The moon has always been an object of
fascination for mankind. It's a
prominent view in our night sky. A moon
massive and close enough that its
beautiful and eerie details are visible
with the naked eye. Mankind stepped on
the moon over 5 decades ago. But to this
day, there's still so much we don't know
about it. As exploring any place outside
of Earth is always incredibly dangerous
and difficult.
While the moon seems like a very
different place from Earth, there's one
thing that excites scientists about
future colonization prospects. There is
increasing evidence of water on the
moon.
But lunar water is mysterious. It does
not always show up where we expect it.
And by all accounts, it shouldn't be
where we find it. Its mysteries are ones
that the nations around the world are
desperate to crack. Because lunar water
is the key that might unlock the solar
system to us. Whoever solves it first
will reap significant benefits.
Where can we find lunar water? How do we
know it's there? And how close are we to
overcoming the moon's greatest dangers
to get it?
I'm Alex Mccoan and you're watching
Astramm. Join with me today as we follow
the progress numerous space agencies
around the world have made to find out
once and for all whether the moon's
surface contains water.
Scientists did not always know that
there was water on the moon. Luna 24 was
an ambitious robotic probe of the Soviet
Union in 1976.
It successfully landed on the moon,
drilled into the lunar surface about 2 m
deep, and sent about 170 g of lunar soil
samples back to Earth. Of greatest
surprise to the scientists was the
detection of water within the return
sample.
Around 0.1% of the sample was water, and
they found that the concentration of
water increased with depth. However,
like the very trace amounts of water
detected in samples obtained during
earlier moon missions, for example,
Apollo 11, this was assumed to be a
contamination from Earth. The question
whether there is water on the moon
remained unanswered.
In 1994, NASA's Clementine mission
showed that permanently shadowed areas
that haven't received any sunlight in
billions of years do exist near the
moon's south pole.
As a result of this, there was a lot of
excitement in the science community
about whether there could be frozen ice
at the bottom of these craters,
protected from the harsh rays of the
sun, where the temperatures would never
rise above about - 173° C. Any water ice
at the bottom of these craters could
probably exist indefinitely at these
temperatures. Excited by this discovery,
NASA launched the Luna Prospector
spacecraft shortly afterwards in 1998,
specifically to hunt for clues that
water may exist there.
While it didn't give us any conclusive
answers to the mystery, it certainly
added to the intrigue. The Lunar
Prospector detected large amounts of
hydrogen at the moon's poles using
spectroscopy from orbit. Data from
Prospector suggested that there could be
somewhere between 10 to 300 million tons
of water ice scattered inside craters
around the lunar poles. But large
amounts of hydrogen do not necessarily
mean the presence of water. It could
also be water's closest chemical
relative, hydroxil.
The Prospector spacecraft subsequently
crashed into the moon's south pole in
1999 with NASA scientists hoping the
impact would blast ejector into space
lit up by the sun so that scientists
could use spectroscopy to prove the
existence of water in the dark craters
of the moon using earth-based
telescopes. Unfortunately, no water ice
was detected from the lunar prospector's
impact. The mystery continued.
Japan's Seleni or Kaguya spacecraft was
launched in 2007 and its mission was to
take highresolution images of the moon
and map the lunar surface. But it also
wasn't able to detect signs of water ice
in permanently shadowed craters around
the south pole of the moon. So after 18
months of orbiting, it too purposefully
crashed into the moon, hoping that this
time it would release enough ejector
into space for Earth-based observatories
to work with. But again no evidence for
water was found.
In 2008, India's first moon mission
Chandrean 1 was launched. Chandrean 1
was different from previous missions in
that instead of relying on sensors to
detect water from a distance. India
included an impactor that could
specifically detect water in its gaseous
form through spectroscopy as it came in
close proximity to the spacecraft.
Scientists believed water vapor could be
in the extremely tenuous atmosphere of
the moon just above these craters. The
impactor probe was released from the
main body of the spacecraft and
descended for 25 minutes before it
crashed near a crater at the south pole
of the moon. As it descended, it sent
the data back to the Chandrean 1 mother
ship. And within that data was the
answer scientists have been looking for
all these decades, a confirmation of
water.
And a few months later, the moon
minology mapper instrument aboard
Chandrean 1 using spectroscopy from
orbit also detected the presence of
water on the moon.
But NASA wanted more proof. They
launched their own lunar crater
observation and sensing satellite
mission as well as the LRO, an orbiter
you will be very familiar with if you
follow this channel. Elcross was a
simple lowcost fasttrack mission and it
had one main objective which was to once
and for all confirm the presence or
absence of water ice in a permanently
shadowed crater near a lunar polar
region. It had a simple straightforward
yet very clever design. In an unusual
move, the first stage of the Atlas 5
rocket LCROSS was launched from stayed
attached to the spacecraft and upon
reaching the moon, it was released to
crash into one of the dark craters at
the south pole of the moon. This impact
was similar to how Luna Prospector and
Japan's Kaguya probes crashed into the
moon to eject a debris plume that rose
above the lunar surface.
But unlike them, the Elcross spacecraft
itself flew through the debris and
collected data without relying on
Earthbased observatories, which clearly
weren't very reliable for studying small
plumes of debris.
As the debris cloud rose above the
crater's rim, it was exposed to
sunlight, and any water, ice, and other
molecules of interest were vaporized and
broken down into their basic components,
which the sensors on board Elcross were
able to detect. only for it to crash
into the moon too after accomplishing
its task. This combination of collisions
produced a large plume of surface
material which the LRO was left to
study.
As LRO traveled over the lunar surface,
it began to notice something unexpected.
Trace amounts of water molecules could
be found over the top of the surface
regalith, the gray rock that makes up
much of the moon. It turns out the whole
moon is ever so slightly wet.
This wetness was even observed to move
around in a sort of lunar water cycle,
both by region and by time of day.
Around noon, when the moon's surface was
hottest, the water seemed to dissipate,
but then would return with the evening.
Nowadays, a staggering 600 billion kg of
water ice is estimated to be on our
moon. Roughly the same weight as 461
million cars. That's a lot of water. But
how could such water be found on the
moon, particularly as ice? Wouldn't it
have evaporated out of space,
particularly under the hot daytime
temperatures?
NASA's Lunar Reconnaissance mission
recorded surface temperatures as high as
127° C on parts of the moon in direct
sunlight.
So, something is either generating the
water or something must be trapping it
there. There are several hypotheses as
to why this might be happening.
Micrometeorites raining down on the
lunar surface, carrying small amounts of
water, could deposit the water on the
lunar surface upon impact.
Another possibility is that a two-step
process whereby the sun's solar wind
delivers hydrogen to the surface and
causes a chemical reaction with oxygen
bearing minerals in the soil to create
hydroxil.
Meanwhile, the bombardment of
micrometeorites could be transforming
that hydroxil into water. It could then
be trapped into tiny beadlike structures
in the soil that form out of the high
heat created by micrometeorite impacts.
Or the water could be hidden between the
grains of lunar soil and sheltered from
sunlight.
But LRO's observation means that the
locations on the moon that might be
viable for a lunar base is suddenly much
wider. If this trace amount of water
could be collected, you would not need
to build your base next to a permanently
shadowed region, which is convenient
because PSRs are far colder than we at
first thought. The moon has very little
axle tilt, a little over a single
degree. This means that at the poles,
there exist craters that are never
pointed directly at the sun. No matter
what time of day or year, the sun never
casts light into their mysterious
basins.
