Thanks to Wren for sponsoring today’s video. Insight is dying. The planet it was sent to study is killing
it. The contest between Insight and Mars has been
going on for four years. The Insight lander has attempted to pierce
the heart of the planet with metal and hammer, and day after day has pried out its deepest
secrets with clever instruments. But from day one, Mars fought back with an
unending assault; using an innocuous tool that never stopped mounting, a pressure that
claimed inch by desperate inch, choking the light from Insight’s components and rendering
it powerless. But not before Insight uncovered what it set
out to find. It has learned things that expanded our understanding
of Mars and the Solar System. I’m Alex McColgan, and you’re watching
Astrum. And so, for what might be the final time,
let’s look over the Insight mission and its discoveries, even as it begins to power
down forever. But as if this were a good crime drama, there
is one more twist to this tale. Insight’s final, dying messages to us might
just turn out to be the most important of them all. Those who are frequent watchers on my channel
will know that Insight landed on Mars back on 26th November 2018. Its mission was to study Mars’ interior,
thus helping us gain a deeper, more accurate understanding of the planet’s structure,
and how it might have been formed 4 billion years ago. As Mars is one of the 4 rocky planets in our
solar system, this would give us insight into the other 3 – Mercury, Venus, and even our
own Earth. However, Insight’s opponent was Mars, and
Mars would not give up its secrets easily. Before Insight won the war, it would lose
battles. And the first defeat came through its sensors. Insight carries two primary sensors for collecting
data. The first is a Seismograph known as SEIS,
designed for detecting the slightest vibrations in the crust that might indicate Martian quakes
or meteorite impacts. The second was a heat flow and radiometer
sensor package attached to a hammering digging device known as the mole. Unfortunately, due to differences in the Martian
soil from what was tested for back on Earth, Insight’s mole quickly found itself struggling
to achieve the 3-5 metres depth that was necessary to get good readings. In fact, it barely managed to get beneath
the surface. Scientists tried to find ways to coax the
mole to dig for over two years, but in January 2021 decided to give up on that element of
the mission. This left the SEIS as the principle means
by which scientists could look beneath the planet’s surface. This was done by listening to the P waves
and S waves of marsquakes. When a quake happens, ripples travel in all
directions through the planet’s crust, core and mantle. When these ripples come up against the transition
points between these three sections, some of the waves can bounce back towards the surface. This means that when SEIS hears the rumblings
of a quake, it will often hear many secondary echoes from that same quake. By detecting the time taken and magnitude
of these secondary echoes, vital insights can be gained into the shape, structure and
density of Mars’ inner workings. But Insight was facing a race against time. NASA’s arch nemesis reared its ugly head. A seemingly innocent, and yet insidious tool
of destruction: You’ve guessed it, dust! As a stationary lander, Insight was made with
two large solar panels that were designed to give it the energy it needed over a two-year
mission. When that mission was extended into a 4-year
mission, however, scientists knew that one of the problems they’d come up against would
be dust. Although it seems innocuous, if it fell on
the solar panels, dust had the potential to completely disrupt Insight’s ability to
collect power. Over the course of the 4 years, more and more
dust did just that. At the start of the mission, these panels
were capable of producing 5000 watt-hours each Martian day. Now, at the time of this video’s release,
they’re only producing 500 watt-hours – about enough to power an electric oven for 10 minutes. Without this power, Insight would not be able
to keep its heaters on, subjecting its components to the -70°C temperatures of Martian nights
– enough to quickly break them. Scientists had not built Insight with onboard
cleaners or fans. Instead, they had relied on the arrival of
little whirlwinds or dust devils native to Mars to come along and remove excess dust
in “cleaning events”. Sadly, although these windy phenomena were
observed, they did not come close enough often enough to clear Insight’s panels well enough. And so, in 2021, Insight started powering
down. However, scientists were not willing to let
this slide, and in early June 2021 came up with an admittedly counterintuitive way of
removing dust from the panels – adding more dust! Although Insight does not have cleaning tools,
it does come equipped with a small robotic arm with a scoop attached, which it can use
to scoop up the sand from the floor around it. The idea was to slowly trickle sand down onto
the panels from the scoop while the Martian wind was blowing. Hopefully, the wind would bounce the falling
sand off the panels’ edges, and as the sand hit the panel it would knock dust loose, thus
removing it. This plan might sound crazy in theory, but
it worked in practice; gaining the lander an additional 30-watt-hours of energy a day. This extended Insight’s mission through
the Summer of 2021 and into the following year, which turned out to be a game-changer. It was only in the final year of Insight’s
life, past the point where it should have died, that it detected its largest quakes. Over the course of Insight’s mission, the
lander detected over 1300 Martian quakes. Most of these quakes were relatively small. Due to Mars’s smaller size, Mars’ crust
is not split into different plates, so it does not have plate tectonics – the process
which causes some of the more powerful quakes on Earth as one plate rubs up against or goes
underneath another. Mars’ quakes are almost always under a magnitude
4 on the Richter scale, which means that unless you were right on top of their epicentre,
you likely wouldn’t notice them. Thankfully, while detecting such small quakes
is very difficult on Earth, on Mars it’s much more possible, and Insight’s SEIS instrument
is capable of detecting mag 4 quakes from almost 1000km away. Mars is less noisy than Earth. On Earth, there are oceans constantly beatings
