I'll scope public lecture series it is
my pleasure to be your host I'm dr.
Frank summers of these office of public
outreach here at the Space Telescope
Science Institute and when you came in
if you noticed them we have pictures
we call these lithographs this one is of
a brand-new one Nevernever everything
this is the multi-wavelength Crab Nebula
what do we mean by multi-wavelength well
if you turn over you can see that this
individual image the different colors
are composed of light from six different
five different wavelengths okay from
x-ray all the way to radio and we have
some explanatory text you didn't grab
one on the way in grab one now or on
your way out our talk tonight is the
plumes of Europa ice water life which
Susana thought would be a cool title to
bring in an audience and it is alright
next month we will have gravitational
wave astronomy which is now a field
something we'd been thinking about for
decades and it's now become a field our
local expert Andy frucht or will be
talking about that the month after that
will feature Fischer is going to talk
about one of my favorite places in the
universe star formation in the Orion
Nebula we're looking forward to hearing
that and then in July we have one of
these really long titles to call with
the Milky Way's bulge from a
hypothesized blob to a remarkably
detailed picture talking about the
center of our galaxy and the stars that
orbit around it out in our center called
the Bulge of our galaxy okay if you want
to learn more about those or remind
yourself of them you can go to our web
page if you go to your favorite search
engine and type in Space Telescope or
Hubble public talks you'll find this
page where we have a list of the
upcoming lectures whoops there we go
I think my my lasers is going all right
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the observatory across the street will
not be open as you might guess from the
weather outside it's cloudy and a little
bit rainy but they also have open houses
on Friday evenings if you go to their
website MD dot space grant dot o RG you
will find that page on the on the right
hand side and in that box that says
Observatory status each Friday evening
by about like five or six pm they post
whether or not they're going to be open
for public observing so yet again we are
unable to take you across the street
after the lecture for that tonight to
the public lecture but hopefully you can
find it on one of the Friday nights and
now our news from the universe for
April 2018 our first story unfortunately
is the James Webb Space Telescope had
another launch delay all right and the
NASA press this is the James Webb Space
Telescope it is a six and a half meter
infrared Space Telescope
that was it's it's it's really one of
the most technically challenging things
we've ever launched into space possibly
the most technically challenging
civilian thing we've ever launched into
space and the NASA press release stated
that the launch window is now targeted
for approximately May 2020
yeah we have to wait another year for it
all the observatory but I I pulled out
specific quotes all right first of all
all the observatories flight hardware is
now complete okay so you've they've got
the spacecraft element and they've got
the telescope element the stuff is
complete and it's all together for the
first time in the Northrop Grumman
facility all right it is undergoing
final integration and test phases that
will require more time to ensure a
successful mission we all remember what
happened with the Hubble Space Telescope
having a problem that needed to be fixed
J DST is going to be a million miles
from Earth it's not gonna be a low Earth
orbit like Hubble was it cannot be fixed
when it is out there so it is extremely
important to get it right and get it
right the first time as one of the
genders T Engineers says we got to knock
this out of the park a million miles out
of the park
all right so yeah we are taking the time
until you to get it correct and then the
other question people have is about the
budget NASA will provide a new cost
estimate that may exceed the projected
eight billion development cost to
complete the final phase of testing and
prepare for launch which means that they
are currently evaluating what the delay
will cost and they will provide it to
the American public when they have that
okay so it is still going to do the same
great science we're just gonna have to
wait a little bit longer for it but it
is as I said really important that we
get it right the first time
so it's to me it's worth the extra time
okay second story tonight planetary
construction dust now this image is up
ace of a a disk or actually a ring
around a star that's called HR 47 96
a-okay and it came out in 1999 this is a
Hubble image and I was really excited
when I saw this because I wasn't here at
the time I was up in New York City and
we were discussing the new discoveries
in our own solar system in particular
the Kuiper belt okay
this new region of objects out beyond
the orbit of Neptune alright and this is
where Pluto lives ok Pluto is now the
largest member of the Kuiper belt and so
when you look in the lower right and you
see that the diameter of Neptune's orbit
is that and this ring of material um is
just larger it kind of got us excited
because we were just discovering the
Kuiper belt in our own system and here
we were finding something of the same
scale however this isn't the Kuiper belt
ok it's not made of ice this is made of
dust and it's you don't even expect it
to be a fully formed Kuiper belt type
thing because the star HR 47 96 a is
only 8 million years old but at 8
million years that's the time scale on
which giant planets form
Jupiter's in such form on timescales of
order ten million years so seeing a dust