Naturally, a location that never sees
any sunlight is bound to be cold.
However, scientists were not prepared
for exactly how cold it turned out these
regions were. For context, at the
equator, temperatures on the moon
fluctuate between 120° C during the day
and minus 130° during the night.
LRO houses a diver instrument which uses
seven thermal infrared channels to
measure surface temperatures. With it,
LRO found a polar crater that had
temperatures as low as -250°
C, making it the coldest temperature
measured on any object in the entire
solar system. That's colder than the
average temperatures of Uranus, Neptune,
or even Pluto. The crater edges
shielding these areas from solar
radiation might have created the perfect
storage location for housing water ice.
But other more interesting useful
compounds could be found there too.
Carbon dioxide, carbon monoxide, d
nitrogen, and argon perhaps.
Furthermore, NASA's Sophia, or
Stratospheric Observatory for Infrared
Astronomy, discovered water on the
sunlit surface of the moon, confirming
that water on the moon may not just be
limited to cold and shadowed places, but
distributed across the lunar surface.
Sophia found that the Clavius crater,
one of the largest craters visible from
Earth, has water in concentrations of
100 to 412 parts per million. To put
that into perspective, the Sahara Desert
has 100 times the amount of water than
what Sophia detected in the lunar soil.
So yes, that is an astonishingly low
quantity, and it might not be of much
use to us, but it helps us in learning
about the lunar surface and how it
works.
Water is known as the oil of space and
finding a successful affordable way to
mine it on the moon could be
gamechanging in the space industry.
It can be recycled inside a lunar
habitat and used for drinking water or
washing. It could also be used to help
plants grow on the moon which are needed
to nourish future lunar colonists. But
the biggest and most immediate
application for lunar water is making
rocket propellant. Hydrogen and oxygen
are two of the biggest materials that
are used to power rockets right now.
You see, getting stuff into space from
Earth is a very fuelintensive and
expensive process. And the deeper into
space you want to go, the more fuel you
need and the more fuel you have to
carry. Having to bring all this from
Earth heavily limits space exploration.
But the moon has 16 of the Earth's
gravity. So if we are able to
successfully produce rocket propellant
on the moon, it's less resource
inensive. And transporting propellant
from the moon to other locations in
space would be nowhere near as expensive
as transporting it from Earth. And
actually, getting something from the
moon to low Earth orbit is less resource
inensive than sending it from Earth
itself, even though that adds 300,000 km
to the journey.
So, the presence of water on the moon
could help make space missions more
affordable and dramatically increase our
capabilities of exploring the solar
system.
China in collaboration with Russia and
other countries is planning to send
three missions by 2029 called Chang 6, 7
and 8 which will be targeting the South
Pole where they plan to establish by
2030 a robotic station. The US also
plans to have a lunar base by 2030 on
the lunar south pole with NASA's
Arteimus program. They plan on launching
their first non-manned flight test,
Arteimus 1, followed by a crude flight
test, Arteimus 2, and finally launch
Arteimus 3, which will happen no earlier
than 2025.
And that may be our first man mission to
the moon since 1972.
All in all, on the moon, the real estate
market is skyrocketing.
While I'm being a little tongue and
cheek when I say that, it is evident
that interest in the moon as a permanent
base for human life is increasing.
Before December 2022, the number of
countries and political unions that had
successfully sent probes either to orbit
or land on the moon has risen to six.
America, Russia, Japan, Europe, China,
and India have all sent spacecraft to
our closest lunar neighbor. As more
countries and companies set their sights
on space, it may make you wonder what's
the end goal. Do we simply want to be a
space fairing species exploring the
solar system for the betterment of
humanity? Or do people smell profit in
space? While researching this video, I
found out a lot of eyeopening reasons
why mining in space and especially on
our moon might well be something that we
see happening in the next couple of
decades.
Why? Well, just wait until you find out
what's actually there to be mined.
The first substance is known as helium
3. You may have heard of helium 3 in
sci-fi stories as theories suggest it is
the ideal substance for a clean type of
nuclear reactor with no radiation and no
dangerous byproduct. It also has uses in
medicine and radiation detectors.
However, it is really rare on Earth. It
does occur naturally and can be found in
deposits of natural gas, for instance,
but it's generally not viable to
extract. As even in natural gas, there
are only around 100 parts per billion.
So, let's say we had 1 billion cub m of
natural gas, you'd only be able to
extract around 15 kg of helium 3 from
it. A lot of the time, that's not
economically viable. We can also produce
helium 3 as a byproduct of the
radioactive decay of tritium. The
problem with that though is that tritium
is a crucial component of nuclear
weapons. And so when the world slowed
down the production of nuclear weapons,
helium 3 stockpiles also started to
diminish. Assuming we don't want more
tritium in the world, it means we need
to find another source of helium 3,
especially if technology improves enough
for helium 3 reactors to become a
reality.
Fortunately, we have a world in orbit
around Earth right now which has been
bombarded by helium 3 for billions of
years thanks to the sun. Earth's
magnetic field deflects helium 3
traveling with the solar wind around the
planet. Whereas the moon with no
magnetic field for protection simply
absorbs it in the top layer of the
ground. We aren't talking huge
quantities. It has at most 50 parts per
billion. But because it's all over the
moon, not just in tiny pockets, it can
be collected alongside any other mining
operation. It could also be used to
power reactors on the moon itself, which
would help a moon base be
self-sufficient.
Some people think that helium 3 mining
on the moon will not be viable. However,
China states that eventually mining
helium 3 is one of the primary goals of
their Chinese lunar exploration program.
American, European, and Indian
scientists have all stated it is
something they will consider further,
and Russia is conducting a feasibility
study on this right now. Even private
companies are eyeing up the possibility.
Because the parts per billion of helium
3 are relatively low, even in the moon's
regalith, it would make sense that
whoever was mining for helium 3 would
also be mining for something else in the
regalith at the same time. But what else
can be found in it? As it happens, the
lunar regalith is packed with different
materials.
Look at this false color mosaic of the
moon. Each color indicating different
deposits of minerals found on the lunar
surface. There are plenty of metals to
be found on the moon in large quantities
like iron, titanium, aluminium, silicon,
calcium, and magnesium. Some of these
metals are locked into hard to access
minerals and oxides. However, separating
the metals will often also produce
useful byproducts like oxygen and
hydrogen. They are super basic and not
rare on Earth at all. But unlocking
these elements on the moon itself will
allow for a colony to be self-
sustaining as oxygen means breathable
air, hydrogen can be converted to fuel,
and combining the two will produce
water. Unprocessed regalith could also
prove useful as it could potentially be
turned into lunarrete, useful for
building infrastructure on the moon
without having to transport the
materials from Earth. Glass could also
easily be produced from lunar regalith.
And while it's not super ideal, some
plants can grow in lunar regalith,
helping any lunar base to be
self-sufficient in growing its own food
short of using hydroponics. But perhaps
the most important resource found on the
moon are, ironically enough, metals
known as rare earths. Interestingly,
rare earths, which consist of this
section of the periodic table, are not
actually super rare on Earth. However,
the difficulty in mining them is that
they have not really collected into big
deposits. Rather, they are dispersed
through the Earth's crust. This means
that they are exceptionally hard to mine
on Earth and there are only a few
countries worldwide that have deposits
large enough to do anything about it.
Even then, most countries don't bother
at all because of the massive
environmental and human damages that
come from the pollution of mining them.
