As researchers learn more and more about the planet Mars, the likelihood of life having developed on the Red Planet increases. Two separate discoveries, one involving the discovery of what may be planet Earth’s oldest fossils, and another that shows that Mars may have had more water on its surface than anticipated, reinforce the idea of life having once thrived on the Martian surface.
The first discovery, regarding what may be the Earth’s oldest fossils, pushes the timeline of the development of life on Earth even further into its past. The fossils in question are of simple, tube-shaped organisms that are smaller than the width of a human hair, that were discovered in the ancient rocks in what is known as the Nuvvuagittuq Supracrustal Belt in Quebec, Canada. These rocks are estimated to have formed 4.2 billion years ago, implying that the lifeforms that the fossils represent are roughly a hundred-million years older than that.
This is important because the age of the Earth itself is estimated to only be 4.55 billion years old, meaning that the organisms had developed a mere 100 to 200 million years after the Earth formed — a blink of the eye, in geological terms. To put this into perspective, that means that lifeforms appeared on Earth in only roughly double the time that has passed since the end of the age of the dinosaurs to today.
But how does life on Mars factor into this? 4.2 billion years ago, Earth and Mars would have had very similar surface conditions, including oceans that the creatures would be able to thrive in.
“Early Mars and early Earth are very similar places, so we may expect to find life on both planets at this time,” explains Matthew Dodd, the lead author of the study. "We know that life managed to get a foothold and evolve rapidly on Earth. So if we have life evolving in hydrothermal vent systems maybe even 4.2 billion years ago when both planets had liquid water on their surface, then we would expect both planets to develop early life."
The second study involves the discovery of evidence that Mars may have been home to vast oceans in its past. As it is, the consensus amongst researchers is that Mars did indeed have flowing surface water that left its mark on the planet, but they differ as to how much was actually there. Previously, the presence of a mineral called merrillite in Martian meteorites was an indication of the rocks having formed in a dry environment. However, merrillite can be formed from another mineral called whitlockite, a mineral that forms under wet conditions.
The researchers created synthetic whitlockite, and then subjected the substance to high-pressure impacts, mimicking conditions that it would have been subjected to in a meteor impact. They were surprised to find that up to 36 percent of the whitlockite had been converted to merrillite. Considering the experiment was only able to reproduce somewhere between 1-10 percent of the force of a natural impact, this could very well mean that any whitlockite present in the meteor could be completely converted to merrillite — meaning that previous evidence of a dry Mars might be rendered useless.
Whitlockite is a substance that also incorporates phosphorus, one of the basic building blocks of life. If future probes sent to Mars are able to find evidence of whitlockite, that would not only shift estimates of the amount of Mars’s water into "very wet", but also provide the presence of the foundation for Martian life to develop.