she ended up blowing my mind with this
fact with this phenomenon that only
happens on the planet Mars of all the
planets in our solar system
thanks to Lego presenting lego city for
their support of PBS Digital Studios
hey I'm Diana and you are probably on
planet earth watching physics girl I too
was on planet earth the other day when I
recently dropped by UCLA to visit a
really cool friend of mine Raquel nuna
is a planetary geologist and I brought
her probably the most boring question
you could bring to such a scientist can
I live on planet Mars pretend this is
Mars I don't want to live there either
planetary geologists are creative and
sneaky and finding out a lot of things
including the hospitable 'ti of Mars if
you want to know whether Mars is gonna
kill you and which of its hostile traits
is gonna kill you first you have to get
creative let's look at all the ways that
Mars is a complete deathtrap and how we
know seems like a useless atmosphere is
a good place to start so one of the
biggest differences is the atmosphere of
Mars so it's about 1% of stick as is
here on earth so it's there's not much
going on there and because there's not
much atmosphere it's it's hard to keep
heat in that's actually one of the
reasons why Mars is so cold
Mars is missing a decent gas blanket
it's like trying to camp on a glacier
with nothing but a bedsheet
it gets really cold the average surface
temperature on Mars is minus 63 degrees
Celsius whoo plus with an atmosphere
that's 1% the thickness of Earth's
atmosphere and 95% carbon dioxide you
would run out of oxygen pretty quickly I
think that that's very crucial for
humans to to live in an environment like
you need to breathe it'd be like trying
to breathe at over a hundred thousand
feet of elevation here on earth we need
an oxygen mask to assist with breathing
when we get up to only 15,000 feet so
for my Mars work what I'm trying to
understand is how the thickness of the
atmosphere has changed over time she
ended up blowing my mind with this fact
with this phenomenon that only happened
on the planet Mars of all the planets in
our solar system Mars has this funny
little thing where it tilts it goes
through cycles where it slowly goes and
tilts and then it comes back up and so
its orbit sometimes it's spinning
straight up and sometimes it's spinning
the sideways Mars is currently tilted at
about 25 degrees which is 2 degrees more
than Earth but we have evidence that it
is tilted from between 0 and 60 degrees
and it's a chaotic cycle it kind of
randomly tilts I wanted to know why it
tilts and so of course I asked Raquel
and we'll get to that answer in a minute
but first what are the implications of
this tilting it is a really dynamic
place you have the poles you have ice
sublimating so that's going from solid
to gas depending on how hot it is and
then when it's more straight up it's the
thing it's cold so it kind of the
atmosphere essentially collapses and and
it forms back on the poles and the water
goes into the soil so not only does Mars
tilt the thickness of its atmosphere
changes over time as more of its poles
are exposed to the sun's light well now
the atmosphere only changes by about a
factor of 10 and we're still trying to
figure out exactly how much it changes
but this is my burning question always
this is always the question I want to
know how do we know how do scientists
know that the atmosphere has become
thinner
and thicker over time you can't just
send a scientist down to the surface of
Mars and ask her to wave her hand around
and then ask her how thick is the
atmosphere large no and forget easily
trying to figure out how thick the
atmosphere was in the past but planetary
geologists are sneaky this is how Raquel
goes about detectiving out how thick the
atmosphere was on another planet
millions of years ago I look at small
super tiny impact craters so if you have
a very thick atmosphere a small Rock
isn't gonna make it through the
atmosphere is just gonna burn up but if
you have a very thin atmosphere it
doesn't care just gonna punch right
through and create a tiny little crater
at the surface what size crater can we
make at the surface depending on how
thick the atmosphere
is and then looking at the evidence that
we find at the surface so Mars tilts
because so a couple of reasons one of
the reasons that it it's got Jupiter so
sometimes it pull it it pulls on it on
Mars and the other big thing it doesn't
have a moon like we have to stabilize
its orbit so it can it can wobble
because there's no moon to keep it just
straight up like we you know we're not
straight up we're like 23 degrees offset
but yet we we don't wobble as much as
Mars does because we have this wonderful
moon see another reason to love the moon
now with a thin atmosphere most people
think of the cold and they think of the
lack of oxygen but there's also no
pressure
Mars atmosphere is six millibar as
compared to Earth's 1,013 millibars so
it kind of just feel like being out in
the vacuum of space not fun how do we
know about Mars atmosphere we've seen
evidence for the thickness of arnaz
atmosphere by looking at unusual things
like projectile rocks that have shot out