ring that's so tightly correlated here
could indicate that a giant planet had
formed in this system has recently
formed in this system and that makes is
exciting now so we can take this image
we're gonna shrink it and rotate it okay
that's the exact same image okay and now
we have a new image of HR 47 96 a that
looks like that yeah more sensitive
looking deeper and seeing dust not in
just a tight ring but actually spread
out across the system see 47 96 a is
about 23 times more luminous than the
Sun right so therefore it has a lot more
radiation pressure and so while giant
planets form on order 10 million years
planets like Earth form on timescales of
a hundred million years and in the
process of building up
terrestrial planets you get a lot of
things smashing together
alright planetesimals accretion and that
produces some dust right planetary
construction dust and the radiation
pressure from 47 96 a can actually blow
some of that dust out of the system like
this alright so the interpretation of
this image is that some of this dust is
coming from the form possibly coming or
as a reasonable hypothesis is that it's
coming from the formation of terrestrial
planets that's kicking up dust and then
being pushed out by the radiation
pressure of this large star spreading it
across the system so that's kind of cool
and here is by the way all of the
details of this so 47 96 a is in that
dark spot there we block it out of
course because if you have the star you
can't see the dust around it you can see
the the ring there's also you notice a
bow shock that curved line because the
star system is moving through medium so
you get a thing and also in the lower
right there's a dark circle there that
is the companion star 47 96 be alright
and actually I what I think is kind of
cool which we didn't mark is in the
lower left
that's a background galaxy so we're
looking at a star in our galaxy but
we're also looking at a background
galaxy in the same image here alright so
we're this may be the dust kicked up by
the construction of planets in another
solar system final story a cosmology
conundrum about a hundred years ago a
little less than a hundred years ago
Edwin Hubble made this diagram and on
this diagram he's plotting galaxy
distance against galaxy redshift and he
found he got a straight line that
galaxies that were further away had
larger red shifts in a linear fashion
and this is the primary motivating
evidence for the expanding universe
right that space is expanding and
therefore distant galaxies appear to be
moving away faster in a linear fashion
however the slope of it is the expansion
rate of the universe the current
expansion rate of the universe we call
that the Hubble constant unfortunately
he got the Hubble
wrong because the way he was measuring
distances depended him on Cepheid
variables and he was using the wrong
type of Cepheid variables so he got it
wrong by about a factor of 10 but
eventually we astronomers got it right
so this plot shows a date on the x-axis
and the value of H naught which is this
Hubble constant starts out in the
hundreds and then finally gets down to
when I was in graduate school
in the late 80s the values were between
50 and 100 so you know we went from
being a factor of 10 off to being down
to a factor of 2 and hey this is
cosmology a factor of 2 is good all
right I keep telling myself I'm an
astronomer a factor of 2 is good enough
for me right and so but that's still not
good enough to do what we call precision
cosmology so when the hubble space
telescope came online one of its key
projects was measuring the hubble
constant by getting accurate distances
to near near galaxies so that we could
really measure the Hubble constant
carefully as an HST key project in the
year 2000 that the data was released and
this is a graphic of the diagram showing
that here the points plotted and
plausible values were between 63 and 77
so that's great we've you know it's gone
from you know being in fact over 10 off
to down to a factor of 2 down to 10
percent okay we had a difference of 10
percent but can we leave that alone
no we're scientists we really want to
beat that down and beat that down so
what they have done with Hubble recently
is they went back and remeasure
the Cepheid in our galaxy the
calibration method as well as doing
other things and we are able in this new
paper that just came out get it down to
a range of 72 to 75 success we finally
have this Hubble constant measured
except in the meantime we have developed
other ways of estimating the Hubble
constant one of them depends upon
measuring the Cosmic Microwave
Background this is the Coby satellite
the
first measurement of the cosmic wave
background which then got refined with
the W map satellite and then got
improved as to still a little bit more
with the Planck satellite and this is
measuring the temperature differences
which is basically the density
differences in the early universe and
from that what we really measure out of
the the cos microwave background is
something we call the power spectrum
which is how much density is on
different scales in the early universe
and from that you know we can
extrapolate through to the rest of the
universe and start figuring out the
expansion rate in particular the second
peak of this power spectrum is sensitive
to the hubble value the expansion rate
of the universe okay
and so its location and its its
magnitude gives us a good estimate of
the hubble constant it doesn't give us a
perfect estimate but it gives us a good
estimate
combine that with two other ways of
measuring things one from supernovae and
one from something called baryon
acoustic oscillations and it's labeled
bao i'm not gonna try and explain that
in 30 seconds here it doesn't work
but trust me combining the three of them
