From its unique composition, to how it sends bits of itself into space, and more!
Join us as we reveal to you Enceladus Saturn's icy moon facts and history!
8.
Discovery and Naming When it comes to the moons and the planets
in space, their discovery is a key part of their history.
So who was the one who discovered Enceladus?
That would be William Herschel in 1789.
But just as impressively, it was during the first use of his new telescope that he got
it done.
In fact, at the time, the telescope he used was the biggest in the world.
The problem though was that due to the position of the moon and how it was basically "shined
over" by the brightness of Saturn and its rings...Enceladus was difficult to observe
from Earth with smaller telescopes.
However, Herschel was in luck, as he found it during a Saturnian equinox, the first moon
to be discovered that way.
The equinox in question removed some of the "glare" from the moon so that it could indeed
be spotted.
Prior to the Voyager missions the view of Enceladus improved little from the dot first
observed by Herschel.
We knew general information about the moon, but not much about the nitty-gritty of what
made it tick.
Thankfully we were able to get more information later on obviously.
As for its title, the moon is named after the giant known as Enceladus from Greek mythology.
But unlike certain other moons, the naming did not stop there, not one bit.
Because unlike other structures, scientists and researchers decided to name various aspects
of the moon.
Impact craters for example were named after characters, whereas other feature types, such
as fossae (long, narrow depressions), dorsa (ridges), planitiae (plains), sulci (long
parallel grooves), and rupes (cliffs) were titled after places.
When all was said and done, 85 features on Enceladus had names.
That's a lot of things to label.
So as you can see they got a little name happy for this moon, but that just led them to detailing
it even more so it may have just worked out that way for them.
7.
Shooting Into Space In 2005 something rather special was found
out about Enceladus.
Specifically, NASA’s Cassini spacecraft discovered that icy water particles and gas
gush from the moon’s surface at approximately 800 miles per hour.
Not something you'd expect from a moon.
From a planet?
Yes.
But a moon?
Not so much.
But it wasn't just that it was shooting into space, it was doing so at quite a rate to
where it was actually reaching the outer layers of the moon, so much so that it supplies material
to Saturn's E-ring.
Only a small fraction of the material ends up in the ring, however, with most of it falling
like snow back to the moon’s surface, and that is a big reason why the moon is such
a bright color of white.
A curious thing indeed, "filling" up a ring with some of the plume, and making the moon
bright white with the other.
Again, not something you'd expect from a moon.
The water jets come from relatively warm fractures in the crust.
Several gases, including water vapor, carbon dioxide, methane, perhaps a little ammonia
and either carbon monoxide or nitrogen gas make up the gaseous envelope of the plume,
along with salts and silica.
Just as curious to those studying it, the gasses are much denser than they first guessed.
Adding more mystery to everything involved.
If you're curious how these plumes really form, that's because there is an ocean in
Enceladus that supplies the jets.
Which is important to note because now scientist are trying to study the E ring of Saturn in
order to study the waters of the moon.
Within the ice droplets that make it to the E ring are peculiar nanograins of silica,
which can only be generated where liquid water and rock interact at temperatures above about
200 degrees Fahrenheit (90 degrees Celsius).
What does that all mean?
It means that hydrothermal vents might be underneath the moons surface.
If that sounds familiar, it's because we have similar vents on Earth.
Ours though happen to be on the ocean floor.
“Enceladus discoveries have changed the direction of planetary science,” said Linda
Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory.
“Multiple discoveries have increased our understanding of Enceladus, including the
plume venting from its south pole; hydrocarbons in the plume; a global, salty ocean and hydrothermal
vents on the seafloor.
They all point to the possibility of a habitable ocean world well beyond Earth’s habitable
zone.
Planetary scientists now have Enceladus to consider as a possible habitat for life.”
Which is a big deal, because in the large scale of our solar system, there aren't many
places that can be openly considered as "possible habitats", that even includes Mars to an extent
because humanity has a lot of work to do to truly make it a viable place to live.
But because of the potential ocean in Enceladus, that changes things dramatic, and more thought
will be put into the study of this moon.
6.
Exploration of Enceladus Given the overall findings and importance
of the moon, it's not surprising that we've sent many craft to go and study Enceladus
in various ways.
The two Voyager spacecraft were the first to get close-up images of Enceladus.
Voyager 1 did it in 1980.
The pictures received weren't the best, but they revealed a highly reflective surface
devoid of impact craters, meaning that the surface might be "young" in terms of the scale
of the solar system.
Voyager 2 followed up on that 1981, and got closer to the moon than the previous attempt.
Thus we got more clear images, which helped really show what the moon was like.
They also revealed a surface with different regions with vastly different surface ages,
with a heavily cratered mid- to high-northern latitude region, and a lightly cratered region
closer to the equator.
These finds also conflict with what other moons of Saturn have, raising various questions
yet to be answered.
Because they couldn't figure out how such diversity could come to the surface of a moon
like this and be so different from others.
The answers to many remaining mysteries of Enceladus had to wait until the arrival of
the Cassini spacecraft in 2004, when it entered orbit around Saturn.
Enceladus was considered a priority target by the Cassini mission planners due to past
runs with the probes from before.
Their results yielded even MORE information about the moon, these discoveries prompted
the adjustment of Cassini's flight plan to allow closer flybys of Enceladus, including
an encounter in March 2008 that took it to within just 48 km of the surface.
Seven flybys of the moon happened between July 2008 and July 2010.
Confirmation of molecular hydrogen (H2) would be an independent line of evidence that hydrothermal
activity is taking place in the Enceladus seafloor, increasing its habitability.
By contrast, the water thought to be on Jupiter's moon Europa is located under a much thicker
layer of ice.