back and forth, which create vibrations that can completely mask smaller quakes. But obviously, Mars doesn’t have this problem. Still, scientists hoped to hear some larger
than Mag 4 quakes on Mars. These would provide the clearest pictures
of what was going on beneath Mars’ crust. For most of Insight’s mission, this hope
was not realised. However, in May 2022 the ground rumbled. Data streamed in. Insight’s SEIS sensor detected a Mag 5 quake,
the largest yet. If Insight had already powered down, it would
never have heard this clear data point. And so, NASA has proclaimed Insight’s mission
a fantastic success. It has provided data that will pave the way
for many future missions to come. But what did we learn from that last message,
and the ones that came before? What does the provided data tell us about
Mars? To begin with, thanks to Insight’s data,
we now know that Mars does indeed have a crust, a mantle and a core, just like on Earth. However, that crust is much thinner than we
expected. It contains 2 to 3 sublayers and descends
20-37km deep, compared to the Earth’s which can have a thickness of 70km. Its mantle is not as hot as scientists previously
believed and descends a further 1,560km. Finally, its core is larger than scientists
thought, with a radius of 1,830km. Surprisingly, it is also less dense than expected. This has led scientists to predict that it
is not simply made of Nickel and Iron, like the Earth’s core, but that it must contain
lighter elements like Carbon, Oxygen, Sulphur and Hydrogen. This is a fascinating insight. It explains why the core of Mars is still
molten. Much like salt’s ability to reduce the freezing
point of ice – which is why you see grit thrown on roads in cold weather – these
lighter elements reduce the freezing point of Mars’ core. It also points to the origin of the planet. These light elements must have been collected
into Mars in the very earliest periods of the solar system’s history, as by the time
Earth was formed these elements were not around in as great a quantity, explaining why Mars’
core has them and ours doesn’t. They were also found further out, indicating
that Mars may have been brought closer into the Sun’s gravity as time progressed, before
finding the stable orbit it navigates along today. It confirms that during the early formation
of Mars, all the cosmic dust that came together must have heated each other up and become
molten, thus allowing the heavier core metals to easily sink to the planet’s centre. During this period, or soon after it, Mars
began to experience its dynamo effect. Mars today has only a weak magnetic field
compared to Earth’s. Most of this field is left over as residual
traces of magnetism, locked into many of Mars’ surface rocks. However, back in its early formation 4 billion
years ago, Mars’ moving metals in its core created a massive dynamo, imbuing these rocks
with their magnetism. When the planet cooled, hot materials were
not able to move about as quickly as they needed to keep the dynamo going. In time, Mars’ dynamo ceased to be. Thanks to the data provided by Insight, scientists
will have a much better idea of the timescales involved in this dynamo. This is relevant because when we talk about
magnetic fields and dynamos, those can affect what the atmosphere was like. And once we understand that, we will have
a clearer picture of Mars’ early habitability. Insight might give us an idea of the time
period when life was most likely to form on Mars. Insight has given us an incredible amount
of raw data, including a fascinating comprehension of Martian weather patterns. Yet, there are still many mysteries. Even though we now know the rough dimensions
of Mars’ inner structure, Insight’s findings have actually disproved some previously existing
theories. For instance, under a particularly volcanic
region on Mars’ surface known as Tharsis – home of Olympus Mons, a volcano two and
a half times as tall as Mt. Everest – there exists a hotspot of magma
that feeds the volcanic processes we see in this region. Due to the absence of plate tectonics, it
was unclear what exactly was causing this hotspot, which seemed to have been present,
unmoving, for billions of years of Mars’ history. Scientists originally thought that this hotspot
was being fed by a lower mantle, but it turns out that Mars does not have a lower mantle. As such, it is back to the drawing board to
explain what is causing this phenomenon. Still, these are the sorts of questions and
discoveries that drive scientific endeavour. And the discoveries that Insight has given
us will inform future missions for decades to come. Scientists will pour over the data, analysing
P waves and S waves, attempting to find patterns and meaning in the sounds of Mars’ rumbling
heartbeat. And who knows how much more we will discover
as a result of this successful mission! If more comes in, I will keep you posted. But as Insight powers down, as it closes its
eyes on the scattered clouds and dusty plains of Mars, it can rest easy. It did what it came there to do. Mars’ inner workings have finally been brought
to light. Worried that our world may end up looking
like Mars? Climate change is something that’s been
on my mind a lot of late, especially as I’m someone who looks through a lot of NASA data. While a lot of CO2 responsibility goes to
big corporations, each of us contributes to CO2 levels in our atmosphere. But what if we could change that? One important step is to know how you are
contributing, and how you can improve on that. This is where Wren is extremely valuable. The website will ask you a variety of questions
to help you understand your carbon footprint, and then give you ways you can go carbon neutral. For instance, one that resonated with me was
a tree planting program in East Africa, and Wren gives me updates so I can see how my
money was spent. With this program, they don’t just plant
and forget. They are constantly monitoring the sites and
checking growth. As a bonus, the first 100 of you to sign up
to Wren using my link in the description will have an additional 10 trees planted in your
name, so be sure to check it out. Thanks for watching! Be sure to check out the InSight playlist
here if you want to learn more about this pioneering probe. A big thanks to my patrons and members for
your support too. If you want to have your name added to this
list, check the links in the description below. All the best and see you next time.
