Hey well welcome everyone good evening
glad you could make it out I'm glad is
happening tonight not last night but I
would have been yeah we like Newton give
it an empty lecture so good job Astros I
just gotta get that out there so you're
joining us online as well thank you for
being here if you're in LA I'm sorry but
style makeup for that
sorry yeah I know yeah just I I heard it
just now yeah all right so we're this is
a second presentation our current series
looking at ocean worlds and the outer
solar system diving into ocean worlds
our first presentation last month was
from dr. Paul shank here at LPI and gave
us like an overview of the Voyager
missions and what they taught us about
ocean worlds or the fact that we learned
we had them other than Earth and the
outer sources were from Voyager tonight
who were here about more specifically
about one of those ocean world's Europa
and in January our next talk didn't you
area 11 is with dr. Jonathan Levine from
Cornell University talking about
Enceladus that should be good and he
sent me the title for his talk at about
two o'clock this afternoon after I'd
print the Flyers
so the Flyers just sayin Stella dust to
look like I'd be a very very interesting
talk though based on that title I don't
it was a long title so I did I head
right down and I all want to let you
know about I don't have fliers for it
unfortunately because we just got
confirmation today on this but December
2nd is it saturday we are going to have
kind of a two-part public event that
afternoon that evening for the Apollo 17
45th anniversary and dr. Harrison
Schmitt will be here the part of the
event that afternoon and then giving a
presentation like this evenings that
night at 7:30
if so those of you who are younger than
me Harrison Schmitt was the only
just to walk on the moon during the
Apollo missions we will be instituting a
ticketing system for that we did this a
few years ago with that movie series we
had because of its popularity it's
pretty simple you'll just basically
you'll register online through our
website and you'll get a little ticket
through your email and just bring that
with you and everybody's name when you
get here because we have this room in
our overflow but we anticipate this
could be much bigger than what we can
hold so we will be doing that we'll send
out information about that in a couple
of weeks and we'll open it up a few
weeks before the event but I wanted to
get that out there
so you all at least be aware of it
December 2nd the afternoon activity will
be from 4:00 to 6:00 the library will
also be having an open house during that
time so if you've never been here
because you always come here after hours
and have another go to library you'll
have that chance that day as well and in
the presentation that any will be at
7:30 just like these so if you are not
our email list and want to make sure you
find out when that registration will
open sign up at the table to the left or
when you're walking out to the right of
the doors put your email there and make
sure you get on our list teachers if
you're here welcome we got PD
certificates for you at the front desk
so grab one of those before you go and
of course we will have a reception in
the lobby that will follow as we always
do so now I'll invite dr. Lewis Proctor
the LTI director to come up and
introduce tonight's speaker okay so for
the last two days we've been holding a
workshop here at the LPI we've had
almost 50 scientists in the building
discussing what we think is going on
inside the ice shell of Jupiter's moon
Europa it's one of the most fascinating
places in the solar system we think and
it's the topic of tonight's lecture I
can't say we figured it out but it's
been a lot of fun trying and it's my
great pleasure to introduce one of the
most eminent of the scientists that has
been here as is dr. Robert Pappalardo
who's going to speak to us tonight
in 1986 Bob received his Bachelor of
Arts degree in geological sciences from
Cornell University where one of his
professors I think inspirations was the
late great Carl Sagan and in 1994 Bob
obtained his PhD in geology from Arizona
State University from there he moved to
Brown University where he became a
postdoctoral researcher and he started
working on the Galileo mission - which
was in orbit around Jupiter and I have
some of you in the audience for you
worked on that mission I think we've
discussed that before and he was an
affiliate member of the Galileo imaging
team and during that time he worked to
plan many of the Galileo observations of
Jupiter's icy galileo galilei and
satellites and that's actually where I
met Bob I was a graduate student at that
time and we became friends and
collaborators we've been collaborating
for over 20 years and I think it's no
under estimate to say that Bob's become
one of my most important scientific
mentors during this time after leaving
Brown Bob became an assistant professor
of planetary sciences at the University
of Colorado at Boulder and he stayed
there until 2006 and at that time he
joined the Jet Propulsion lab in
Pasadena California where he first
became the project science scientists
for the Cassini mission which of course
just ended sadly it was a wonderful
mission and he is currently the project
scientist for NASA's new mission to
Europa which he will tell us about
tonight Bob Stern research focuses on
processes that have shaped the icy
satellites of the outer solar system
especially Europa and the role of it's
probable subsurface ocean so please join
me in welcoming dr. Bob Pappalardo
really appreciate it here to talk with
you about Europa one of the most
fascinating moons of the solar system
and oh yeah I don't have my lavalier mic
on that's the problem
let's yes there we go I want to talk
with you about Europa one of the most
fascinating moons in the solar system
you'll see why because this ocean world
has a chance to support life so it's
it's fascinating geologically and geo
physically but why does most of the
