good evening everyone
before them
you see the planet behind me
who have good blue gimbel who looks
a lot to the earth and in fact it’s
March
so it’s not mars like you
know today who is red
but as it could have been, there is
four and a half billion years and
so as it was said I’m not
astrophysicists I am a doctor in
experimental petrology so there you
you ask why someone who
works in the oil comes to you
talk about March
so for a simple reason it’s that
experimental petrology it’s not
the experimental study of oil is
the study of mechanisms of formations
rocks and especially his two
to try to recreate the pressures and
the temperatures that pre-existed
inside the planets in sum it’s
make the trip to the center of the earth from
jules verne but realistically and
not only can we make this trip to
center of the earth but we can also
make our own planet
artificially
so I feel that I have the impression
that I’m surprised a little people but
I have in my pocket small
artificial planets I will show it
then I will give you the
recipe for making these planets
if you do it at home then but
before that we’ll start with
beginning how do the planets get
are formed so the planets
it is formed by a phenomenon that
Calls the phenomenon of accretion
planetary so it’s simple if
you leave small objects and you have
riveted to dgo so how’s it going
you have the sun the young sun who
is in the center of a disk that’s called
an accretion disk and this young sun
it recovers 99 % of the available mass
and what’s left around is the 1% that
rest is dust that are very
small ones that are 1 mm and turn around
from the sun and stick to each other
others to form tall objects
intermediary we call
planetesimals planetesimal trials cd
object that looks a bit like
today’s asteroids so they do
a few meters to a few kilometers
continues the movement that was launched
by the dust
except that gravity begins to play
so it ‘s called more a pact outright
and it speeds up the movement and we
gets planets that make several
thousands of kilometers so this phenomenon
of accretion it takes about one
billion years ago and so there are 4
billion years
cattenières and a half by which we get
a solar system much like we
know him today
so to know with two types of
planets of terrestrial planets
what are called telluric planets
mercury venus land and mars who are
near the sun and planets of
gaseous type jupiter saturne uranus and
neptune that are far from the sun and the
first question that arises is
why do we have the gaseous planets far
and nearby telluric planets whose
tips to get back to the disc
of accretion in this disc you have
the closer you are to the sun the more he
is hot so what will survive is
metals and rocks and that’s what
makes you telluric planets and
the further you get away from the sun the more he goes
to be cold and so there you go
to be able to survive the water of the
gas ice and so make planets
gaseous and comets
so from the ground theoretically the ground
there is no water
hold your breath and no gas
no more obviously it does not work
so for that there are several hypotheses
to try to explain why we have
water on earth
one of the first was to say that
the water had arrived later via the
comets and suddenly we sent the probe
rosetta to check and that’s not true
so we had to find another
hypothesis is the assumption we use
same bench is to say that there are
the water in this hot zone and do we know
she is hidden in the rocks that are going
form the planets and this is two
impacts to know firstly if there is any
water it’s going to be the effect of water
on the formation of planets and
secondly how much water there was
so we will try to answer these
questions but before answering
Questions
we will pass I will present you a
little my study objects that his march and
the earth so first thing that strikes
March is much smaller than the
earth and that it has a direct effect that’s
that inside March the pressures
and the temperatures are a lot
much lower than on earth and
that’s why on earth you have
this structure a little odd complicated
so now let’s look in detail
so on earth we will summarize things
saying that you have a nucleus that is
metal in the center that surrounded by a
coat that is silicate so that’s
rocks 6 4 and a crust that is
totally negligible whether
thickness or mass it counts for
nothing at all and chemical is missing in this
Earth’s mantle we know that there is 8 %
of oxidized iron
now let’s look at march on march
there too you have a kernel that is
metallic that in the center and a coat
which is silicate and that is self and
a crust that again does not count
really for nothing at all
on March you have 18% iron oxide
so we have to explain why we
8% on land and 18% on March
so be you say the planetesimals
he was very different at first and
you have something very
different on arrival you can nothing
say more or you say give up the
internal conditions that will change the
mantle chemistry why because the
kernel he is not he has not formed
first in the center
and then the rocks have arrived
everything is a bit strong but at the same
time in what’s called an ocean
deep magmatic so this is the schema
that you have as soon as you see
behind me you have at the moment of
aggression
a lot of heat that is released
because it’s impacts so that
heats up and you melt everything
what’s in planetesimals so the
rocks like metal so you have on
the whole surface of your planet a
lava ocean with inside the
metal which is heavier and which
eventually sink and form the nucleus and
so we all know that the
chemistry is going to be given by the reactions
happens between the metal and the
rocks that surround it in this ocean
deep magmatic but me what I have
wanted to do is add water in
this magmatic ocean and see what effect
so that’s so it took me
remake deep magmatic oceans in
laboratory with water and when I
cool down I know I get it a
planet so we’ll go to the party
a little culinary from the presentation to
know how does one cook one’s
planet so firstly here is my
cooking that’s a multi press
anvil that allows for pressure
very very high so it’s pressures
that we express in giga pascal then for
give you an idea its a giga pascal
10,000 times the atmosphere you have
on your shoulders or more visually a
water column of 10 km on a centimeter
square with the must not too much how
that’s it but it’s 10 km from where and with that
we can go up to 20.25 pascal
relatively easily
it corresponds today on earth to
a maximum depth of 800
kilometers roughly and on march like
the pressure is lower at
inside at every pressure we
can do so from scratch all
depths from zero to 3390 km and no
only we can compress it we can
also heat and you can heat
