Once a successful pattern was established, the template continued through evolution. Proteins and enzymes, small controllers inside the cells, fit as a puzzle. If life arose with left -handed amino acids, changing to amino acids left later could have prevented everything from working. There are great advantages in uniformity: if people were based on skilled amino acids, they could not eat and digest plants or animal products based on left -handed amino acids.

Researchers have done Biological protein reflex versions with right -handed amino acids in a laboratory. They work in a comparable way, but they are much more difficult to destroy. The enzymes that would generally break down become useless. Like its hair dryer on an international vacation, the tool will not work if the plug and the output do not match.

A diagram of a left -handed and right -handed version of an amino acid from a meteorite.
Credit: NASA Illustration

Some scientists who consider the implications of this problem have expressed concern about the future development of mirror cells in laboratories. If people infected with harmful mirror bacteria, their immune systems may be defenseless, unable to free any counterattack. A group of biologists recently wrote An extensive paper about the risks, as reported by The New York Times.

Despite Glavin’s disappointment that Bennu did not present a bias of chirality, the investigation continues. He and his collaborators plan to study more asteroid samples to investigate the hand of other amino acids.

And there may be a silver coating: some astrobiologists have proposed to use disproportionate crafts of the molecules such as Biosignura. A uniform mixture of both types in an extraterrestrial sample could suggest that the molecules were made chemically without the participation of living beings. But an excess of a type could be a clue for alien life.

“Frankly, I could actually facilitate the search for life in some aspects because we do not have this potentially positive risk,” Glavin said. “(We could) believe that if there is an amplification of one or the other, that there may be biology behind this.”