public care and why does NASA care
because Europa has a chance to support
life and it's it's not exactly let's see
the kind of life we're talking about is
not not little green man by the way so
you know I'm originally from New York so
so yeah besides no don't worry I hate of
the Yankees don't worry I hated them as
much as you do that's not a problem well
exactly so it's it it's really it's hard
living in LA because you hate the
Dodgers cuz they left but you know I
can't do so Houston was the better team
there was no doubt in this series so
we're not looking for this guy
exactly but to understand whether there
could be microbial life at your right at
Europa
all right we're talking single-celled
organisms why because people work that
green thing that we imagine need a lot
of energy to survive a place like Europa
is probably rather low in energy we'll
talk about that but it might have enough
to support life when we talk about
searching for life you know that doing
that really means going to the surface
of a place like Europa
and scooping up some stuff and looking
at it in a microscope and putting it in
a mass spectrometer that's not what we
plan to do is our first mission what we
plan to do is a mission that's a
multiple flybys of Europa from orbit
about Jupiter we're gonna fly by Europa
many many times a couple of dozen times
at least few dozen times at least and
get the first really close-up really
global data set of Europa because we're
trying to understand is it a habitable
environment that's the first step we
want to understand are there the
planetary ingredients for life water the
right elements to build organic
molecules chemical energy so that
essentially means to do the energy
sources exist for chemical reactions to
take place that could support life and
is it a stable environment one that's
probably been around a long time as we
think of it it probably has been so um
parallel to the exploration of Mars
first we want to understand Europa
globally understand is it a potentially
habitable environment and then with a
future mission we can go down and
literally search for her life go for the
for the brass ring so and it I'll feel a
bit about what makes Europa fascinating
why we think there's probably an ocean
within and how we tend to go explore it
so first some context one of the first
images of Europa so over 400 years ago
Galileo Galilei first and his primitive
spyglass to the heavens and saw the
Jupiter had these four little what he
thought were stars next to it and then
he realized night after night observing
that these apparent stars were actually
going around Jupiter and that
revolutionized our understanding of our
place in the universe because there was
this idea from Copernicus that maybe
maybe the earth was not the center of
the universe
maybe instead earth went around the Sun
and our Moon went around the earth and
that was a pretty revolutionary idea and
by seeing that these that Jupiter was a
center of motion with these moons going
around it that led to the Copernican
revolution and changed our sense of
place in the universe earth was not the
center of the universe after all this is
what we know of those four largest moons
of Jupiter the Galilean satellites named
for Galileo Galilei Io Europa Ganymede
and listo Ganymede and Callisto were
kind of half ice and half rock io is the
most volcanic Li active body in the
solar system all rock and an iron down
below Europa is probably most the Iraqi
object with a thin skin of water and ice
as we'll talk about and a real hero of
our story is the Galileo spacecraft as
Louise mentioned which orbited Jupiter
from 95 to 2003 and made about a dozen
flybys of Europa most of what we know
about Europa is from that mission
Europa's surface looks a lot different
than say our moon which is of course
covered with craters here you see this
one about 20 kilometers in size quail
who are put well I'd say all right um
but there are not many well here's one
more so actually by the by the paucity
of craters we can estimate the age of
Europa's surface as about 60 million
years old that sounds like a long time
but that's only about one percent of the
age of the solar system so the moon
Europa has been around the whole age of
the solar system but something has
repaved its surface over the last 60
million years or so since the time
dinosaurs roamed the earth
this is what Europa looks like close up
it's this bright stuff is ridge Plains
consisting of criss-crossing ridges and
grooves and the darker stuff is a lot of
it is made up of this chaotic terrain
that kind of looks like that that older
Ridge Plains has just been fried on a on
a grill or something and we'll talk
about what might make these features
this is what we think we know about the
interior of Europa probably has an iron
core down to the center probably has a
rocky mantle which makes up most of the
moon and then this outer skin about a
hundred kilometers thick exaggerated
here a little bit so you can see it of
h2o and
surface of Europa is so cold 100 degrees
Kelvin
that there has to be ice at the surface
ice that's so cold that it acts like
rock and the question is how much if any
is liquid water below that earth most
important really ingredient for life
in fact if we're right and we think
there's probably about 80 kilometers or
so or 100 kilometers worth of liquid
water down there then Naropa has more
water within it then all of Earth's
oceans combined
um so how do we really know what
Europa's interior is like well one way
is from gravity by flying by the moon we
can get an idea of how centrally
concentrated the moon is that's why we
know there's an iron core we're probably
an iron core and this outer lower
density layer that's probably h2o but
how do we know it's liquid well the most
important way I'm a geologist by
training and you'll see a lot of
geological evidence for an ocean but
that's kind of that's very indirect the
most direct evidence is chrome Europa's
magnetic field and that magnetic field
is probably not intrinsic to Europa