because microwave background baryon
acoustic oscillations and the supernovae
you can get another estimate of the
Hubble constant independent of the
Cepheid variables and all that and it
comes out to 65 to 69 here's the problem
both of these methods are tried-and-true
both of these methods are we believe are
estimating their errors well alright the
local ones 72 to 75 the large-scale ones
65 to 69 and the quote from Adam riess
the head of the researcher says both
results have been tested multiple ways
so barring a series of unrelated
mistakes it is increasingly likely that
this is not a bug but a feature of the
universe that our local estimates of the
Hubble value Hubble constant value
differ from our large-scale measured
estimates of the Hubble value what do we
do okay well if you read the news bag
and news news about this astronomers are
baffled no we're not baffled okay we're
intrigued we're excited
because frankly if we knew everything
we'd be out of a job so this gives us
something new there's something new in
the universe with either our problem
which it's unlikely or there's some new
feature in the universe okay
so of course we can come up with new
ideas and so some of the new ideas are
perhaps there is an undiscovered
subatomic particle such as a neutrino
with mass that changes the measurements
that we would get from one of the one of
these values basically that would be a
large scale or maybe dark matter doesn't
behave exactly the way we think it is we
think Dark Matter only behaves
gravitationally maybe there's a little
bit stronger interaction between dark
matter and normal matter or the most
popular one that you can think of today
is what about dark energy we don't know
much about dark energy we've got a lot
of ignorance there maybe some of that
ignorant effects one of these measures
okay so we have a lot of hypotheses and
ideas on what might resolve this but
also I can really say is stay tuned
because we have identified a discrepancy
all right and the process of science is
we're gonna hack at it and we're gonna
hack at it wearing a hack at it till
either we figure out what's wrong with
our observations or we come up with a
really good idea
that can explain this discrepancy and to
me that's part of the joy and excitement
of science when you find something that
you can't explain then you're just like
oh we got to figure this out
unfortunately it'll take a decade or two
that's actually four five out so stay
tuned and keep coming to the public
lecture series I'll make sure that I
have it for you all right okay and
that's our news from the universe our
featured speaker tonight is Susanna de
use to ax she has been here for what 10
years and she works in the AI NS
division on the Hubble instrument Wide
Field Camera 3 or we just call it with
c3 and she I asked her for some
interesting things about her and she
said that she fly Fitch's fly fishes
from her kayak combining kayaking and
fly fishing together
and that once she did jump out of an
airplane even as well as having never
been on the Space Shuttle okay so here
to tell us about Jupiter's moon Europa
is Susana Deus Troy thank you and I
think I'm number one or three maybe I'm
three okay all right so we're going to
talk a little bit about the water plumes
what's happening here
it recalibrated after I disconnected
sorry yeah it's fine we're patient
somebody needs to sing the jeopardy tune
okay so with any luck I'll be able to
tell you a little something about the
plumes on Europa water ice life which is
a little bit like our Baltimore winter
this year see which way does this go so
this is the abstract that I put together
but more importantly is there are lots
of people working on understanding
what's going on with Europa in advance
of perhaps actually sending a dedicated
mission and I was trying to play around
to figure out but this was team a or
team B or the raw team or the sparks
team and I gave up on that because
people go back and forth and people talk
to each other so there I'm sure that I'd
laugh I inadvertently might have left
off some people but I apologize if I did
that so more importantly is as an
observer probably not tonight
but maybe when it's clear if you go out
and they look in the southeast kind of
find where the moon is and you will see
Jupiter and so Jupiter is a planet as
you all know that we've known since
antiquity when our ancestors first
became Homo sapiens I am sure they
looked up and saw Jupiter and named it
something and 400 years ago in 1609
Galileo as we know in I wouldn't say he
invented the telescope but he was one of
the first to put it together and
incidentally he was very ill he had like
the flu or something when he was putting
together and hid the telescope I guess
he kept them from being too sick and
later he turned that telescope and he
was the first to point at a celestial
object and in his case it was Jupiter
and what he saw over
a period of time were a series of moons
or objects are little stars that were
revolving or moving around Jupiter and
this is just a blow-up of that letter
that I showed which is a letter he wrote
to the dog a of Venice in 1610 and he in
that letter he is describing his
observations so 1609 first observations
of Europa and if I can do this I will
start the movie because this is kind of
cute I love the Internet this is a movie
that put together by a gentleman named I
think somebody right he has a website
he's a computer scientist by profession
and what he did is he took all of the
observations that Galileo had recorded
and he's juxtaposed those on a on the
ephemeris and so what you see now is the
beautiful pictures on the top and then
Galileo's observations on the bottom
this is just sort of a fun little thing
and it'll go through so sort of the
