Does it feel like all eyes are on Venus these days? The discovery of the potential biomarker phosphine in the planet’s upper atmosphere last month got a lot of attention as it should. However, there is still some uncertainty about what the phosphine discovery means.
Now a research team claims that they have discovered the amino acid glycine in Venus’ atmosphere.
The paper announcing the find is entitled ‘Detection of the simplest amino acid glycine in the atmosphere of Venus’. The main author is Arijit Manna, a Ph.D. Researcher in the Department of Physics at Midnapore College in West Bengal, India. The newspaper is available on the pre-printed site arxiv.org, which means that it has not been peer-reviewed and published in a magazine… yet.
There are about 500 known amino acids, but only 20 are present in the genetic code. Glycine is the simplest of them.
Although glycine and other amino acids are not biosignatures, they are some of the building blocks of life. In fact, they are the building blocks of proteins. They were also some of the first organic molecules to appear on Earth. Glycine is important for the development of proteins and other biological compounds.
The researchers used the Atacama Large Millimeter / Submillimeter Array (ALMA) to detect glycine in Venus̵
In their paper, the authors write “Its detection in the atmosphere of Venus may be one of the keys to understanding the formation mechanisms of prebiotic molecules in the atmosphere of Venus. Venus’ upper atmosphere may go through almost the same biological method as Earth billions of years ago . “
These two sentences contain a real blow. Could some kind of biological process take place in the clouds of Venus? It “can” be one of the keys, and it “possibly” goes through the same thing that Earth did. What does it mean?
First phosphine, then glycine
In mid-September, a research team reported that they found phosphine in Venus’ upper atmosphere (Greaves et al, 2020). Like glycine, it was also detected more strongly at medium latitudes. Phosphine can be a biosignature and is found on earth. But it can also be created chemically, even if it requires a huge amount of energy. It has been discovered at Jupiter and Saturn, where there is ample energy for production. But Venus does not have the energy required to create it.
The research team that discovered phosphine was cautious about their own findings. In their paper, they almost asked other researchers to account for the presence of phosphine without invoking life. “Now astronomers will think of ways to justify phosphine without life, and I welcome that. Please do so, because we are at the end of our ability to show abiotic processes that can make phosphine.”
So a few weeks later, another research team did just that. In their paper, called a hypothesis perspective, they said volcanoes could account for the phosphine.
“We assume that trace amounts of phosphides formed in the mantle are brought to the surface by volcanism and then thrown into the atmosphere, where they can react with water or sulfuric acid to form phosphine.”
The detection of phosphine forms the background for this latest discovery. Both discoveries are part of the larger questions surrounding Venus: Is their life or the potential for life on Venus? Or are these chemicals not related to life?
Scientists have identified a region in Venus’ atmosphere that could possibly host life. It would be a bizarre and unusual arrangement from our perspective.
Venus is extremely inhospitable, for the most part. The atmosphere is sour, the temperature is warm enough to melt spacecraft, and the atmospheric pressure is crushed. But high in the clouds, between approx. 48 and 60 km (30 and 37 miles) above the surface, the temperature is not so lethal.
At that altitude, the temperature varies from -1 C to 93 C (30 to 200 degrees F). It is very controversial, but some scientists believe that a type of simple life could survive there, reproducing forever without ever touching the surface of the planet. Phosphine is easily degraded, so it must be produced continuously for it to be detected. Life at that altitude could be the source of the phosphine.
This new discovery of glycine only adds to the mystery and uncertainty. In their paper, the researchers suggest that Hadley cells could be responsible for providing a home for life.
“Mid-latitude The Hadley circulation can provide the most stable life-supporting condition with circulation times of 70-90 days sufficient for (earth-like) microbial reproduction of life.”
Detection of glycine also matches the detection of phosphine. “The latitude-dependent distribution of glycine is broadly consistent (within? 10?) With the detection limit of newly detected phosphine and with the proposed upper Hadley cell boundary, where gas circulates between upper and lower altitudes.”
Do not start the spacecraft yet
While an exciting find and worth investigating more, the presence of glycine is nowhere near a knockout blow in the quest to find life elsewhere. The authors know this and are careful to point it out.
“It should be noted that the detection of glycine in Venus’ atmosphere is an indication of the existence of life, but not robust evidence.”
It is an ingredient used by life, but not an indication of life.
Their paper points to some historical experiments designed to test the chemical origin of life on earth. In 1953, the now famous Miller-Urey experiment recreated the early conditions on Earth. The researchers created a chemical mixture of water, methane, ammonia and hydrogen and then applied energy to mimic lightning. The result was a soup of more complex organic compounds.
The experiment produced glycolic acid, a precursor to glycine, and the results supported the abiogenesis theory. The glycine discovered in Venus’ atmosphere could have been produced via the same pathway as the Miller-Urey experiment. There are also other chemical pathways to glycine that are possible in Venus’ atmosphere.
“In astrophysics, chemical physics, and biophysics, synthetic pathways for the simplest amino acid glycine from simple molecules are of great importance with chemical evolution and the origin of life,” the authors write.
“Detection of glycine in the Venus atmosphere can indicate the existence of an early form of life in the solar planet’s atmosphere, because amino acid is a building block of protein. Venus can go through the primary phase of biological evolution.”
Or maybe not.
“Although glycine on Earth is produced by biological procedures, it is possible that glycine in Venus is produced by other photochemical or geochemical means, not commonly on Earth.” Venus is very different from Earth, and processes are taking place that are not present here on Earth.
This is where all the warnings come in.
The paper itself has not been peer-reviewed yet. And there are some weaknesses in the results.
For example, the spectroscopic signal from glycine is very close to sulfur oxide, so it is possible that there is an error in the detection of glycine. And this is only a single detection, not duplicated or verified. In addition, glycine is the simplest of the amino acids and has been found elsewhere. It has been discovered on comets and meteorites where there is really no hope of life.
Nor has it been seen on planets other than Earth, which means it would be surprising to look at a world as hostile as Venus.
To find out, we need more spacecraft visiting Venus. “A Venus mission with direct sampling from the Venusian surface and the cloud can confirm the source of glycine on the planet,” the authors state.
Detection of glycine, if confirmed, is another exciting development in the quest to understand the progress of life. Or it might show us that chemistry that appears to be prebiotic is only rarely prebiotic, and the rest of the time it means almost nothing. There’s so much we do not know, and missions to Venus are the only way to find out more and answer some of our questions.
But for now, we can be sure that no life has been found on Venus. Instead, we may have only uncovered a piece of the puzzle that is Venus’ complicated atmosphere.
This article was originally published by Universe Today. Read the original article.