instead it's because Europa is moving
through the gigantis magnetic field of
Jupiter and in moving through Jupiter's
magnetic field from Europa's perspective
Jupiter's magnetic field is changing as
Europa orbits because well I won't go
into too much detail but because Jupiter
is rotating and that magnetic field is
tilted the the effect that Europa is the
magnetic field changes as your open
minds its business and orbits around
Jupiter and what the Galileo spacecraft
did as if who buys it noticed some
unusual signals as it flew by Europa
there was there were blips as if Europa
does have its own magnetic field
but then when Europa was in a different
part of Jupiter's magnetic field the
signature was much different
so it seems that Europa is responding
the Jupiter's magnetic field and how
does it do that well it's because it
probably has a conductive material
within it
liquid water near the surface a way to
think about this is if if you carry your
keys through the airport metal detector
metal detector goes off because your
your keys can conduct electricity the
metal detector is big magnet and you
walk through it so Europa is kind of
moving through Jupiter's magnetic field
and set off the metal detector if you
like that
the Galileo magnetometer measured and so
we know that it's conductive and the
iron core is too far away to explain the
results the best explanation is a liquid
water ocean and it's not that that's a
total surprise because there is a reason
to think that Europa could have an ocean
based on the geophysics based on how
Europa is deformed as it orbits around
Jupiter so as you as Europa goes around
Jupiter orbits around Jupiter it gets a
little closer and a little farther in
its orbit this is exaggerated but just
just to make it clear and when it's
closer to Jupiter it's stretched out
more and when it's farther away from
Jupiter it's not stretched out nearly as
much Jupiter is enormous enormous
gravity field so holes on Europa this
animation is showing
orbiting Jupiter from Europa's
perspective so you're traveling along
with Europa and again not to scale its
exaggerated but looks like your rope is
breathing it's flexing it's moving in
and out because when it's closest to
Jupiter its stretched out and when it's
farther away it contracts a bit
well that generate all this flexing and
the heat is generated where the icy
shell of Europa is softest down in its
interior warmest and therefore softest
down in its interior and that's enough
heat to maintain an ocean within Europa
below an ice shell something like 20-ish
kilometers thick that's what about 13
miles thick but again that was just the
theory and then along comes the Galileo
spacecraft of the magnetometer and says
look at that there seems to be a
conductor about 20 kilometers down below
the surface of Europa
when we look at the geology as the
scientists who were here the last few
days we're talking about it's covered
Europe has covered with these bizarre
ridges and grooves so this is a double
ridge very typical of Europa's surface
and what is it twenty years since we got
this data we still don't really
understand how these ridges formed there
are good ideas there was probably a
crack in Europa's surface ice and all
this flexing may cause the ice to move
back and forth and again like rubbing
your hands together that generates heat
well warm ice ice is heated Rises and
may push up the surface above it that's
that's a model that I tend to believe it
doesn't mean it's the right model and we
need more data to really understand how
these ridges form on Europa's surface
and what they might be telling us about
liquid water below
we also see these things bands those
ridges by the way they were there
typically a few kilometers across so if
you see a picture with a big ridge that
bridge is probably Oh 2 to 5 kilometers
across the this band is more like 20
kilometers across this feature snaking
across the surface of Europa you see
these hints of ridges within you can
also see that older features out here
look like they were just broken by this
band well you can play a game of of
matching up the older features in
Photoshop like these two and these two
and and putting them back together and
they match just exactly
oh sorry I don't have any other
reconstructed versions here but but I
think you can picture it here's another
one this wedge-shaped band that just
opened up on Europa's surface this is
this part we zoomed in on with Galileo
reason I and others at Brown University
planned these images of Europa's surface
back then and Louise is one of the is
really the the the person who has
studied bands the most on Europa surface
and explain them as possibly like
seafloor spreading on earth place their
places on the Earth's ocean floors where
a new crust is made as as the as the
seafloor is pulled apart and new
material moves up and recently I have a
colleague postdoc working with me at JPL
who's been doing models so at least just
last night I replaced your beautiful
sketch of how these bands work with the
Sam's model of how these bands may open
up so this is showing a cross-section
his model of cold stiff ice here and
warm flowing ice below that colors that
kind of backwards of what you might
imagine but that's okay
and if we put a movie in motion pulling
on pulling on this ice causes rifting
and stretching and warmer ice to rise up
below and ultimately come out onto the
surface in this story in this movie it
cuts off just a little too soon and so
we're starting to understand all years
later a bit of the specifics of how
these bands may open up as Europa's
crust is somehow pulled apart well if
there's always pulling apart making of
bands oh and and where's the ocean come
in well the ocean is probably down there
below that warm blowing ice
but what's interesting is that these
bands could be places where ice that's
now frozen again in the ice shell was in
contact with liquid water and brings
that watery material up to the surface
so these bands may be places to go look