modern and the end the ancient okay so
let's just put this in context a little
bit when we talk about the moons it's
you know it's natural to think of it as
being like our moon so here's our moon
here this is Europa and it's about the
same size over here so that's kind of
comforting the moons can be the same
size as our Moon this is Callisto
Ganymede Europa and IO or IO
the four Galilean moons of although
Galileo called them the Medici moons as
you remember because the Medici was
where his patrons it's always good to
keep your patrons happy anyway so here's
your rope it is not the largest of
Jupiter's moons but it is certainly one
of the most interesting along with you
and neo is known to have volcanic
activity and just for fun and scale
here's one of the bands on Jupiter so
you get the sense that these are
actually relatively small and you
is very very big so we will skip forward
a few hundred years to the Voyager
missions and the Voyager I think are the
most successful missions in my view that
nASA has put together they have been
going through the solar system for over
30 40 years returning good data ever
since and it this was one of the first
images that we had close-up images that
we had of Jupiter and its moons this
over here is yo and this is Europa down
here question and these little dots are
just some fiducial marks on the imaging
system of Voyager about 20 years later
there was another mission this time
called the Galileo mission which also
went to Jupiter and what I think is
remarkable and a lot of people have as
well is that we see Europa this was
taken about I don't know almost six
sixty thousand miles away is that Europe
is relatively smooth it doesn't have big
huge craters it doesn't have big huge
mountains and it's got all these little
striations all over it and some dark
spots so it's a very interesting moon
it's an interesting object in and of
itself and this is a beautiful image
that got reprocessed in the imaging
department by somebody so to highlight
the striations and sort of false color
images and what you see is that these
look like cracks in the ice fissures in
the ice which tells you something about
what is going on in on the moon and this
is a blow-up also from the Galileo
spacecraft where you can see these
cracks and fissures and apparently some
deposits of material because it's not
all white and icy so this points to and
there been a lot of papers and people
got really busy and said this could this
looks a lot like cracking of ice and
maybe it later looks a little
bit like plate tectonics like we have on
earth suck the the continental crusts
and are shifting around in subducting
and separating in this case this is on
the icy surface so it's a very very
intriguing but in addition one of the
things that the Galileo spacecraft had
with it was a magnetometer so it was
measuring the magnetic field around
Jupiter and an interesting thing is that
if you have another source of
electromagnetism it's sort of like
having two magnets if you try to put the
two South Poles together you get a
little deflection have you ever tried
that when you were kids so you'd see
something similar if you had another
source nearby you would see a little
deflection in the magnetic field
so when gyro PI was passing through
Jupiter's magnetic field the
magnetometer detected a deflection and
that deflection was consistent with it
another conductive or an inductive body
and it probably had to be something like
slushy salty water because it had to be
something that was globally connected he
couldn't just have one little pond it
had to be all all around and about the
only thing people could think of at the
time was some slushy icy material which
of course makes things really really
interesting because now we have ice on
this planet and potentially also water
and so this is a sort of a model of what
this might look like here's the the
water down here some kind of a thick
warm ice shelf and here you can see the
cracks on the top subducting just like
they would on on earth TV had plate
tectonics and we're there little soft
spots you might see sort of cryo lavas
so instead of being molten lava I would
be molten water otherwise known as
liquid water and this would be something
that would build up over time and the
other clue to this is that was because
the surface of Europe is so smooth it
doesn't have a lot of cratering which
also indicates it's a young surface and
the only way you get a young surface is
if you have some regeneration of
material that covers the cracks and the
in the craters so this is all pretty
fascinating and people got really
intrigued but this wasn't really enough
to answer the question because you could
still imagine having a rocky core in the
planet ice warm ice and then cold ice on
the surface or maybe you had a rocky
interior and then a water layer down
here and then ice and this was something
in play if you have a lot of ice it's
probably not so interesting or maybe it
is but if you have water now you start
thinking could you possibly have
something really interesting going on if
you have water and the answer of course
and what we're working up to is if you
have water then you have life or you
have the possibility of life but the one
question is Europa is far away it's very
far from from the Sun it's and you have
this icy cover so how would you get
heating of the material to in order to
have a liquid water ocean and so one
potential answer and then this is
probably the right one is something
called tidal heating and what that does
is as as as Europa goes around Jupiter
it's not in a perfectly circular orbit
so you have gravitational forces acting
on the moon itself sort of pushing and
pulling it you can think of it as either
you know and you bend a spoon you get a
