Could there be life on Mimas?
Hey! Welcome to insane curiosity.
Do you think there could be life somewhere in the universe?
I mean...life as we know it, maybe on another planet.
It could exist in a galaxy far far away, or maybe on a planet around a star in our
own galaxy, the Milky Way. Wouldn't it be nice though,
if one day we discovered that life was hiding much closer than we thought?
Maybe in our own solar system?
This is actually not impossible. It could be plausible to find life as we
know it in our solar system. The only question is: where?
Follow me in this video to understand why a Saturn Moon, called Mimas, could be the right target.
Usually, when we think about life in our solar system, we think about Mars.
This is because, in the past, Mars was actually not so different from Earth.
From what we know, it hosted oceans of liquid water, it had a noticeable magnetic field
and an atmosphere. All of these things put together could have contributed to building
a nice environment that could support life. Perseverance rover will use its instruments
to look for signs of ancient life in the delta and lake deposits in the so-called Jezero crater
and will hopefully allow us to finally answer the question of whether there was ever life on Mars.
In addition, Perseverance will begin the process of collecting samples that could one day
be returned to Earth. Once returned to Earth by a future mission, these Mars samples can be
subjected to more detailed analysis by a much wider set of instruments than can be carried
by Perseverance. Moreover, sample archiving can preserve material for future analysis here on
Earth by new and/or more detailed instruments that may not yet exist. So even if Perseverance does
not find evidence of past life, it will collect samples that, once returned to Earth, could
provide new insight into the evolution of Mars and whether there was ever life on the Red Planet.
So we are already working on Mars. But this doesn't mean that we
should only focus on this planet. Could there be some other places where to look at?
In some of our past videos, we discussed the possibility for
some of Saturn or Jupiter's moons to host life. For example, Enceladus and Europa are all covered
by ice, as it is quite evident if you look at these pictures taken by spacecraft some years ago.
If you look carefully, for example, you can notice
some sort of rivers covering the whole surface of Europa, on the left side.
Europa's vast and unfathomably deep ocean is widely considered
the most promising place to look for life beyond Earth. A passing spacecraft might
even be able to sample Europa's ocean without landing on the moon's surface
because it is possible that Europa's ocean may be leaking out into space.
Conjectures regarding extraterrestrial life have ensured a high profile for Europa
and have led to steady lobbying for future missions, so I think we will hear soon some
news coming from this distant moon. In particular, we will have Jupiter
Icy Moon Explorer (JUICE), which will include 2 flybys of Europa.
Another important mission in the program is Europa Clipper.
It aims to explore Europa to investigate
its habitability and select sites for a future lander.
Imagine how amazing it would be to find that there's life on a moon in the solar system!
Anyway in this video, we want to talk about a new study which could turn out to be
really interesting for what concerns the finding of life in our solar system.
Let's see what astronomers found.
Let's begin by looking at Mimas from closer.
Here it is. A small pretty sphere orbiting around Saturn.
The big crater on the right side it's huge. Its diameter's extension is something like
one-third of the diameter of the moon. It is called the Herschel Crater.
It was named in honour of the astronomer William Herschel,
who discovered Mimas and Enceladus in 1789. On September 17 of that year, the astronomer
pointed his telescope in the direction of Saturn and discovered Mimas. The small satellite - just
396 kilometres across - is the seventh of Saturn and the twenty-first of the solar system in size.
Mimas is also the smallest celestial body known to have a spherical shape
due to its gravitational field. Its diameter is approximately 140 km,
its walls are approximately 5 km high, parts of its bottom reach a depth of 10 km,
and the relief in the centre rises 6 km over the surrounding land.
Proportionately, a similar crater on Earth would be over 4000km across and larger than Canada.
The impact from which Herschel originated must have nearly disintegrated Mimas;
on the opposite side of the satellite, there are in fact evident fractures
that could be due to the shock wave of the impact. The fun fact is that Herschel crater's presence
makes Mimas curiously similar to the Death Star from Star Wars,
the weapon through which the Empire perpetuated its regime of terror, capable of destroying
entire planets. A regime, the one established by the Empire, destined to be overwhelmed by
a revolution as in France only a few years after the successful discovery of Herschel.
MIMAS AND DEATH STAR
However, this is a mere coincidence, as the crater was discovered several
years after the film was made. But what does this have to do with
water and life as we know it? Well, apparently nothing.
If you take a look at Mimas and then you take a look at Enceladus, for example, you will notice
that they are completely different. In fact, Mimas doesn't seem to host
an ocean of liquid water. While on Enceladus we can
clearly see signatures of moving pieces of ice frost on the surface, which means they
are moving on a liquid water ocean, Mimas doesn't show the same characteristics.
That's why, at first sight, astronomers soon discarded the possibility for Mimas to host life.
It was simply not the right place! But then, when the Cassini probe sent
data from Saturn in 2014, the game changed. NASA's mission, which orbited and studied
Saturn for over a decade, detected an unexpected oscillation in Mimas's rotation.
As it spins on its axis, Mimas wobbles slightly – an effect called libration.
That was something to be explained. Why was it happening?
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Someone suggested that this could be due to the shape of Mimas' nucleus.
A very elongated nucleus could cause the observed libration movement.
Does Mimas' have such an elongated nucleus? Well, the same huge impact which created
the Herschel crater might have led to a stretching of the layers at the nucleus level.
So maybe we can consider this option, but what observations say is that other moons which have
experienced huge impacts in the past don't show such an important libration movement.
So maybe there is something more to be studied in detail.
After three years of continuous observations, astronomers decided that Mimas was
geologically inactive, and therefore no oceans could be found on its surface.
They simulated what's going on in the interior of the moon, and they tried to reproduce the
same surface we observe by imposing the existence of an ocean at the same time.
Needless to say, all the simulations gave the same answer:
no ocean configuration can lead to the observed surface.
But we all know that technology improves as years pass by.
And simulations get more and more accurate. The power of new computers is astonishing,
and they can predict behaviours in a really precise way.
So in January 2022, a team of astronomers gave another try to simulations and found
that some configurations exist that reproduce both a liquid ocean and the observed surface.
"If Mimas has an ocean, it represents a new class of small,
'stealth' ocean worlds with surfaces that do not betray the ocean's existence," Alyssa Rhoden, a
geophysicist who led the analysis at the Southwest Research Institute, said in a press release.
Of course, it's still no guarantee of a secret Mimas ocean. Researchers need
to investigate the moon for further evidence. The work doesn't prove that there is a subsurface
ocean on Mimas, but it does show that an ocean is perfectly consistent with the available
data and our understanding of the physics, and the authors are appropriately cautious about this.
If Mimas has water, it will become the third of Saturn’s 82 moons
known to contain underground oceans. This result could be really interesting
because it would imply that we could have life even in places where we didn't expect it to be.
In short, we are not able to tell which moons in the outer solar system
may have subsurface oceans just from their surface geology.
As you can see, the universe always surprises us with its creativity.
Who knows, maybe we will find life on some exoplanets or maybe
we will first find it in our solar system. And maybe we will find it on a planet, or a moon.
Who knows? Of course,
everything is possible! There is also another creepy option:
we could be completely alone in the universe. Maybe we are the exception.
"This video ends here! Thanks for watching everyone! Do you think we will ever find
life on another moon or planet? Did you know about the existence of Mimas? Let us know in
the comments below, be sure to subscribe, and I'll see you next time on the channel!"