for whether there's evidence or life in
the ocean because they're dredging up
deep material to the surface see if I
can make this
so Louise along with another researcher
just a couple of years ago published
nice paper very nice paper on where how
do you compensate for all that pulling
apart in making these bans well there
are some places Louise and Simon cotton
Horne
believe from reconstructing the surface
are places where cold ice is sinking
down back into that warmer ice for those
who know or geology may know of
subduction zones they're big earthquakes
at subduction zones so we hear about
them on the news the hard way and
something like that may be going on in
Europa and that's a model that continues
to be tested so again the ocean is down
here not directly participating in that
cool geology um there are some impact
structures on Europa as I mentioned the
smaller crater is this one about ten
kilometers across kind of look like
craters on the moon but bigger craters
like hook here will Orman Annan look
very flat like they formed in a warm icy
shell relatively warm I where the ice
could flow and fill in the craters and
the two biggest impact structures are
completely bizarre looking like
bull's-eyes because the impact probably
penetrated all the way through the ice
shelf to water and that ice then blowed
inward to the center and filled in the
crater and made these concentric rings
so actually the idea that the ice shell
is probably about 20 kilometers across
largely comes from these two big impact
structures where we'd say well it looks
like from the measurements of the size
of these that that the ice shell was
about 20 kilometers across a twenty
kilometers deep to make these impactors
about 40 impact sites about 40
kilometers across
things on europa the fancy names
lenticular that's just latin for
freckles there they're about oh seven
kilometres across and they too probably
have to do indirectly with an ocean but
more a reflection of what's going on in
the ice shell so I bet a lot of you
remember of lava lamp recent still good
don't know guy want to go on my office
to remind me of of convection in Europa
because in a lava lamp there's a light
bulb here and it warms the wax and it
rises up through the cooler oil and then
the wax cools off and it sinks back down
or a different density oil and the same
may be going on Europa where the tidal
heating allows these blobs of warm ice
to rise up to the surface and make these
pits and spots these lenticular that we
see and this is a model by amie bar as
researcher now in Germany and she's
modeled again the ocean down here it's
warm right I need my cheat sheet of
temperature conversion about 260 Kelvin
minus 10 Celsius about 8 degrees
Fahrenheit so that's the warm stuff the
cold stuff at the surface about 100
Kelvin about minus 170 Celsius about
minus 280 Fahrenheit so this ice is
really cold and stiff and hard and this
ice blows because it's warmer but not
nearly as quickly as it shown here it
takes probably about 100,000 years or
the ice to rise up from the bottom to
near the top of the ice shell and then
it's pretty tough figure out how to get
it out of the ice shell probably has to
crack Oh get that stuff out
they're also these regions of Europa
called aptly named chaos where where the
bright icy stuff as we saw before looks
like it's kind of crumbled in place
there's some plate that that have old
ridges that look like they've tilted
foundered somewhat and and this looks a
lot like Arctic sea ice when this was
first seen it was thought well is this
the ocean coming right to the surface
telling us there's water right there
today um or is it warmer ice that's come
up to the surface and disrupted the
surface in some way and to give you a
feel for the scale of this specific
chaos region at suprem you can see the
Ring Road around there so this blocks
about five kilometers across yeah
one more very cool feature
there might be plumes as you'll hear
from Jonathan Levine he's talking about
and telling us he's gonna talk about the
amazing plumes of Enceladus where we
know there's water shooting out of this
moon of Saturn
well Europa not to be upstaged might
have plumes but Europa is being a bit
secretive about it here from a Hubble
image so from viewed from orbit around
Earth we can see we've seen glow of
hydrogen and oxygen off of the the edge
the limb of Europa and it's thought that
Europa might sporadically have a burst
of water a plume like in this artist's
conception that then breaks down into
hydrogen and oxygen and glows where the
Hubble Space Telescope was able to see
it the problem is they're not consistent
they're right on the edge of detection
so there's a big program by the Hubble
Space Telescope to keep searching or
possible plumes at Europa and why do we
care so much because then you could fly
a spacecraft right through one of these
things and directly measure what the
composition of the subsurface is as
Cassini has done at Enceladus
oh sorry I didn't mean to have sound
ah that
over narration
going whoops and we turn the sound down
I don't know how my computer is not
making it go downs it's cool but it'll
keep saying it over and over the movie
so this is an example of a black smoker
on earth as the narrator will tell you
it secreted over seven
it's a place on the Earth's ocean floor
where water has seeped down through
cracks at one of these at a place where
there is a very hot rock in the
subsurface where warm rock has moved up
to just below the surface of the ocean
floor and water seeps in there and then
and then escapes just charged with
chemical nutrients that kind of
environment is fantastic in supporting
life very locally around these things
that are called black smokers and Europa
may similarly have a hot rocky mantle we
don't know um
if so then water can seep down there and
emerge charged with chemical nutrients
that would potentially support microbes
in the ocean of Europa so what we really
need to understand is what's the