The only country that did not waver from
these problems is China, as China has
around 30% of the planet's rare earth
supply. And because it is one of the
only countries mining for them, they
have a 95% control of the market, which
puts China in a powerful position
worldwide, especially seeing as these
minerals are so valuable to our society
being components of various electronics
and batteries. Are countries with
somewhat sizable deposits like the US,
Canada, Australia, and South Africa
going to start digging up their backyard
to extract them? or rather than pollute
the Earth further in our attempt to go
green, is it actually more feasible to
get these rare earths off the moon
instead? Rare Earths aren't any more
common on the moon than on Earth.
However, some deposits have already been
identified, and pollution on the moon
would certainly not have any of the
devastating environmental and human
consequences attached to doing it here.
As demand for these elements inevitably
goes up in the coming decades, it could
well be that mining for them on the moon
becomes economically viable. And not
only that, but a control on the market
means control of the market price and
whichever country is in control will
have a tremendous advantage. Will it be
China maintaining their position or will
some of the other space fairing
countries and companies want a piece of
the pie? Only time will tell. Which
leads on to another curious question.
Who actually has mining rights on the
moon? Well, it's a bit unclear. The main
space treaty, which most countries in
the world have signed up to, is called
the Outer Space Treaty and covers things
like disallowing weapons of mass
destruction in space, disallowing
military bases in space, and disallowing
claiming any celestial body. However, it
doesn't really cover mining. Other
treaties have been put forward which
would cover mining in space but so far
only non-space fairing countries have
signed up for it. Right now it could
just be a matter of first come first
served. This makes mapping the moon
surface and finding sources of usable
lunar water all the more vital. If we
intend to colonize the moon, utilizing
this water will be incredibly important.
However, collecting this water ice might
be more challenging than you'd think.
And I don't just mean the cold. There
are bigger problems we'd have to face if
we want to collect and use water, ice,
and other resources from the poles. One
of them is electricity.
Because of the moon's low inclination,
solar winds, mainly made of ions and
electrons, pass by the polar regions and
the terminator almost horizontally,
hitting the crater's leewood. Once
there, the negatively charged electrons,
which are 1,000 times lighter than the
positively charged ions, rush down into
the craters inside walls and bottom,
causing these surfaces to become
negatively charged. As the electrons
rush down before the ions, a difference
in charge is formed, causing an electric
field to form. A negative charge is
created at the bottom and inside walls
of the crater, while a positive charge
forms above until the positively charged
ions are driven into this electric field
by the electrons.
As you can imagine, the most prominent
separation between the two occurs at the
crater's leewood, where the solar wind
hits. This division between electrons
and ions will eventually hit a critical
level. Because of this effect, these
areas could be charged up to hundreds of
thousands of volts, which would have
deadly consequences for an unwary
explorer.
But even if you avoid the poles, that
might not be the end of the electrical
problems you could encounter on the
moon. Another occurs when combined with
the fine surface dust of the moon,
regalith.
The moon has no magneettosphere, so any
incoming solar wind directly hits its
surface causing the surface to become
negatively charged and the covering fine
dust on the moon regalith becomes
electrostatic.
Regalith is a fine dust with sharp edges
which can have abrasive effects. In
fact, during the Apollo missions, it was
reported that regalith would stick to
everything due to its electrostatic
charge. This could potentially damage
spacuits and instruments which would be
a huge problem. On top of that, regalith
also causes some negative effects on
health causing redness and cough as it
can be highly toxic.
Space suits in the Apollo missions were
made of a material called woven teflon
which attracted the electrostatic
regalith and trapped it into its
material. Woven teflon can also cause a
tribbo electric effect making the
astronauts a medium between the
negatively charged ground of the moon
and the positively charged solar wind
flowing above their head.
This is similar to what happens when you
rub your feet on a carpet and then touch
the metal handle of a door, causing you
to get a small electric shock. A
laboratory experiment has even proved
that woven teflon covered in a simulant
regalith was more prone to an electric
arcing.
Luna exploration would be much less
appealing if you are constantly getting
electrically shocked.
So, if the dust and the woven teflon
made the astronauts so susceptible to
getting electrocuted, why haven't we
noticed before? Wouldn't it have
happened during the Apollo missions?
Well, this static effect can be offset
when photons emitted from the sun kick
off some of the electrons from the
ground in a process known as
photoelectric emission. This causes the
ground indirect sunlight to be more
positively charged and balance the
negative charges brought by the solar
wind. Because landers of the Apollo
missions landed on a part of the moon
which was constantly hit by sunlight,
our astronauts had very low chances of
getting electrocuted. But that's not to
say it wouldn't be an issue elsewhere.
So, how can we keep our astronauts safe
from extreme temperatures, toxic dust
that could potentially contaminate moon
bases, and the high chances of
astronauts getting electrocuted by up to
hundreds of thousands of volts of
electricity.
To avoid that, we would need to design a
new space suit with dissipative
properties that would never allow
potentially dangerous electric charges
to damage them or cause harm to the
astronauts wearing them. You might think
a good insulating material is rubber,
and you would be right. But this would
have to be balanced against the extreme
temperature fluctuations these suits
would have to face. After all, what
would happen to rubber in an environment
where temperatures could potentially
reach -247°
C.
There are multiple undergoing projects
though that are working on finding a
solution to these and other problems,
but so far nothing definitive has come
of it yet. To avoid regalith, a team at
the Washington State University was
granted $130,000 by NASA on a project
involving liquid nitrogen, which has
properties that allow it to capture dust
like regalith from surfaces, allowing
lunar bases to be kept cleaner and avoid
risks of getting it contaminated. NASA
is also working on a technology
involving electronamic dust shields
consisting of electrically charged
panels which through wires shoot
currents able to wipe away the regalith
from surfaces. A pretty cool way of
cleaning. There is also a revolutionary
new technology being developed by
intention a Norwegian tech company which
is working on a project called ASG.
This technology could potentially enable
remote human explorations and missions
by using a human machine interface which
allows people to control rovers, robotic
arms or even machineries with the swing
of one hand. They are working on
including this technology in space suits
which could have fascinating
implications for future missions to the
moon and even Mars. This would allow
astronauts to stay safe inside bases
while the machines are doing the job on
the field.
It's exciting to see different hurdles
being overcome in the mission to find
and gather lunar water. But while there
are successes, there are also failures.
In July 2024, NASA announced that it was
cancelling its volatiles investigating
polar exploration rover or Viper, which
had been intended to be the first ever
mission to explore the moon's south pole
and search for water ice. The mission
was intended for 2023, but due to delays
in the rover's construction and a
tightening NASA budget, Viper got pushed
back to 2025 and then was cancelled
entirely. The rover, now already built,
may be scrapped for spare parts.
This is a big blow as no other US
project over the next few years is
scheduled to have the same capabilities
as Viper, which was both mobile and
capable of exploring the subsurface of
the moon, not just its surface, to see
if water ice could be found there. Many
scientists outside of NASA were
surprised at the cancellation, with some
calling it a dark day for Lunar Science.
Hopefully, another space agency or
company will step in to make use of the
operational rover. Otherwise, it seems
to me to be a terrible waste of time,
money, and expertise.
But NASA is not the only space agency
finding Luna exploration challenging.
Five of the previous nine moon landing
attempts have failed. But even if they
had succeeded, perhaps they would have
been surprised. As it turns out, lunar
water, that precious resource vital for
the establishment of any human colony on
the moon, is proving oddly difficult to
actually locate. We have repeatedly
detected it in spectroscopy readings.
And yet, when we take a closer look at
where it ought to be, instead a mystery
appears.
