Methane found in the ancient Martian atmosphere, alongside hydrogen and carbon dioxide, may have led to a greenhouse effect on the planet about 3.5 to 4.5 billion years ago, new research has discovered.
The interactions among methane and the two other gases may have led to warm periods, a time when Mars could maintain liquid water on its surface. This presence of water is deemed a paradox, as the planet during this exact same period was supposed to be too cold to support such water existence.
“Early Mars is unique in the sense that it’s the one planetary environment, outside Earth, where we can say with confidence that there were at least episodic periods where life could have flourished,” reported first author and Harvard assistant professor Robin Wordsworth in a statement, adding that a close understanding of early Mars may lend insight into the search of life outside of Earth.
More Than CO2
About four billion years earlier, the sun was approximately 30 percent fainter than it is today, and substantially less solar heat or radiation reached the Red Planet’s surface. The scan radiation failing to reach the planet became trapped by the atmosphere, which led to warm and wet episodes.
It has taken decades for scientists to model how ancient Mars became insulated. The signs point to carbon dioxide, forming 95 percent of the Martian atmosphere and remaining as the most known and abundant greenhouse gas on our own planet.
But it can’t just be carbon dioxide causing early Martian temperatures. Rocky planets’ atmospheres eventually lose lighter gases like hydrogen to space, but there must be something else that created a greenhouse effect.
So the Harvard team focused on long-lost gases to potentially explain early Martian climate, particularly methane. The gas is no longer abundant in the Martian atmosphere today, but ancient processes may have released significantly more of it into the atmosphere.
Methane potentially converted gradually to gases like hydrogen in a process resembling that on Saturn moon Titan.
Wordsworth explained that when they looked at the collision and interactions of methane, hydrogen, and CO2 with photons, they saw that the combination leads to a very strong radiation absorption.
It’s the first time methane emerged as an effective greenhouse gas on ancient Mars and the first time that researchers effectively calculated its greenhouse effect. Carl Sagan, however, first investigated hydrogen warming in 1977 as a crucial occurrence on young Mars.
The warming effect of methane and hydrogen, especially in the context of their interaction with CO2, may have been significantly underestimated, Wordsworth added.
The findings were discussed in the journal Geophysical Research Letters.
Microbial Survival
In another recent study, scientists revealed that a group of microorganisms known as methanogens can survive tough conditions like those on Mars, albeit in the laboratory.
This is an exciting possibility even though human survival on Mars remains a question mark.
Methanogens, specifically cultivating in marshes and guts of cattle, produce methane. They are not dependent on oxygen or the process of photosynthesis to survive, so they retain chances of survival if they can cultivate in the underlying surfaces, hidden from the ultraviolet rays.