chemistry of Europa's surface and and
what's that telling us about the
chemistry of its ocean and whether that
might be a habitable environment
okay okay okay so now it's not gonna
give me my words that I wanted to see
that's the one part I didn't test was
the sound so you're a problem they're
all the organisms swing swimming by
um so Europa in terms of the ingredients
for your life probably has more water
than all of Earth's oceans combined as
far as the essential elements for
building molecules probably from
Europa's formation and from impacts but
we don't know yet because the Galileo
mission didn't tell us enough about the
composition of Europa's surface we have
some idea there salt there magnesium
sulfate and probably some other salts
but we don't know for sure and we
haven't detected organic materials yet
on Europa surface we need to look more
carefully with better instrumentation
the chemical energy in Europa it might
come from below in these in these black
smokers if they exist there um and it
could come from above because radiation
charged particles hitting Europa's
surface make oxygen-rich materials if
those oxygen rich materials can get into
Europa's ocean and if your oppa has
black smokers down below then be a very
favorable place for life in terms of
chemical energy as far as how long
Europa's environment has been stable
probably for the age of the solar system
that's a bigger question that's gonna be
hard to address from our mission but
combined with other data sets like from
the European Juice mission which is also
going to the Jupiter system we might get
a feel for how old let's see how to put
this for how long this tidal heating has
been going on at Europa
okay okay
uh-huh so what do we want to do with a
mission in my last few minutes here
overall our goal is to explore Europa to
investigate its potential habitability
now what does that really mean that
really means understanding its ocean and
ice shell and the processes within
understanding Europa's composition like
these dark swatches and try to
understand what they're made of and
whether that stuff's coming from the
ocean and understanding its geology
which tells us about how it got to be as
it is and how long have those processes
been going on we also want to understand
Europa at really high resolution the
best image of Europa surface from the
Galileo mission was at about eight
meters per pixel and somewhat oblique
and boy is it a jumbled mess we want to
understand are there smooth places where
we could someday hopefully not too long
from now little Lander down on Europa's
surface based on the information from
the Europa clipper mission this is our
spacecraft as we understand it today
we're getting closer and closer to a
design where we are in phase B of the
mission for those here that means
something - we're essentially in in the
in the design phase of mission and the
spacecraft keeps maturing we're a
solar-powered spacecraft there are four
and a half solar panels per wing here
let me put some labels on here
there's our high gain antenna during the
flyby
it's just pointed up away from Europa
this is magnetometer boom what else can
point out here
remote sensing instruments cameras
spectrometers are looking down during
the flyby and there are two mass
spectrometers one for dust and one for
for neutral gases that are in the direct
pointing in the direction we're flying
so this allows us to gather data from
all the instruments simultaneously
that's something that the Cassini
mission could not do because the
instruments kind of slapped all over the
spacecraft you could only use a couple
of them during any flyby of Cassini yet
say Titan but we don't have that time
because there's an awful radiation
environment at Europa that we're
battling so with every flyby it's it's
immersed in more radiation in the
vicinity of Europa we have an ice
penetrating radar that we've built right
into the solar or our building or going
to build right into the solar panels for
VHF antennas and to HF high frequency
sorry versus very high frequency
antennas that will be used to plumb the
ice shell to tell us where is there
liquid water below the surface of Europa
I'll run through the instrument suite in
total just a minute here
um so how're we gonna accomplish this
mission we're not in orbit er we were
originally planning to go into orbit
around Europa that's really expensive
because of the radiation environment
because then you're the parts of that
your spacecraft is built from and all
the instruments have to be very
radiation hardened and that's very
expensive so we cut the proposed cost of
the mission down about an half by
instead being in orbit around Jupiter
and making many many flybys of Europa
so that's analogous to what Galileo did
but here we're concentrating just on
Europa getting about 45 v ice and with
modern instrumentation that is designed
to understand Europa's habitability and
look to water and look for organics and
image the surface at super high
resolution things we were not able to do
with Galileo
this is the kind of thing what oh oh oh
I missed my little story here right so
for those for the trek for the Trekkies
in the crowd I'd like to think this is
the Tholian web essentially that we're
we're immersing europa in a web of
flybys like those aliens did
um so what's the science we want to do
all its synergistic science because
really it's the sum total of all the
instruments that get us what we want to
know well there's gravity as your open
goes up and down not to scale it tugs on
the spacecraft and and how it tugs on
the spacecraft tells us about how much
Europa is flexing now from orbit you can
imagine this is easy to measure as
you're flying around Europa but but from
a flyby mission we fly by when it's like
that and then later we fly by when it's
like that and putting that all together
we can understand how Europa is flexing
as its orbiting around Jupiter and be
able to confirm an ocean if there's an
ocean it'll be flexing by 30 meters
every time you open goes around Jupiter
