Ever since humans first began looking up at the night sky, the one question that always burned in the mind has been: are we alone?
There are many legends among ancient civilizations that talk of visitors from the heavens and some even built entire religions on this idea. But, in more modern times, we have little to no evidence of life beyond our little blue marble.
In 1976, NASA sent two Viking Landers to Mars in an attempt to find that answer, with the help of Gilbert Levin.
As the principal investigator of the Vikings’ Labeled Release experiment, it was his job to determine whether life has ever existed on the Red Planet.
Unfortunately, while the results were positive for signs of life, the scientific consensus deemed those findings as inconclusive because certain other chemical reactions might be able to produce the same results.
Forty years later, the topic is still hotly debated, especially given that Mars has seasonal methane spikes. And with Italy finding, what they believe to be, a subterranean lake in the southern polar region of Mars, the idea of microbial life existing there has become even more tantalizing.
The one thing life as we know it MUST HAVE is water. Geological signs of ancient water flowing on Mars are evident. But with its weak magnetic field, solar wind and radiation make holding liquid water nearly impossible on the surface. And given its distance from the sun, Mars is also very cold.
That means that any surface water would likely only exist as ice, as is evident in the north and south polar caps, much like we see on Earth.
There’s no doubt that Mars has fired the imaginations of humans for centuries. However, it’s not the only body in our solar system that could have, or may still, house life. Europa, a large, icy moon of Jupiter, is thought to have a subsurface ocean.
Scientists theorize that this ocean may be able to remain liquid because of thermal vents deep below the ice.
Set to launch sometime between 2022 and 2025, NASA is working on a spacecraft designed specifically for investigating Europa. Called the Europa Clipper, this mission will orbit Jupiter and conduct a detailed investigation of the icy moon.
During the normal part of the mission, the Clipper will perform 45 flybys of the frozen satellite to confirm findings made by Hubble of water vapor plumes that seem to emit from the southern polar region.
Studying the composition of these plumes will help NASA determine the potential habitability of Europa.
Similarly, Enceladus, another frozen moon that orbits the planet Saturn, could also house a subsurface ocean deep beneath its icy crust.
But our solar system is not the only place in the cosmos that might have water.
Earlier this year, scientist announced seven planets orbiting Trappist 1, a star located 39 light years from our sun. These planets are similar in size to Earth and Venus and are rocky. Because the planets transit their star, the light from Trappist 1 shines through the atmospheres of the far away worlds.
All seven planets have a solid core, and spectral analysis of their atmospheres shows evidence for the existence of water. In fact, scientists believe it’s possible that some of the planets are 5% water by mass.
This would mean that they likely have MORE water than Earth does.
As scientific research and analysis continue to advance our understanding of what’s out there, it seems likely that we won’t have much longer to wait before we know, definitively, that we are, in fact, not alone.
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