Which would be problematic to be reach, and produce life.
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5.
Orbits and Rotation Enceladus orbits Saturn every 32.9 hours,
fast enough for its motion to be observed over a single night of observation.
Very helpful for the scientists wanting to learn more about it.
Like most of Saturn's larger satellites, Enceladus rotates always has one face pointed toward
Saturn.
Unlike Earth's Moon, Enceladus does not appear to liberate more than 1.5° about its spin
axis.
However, analysis of the shape of Enceladus suggests that at some point it was in a 1:4
forced secondary spin–orbit libration.
4.
Surface Voyager 2 was the first spacecraft to observe
Enceladus's surface in detail as noted earlier.
Because of that we know that there are five different types of terrain on the moon.
Possibly even more that might have been missed.
Including several regions of cratered terrain, regions of smooth terrain, and lanes of ridged
terrain often bordering the smooth areas.
In addition, extensive linear cracks and scarps were observed.
So also as noted, it's a diversity rarely seen before, which makes it all the more exciting
to those who want to learn more about it.
Given the relative lack of craters on the smooth plains, these regions are probably
less than a few hundred million years old.
The fresh, clean ice that dominates its surface gives Enceladus the most reflective surface
of any body in the Solar System, with a visual geometric albedo of 1.38.
Because it reflects so much sunlight, its surface only reaches a mean noon temperature
of −198 °C (−324 °F), somewhat colder than other Saturnian satellites.
Yet that makes sense as we are warm here on Earth because we only partially reflect away
the suns light and warmth as we don't have a reflective surface as intense as this moon
of Saturn.
Numerous fractures were found within the older, cratered terrain on Eceladus, suggesting that
the surface has been subjected to extensive deformation since the craters were formed.
Some areas contain no craters, indicating major resurfacing events in the geologically
recent past.
There are fissures, plains, corrugated terrain and other crustal deformations.
There are parts of the moon though that are a bit odd, such as the bizarre terrain near
the south pole which wasn't able to get fully imaged by the passing poles.
All of this indicates that Enceladus's interior is liquid today, even though it should have
been frozen long ago.
Further suggesting a rather odd history and origin (more on that in a bit).
While this may not seem interesting, knowing how the surface of a moon (or even a planet)
is formed and affected by things in space is important in understanding its history.
We're still learning things about Mars because of things that keep being found on the surface.
3.
Shape and Size To be honest, this moon is a rather small
satellite composed of ice and rock.
It is a scalene ellipsoid in shape; with it being 513 km between the sub- and anti-Saturnian
poles, 503 km between the leading and trailing hemispheres, and 497 km between the north
and south poles.
Enceladus is only one-seventh the diameter of Earth's Moon.
It ranks sixth in both mass and size among the satellites of Saturn.
Yet that hasn't stopped it from being viewed as one of the more important moons of Saturn.
2.
Paradoxical Origin Aside from its unique surface, there is a
bit of a debate as to how Enceladus actually formed, and how it's so different from another
moon near it...Mimas.
Mimas, the innermost of the round moons of Saturn, is a geologically dead body, even
though it should experience stronger tidal forces than Enceladus.
This apparent paradox can be explained in part by temperature-dependent properties of
water ice.
Some predictions state that in regards to Enceladus, there are various temperature states
that would work to keep the moon stable.
From a low convection temperature to a much higher one.
But this is just one phase of the paradox itself.
Because Mimas is the other half, and according to models, only a low-energy state is expected
to be stable.
Even though unlike its counterpart, it's much closer to Saturn.
So the model predicts a low-internal-temperature state for Mimas but a possible higher-temperature
state for Enceladus.
So thus you have the paradox because many aren't sure how Enceladus was able to enter
the high energy state that it's currently in.
It defies many forms of logic.
The significantly higher density of Enceladus relative to Mimas has also been cited as an
important factor in resolving the Mimas paradox.
It has been suggested that for an icy satellite the size of Mimas or Enceladus to enter an
'excited state' of tidal heating and convection, it would need to enter an orbital resonance
before it lost too much of its primordial internal heat.
Mimas is of course smaller than Enceladus, and thus would have a much shorter window
to cool down, thus adding even more mystery to the paradox.
When we'll find out the answer to this mystery is unclear, but many theories have been proposed.
1.
Future Exploration As you can see, Enceladus has gotten many
researchers and scientists excited about what this moon could mean not just for the study
of the solar system, but also for the growth of humanity in the solar system expansion
that is being planned.
So thus, many more missions are aiming to learn more about it.
Such missions include a lander by the German Aerospace Center to study the habitability
potential of its subsurface ocean.
The European Space Agency (ESA) was assessing concepts in 2008 to send a probe to Enceladus
in a mission to be combined with studies of Titan: Titan Saturn System Mission (TSSM).
Though obviously those didn't come to be, mainly because the project was competing for
funding with another project.
In November 2017, Russian billionaire Yuri Milner expressed interest in funding a "low-cost,
privately funded mission to Enceladus which can be launched relatively soon."
NASA also had their own mission they wanted to do to send a craft to the moon.
Yet...it hasn't happened yet.
Yet.
But, it's clear that many want to study these waters to see what it could mean for us in
the future.
Because if something incredible is found, it could change even more how we view certain
moons in our solar system.
As well as seeing whether we might want to try and land people on there in the future.
Thanks for watching!
What did you think of this look at Enceladus and what it might mean for the solar system
as a whole?
Were you shocked to hear that this moon has an ocean that could support life?
Do you think we'll ever get to see a colony there or a proof of life found there?
Let us know in the comments below, be sure to subscribe, and I'll see you next time on
the channel!