every 30 sorry every 85 hour at 3.5 5
days if flex is 30 meters but if there's
no ocean it'll flex by 1 meter and we
will barely measure anything but most
likely we think this notion and we'll be
able to measure that
we want to measure the magnetic field
around Europa too essential it's in some
ways repeat what Galileo did but do it a
lot better with 45 flybys we can measure
we can get out of the data not just
whether there's an ocean down there like
we did with Galileo or pretty sure
there's notion down there from Galileo
but instead we can get its thickness and
how sulfated how inductive that ocean is
it's much more precisely and the plasma
data measures the the ions that the
charged particle environment around
Europa which is needed to correct and
understand that magnetometry signal
um will be imaging so instead of a a
bald surface as this is illustrating
we'll be able to understand what's going
on in detail Oh
we'll get the whole moon at about a
hundred meters per pixel or better and
we'll get spots up to a half metre per
pixel
we'll use infrared spectroscopy to
understand what the chemical signature
of the surface is like where are their
organic materials where are their salts
what kind of salts what kind of organic
and other material we have a thermal
imager to look for hot spots as Jonathan
Lu Nino will tell you about it and sell
this we can see Enceladus is warm enough
that it essentially glows in the in the
in the long wavelength infrared because
it's so much warmer than it should be
not that it's hot I said it's a hundred
degrees Kelvin though i hot spot might
be 150 Kelvin something like that but
that's that's warm for Europa and that's
the kind of thing we've seen that in
celibacy and then with the
ice-penetrating radar we can understand
what the subsurface plumbing is like we
could find Lakes below the surface and
that's the most popular model now for
how that chaotic terrain forms by
collapse into a subsurface pocket of
water at Europa we'll be able to tell if
that ice shell is really conducting down
there
in the ultraviolet we can look for the
glow that might be associated with homes
places where Europa is leaking material
into a very very thin atmosphere
and then finally through spectroscopy
mass spectroscopy we can get at the dust
and the gas as I mentioned a little dust
and gas appeared there around Europa to
get at the detailed composition of what
might be leaking out in terms of the gas
or what might be blasted off the surface
in terms of the the dust so all these
instruments work together and my my
vision of what I would love to see from
here OPA would be to find some sort of
oasis like this is trying to illustrate
here a region where there's liquid water
there organics there there's warmth and
that's the kind of place where we would
want to send a future lander
so I've were late on time drive few
minutes to show this cool animation okay
um oh yeah like it's not too bad thank
you oh this is a cool animation now that
you know
instruments you'll see you'll see down
here is illustrating where Europa is in
its orbit and here's the Europa clipper
coming along to intersect Europa the
Earth and Sun are out that way so here
are our solar panels charging up for an
encounter
not in real-time and now the spacecraft
is turning to be able to do some
ultraviolet scans of Europa there is a
key to the to the code of our
instruments over at the bottom left and
the purple is the ultraviolet and come
over here so I can read it as this is
going on you'll see a couple of flashes
of blue that's the narrow angle camera
that orange was a calibration of the
thermal instrument spacecraft turns into
an orientation where it can scan across
oh I see it's doing the thermal
observation there it's doing an infrared
observation and here it's doing a scan
across the surface with multiple
instruments that aim I'm
as we pull in doing some of that
infrared spectroscopy the thermal
instruments is going all the time
integrating to measure the temperatures
more splashes of narrow angle and the
wide-angle camera which covers much of
or all of Europa there
of the solar panels wing around to an
orientation where the radar can do its
job as we fly by and all instruments go
on at once below a thousand kilometer
picking up more data than the typical
avionics could handle as we've now
learned in putting our spacecraft
together and we've had to God go to a
more primitive avionics system than we
were hoping just because it's so hard to
gather so much data at such a high speed
during our flybys and then we rinse and
repeat or do it backwards as we fly out
there's that joint scan again so we want
to have very simple repeatable
observation types is is the goal here
and this is something that the
scientists on a mission about a hundred
thirty-five people have been negotiating
through the principal investigators for
the most part that the nine people who
are in charge of each of the instrument
were one principal investigator or
instrument
so
No how do we or an ultimate note how do
we get there we could the earliest we
can launch is about May 20-22
and if we launch on a conventional
rocket and Atlas Delta for Falcon Heavy
then we have to
go in toward the inner solar system do a
couple of Earth flybys do Venus flyby to
to allow those gravity assists to get us
out to Jupiter and it will take seven
and a half years to get there and it'll
be twenty thirty by then um it'll be
much better if we get to go on the Space
Launch System that NASA is developing
which has the launch capability to send
us on a direct trajectory to Jupiter in
less than three years and then I won't
be retired ya can see this mission to
fruition thinking beyond that though is
the idea of a lander we looked at
whether we H want this mission but that
would be too expensive and too massive
so JPL and s are looking into whether we
could send a separate mission that would
land on Europa with the goals of
searching for evidence of life or
assessing the habitability of Europa