such as to melt rocks and
metal so for that you have to mix
his rushes and this metal and put it in
the press and that’s where we get to the
planets recipe
because obviously you need
ingredients
then the ingredients you need a
coat a core so the coat is
of oxidized powders so I speak of
silicate since just now it ‘s
of the western silicon of oxidized iron
of magnesium you mix all that in
the mortar that is at the top right and
you touch more you add iron
cobalt nickel and sometimes
silicon or sulfur and there you have
your greenhouse powder too and you have
your core
now if you want to make a
planet that is hydrated initially it
must add water then it is necessary
especially not pour water directly
in the mortar because it’s not very
very clean we must add also the
powder and this powder is hydroxide
aluminum so we agree it’s
no water is hydroxide
aluminum
but at 600 degrees this hydra oxide
aluminum
he’s going to transform himself and he’s going
produce aluminum oxide and
water is like that I will have two lots
in my experience without putting water
steps not now you recover
your powder you beating some and
you put it in a container that is
in graphite called a capsule and
this capsule
you put it in what’s called a
assembly our pressure so that’s the
little byte that you have there and I
have in my pocket
yes so that looks like for you
see this so the capsule is
in the center because after you have to put
the round sheath and so it’s suddenly
here and so you put that it’s at
theater in carbide cubes
tungsten is a metal that is more
hard as diamond that’s what will you
allow to rise in pressure so
you put a second set of cubes
over the one you already see
you fixed all with plates and you
put in the press she admits to spend
at the thigh so first have you
compressed then you heat up
way to melt the rocks and the
metal at the same time you cool
you decompress and you can
retrieve a dhr object that were
understood and so suddenly it gives that
so there it is after after and before that
well been compressed is your planet
so she’s in the center of the water
Maybe you see it above
now i’m going to introduce you two
types of planet that can be obtained
first planet
so here it is to show you that I have
not lied I have a metal that’s the
core a silicate is the mantle so
I have a planet so this one is
so in graphite
since it’s the capsule that contains
seven planets seven planets there she is
easy to get
she does it’s a pressure of 5 gigas
pascal 2000 degrees of temperature and
so it’s relatively easy it’s
relatively big it’s even very big
it’s 1 mm high and 0.3 mm wide
it’s really very very big why
because when you increase the
pressure it is necessary to reduce the volume and in
more of that there are other problems that
so arise now if we go up the
pressure at 20 Pascal and the
temperature at 2502 gets this one
and here it’s a planet paste
so it’s still a planet you
have the metal is silicates that is
much much smaller so that’s it
does 200 microns on 200 micro 0.2 mm
about 0.2 mm
and on top of that your graphite at these
pressures there it turns into
diamonds and that’s a problem it’s
a problem why because because
this diamond is very very difficult to
remove and not in addition to that to
the interior is really small
to give you an idea
I have one so has this same
pressure the goal of the game is to find the
planet at the bottom in front of those who have a
good view can try
so that’s pretty much like that
so that’s the actual size and then
that’s to justify the purchase of
microscopes and so is this diamond in
does they really come for it’s
very difficult to remove and hygiene
for the analysis because obviously I
do not planets just for the
pleasure is also to analyze them and
understand what’s happening on the real
planet and so I ‘m going to show how
we analyze then we will resume the
early planet because it’s more
simple so there now there is more than
legend recover all alone
core the coat of specialists of the
planets is what we do is we
look at the composition so of the metal and
silicate and in particular that of
iron so if you do not have water you
had to do that is basically
in the metal and you have a little
of oxidized iron also in silicate and
now if we add water in
this planet so ol will react with
do it to form iron oxide
so is you removing iron from the metal and
you must have done in the in the
coat of the coup we did it on this
planet puts on many other
planets full on many others
experiences complains pressures
different water content complaints
different and so scientifically that
looks like that and that just means
that every time you add
the water you take off had to do and you
add iron oxide to the
coat
and it’s simply interpreted by
a stupid reaction that is doing it
more blurred gives the iron oxide and the
of hydrogen so that’s a reaction
oxidation and to make you simple in
surface it’s rust so here
you put two nails that’s exactly
the same reaction is not quite
the same oxides but it’s the same
principle is so there you answered to
the first question we asked ourselves
just now what is it
happens when we put water in the
planets have rusted the planet
simply now second
question how much there may be you
reuse that reaction that you
knows and
as it is true at all pressures
it works whatever the depth
and the size of the planet and how
knows the iron oxide content March 2
and earth with this reaction for
go back to the water content that there
had four and a half billion ago
years old for a few
calculation assumptions is so I you
pass all the assumptions but we will
that’s what we did and so there is
four and a half billion years this
what we find is that there was
a lot more water on mars
twice as much water on mars
relatively speaking that on earth and this
which makes it one of today’s pours
today you have ten times less
of water on mars than on land then of
it’s not water that has
oceans on mark already there is no ocean
and on earth most of the water in
does it is in the rocks as in
early it is hidden inside the
boat and why do we have these
numbers there because already at March to
rust so water reacted with the
do and besides mars is tiny
so the gravity is low and so
the hydrogen that has been produced is
totally part while on earth we
kept a little water so that
when we look at the planets
today so peace the earth and
march so march which is red the earth
who’s blue ya four and a half billion
of years March looked more like the
earth that we see today that the
earth itself is potentially there
had possibility that life was
developed much earlier on march
so rather in two words than on earth
Thank you for your attention
[Applause]
[Music]
”
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