Data suggests that alien life elsewhere in the universe is likely. But,
further life in just our local system of planets - the solar system - is forever a
point of debate. Nevertheless, there is recent research to suggest that
Earth isn’t the only place around here where something’s happening.
This is Unveiled, and today we’re answering the extraordinary question;
is there alien life in the solar system?
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We’ve asked it once, we’ll ask it a thousand times - where are all the aliens? Scientists
still haven’t found definitive proof of life existing today (or ever) on another planet.
Due to the sheer number of other planets in the universe, however, the multi-trillions
of other worlds that are out there, many believe there must be ET life to discover.
The positive news, for anyone hoping to find aliens soon,
is that science has spectacularly advanced in recent years, to better understand the planets
of the solar system and the exoplanets beyond the Oort Cloud… and scientists are now a dab
hand at identifying the ones most likely to at least be habitable. In 2021, for example,
astronomers were able to create an all new category of exoplanet, called Hycean worlds,
that are deemed especially noteworthy thanks to the large amounts of water and hydrogen in their
atmospheres. Meanwhile, and again in 2021, another research team found evidence for the
first time of specific, complex, carbon-bearing molecules - some of the potential building blocks
for life - scattered actually in space. Now, more than ever, we’re on the aliens’ tails.
But, really, our immediate solar system remains the first place we should be searching. And there
are a number of especially interesting planets and moons here - including the likes of Mars,
the Jovian moon Europa, and the Saturnian moon Enceladus. These all rank quite highly
for their possibility of harboring simple life, at least, because they all show a
combination of variously strong signifiers - such as the presence of liquid water,
an abundance of organic materials, and/or relatively mild temperatures. On the flip side,
we can also rank the nearby places where life is most unlikely to survive. Our own
moon and the planet Mercury, for instance, both contain close to no atmosphere and host extreme
temperatures… meaning that it would be much more of a surprise if life turned up there.
And so, to that poster planet of alien study for more than 100 years: Mars. Ever since the
French astronomer Étienne Trouvelot theorized in the 1880s that the seasonal changes on the
Martian surface could be due to vegetation there, scientists have debated the possible
presence of life. We’ve advanced so much since then that we’re now able to send
mechanical rovers to the Red Planet, to directly explore and search for living things - although,
for the most part, we’ve merely uncovered just how inhospitable Mars may be. However,
there’s fresh research to suggest that we might’ve just been looking in the wrong places. The Martian
surface is certainly hostile for organic life, but underground on Mars it’s different.
The biggest question regarding potential underground life on Mars has long been
whether it could exist in a completely independent ecosystem? Whether it could be wholly non-reliant
on any materials on the planet’s surface? That way, it could stand more of a chance. In 2021,
to better understand this, the geobiologist Matthew Selensky and his team studied lava
caves here on Earth. Since volcanism is a common feature of terrestrial planets,
most others will also have lava caves like Earth’s, or something similar. And Selensky’s
team found that bacteria is able to survive in these caves with no help from the surface for
food. By dissolving chemicals in the minerals around them, a process called lithoautotrophy,
lava cave bacteria is able to build the molecules they need to survive via
the carbon they harvest in the walls. It’s a lonely existence, sure, but an effective one.
The study then suggests that underground life could exist in an independent underground
ecosystem on Mars, as well, no matter the fact that the surface above is terrible for life.
More broadly still, it proves that surface level observations of any planet can likely
never prove that that planet is barren. There could still be so much more happening below.
Moving to Jupiter’s moon, Europa, and another object long deemed to be habitable… but now with
more reasons to believe. New research, released in 2022 by the geophysicist Riley Culberg and
his team, hones in on the suspected ocean of liquid water beneath Europa’s ice sheet. It
had been assumed that this ocean was probably miles below the ice… but, the new study shows
that it might not be quite so deep. If true, this could be an important factor for life
there… in almost the opposite way that life in the lava caves of Mars could still thrive. Now,
being closer to the surface is a good thing. It potentially allows for Europa’s
water to be exposed to interesting molecules and chemicals from space.
Culberg and his team were able to make this discovery by noticing a strange pattern on
Europa’s ice sheet, something called a double ridge formation. The researchers recognized
that the same feature is present on Earth, in Greenland’s ice sheet. In Greenland’s ice, we
know that those characteristic double ridges are only formed in a specific way, when the water from
the depths is brought to the surface and refrozen. So, if this is also how they’re created on Europa,
which seems likely, then it not only means that there’s a large abundance of water available…but
also that water in the depths is being regularly cycled back to the surface. Such complex processes
really can help to facilitate the development of life, reconfirming Europa as a primary case study.
But finally, to Saturn and another moon that’s received a massive amount of recent interest in
the search for alien life; Enceladus. Since at least the Cassini spacecraft mission, which flew
directly through plumes of water that had erupted from the surface of Enceladus, it’s been all eyes
here hoping to find something further. Scientists have analyzed in detail the data from those plumes
sent back by Cassini before its mission end. Notably, the early studies found that the water
contained almost all the basic requirements for life, but that there was one thing holding it
back - phosphorus. On Earth, phosphorus is vital because it creates phosphates, which are essential
for allowing lifeforms to build DNA, RNA, cell membranes, and other necessary bits of equipment
for life. The fact that it had seemed to be absent from Enceladus, then, was a problem.
However, and again in 2022, new research completed by the geochemist Christopher Glein
and his team unveiled evidence that phosphorus actually does exist in the water on Enceladus.
The study took data from Cassini and used it to build a model for how the minerals
present in the plumes should dissolve… and it ultimately showed that Enceladus
as a whole should be rich in phosphorus, even if it appeared not to be, at first. In fact,
the updated model predicts that it’s almost inevitable that phosphorus is on the moon,
and could even be more abundant there than it is on Earth. Glein said of the research that it
means we can be “more confident than before that the ocean of Enceladus is habitable”.
So, what’s your verdict? On Mars, Europa and Enceladus, could we be closer than ever to
proof of aliens? Any discovery of other life in the solar system would potentially be the most
significant discovery in all of human history. It would provide a definitive answer to that huge,
fundamental question; are we alone? And would open our eyes to all new
possibilities within our local region, our immediate galaxy, and the wider universe.
For now, we have all the tools in place. There’s the James Webb Space Telescope, which can look
with unparalleled precision at exoplanets far, far away… even identifying key gasses within
their atmospheres as potential signs of biological life. There are also various near-future missions
planned by NASA (and others) to study our closest neighbors, including Mars, Europa and Venus. So,
although we haven’t found alien life just yet, it may only be a matter of time before we do.
What do you think? Is there anything we missed? Let us know in the comments, check out these other
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