The established belief among scientists
today is that the permanently shadowed
regions of the moon are one of the most
likely places to find frozen water ice.
But because it's so dark down in these
craters, it's difficult to know for sure
exactly which craters house what, it
would be unfortunate to build a
scientific base only to discover that
the crater next to you was completely
empty. Sadly, LRO, the NASA Luna Orbiter
tasked with mapping out the entire
surface of the moon, has its
limitations. His on camera, the LC, is
not capable of piercing this darkness.
But there is a new camera circling the
moon that can.
The reason why I said earlier that six
countries had sent probes to the moon
before December 2022 is that on the 16th
of December. That number actually rose
to seven. After a 4 and 1/2 month
journey, South Korea's Denuri probe
arrived in lunar orbit and Denur's
discoveries provided even more insight
into lunar water as well as raising
further mysteries.
NASA has actually been working closely
with South Korea on Dauri, providing
them with scientific expertise and
communications and navigation support in
a spirit of mutual international
scientific collaboration.
In thanks, South Korea's Kari Space
Program gave NASA 7 kg of space on their
Korea Pathfinder Luna Orbiter or Duri as
it's locally known. a composite word
made from dal which means moon and
nurida which means enjoy.
NASA considered what scientific
instrument could be best placed on
Daeneri and in the end they went with a
device known as shadow cam a younger
sibling of LRO's own narrow angle camera
with one notable enhancement. Thanks to
its 200 times sensitivity, it turns
images like this
into images like this.
This incredibly clear image is of
Shackleton Crater found at the moon's
south pole, the first ever site
photographed by LRO. And now, thanks to
Denuri and Shadow Cam, we can properly
peer into its inner basin. It turns out
that Shackleton does not look that
different from many of the other craters
on the moon. Its cratered floor is
covered in bumpy hummus.
But strangely, there is no obvious ice
here. Perhaps this is because Shackleton
is a smaller crater, meaning that the
temperatures within do not drop quite so
low as would be needed for ice to
reliably form.
One point of interest is the clear trail
left by a boulder as it rolled down the
crater side, visible near the top of the
image.
Such tracks are common on the moon as
the lack of wind means that any
disturbance of the dusty ground is never
covered up again. This track could be
extremely old.
I said that perhaps the reason no ice
was found in Shackleton was because
Shackleton was a small crater. But
Shadow Cam has now peered into many
different craters in both the North and
South Pole regions. And as of yet, its
discoveries have only deepened the
mystery of lunar water. In spite of
Shandrean 1's findings all those years
ago, none of Shadow Cam's captured
images showed the telltale glint of
water ice, either in glaciers or as a
light smattering of frost.
And it only gets stranger when we
considered one of the findings of
India's Chandrean 3 mission. It was
Shandrean 1 that first detected evidence
of water on the moon's surface. But
Shandrean 3 would take an even closer
look only for its findings to come back
quite different from what scientists had
expected to see.
India Chandrean 3 Moon mission had
already proven historic. It put India in
the history books for being the fourth
nation to ever successfully land a
spacecraft on the moon and the very
first to ever land at its south pole.
Sorry, Viper. The lander Vicram and the
rover Prag already made discoveries that
could profoundly impact our
understanding of the moon's chemical
composition and geological history and
has given the world vital data that will
aid future return missions to our lunar
neighbor. And yet for all the praise
which is welld deserved, it's what
Shandrean 3 did not discover but should
have that I find the most intriguing.
Have you noticed it too? India's NASA
equivalent, ISRO, the Indian Space
Research Organization, made press
releases before the launch and there was
always one thing they claimed they were
primarily there to find. One reason the
South Pole was picked out over all other
locations.
One mystery about the moon that is
deepening the more we investigate and
yet needs to be solved before we can
expect to start setting up permanent
bases up there. Simply put, where is all
the water?
Chandrean 3 was launched on the 14th of
July 2023. It was made up of a lander
module called Vicram, a small rover
called Pragyan, and an orbiter module
that carried the other two components
across the Gulf of space. On the 23rd of
August, Vikram with the little Prag
tucked inside touched down on the moon's
surface at the beginning of a lunar day.
But time was not on their side.
Shandrean 3 was a surprisingly
cost-effective mission. While NASA's
Arteimus mission launches will each cost
on average $4.1 billion, the entire
Shandrean 3 mission only came to $6.15
billion rupees or about $75 million.
Ironically less than what many modern
blockbuster space films take to produce.
Perhaps Hollywood should consider
filming their next moon film on site.
However, with this lower budget came
technological limitations. When the
lunar night fell, Vikram and Pragyan
would be subjected to temperatures of
-20°
C. Temperatures they were not designed
to survive.
A Luna day lasts 14 Earth days. The
Shandrean 3 mission would need to
complete its major objectives in that
time as their odds of surviving to the
day after that were slim.
And so Vikram lowered its ramp and
Pragyan the rover powered up and headed
out down onto the moon's surface.
Prague is a 27 kg six- wheeled rover
that came equipped with an alpha
particle X-ray spectrometer for
analyzing the chemical composition of
the moon by firing radiation at it and
seeing what wavelengths bounce back and
a laser induced breakdown spectroscopy
instrument that does a similar thing but
this time by firing a laser at the
target of interest and analyzing the
light wavelengths that are released by
the resulting plasma.
These two tools together would be enough
for Prag to attempt to find water or any
other interesting substances, confirming
their composition for scientists once
and for all. And so it set to work
deploying both instruments on the ground
next to it. Within days, the results
started to come in. Aluminium, calcium,
iron, chromium, and titanium were all
found on the moon's surface along with
other interesting elements like oxygen.
Indian scientists were most excited at
the first ever insitue measurement of
sulfur at the moon's pole. Sulfur is an
exciting element to find as it helps us
understand the evolution of the moon
over time and indicates there used to be
volcanic activity in the region. But in
spite of all these discoveries, there
was one element that was not showing up
in the analysis. The allimportant
hydrogen was notably absent.
Pragyan set off to explore further a
field. Guiding the rover was all done
manually by scientists back on Earth.
Looking through Prague's onboard
navigation camera. This had to be
carefully done as the signal delay
between Earth and the moon meant that
orders for the rover to halt lagged by a
little under 3 seconds. Time that might
make all the difference if the little
six- wheeled rover was to avoid
overturning. And indeed, this nearly
happened. Early on in Pragun's journey,
the rover had to speedily stop to avoid
falling into a large 4 m crater
scientists hadn't initially realized was
there. I say speedily, Pragun's move
speed was 1 cm/ pers, hardly the fastest
of sprinters.
Over the course of its twoe life, Prag
traveled no more than 100 m from Vikram.
Fortunately, the crater was detected in
time and scientists were able to turn
around and choose another route.
However, when you look at Pragen's
route, you notice that there was a
second moment where Praan did not travel
down into a crater it came across,
instead electing to go around. No photos
of this second crater are currently
available. So, we are left to conclude
that no ice was spotted there.
Vikram itself did not remain idle during
this time. It performed temperature
readings of the moon's surface, digging
10 cm deep to measure the moon's warmth
at different depths. It measured the
plasma content of the atmosphere. Good
news, there's not much up there, so
radio communication to the moon likely
won't get much interference. It detected
a possible moonquake, which given the
small 2E window was some excellent
timing.
At the very end of its journey, in a
moment of final enthusiasm, the Vikram
lander even successfully performed a 40
cm high hop, firing its boosters to lift
itself off the ground, moving 30 to 40
cm along from its previous destination.