from the ground and characterizing the
surface and subsurface to enable yet o
more distant future exploration and with
that here's our website for future
reference
ten bums thank you very much okay so
we'll take some time for questions now
so please raise your hand and we will
bring a mic to you as your folks here
want to hear maybe in the overflow at
one here as well as those who are all
online we'll start right over there how
big is your oppa well I'm sorry I didn't
say it's about the size of Earth know
the size of Earth's moon yes okay how
far is it away from Jupiter um why do I
know the numbers I don't know the
numbers by approximate but I think I Oh
I think the Earth's moon cailed that
system would fit between IO and Europa
somewhere so I don't remember my head
really uh but but a bit farther than the
earth-moon distance how far away was the
Clipper from oh yeah
so our flybys would be from a hundred to
about 25 kilometers off the deck that
close of Europe and the gravities
doesn't pull the clip out of not a big
issue I mean that that's factored in
with Cassini flying by and cell with us
we've done it to a 500 meter several
fine thank you
yeah is there any evidence of islands or
mountain tops on Europa poking through
the ice there is not any direct evidence
for or topography poking above or into
the ice shell and and that's consistent
with the with the h2o layer probably
being close to 100 kilometers thick so
the ice shell doesn't seem to be
grounded but you know we could be
surprised well actually there there's
there's a lot of geological evidence
that says the ice shell can I make him
stop
plaque there's there's a lot of evidence
that suggests that the ice shell has
actually moved relative to the interior
and that might help in making those
cracks so I talked about the tight
flexing but is also the idea that whole
I shall moves relative to the interior
so that would be really hard if it were
rounded but much easier if there's an a
global ocean
what is the value of Europa's gravity
compared to Earth's gravity Oh against I
don't have all the numbers memorized let
me see
it's so moon's gravity is is y 2 6 so
your rope is about a seventh if I
remember right of Earth's gravity lunar
like moonlight are there any questions
what's the composition of the atmosphere
Oh so very thin atmosphere a Pico bar
that is ten to the minus twelve of
Europa's of Earth's atmosphere and and
it's mostly it's mostly h2o and and and
oh and in the atmosphere yeah yeah
because it's stuff that's knocked off of
the surface of Europa and and the the
hydrogen is mostly gonna fly right away
and that leaves h2o and O sitting around
at Europa
you
have you been able to identify any
difference in thickness of the ice shelf
say I put the pole the pole volts versus
a equator good point sorry I just
remembered and Oh H I should say cuz h2o
breaks apart oh wait so it's expected
that the ice shell at the poles should
be thicker because it's colder and
that's actually why we think that Europa
might flip over every once in a while
because the ice shell is thicker and
that wants to be at the equator and so
that would predict that it flips over
and then it thickens again it looks over
again we don't have direct evidence in
terms of the geology for that sorry for
the thickness differences there is some
evidence that Europa has actually
flipped over and moved around but that's
something that hopefully we can test
with the radar if it can penetrate all
the way through the ice shell or even
the magnetometry can get us an idea of
the thickness of the ice shell but radar
would be best for looking for variations
and thickness but it's not just hole to
equator this tidal flexing but the
the heat it creates predicts that there
should be thickness variations around
the equator to because different parts
of Europe are flexed differently as as
this is going on right it's not flexed a
lot at the places pointing to and from
Jupiter it's flex a lot some distance
away from those points and that
translates the heat and that translates
to the thickness area we think
yeah I actually had a question about
observing the ocean but I forget that I
mean this flippin thing are you talking
about are you talking about the the icy
crust flipping or the entire core ocean
everything and what would that do to the
planets axis right the icy I'll go back
to this picture
so the icy crust above above the rocky
mantle so this doesn't happen to the
moon our moon because there are density
differences that lock the moon in place
facing toward Earth
well and and so that's probably true of
the interior of Europa probably locked
facing Jupiter but the ice shell is
allowed to slip and there are some some
forces some torques that well there are
various mechanisms that can allow it
this left so yeah we're talking about
the ice shell moving above the interior
can you indulge me let me ask my
original question sure so what's and I
know this is way out there since the
lander has been disposed of for the time
being but exploring the the subsurface
ocean what
you look at it because you got a drill
through a ton of ice and and and and and
then you know you're not gonna have any
light source if you have some sort of
submarine vehicle what what's like what
are you talking about there that way oh
there's a whole issue of the drill hole
freezing back up yes so yes it would be
an enormous challenge to try to get into
Europa's ocean I think it would be a
much more reasonable challenge to try to
get into the pocket of liquid water if
we find such with the Clipper yes I
wouldn't want to try to melt through 20
kilometres but maybe through 3
kilometres into a lake now would a
subsurface lake be an interesting place
to look for life I think we don't know
yet really in terms of what what's the
chemistry like from there what would
there be the energy that could support
life in and circulate if this came up in
our workshop people like a lot yeah
think about that but it's no-one's
really thought about it so in terms of