little heat or you're stretching a
rubber band and you feel it it gets a
little hot so sort of like friction and
that is probably the source of the heat
that keeps the water liquid then the
Galileo mission I think has given
planetary astronomers a lot to work on
but I think it's it's been about 30
years and we're about to you for NASA
guys if you care about you for another
mission so this is a particular region
on Europe and you can see the striations
there this region is highlighted and
this is now work that comes from a
British Schmid who's been working on
this on Europa since she was I think in
grad school and what this shows is a
region that it looks very chaotic it
looks sort of crumpled II like something
happened there it's not a it's not a
crater some typical crater has a little
cone shape and you see the material
inside but this seems to indicate that
there might have been a region on the
planet I mean on the moon that might be
the source of some kind of flow of
material a crack in the ice raises a
material and so there was she developed
a model that seemed to indicate that you
had to have some kind of water driving
this type of feature liquid and Galileo
get to the rescue again and one of the
John Spencer studied the thermal mapping
of Europa and just because even you want
to know what's going on what's the
temperature on the surface is it all one
the same temperature all around is there
variation in the temperatures at hot
cold is it like that the Earth's where
the poles are colder etc and so he did
this heat map if you will it measured
the temperature in various locations
this is sort of at the South Pole this
is sort of hot you have regions where
you go from warm relatively warm to cold
and these are degrees I think Kelvin so
this also tells us that it's not as
solidly single temperature situation
which just adds to the to the intrigue
so this is a bit of an artist conception
I think that between Galilean Voyager
and a lot of have
lifting by planetary scientists we sort
of came up with the idea that we had a
salty liquid ocean and that potentially
you could have some kind of geyser
activity if you had liquid water
depositing here's sort of one of those
little chaos terrains like the one I
showed you earlier pool of water
underneath this is probably some thin
layer of ice about a hundred kilometers
thick you get a little water pooling up
and it comes up and maybe you could see
geysers and so this seems to indicate
all that it seems to indicate that this
is really the right idea the right model
for Europa so you do have a liquid ocean
a salty liquid water ocean underneath
ice and now things get really
interesting because this is not Europa
this is Enceladus which is a moon of
Saturn and Cassini which was not did not
go up forty years ago more recently than
that took a picture of Enceladus and
noticed that there was water vapour on
the South Pole hmm so if Cassini has
this what about Europa
so if Europa also has plumes of water
vapor then maybe we can learn something
about its ocean without necessarily
having to go and send a mission and do
ice cores and drill down a hundred
kilometers into the ice
so this is where Hubble comes in so and
this is work that started roughly around
2010 so this is Lorenz Roth it all came
up with one technique and it's called
spectral imaging and I wasn't there
which is not the same thing as direct
imaging so we think of a spectrum as
white light
through a prism or a dispersing piece of
glass and then getting broken up into
its constituent colors we've all seen
that or a drop of water or your hose or
the rainbows they all work the same way
and if you remember from your physics
class whether it was high school or
college or a graduate school or maybe
even last week and you're analyzing some
data typically when we do spectroscopy
we talk about having a slit and then you
have the dispersor in this case it's a
prism and this is just a model it gets
sent off collimated and what you see
then is a bunch of lines either
absorption lines in this case or
emission lines and that's a normal way
of doing things but in actuality what
these little lines are are actually an
image of the slit so what happens if you
take a moon and you use your traditional
small slit well you can't see the whole
moon but if you make the slit bigger and
fortunately Hubble is one of Hubble's
instruments the Space Telescope imaging
spectrograph has a slit that's about two
arc seconds wide and Europa extends an
angle of about one in a bit so you open
up the slit and you go through your same
system so this is now standing in for
the entire set of optics that are
complicated and what you get is an image
that's no longer those straight lines
but rather an image of the source
because you've made the slit large
enough and then the idea then is that we
know that if there is a plume of water
when water hits the atmosphere water's
hydrogen h2o two hydrogen's and an
oxygen when it reaches the atmosphere
will dissociate or it exits the
atmosphere it will dissociate break
apart into hydrogen and oxygen so the
logical thing to do would then be to
look for the dissociation products of
water which are hydrogen
and oxygen and in the ultraviolet there
are two lines of hydrogen and oxygen and
this is what Lorenz Roth and his team
took advantage of and so in 1999 this is
the series of images this is this is the
hydrogen lines these are the oxygen
lines in 2012 they took the another
series of images but in December of 2012
when they saw those images what they
noticed is that unlike the earlier
images there was a little excess of both
hydrogen and oxygen down here and that
indicates that there was a plume and
they wrote a paper in science which is
here came out in 2014 there were
subsequent observations almost seventeen