Indian scientists had wanted to test how
easy it would be for future landers to
one day propel themselves back into
orbit from the moon. And this was a
useful practice run. But none of this
helped the Shandran 3 mission to find
water ice.
By the 4th of September, time was up.
Vikram and Praan were ordered to power
down. Israel scientists had hoped to
wake them up again once the night ended,
but this hope proved to be fruitless.
The two lunar explorers had communicated
with Earth for the last time.
ISRO and the scientific community at
large lorded their efforts and called
the mission a success. And indeed it was
as India had gained firthand data from
the moon that would be extremely helpful
in building a picture of conditions at
its poles along with furthering our
understanding of the moon's history.
However, it definitely raises a mystery.
When I first heard that water ice had
been detected on the moon, I envisioned
in my mind frozen ice lakes or possibly
tall penitentes,
perhaps a light frost as vapor from the
moon's atmosphere ended up trapped in
these darkened craters, freezing over
the surface and building up over time.
We know from orbiters like Shandrean 1
that water ice is indeed in these
craters. And yet, Chandre Ensuri has
joined other missions in failing to
actually see this ice for themselves.
Given that Prag's analysis of the lunar
regalith revealed no signs of water
molecules, where is the water ice the
Chandrean 1 detected?
While this mystery is confusing,
Shandrean 3 offers us a possible answer.
not through Pragian's explorations. It's
actually Vikram that possibly hinted at
the solution.
When Vikram used its chasteed
temperature sensor, it was able to take
10 different readings of the moon's
temperature, starting at the surface and
working its way down in 1 cm increments.
What it found in the space above the
moon's surface was a temperature a
little under 60° C. definitely too hot
for you to walk around in if you happen
to be on the moon and somehow didn't
care about the lack of air. But
curiously, as Chase measured deeper and
deeper beneath the surface, this
sweltering temperature dropped off fast.
By 8 cm deep, the new temperature Vicram
was detecting was - 10° C. That's a big
drop. From this, we can see that Luna
Regalith is a really poor heat
conductor. But that also indicates quite
clearly that the best place we're likely
to see ice is not resting on the moon's
surface. But we actually need to look
beneath it.
There's much we don't understand about
the moon and its water cycles. There's
growing evidence that the moon contains
quite a lot of water. And yet extracting
it will take understanding where that
water can be found and how it moves
throughout the long lunar days and
nights. Is it affected by solar
radiation? Is it trapped in hidden
deposits? Although Chandrean 3 only
lasted 2 weeks, which I'm sure is less
time than ISRO scientists would have
liked, it has offered us vital insights
into the conditions on the moon. As far
as water is concerned, at the very
least, it's given future astronauts this
one piece of advice. If you want to find
a drink of water on the moon, you might
want to start by bringing a shovel.
Do you know the many surprising
connections between the deepest parts of
space and the deepest recesses of our
ocean?
Both are cold, dark places where humans
cannot breathe and where the pressure
alone is enough to kill you. Both upset
our normal experiences of gravity.
providing explorers with a strange
weightlessness or buoyancy if they could
somehow survive being there in the first
place. And both contain many unsolved
captivating mysteries. Our oceans are
filled with life we've never seen
before. And who can say what lurks in
the unexplored corners of space?
I was initially caught off guard when I
heard that NASA had turned its attention
towards exploring the hallel zones deep
in the ocean. After all, NASA is
normally about space. What are they
doing deep under the water and on Earth?
I'm Alex Mccoan and you're watching
Astramm. Put on your diving gear and
join me in a world of undersea
facilities, uncanny life, and an
environment so hostile we've mapped more
of Mars than of this terrain on our own
planet.
In 1957, a year before NASA was founded,
a paper published by the Journal of the
Royal Society of Arts claimed the deep
oceans covered over 2/3 of the surface
of the world. And yet more is known
about the shape and surface of the moon
than is known about that of the bottom
of the ocean. This was a reference to
the fact that in the world before
echoing technology was commonly used to
map the seafloor, we didn't know much
about the topography of what was down
there. We've come a long way since then,
but while we have mapped the moon thanks
to satellites and telescopes, we have
still only mapped 23.4% 4% of the ocean
floor in high resolution.
In fairness, this still represents an
area of 120 million km, about 3 times
the moon's surface area. So, the old
saying no longer holds entirely true.
Hence why we can instead talk of Mars,
which has a surface area of 145 million
km. But still, it's a profound gap in
our knowledge of our own world.
NASA was founded in 1958 with the
purpose of expanding human knowledge of
phenomena in the atmosphere and in outer
space and developing vehicles and
technologies that would help them to do
so. Exploring the ocean was not
originally on their radar or sonar.
However, in 1978, NASA began monitoring
the ocean with their first dedicated
oceanographic satellite, SESAT, which
was capable of collecting data on sea
surface winds, surface temperatures,
wave heights, and other features. This
helped them learn more about our
planet's oceans and their impact on the
global climate. Still, some of NASA's
most exciting foray into the ocean only
began at the turn of the millennium.
One way in which the sea can prepare
astronauts for space is through
simulated space experiences.
About 8.7 km off Kilago in Florida is
the world's only undersea research
laboratory, Aquarius Reef Base. Built in
1986, it is a small three- roommed
habitat large enough to house six people
at a push with a main room that combines
sleeping and living quarters, an entry
dock, and a wet porch for entering the
sea around it. It was originally
designed to help aquinauts remain at the
bottom of the sea for weeks at a time
through a technique known as saturation
diving. By remaining at the depth of 19
m, the human body becomes saturated with
gas dissolved in its bloodstream, which
allows these researchers to stay at
depth without ill effects for much
longer periods of time, 9 hours for one
dive rather than 1 or 2 hours. This made
it ideal for biologists wanting to study
the local environment in situ. In 2001,
however, NASA along with other space
agencies such as issa realized that it
made a great space training location.
The cramped living conditions mimic
those found on the International Space
Station, so astronauts who spent a week
at Aquarius Reef Base would get a vital
taster of what life would be like up
there.
It also allowed them to practice
performing experiments and generally get
used to the expected and unexpected
aspects of life in a hostile
environment. NASA began the NEMO program
or the NASA extreme environment mission
operations and that same year began
sending their astronauts to the habitat.
There have been 23 Nemo missions since
then, merging astronaut crews from a
variety of different space agencies
which lasted up to three weeks.
Astronauts there became aquinauts and
got the chance to dawn deep space suits,
getting a taste for what space walks
might be like outside of our planet,
readying them for the day humans return
to the moon or go to Mars. This was not
the only use NASA had for the ocean,
however. Perhaps the most significant
training was not for NASA's astronauts,
but rather for the machines that would
one day visit the largest oceans outside
of planet Earth.
Let's now go deeper and consider the
exploration of alien oceans.
Our solar system is home to many large
oceans outside of Earth. Jupiter's moon
Europa and Saturn's moon Enceladus, to
name just two, have significant bodies
of water beneath their kilometer thick
icy surfaces. In spite of only being 1/4
of the Earth's diameter, scientists
believe that Europa holds twice as much
water as all of our oceans combined.
This is an intriguing concept as even
though no sunlight penetrates down to
those steps, the mixture of liquid water
bordering a rocky inner crust would make
both of these locations ideal candidates
for life.