technical challenges yes this is
enormous technical challenge they just
had a workshop Louise was there though I
wasn't about how we could drill in my
post-doc was there who would particular
showed in her band picture and he said
he came away from there saying you know
this is something we could actually do
did you have time impression that
better it's not so impossible with as we
might yeah I was also quite encouraged I
think that big problem actually is just
getting down to the ice and getting your
drilling rig situated but actually I was
more encouraged about being able to
drill through the ice once you're on it
or in it because you can melt through
icy can't easily melt through rock you
know be the actual material makes it a
little bit easier once you're there the
problem is that right now in the
Antarctic if you want to drill you know
they have these kind of wagon trains of
material that they take down there and
you know multiple people and they go for
weeks at a time and you know if we can
get our material to Europa and and
miniaturize our drilling equipment I
think you know and actually get into the
ice that this starting problem is the
hard part
once you're in the ice I think I'm more
enclosure yes you probably could get
through a few kilometres without a huge
amount of technological advancement and
and actually do it I think I think we we
can figure out how to do that yeah it's
an interesting problem
I forgot Sam is here he's just gave a
big thumbs up because thanks yeah no
this is wild so the really encouraging
thing about drilling through Europa's
ice shell is that we possess these
nuclear batteries where we harness their
heat energy to turn it to electricity in
space and if we bury these to melt the
ice you've made a race car without
brakes you can't turn nuclear heat off
this radio isotope heating and so if you
can get the thing started you can't
actually stop it and so the the
challenge like we said is you got to be
in the right position with equipment to
handle the journey down but the the
major problem isn't how do you keep
going down because that's going to
happen once you start it's how do you
get the whole project start
real quick anything uh overflow I just
wanted to ask about the best idea for
the car of the stripes is that still
thought the ready stuff key meow yeah I
sort of skipped through that but I'm
gonna go I can take a moment to go back
to my little inset picture that had that
so from Galileo we we look at the the
fingerprints of the light that's
reflected off the surface so this is
showing wavelength and this is showing
how much light is reflected off as
function of wavelength and and ice as
has very particular shape of this curve
and when we look at this reddish stuff
it has a different shape that tells us
that there's probably magnesium sulfate
salts and probably battery acid so so it
might be epsom salts or Mikey battery
acid down there what's probably true is
a combination that that the Epsom salts
magnesium sulfate is probably we think
coming from deep down in the ocean
whereas the battery acid is made at the
surface by radiation coming in and
breaking molecules apart and letting
them recombine um but again you know
it's it's still somewhat speculation we
need we need the we're gonna have
incredible spectral and spatial
resolution from the clipper spacecraft
to try to get at the nature of those
particularly solved
and hopefully organic they're there okay
how's the pressure at the bottom of the
ocean on Europa compared to the pressure
of the Boeing ocean earth so the the
pressure at the deepest part of the
ocean floor of the earth the Marianas
Trench is about the same as the pressure
at the bottom of Europa's ocean ocean at
the ocean floor of Europa so we know
life can exist under the pressure of of
the deepest parts of Earth seafloor so
pressure doesn't seem to be a limiting
factor in allowing for life at Europa
hey since you've been if I understood
your schematic you're the clipper will
be between Jupiter and Europa so what
sort of instrument are you going to turn
the same instruments on to Jupiter that
you're doing into Europa good good
question that that the scientists have
been asking - so - to ensure that the
costs are manageable on this mission
come the the instructions from NASA are
we're looking just at Europa now what a
lot of the scientists hope is that once
we build a spacecraft and looking at
other places it's driving the cost then
hopefully we can look over to Jupiter
we're certainly going to do some
calibration Academy you'd like test out
instrument although the Ganymede flybys
are in the dark um but if they'll use
radar and SML and another instrument so
we actually fly on both sides of Europa
so sometimes we're between your open
Jupiter and sometimes we're just on this
side of Europa and the only observations
we currently have planned are Europa in
front of Jupiter to look for evidence of
booms that may be on the limb of Europa
that's one of the techniques that Hubble
use possible we'll take one more
question how many flybys and how long
would the mission last for oh so right
now we're planning about 45 flybys and
that may change as the give or take and
the whole mission three and a half years
for the nominal mission those 45 five
eyes but a year and a half of that is
big long looping orbit that first get
into the resonance where we encounter
Europa every two week so every four
times the Europa comes around here comes
the Europa clipper to meet it and the
Galileo mission lasted three times its
design lifetime
so maybe we'll get another five ish
years out of it I hope exactly so we're
hoping we'd have an extended mission
that would allow us to focus down on
specific things we find if we find
clothes that be great opportunity to buy
through all right well let's thank our
speaker one more time so we'll see you
back here in January or December 2nd but
till then join us 3 I'll leave her
reception those of you watching us
online thank you very much