detection or orbits li and there were no
additional plumes discovered so now that
Lucknow just like with the presentation
earlier is this the data did we use you
know everybody thinks did we screw
something up what's going on that we
don't see it again get really panicky
you think you've done something wrong in
the analysis and you go back you do the
reanalysis in Psych know this was
correct that really but because they
didn't see the plumes again there was
already hints that Europa could not be
like Enceladus and so this is very
regular cryovolcanism if you will so if
you wanted to get a pretty picture and
put it together so this is the location
of the plumes and then here is Europa
okay the other thing about science is
that you like people to repeat your
experiment in some other way so that you
have some confidence of what you're
doing so the second method was to
actually use direct imaging so no longer
using spectrograph but just direct
imaging just like you do with your
camera take a picture of somebody or the
tree or the Pussycats
okay that's direct imaging in this case
there have been an example
in 2000 John Spencer had looked at EO in
the ultraviolet so this is EO and this
is Jupiter in the background you can see
there's a little plume here remember yo
really is volcanic and so the idea was
that look if this worked for AO where
you can have Jupiter effectively back
light so you're seeing Jupiter in the
back back lighting the atmosphere of the
of the of the of the moon the tenuous
atmosphere if there's anything going on
you should be able to detect it so the
second idea then was to do direct
imaging in the farl travaille ilat
around a hundred and fifty hundred and
sixty nanometers this is a region that
is of course not accessible from the
ground and we took images for up almost
three years well two years and we had 12
images of Europa in transit and what we
were doing then was measuring the
atmosphere not necessarily looking for
Jets but just changes in the in the in
the thickness or the opacity of the
atmosphere and we also just to double
check had images taken out of transit
just in case I had something to do is
being in front of Jupiter and the
analysis of this data was pretty
straightforward here's the real image of
Europa and this is Jupiter in the
background and what you want to make
sure is that that when you do the
subtraction in the analysis of the image
that you're not doing anything crazy
so the standard thing to do is to say
assume a circle with a and you assume
some kind of illumination pattern you
figure out what Jupiter looks like in
the background you make a model and then
you subtract the model well you actually
I also have to add you know the effects
of the instrument on your model so you
basically you're making a fake image so
here's the fake image and here's the
real image and they look okay they look
plausible this is one that doesn't have
plumes and this one in the model doesn't
have it either so this tells you
something about the gives you some
confidence
your method is actually going to work
and then just for fun you're just what
these images look like here because
Jupiter moves now here's the fun part of
doing planetary science which I hadn't
quite appreciated until I started doing
it myself
is that everything moves Jupiter moves
Europa moves the satellite moves so
everything has to somehow work together
and you have to decide whether you're
going to track on the moon or Jupiter or
both so this is what it looks like if
you assume that Jupiter isn't moving and
then here if you assume Europa isn't
moving so here's Europa and here's a
shadow and there's an O lovely aurora
and then I have to show this because
this is kind of fun if you put all the
images together and you D rotate
everything then you can make fun images
that show you here's Europa you're zero
here's the Great Red Spot and obviously
it's a partial image because we're not
imaging the whole of Jupiter's face so
that's kind of fun and the reason we
could do this is that one of the
advantage of the stiff spectrograph or
Imaging's system is that you can
actually take observations at what's
called trim tags so that the separation
each each exposure is 0.125 seconds and
you just can keep doing that so every
tenth of a second you have a new image
which is one of the things that lets you
make these lovely movies but it also
helps if you're trying to look for
features and then you can also play some
more with these images and this was made
by Sean Lockwood who's also on the staff
here and from the same data because the
movies are kind of fun what's the point
of doing this if you can't have fun so
here you see the Aurora which is kind of
fun it changes with time and here is
Europa so this is you know not not
enhanced at all and then if you really
want to see but again unenhanced so
we'll just skip right right past this
because the thing that's interesting is
that what we're looking for is three
thousand kilometers and this is Europa
snore
and then just to show you cuz you got to
show the data I've talked a lot about it
I've shown some pretty movies but I
haven't shown you the data but you
should always ask so these are the
twelve ten of the twelve observations
that we took and one two three four five
actually one two and they're given in
time so we started in twin December of
2013 through March of 2015 and we did
that whole careful analysis subtracting
out the model making sure and you'll
notice if you look carefully that there
are only three of these images that
should look that show something
different three of these are not like
the others and those are the plumes
maybe okay and this is just a close-up
and what these are done here is you
subtract the model out and again you see