Scientists have considered how to best
test to see if life really has arisen in
the oceans of icy moons. In 2024, NASA
will launch the Europa Clipper with the
mission to fly by the moon Europa and
scan it to learn more about the depth of
its icy shell to try to determine the
composition of its oceans and generally
get a better picture of the moon as a
whole. However, Europa Clipper will only
be laying the groundwork for future
missions, which one day might see
cryobots melting through the 10 km thick
icy shell of Europa using nuclearpowered
radiators to penetrate its oceans and
see firsthand what lies below. Once down
there, no radio signal will be able to
reach them easily. Messages will be
relayed via a vast cable brought down
through the ice along with the cryobot.
This means that such cryobots will need
to be able to autonomously descend a
further 100 to 200 km to explore the
dark, chilling, and highly pressurized
environment they're likely to find to
see what alien life might swim in those
waters. So, with a mission objective on
the horizon to explore deep, dark waters
in search of neverbeforeseen life, what
better place to start than the
unexplored oceans we already have at
home? The deepest parts of the oceans on
Earth are only 11 km deep. But due to
the gravitational differences between
Europa and Earth, the pressure you'd
experience between the two are much more
comparable than you might think.
Europa's 100 km deep ocean is thought to
have a hydrostatic pressure between 130
to 260 megapascals,
which if it existed in an ocean on Earth
would equate to a depth of around 13 to
26 km. This is much better than if you'd
had to go hundreds of kilome down on
Earth, but it's still no picnic.
Pressure at the bottom of the Mariana
Trench, the deepest place in our ocean,
is 1,100
times the pressure on the surface, which
is enough to crush the individual cells
in the human body or to implode most
submarines.
And yet, life survives there. And it
doesn't just survive, it thrives.
The deep sea explorers of the Galapagus
hydrothermal expedition in 1977, using a
specially reinforced, remotely operated
vehicle that could survive those
pressures, were shocked to discover not
a barren wasteland, but thriving
ecosystems gathered around hydrothermal
vents on the ocean floor down there.
Tubeworms, crabs, and fish were found in
rich abundance. As scientists performed
more dives, they found all manner of
strange life forms down there. Shrimp
like amphipods the size of your hand.
Giant ethereal big fin squid. Squid that
were 8 m long and looked positively
alien. In the depths between 6,000 and
11,000 m, in an area known as the Hadel
zone, named after the god of the
underworld, Hades, life had learned to
adapt to conditions in ways no one could
have imagined possible. And this
incredible adaptability gives scientists
a better understanding of what might be
possible on other worlds.
The deepest parts of the ocean are
mostly found near the fault lines of
continental plates, where one plate
subducts under another. These deep
trenches create a unique V-shaped
environment that channels organic debris
from above down into a sludgy pool.
Whenever a carcass falls down there, the
organisms in the Hadel zone are somehow
able to quickly detect it and arrive
within minutes. Other organisms rely on
nutrient-rich liquids pumped out of
thermal vents. If you added up all these
trenches into one land mass, you would
end up with an area the size of
Australia, a whole unexplored continent.
NASA wants to explore these regions
using autonomous drones, perhaps whole
swarms of them, that would be able to
detect locations of interest such as
thermal vents and would be able to map
out the terrain using cameras and
onboard AI similar to that used by the
Perseverance rover on Mars. It's a
challenging task. Not only would such a
drone need to be able to withstand the
excessive pressure, but the temperature
around such thermal vents can spike to
hundreds of degrees. Drones would need
to be able to survive rapid temperature
swings if they are able to survive. In
2014, one such deep sea drone known as
Narius was sent into the Kerdc Trench
off the coast of New Zealand. This is
the area NASA has selected as testing
ground for its new equipment. However,
sadly, Narius was not able to survive
the pressure down there in spite of
having succeeded on Hadel dives before,
and it imploded. Pieces of plastic were
later found floating to the surface.
NASA's latest drone is Narius's
descendant, a smaller, lighter,
autonomous submarine known as Orpheus.
Orpheus has yet to enter the depths of
the Hadel zone. Instead, it is being put
through its paces in shallower waters.
But if it works, its lighter design
would make it easier to transport on a
rocket to the oceans of Europa at some
point in the distant future.
Although this dream might not be so
distant after all. In 2023, NASA's
Planetary Exploration Science Technology
Office gathered a team of 40 top
researchers from multiple fields in the
California Institute of Technology to
discuss how close we might be to making
this trip. A surprising amount of
technology needed is already there.
Their conclusion was that the mission
was feasible, scientifically compelling,
and the most plausible near-term way to
directly search for alien life in situ
on an ocean world. With the combined
information being gathered by Europa
Clipper and the technical
experimentation being done with Orpheus
and other autonomous submarines like it,
perhaps it is something we will see
within our lifetimes, although no
concrete plans have been made yet. When
it finally does happen though, and a
human-made drone starts to swim in those
dark seas across the Gulf of space, what
will it see? Perhaps it will feel
strangely like home. We are waterbased
life forms here on Earth. The first
large complex animals formed in our
oceans. All life is dependent on water
to live. Rather than arid, rocky, and
dusty wildernesses, there will be
something strangely soothing about
exploring oceans beyond our own, like
entering a place we already know, even
though we've never been there before.
Does something lurk in those alien seas?
Although it's only speculation, the
sheer fact that this might be true is
enough. To discover that life came to
exist not once but twice in just our own
solar system would have massive
implications on life's prevalence in the
universe as a whole. It would mean life
is likely abundant and we ought to be
ready to see a lot more of it out there.
But proving it is the challenge. Only by
perfecting the technology here on Earth
will we be able to crack open those
frozen shells, enter those inky depths,
and find the definitive answers we seek.
For NASA, their mission to find life in
our solar system begins in our oceans.
Enceladus,
perhaps one of the most intriguing
objects in the entire solar system.
And yet, it is only the sixth largest
moon of Saturn, and in natural light, it
looks very unassuming.
However, there's a lot more to Enceladus
than meets the eye. It's an active icy
world with jets of water vapor pouring
out from its southern hemisphere.
Thanks to the remarkable Cassini
mission, we have studied and observed
Enceladus in exquisite detail and
perhaps know more about it than some of
the closer and bigger Jovian moons.
However, although we've seen a lot from
the outside, it's the inside of the moon
that still holds so many mysteries.
I'm Alex Mccoan and you're watching
Astramm. And together we will explore
some of the most fascinating details of
Enceladus, piecing together photos and
data from a variety of missions to find
out almost everything you could want to
know about this special moon. So stick
with me on this journey of discovery.
Let's first of all discuss where
Enceladus fits into our solar system.
Enceladus is currently Saturn's 14th
closest moon. I say currently as Saturn
has some tiny moonlets hidden in its
rings that may or may not be classified
as moons in the future. It is the second
closest major moon though, second only
to Mimis. That means that its orbit
takes it just outside of Saturn's major
rings. Its orbit follows the planes of
the rings very precisely, and it only
takes 33 hours to orbit Saturn once.
Interestingly, it is in a 21-1 orbital
resonance with Dioni, Saturn's fourth
closest major moon. In other words, it
orbits twice around Saturn in the time
Dioni orbits once. This orbital
resonance is believed to prevent
Enceladus's orbit from ever becoming
perfectly circular, which causes
Enceladus to undergo tidal deformation.
This is significant as these tidal
forces heat up Enceladus' core.
You see, as far as we can tell,
Enceladus's surface is predominantly
made of clean water, certainly with
little to no rocks or much else there.
Because Saturn is situated so far away
from the sun, it means the outer layer
of water on Enceladus has frozen over.