of volcano eruptions and we've observed
how far away they landed this can tell
us how much air resistance the rocks
experienced when they were flying
through the air which is correlated with
how thick the atmosphere was so we're
able to learn a lot of things like this
before we even landed on Mars a surface
by doing flybys like the 1965 Mariner 4
flyby now we can learn a lot about
Mars's atmosphere from probes that we've
actually landed on the surface and some
that we've crashed
Oh besides a good atmosphere there are
other missing protections on Mars too on
earth we've got this weird invisible
thing that goes to charged particles and
other harmful cosmic rays that hit Earth
it is Earth's magnetic field it does
really wonderful things for us and Mars
doesn't have one and then another thing
that I think is really big that people
don't think about that the Sun is always
blowing out massive amounts of charged
particles and through just out through
the solar system and we're really lucky
that we have a magnetic field that sort
of deflects most of those particles some
still do make it to us but Mars doesn't
have that so all of that ionizing
radiation comes in and hits the surface
is centrally sterilizing it that's very
dangerous for for life mm-hmm
how do we know about Mars's magnetic
field well now we can measure it but
before that there were actual rocks from
Mars that landed on earth with evidence
of magnetic metals that were once
aligned by a magnetic field and then
frozen in place when they cooled so you
see that evidence for an ancient
magnetic field so we think that at some
point maybe early in its history where
it still had a liquid core a much bigger
liquid core that it did have a magnetic
field but it cooled down we're not sure
why or how but it could have just been
over time the planet cooled down and
they essentially turned off that the
magnetic field of Mars so Mars is
smaller than the earth so it's cooled
down a lot faster and we think that you
need a liquid some sort of liquid
component metal inside the core to be
able to generate dynamos which are is
what we call like magnetic fields and
then there's this the biggest volcano in
the solar system is on Mars which is
amazing to think about so one of the
things that that makes the volcanoes on
Mars different is because there's no
plate tectonics here on earth when the
crust moves as a crust moves the hot
spots create a new volcano
on Mars that doesn't happen so they get
to be really big because of that stuff
comes out of the same place over and
over over millions of years and that's
they get so big okay so for habitability
we're not sure if the volcanoes are
still active or not there could still be
some sort of volcanic activity going on
that could potentially erupt in the next
few million years on on Mars so if we
have a base somewhere on Mars you want
to make sure that you're not near a
volcano probably because we just don't
know there's a lot of things that we
still need to learn before I think we
can determine whether or not a volcano
could affect human settlement on Mars
interesting right so then a final
challenge in trying to live on Mars is
finding an energy source take solar some
time as we look through telescopes at
Mars and we see that the entire planet
is fuzzy turns out there are planet-wide
dust storms so there they can be massive
they can actually incorporate the whole
planet what we call a global dust storm
it's pretty nuts sometimes you look at
images from the spacecraft that are
orbiting Mars and the whole thing is
just blurry because the whole planet is
covered in these dust storms you know
like in the Martian that was the whole
premise of the movie was this massive
dust storm caused all sorts of problems
but in reality it wouldn't and even
though the wind speeds are really high
the there's not just not enough stuff to
to go around and actually cause any
damage it'd be just like a gentle like
breeze in your face oh my god this is
nice
and you know what dust isn't good for
solar panels trying to get sunlight and
there's only about 40% of the amount of
sunlight reaching Mars as here on earth
then there's geothermal energy there's
hardly any geological activity on Mars
because Mars is such a cold planet wind
is weaker for wind turbines cuz there's
no air bro and forget fossil fuels
because we haven't discovered any
evidence for any types of life on Mars
not even frogs so while there's still
hope for crazy life-forms that can
survive in harsh environments like Mars
it's still a long shot for humans until
Mars rolls over and gets that thick
atmosphere and warms the heck up until
then enjoy your internet video
here on earth and happy physics Inge
thanks to Lego presenting Lego city for
their support of PBS Digital Studios can
you believe it's been 50 years since we
landed on the moon it started out with
one small step for man and now the
journey to Mars
is right around the corner featuring
sets inspired by real aerospace
technology lego city space aims to
inspire future space explorers to
imagine what role they can play to get
us to the Red Planet
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