the enhancement so I know that we had a
lot of discussion because now we saw
three-d-- we didn't see them
sequentially and then we looked at the
roth paper and it looked like they were
in the same location and in addition we
actually found a plume in a different
location but the other ones were down
here in March of 2017 we actually found
something a little Pucci thing over here
that repeated again there so that that
would be a second second plume that's
really cool this is just more of the
images and then just to prove that we
weren't kidding ourselves we added
subtracted and convinced ourselves that
that was right so where are these plumes
found so the ones that the eight the the
direct method the direct imaging method
found right just north of the South Pole
and then right here near this crater
called quill and we saw it twice so the
plume at will be repeated we saw that
twice this
we've only seen once and this is the
location of the plume as seen it with
the spectroscopic method so we have one
two three
plumes if you count them and one of the
things that's really need you've seen
this image before because I showed it to
you earlier is that here's well this
region here is like two degrees warmer
than the surrounding region and that's
coincident with what with that repeating
plume so the question we're asking is
are they related is it possible that you
could have a slight warming of the ice
would that be enough to allow some
liquid water to come through to sort of
break through it's a it's intriguing we
we don't know but it's a possibility and
so this might be what that looks like
that plume 100 rising hundred
twenty-five miles above the surface and
of course there's a Jupiter in the
background so um looks like there it's
probably water on on Europa and the
observations continue we didn't just
stop in 2017 both groups have has
amorphous as they are have are
continuing their observations using
different techniques and different
analysis methods so this is from our
most recent 2017-2018 data taken with
the Hubble Space Telescope and again
it's really kind of fun to see them and
move around this is Ganymede up here by
the way that isn't just a splash you can
see you rope over there and you can see
that lovely I love the aurora on the on
the poles of Jupiter okay so that's fun
there's a close-up of Ganymede so if you
have water we have ice we think we have
water the good thing is that both groups
got the same value when you do all your
calculations not only were the plumes
coincidence so that the sparks team in
the Roth found one plume coincident or
near each other and we saw one that
repeated but we also determined the
amount of water based on the on the
images that the amount of water was
about the same so you don't get the same
numbers unless you're more or less on
the right track so now we have the
ingredients for life so we have so what
do you need you need atoms you need
molecules you need the most important
molecule of all h2o and you need energy
now a nurse the energy that life as we
know it uses tens it comes from the Sun
plants the animals that eat the plants
algae slime mold bedbugs etc I'll derive
the energy required to synthesize these
elements into the amino acids along
biochemistry chain that happens
sometimes on earth we have hydrothermal
vents go to the bottom of the ocean
there are there's well volcanic activity
and that heats up the water and you get
these hydrothermal vents and we found
what we yeah and people have looked and
found at life bacteria and so forth
living there and this is a model sort of
indicating the tidal heating so if you
don't have direct energy from the Sun
and you may or may not have hydrothermal
vents
you still need a source of energy in
order to be able to do the the chemistry
that allows bio the biology to happen
and in Europa this is this would be due
to the tidal heating so there is an
energy source and many years of people
studying evolution so life on Earth is
divided into three clouds okay three
different groups we have what's what are
called the bacteria some of them we
don't like
these are single-celled generally
single-cell animals we have what's
called the archaea and those are
generally the those those extremophiles
those organisms that like to live or
it's super salty super acidic super
alkaline super hot super cold super high
pressure super low pressure and then we
have the Eukarya and that's everything
else
this is slime molds bedbugs people cats
dogs your neighbor and I just put down
this last common ancestor because it's
kind of cool to see the quote unquote
Tree of Life if this one gets very messy
and so does this one
so I just put clouds but the main
difference between the left side and the
right side is the kind of cell that
makes up the different kinds of life and
I have a question mark for the viruses
because I don't nobody really knows
where they fit in so these guys have one
particular kind of cell is very simple
and these organisms over here do are all
single-cell organisms whereas as we know
on this side whoa on this side we have
multicellular organisms as well as
single cellular organisms and the cells
are more complicated how you know things
like that then you start getting into
things like how is the information for
replication or reproduction carried in
in the cells of different structures
that do that I think on this side the
eukaryotes over here on the right as you
can see these are real electronic
scanning electron images of these
critters so this cell has here's the
nucleus this is where the DNA lives all
the genetic information and you see they
have all these structures of
mitochondria furtive doing like
mitochondrial DNA and analyses to see
where people came from that's what
they're looking for is the DNA that's in