Enceladus is essentially a frozen ocean
world, a giant ball of water ice.
Because it is free from other materials
on the surface, the moon is one of the
whitest objects in the solar system with
a bond albido of 0.81,
which is pretty much as high as snow. As
such, it is one of the coldest
satellites of Saturn with a noon
temperature of -200°
as the white color of its surface
reflects a large percentage of the
sunlight reaching it back into space.
However, about 30 to 40 km down under
the surface of Enceladus, pressures
start building and heat energy generated
from the tidal defamation of its orbit
has increased the temperature of the
water ice to the point where the water
at this depth can exist in a liquid
form. It could well be that there is an
entire mantle or a global ocean of water
that the ice crust is resting upon, very
much like the magma mantle that our
rocky crust on Earth rests upon. At the
very least, scientists expect there to
be a huge pocket of water under the
moon's south pole. How do we know this?
Well, the most obvious indication are
the huge plumes of water being ejected
from the cracks in the crust. Something
referred to as water or cryo volcanism.
These jets are really active,
consistently blasting around 250 kg of
water into space every second at speeds
exceeding 2,000 kmh.
This is powerful enough that most of the
water vapor particles escape Enceladus'
weak gravity, and they end up in orbit
around Saturn, forming Saturn's E-ring.
This ring around Saturn is very diffuse,
and so isn't really visible unless it is
backlit by the sun.
From this angle, the light shining
through the water particles make the
ring appear exceptionally blue. In fact,
this ring is considered the bluest
object in the solar system, even more so
than Neptune due to the ring's
uniformity.
The E-ring is Saturn's second outermost
ring, and it is 2,000 km wide. Its shape
is also heavily influenced by the orbit
of Enceladus. Enceladus' plumes create
tendril shapes in the rings as more
material erupts out of it. However,
these sections of the ring tend to
smooth off as Enceladus moves further
away along its orbit.
During the course of Cassini's mission,
Cassini was able to pass through these
plumes to detect the substances being
ejected from them.
Cassini wasn't designed with this in
mind. Scientists didn't know about the
plumes until Cassini got there. However,
Cassini was equipped with an instrument
called the cosmic dust analyzer designed
to detect what the tiny dust grains in
orbit around Saturn are made of. And it
was able to use it for Enceladus'
plumes, too.
As it wasn't specifically designed with
this in mind, it might not have given us
the full picture of what's in these
particles. But while water was the
predominant substance detected, amino
acids, carbon dioxide, nitrogen, and
methane were also found. Amino acids are
significant as they are the building
blocks of life and can be found around
the thermal vents at the bottom of
Earth's oceans. Does this mean Enceladus
has thermal vents of its own? And if so,
do they have ecosystems of life around
them?
While evidence for an underground ocean
is abundant, scientists still aren't
completely sure about Enceladus's
internal structure. At some points in
the past, scientists believe that
Enceladus was water all the way through.
However, data from Cassini suggests that
Enceladus' mass is in fact greater than
previously thought, meaning it must have
some amounts of iron or silicut material
in its core. Scientists are starting to
lean towards the theory that the
internal structure is differentiated,
meaning it's a celestial body with
defined layers within it. An object of
this size really doesn't have to be
differentiated. In fact, it's so small
at only about 500 km across that it is
right on the borderline of being in
hydrostatic equilibrium or in other
words being rounded by its own gravity.
There are a number of objects out there
of similar or smaller sizes that are not
in hydrostatic equilibrium like
Neptune's Proteus. In any case, assuming
it does have a differentiated interior,
this core is likely to be predominantly
rocky. This is important as thermal
vents in Enceladus's water ocean would
have to come from a rocky core. A rocky
ocean floor would also provide nutrients
and minerals essential for what we
believe life would need to form and
evolve. Thermal activity clearly does
exist due to the way Enceladus has
plumes in the first place. And the amino
acids detected in the plumes suggest a
rocky core.
As Cassini passed over Enceladus, it
also mapped out the thermal emissions
from the moon. It turned out that the
jets line up with what has come to be
known as Enceladus' tiger stripes. These
are large depressions roughly 130 km
long, 2 km wide, and 500 m deep. It is
believed that these are tectonic
fractures in the moon's icy crust.
What is really interesting about the
surface features of Enceladus is that
there are virtually no impact craters at
all over the southern hemisphere and not
many anywhere else.
This implies that Enceladus' surface is
very young. As while it does have a thin
atmosphere made up from the ejected
water from the plumes, this isn't nearly
enough to burn up asteroids before they
hit the surface. Some water from the
plumes obviously settles again on the
surface which smooths it off over time.
This is another reason why Enceladus is
so round for such a small celestial
body.
In fact, apart from the tectonic
fractures and few craters, Enceladus'
topographical variation is really quite
minimal. There are no mountain ranges to
speak of, although there is what you
might call a rough terrain around the
South Pole if you zoom in far enough.
This is perhaps the highest resolution
image we have of its surface. And as you
can see, it really does appear like a
giant glacier. It's interesting to note
that even in this small view, there are
some smooth sections of ice, but also
jagged regions.
Over the north pole, the clear
difference is the number of craters
present there. While there are tectonic
fractures here, too, there are no plumes
on this side of the moon. So the surface
here is clearly a lot older than around
the South Pole, which is why it has more
of a cratered surface. As Cassini flew
through the plumes around the South
Pole, it also took the opportunity to
image the surface closely around the
tiger stripes.
The surface here is pretty incredible,
unlike anything you would have seen on
Earth. It's like the surface has been
folded, squashed, and shifted around,
leaving these remarkable fracture lines
and formations in the surface ice. The
fact that Cassini was able to get so
close to Enceladus is a feat in and of
itself. It's fantastic that we can have
such a close-up view of something so far
away. Unfortunately though, since the
Cassini mission has ended, we no longer
have anything in orbit around Saturn
that can study Enceladus further.
There have been plenty of mission
proposals in the past, but all of them
were cancelled before they came to
fruition. What would be incredible is a
probe that could either make its way
into Enceladus's ocean somehow or at the
very least search the plumes for signs
of life. There is already a mission
called Dragonfly going to the nearby
moon of Titan. However, this won't have
anything to do with Enceladus.
So although a couple of mission
proposals are currently under review to
go there, that means we are
unfortunately still a couple of decades
away at least, which is a shame because
who knows what secrets lie in wait under
that crust.
So, there we have it. A look at the
intriguing little moon of Enceladus.
Europa,
one of the most exciting moons in the
entire solar system. It is a beautiful
world filled with mysteries.
This is the first ever close-up image of
Europa taken by the Pioneer Probe back
in 1973.
Since then, we've had the Voyager and
Galileo probes explore the moon, and
with each visit, Europa has never failed
to surprise us.
We are yet to solve a lot of Europa's
puzzles, but there are many things that
we are starting to piece together.
I'm Alex Mccoan, and you're watching
Astramm. Stick with me in this video and
together we will explore some of those
fascinating mysteries and delve into
almost everything there is to know about
this intriguing world.
Let's first of all see where Europa fits
into the Jovian system. Europa is the
second and smallest of the four Galilean
moons. Although it's still the sixth
biggest moon in the entire solar system,
just behind Earth's moon with a diameter
of about 3,000 km.
It takes Europa 3.5 days to orbit
Jupiter once. Interestingly, the first
three Galilean moons, Io, Europa, and
Ganymede are locked in a 421 orbital
resonance due to their gravitational
influence with each other. This means
that every time Ganymede orbits Jupiter
once, Europa orbits twice and Io orbits
four times. This orbital resonance and
the constant gravitational tugging from
the other moons keeps the orbit of
Europa from ever becoming completely
circular.
Due to Europa's slight ecliptical orbit,
the magnitude of the gravitational force
acting on it from Jupiter increases and
decreases as it orbits. This creates
tides that stretch the moon's surface.
These forces are significant as they
have a big influence on the moon's
appearance and what goes on under the
surface.
Europa's surface is made predominantly
of water ice. As you can tell, it looks
very remarkable and distinctive due to
these long continuous fractures and
cracks. These are called lineier, which
translates to lines in Latin. These
lineier are often only about 1 to 2 km
wide, but can extend for thousands of
kilome across the moon's surface. We
aren't sure how or why these linear are
formed at present, but the most likely
theory is that as the crust pulls apart
from tidal flexing, warmer material from
beneath fills the gap in a similar
fashion to the ocean ridges on Earth.
In this image taken by the Galileo
spacecraft, you will notice some dark
brown spots. They are very small, only
about 10 km across and they are known as
lenticullet.
They are also believed to be formed by
the upwelling of hot less dense material
to the surface either by pushing the
existing crust up or by breaking through
altogether. Should the underground
material have broken through, what we
can then see are these strange, unusual
terrains called chaos terrains. They are
really rough patches surrounded by a
rather smooth surface. These spots are
expected to be soft and may contain
significant information about what's
under Europa's surface, which we will
get to later in the video. Data from
Galileo also indicated that Europa's
equator may be covered in icy spikes
called penitentes.
These vertical cracks may be up to 15 m
high and will have formed from direct
overhead sunlight on the equator.
Interestingly, penitentes are found on
Earth 2 in dry regions at high
altitudes, although nowhere near as
large as on Europa.
Despite being roughly the age of the
solar system, Europa barely has any
craters. Europa has less than 50 major
craters, whereas the Earth's moon has
more than 5,000 craters with a diameter
above 25 km. This indicates that
Europa's surface is constantly changing
and reforming. Models suggest that
Europa's surface is only about 30 to 180
million years old, which is very young
in geological terms. Additionally,
Europa's icy surface is the smoothest
surface of any known solid celestial
object in the entire solar system. Its
icy crust also has an albido or light
reflectivity of 0.64,
one of the highest of all the moons.
Europa's albido makes it five times
brighter than our moon. The surface is
bombarded by a constant and intense
blast of radiation from Jupiter. The
radiation level at the surface of Europa
is equivalent to a dose of about 5,400
milliseverts per day. Exposure to
radiation at that level would be enough
to kill a human in a single day. The
reddish brown color spread across the
cracks and fractures of the moon is
believed to be due to salt and sulfur
compounds mixing with water ice and then
modified by Jupiter's radiation.
A recent study from JPL suggests that
Europa might even glow in the dark.
Energetic ions from the radiation
penetrates the surface which would
energize the molecules beneath which
would make them release energy as
visible light. Unfortunately, we cannot
see Europa's dark side from Earth as we
are between it and the sun always. So,
we are going to have to wait for future
missions to Europa before we can prove
this.
Radiation received from Jupiter plays a
significant role in Europa's atmosphere
as well. Europa has a very tenuous
atmosphere composed primarily of oxygen.
Unlike on Earth, the oxygen on Europa is
formed by radiolysis or in other words,
the process of radiation bombarding the
water ice surface, separating the H2O
into oxygen and hydrogen. Hydrogen
escapes Europa's gravity altogether
because it's so light. whereas a lot of
the heavier molecular oxygen remains.
The hydrogen and oxygen that escape
Europa's gravity form a disperse neutral
cloud which follows the orbit of Europa
around Jupiter.
In 2012, the Hubble Space Telescope
discovered plumes of water vapor
erupting from Europa's south pole. This
image suggests that the water plumes
rise up to 200 km from its surface.
In 2018, astronomers found additional
evidence of water plume activity on
Europa when they looked back at the old
Galileo data with a new data analysis
technique. A dedicated mission studying
these plumes can also help us understand
what's inside the moon without having to
land on it. Because what may lie
underneath that solid ice surface is
perhaps the most fascinating thing about
Europa. There is likely to be a global
ocean between a rocky mantle and the
water ice crust. The first clue that
this amazing ocean world was hidden
under its surface was provided by the
Voyager and Galileo probes in 1979 and
the late 1990s respectively.
Between these missions, there was a
drastic change in the magnetic field of
the moon, which is not possible unless
there is some electrically conductive
fluid beneath its surface.
Europa's crust also indicates the
presence of a liquid layer beneath it as
it rotates with an angle of 80° which is
not possible if the crust and rocky
mantle were mechanically attached.
Instead, it is likely that the icy crust
floats on the ocean and it is believed
to make one full rotation around the
moon once every 12,000 years. The fact
that this ocean is not attached also
explains the multitude of lineier on the
surface.
Tidal flexing should cause lineier to
form at specific points on Europa, not
all over. However, because the position
of the crust changes over time, and one
spot never stays in the same place for
long, hence why more and more linear
form.
Europa is 780 million km away from the
sun, which is five times further away
than the Earth. That makes the sunlight
about 25 times fainter here. As such,
Europa or any other moon in the Jovian
system for that matter barely receives
any heat from the sun. So,
unsurprisingly, it's cold enough here
that the surface is frozen. In fact,
Europa's surface temperature averages
about - 160° C at the equator and -220°
C at the poles, keeping Europa's icy
crust as hard as granite.
However, tidal pressures exerted on the
moon as it orbits Jupiter heats Europa's
core. So, geothermal activity from the
core should keep the subsurface ocean in
a liquid state. This ocean is believed
to be under only 15 to 25 km of solid
frozen crust. The ocean itself is
probably about 60 to 150 km deep.
Interestingly, Europa is only 1/4 the
diameter of Earth, although it may
contain twice as much water as all of
Earth's oceans combined.
What's most interesting about Europa's
ocean is that scientists believe that it
is in contact with Europa's silicut
rocky mantle. This makes Europa's ocean
a suitable environment for life as we
know it to exist. We believe that life
requires water, minerals, and energy to
form. And Europa seems to have all these
requirements. From the evidence we've
seen so far, scientists are extremely
confident that this ocean not only
exists, but that chemical reactions can
take place there and that there is
enough tidal energy heating the core
that geothermal activity may exist on
this ocean's floor. As we have seen on
Earth, whole ecosystems can exist in
such places far from the sun's light. So
for now, Europa is one of the most
likely places we can find life outside
of Earth. Now, NASA's Europa Clipper
spacecraft is scheduled to launch in
2022 and is likely to reach the moon by
the end of the decade. It is scheduled
to perform more than 42 flybys of
Europa.
Is also working on their own spacecraft
called Juice or Jupiter Icy Moons
Explorer, which will explore Jupiter and
three of its largest moons, Ganymede,
Kalisto, and Europa. Juice is also
scheduled to launch in 2022 and is also
likely to reach the moon by the end of
the decade. These probes are
specifically designed to examine
Europa's water plumes and atmosphere.
NASA is also planning a Europa lander
mission, but this mission is going to
launch well after the Europa Clipper
mission. These missions will help us
know more about Europa and hopefully
confirm the answer to the most
tantalizing question of all. Does it and
can it sustain life? At the very least,
these missions will give us a new
perspective of our solar system and help
us understand how it works.
So, there we have it. Almost everything
you could want to know about the
fascinating world of Europa.
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