the mitochondria you have
plasma you have a whole bunch of
structures and this is where all the
biochemistry happens that that is life
whereas on this side these are the probe
the prokaryotes whether they're bacteria
or archaea they're really simple
they here's something that's called the
nucleoid and all the DNA is is there and
then you can see there's just a couple
of structures in there so they're very
simple and of course on as we know from
you know everything that's the Eukarya
we have plans so they have solid cells
so the cells on this side er are very
can be differentiated and have specific
purposes so here we go so life on Earth
the bacteria this is actually a picture
of e---coli I had to find one that was a
key this is a meth an o-5 philic animal
it loves methane and lives where there's
a lot of methane this is a single-cell
organisms rather than algae and then
here's the great white whale so this
side we have a lot of diversity here we
have a lot of diversity but there's but
they're unicellular so then let's ask
the question of what would life on
Europa look like and it is probably not
going to be what we think of life it is
probably going to be something called
extremophiles now there are some
bacteria that are extremophiles and some
of these guys are extremophiles so these
are sort of the temperature ranges - 18
to 15 degrees Celsius 60 121 degrees
remember water at sea level boils at a
hundred degrees Celsius
pressure is like from 1/100 of an
atmosphere to 1,300 times our nurse
atmosphere so obviously this would be at
the bottom of the ocean in the deep
trenches this might be sort of on the
top of a mountain
they can live in places that are up to
38 percent salt and just as an example
seawater is only three percent salt
whoops
some of them like to be really acid
sulfuric acid is about two and then we
have very basic eight to twelve most of
us love like seven and then some of them
can also withstand a lot of ionizing
radiation so that would be x-rays gamma
rays ultraviolet even some of the
products from radioactive decay and they
also seem to be very resistant there are
some that are very resistant to cosmic
rays and you have to remember that for
example when people are talking about
traveling from Earth's to Mars or to any
of the other planets humans one of the
things that people worry about in
transporting humans across space is the
effect of cosmic rays these are very
high-energy charged particles and they
damage cells and can lead to things like
like cancer and disease so that is
always a concern on say interplanetary
travel for humans is how to protect
living creatures from cosmic rays but it
turns out there are some of these
extremophiles that are happy to deal
with it
so here I have two images here's another
bacterium this is actually a hallow
salt-loving bacterium and this is a
giant squid and Europa probably doesn't
have the giant squid so I think we're
going to see the bacteria and the
Archaea living in Europa and where would
they be found well here's a scale so
here's only some somebodies view the
view is that there is probably a
hypothermic vent or hyper thermal vents
in the deep ocean of of Europa
that heats up the water and then you
sets up a convection which allows the I
want to call it the nutritive 's but the
basic elements that are used by for
biochemistry as we know it carbon oxygen
phosphorus etc and then life bacteria or
archaea would end up living at the
bottom and sheets perhaps or upside down
rounds on the bottom of the ice some of
them might actually if there were soft
ice or event some of these um living
creatures might actually end up working
their way up to the surface much the
same way that rocks and meteorites in
the South Pole work their way up to the
surface they just get dredged up or get
what the actual word is for it
well dredged up by the physical forces
and from the surface of Europa you can
get some of the oxides
I think alum molecules with oxygen in
them might also make their way down sort
of in the same way through fissures in
the in the ice and so it is highly
likely that you would end up with life
on Europa living on the ice shelves and
so the next question is what comes next
and there are NASA has been looking at a
concept called the Europa clipper which
is a mission to go to Europa and
possibly fly through a plume and see if
any of these if there was any what's
what's in the plumes could there be some
biological material in the plumes
desiccated of course but would they be
there would it be possible to send some
type of a probe that would land on the
surface of Europa and perhaps be able to
either cozy up to one of those little
chaotic pieces of terrain or a soft spot
or near one of these plumes and actually
do some contact excavation
and I I think that would be really
really cool so but this is something
that is being studied very actively
because this would be perhaps Europa is
after Earth's we were we know there's
life would is the next most likely
location suitable for liquid carbon life
as we know it in the solar system and
that would be super exciting I think if
something went there and we discovered
there was life there I think it would
also be super interesting if we didn't
find life there because then you could
ask the question was there ever life how
would you know would you be able to find
fossils on earth we do find the people
who look for them have found fossilized
bacteria so it's possible one could find
telltale signs of past life or perhaps
life hasn't actually started yet these
are all possibilities so I'm just going
to and here with one last slide I don't
know if it was Galileo's dream to go to
Europa or not in 400 years ago but I
think he would certainly be interested
and would probably be a promoter of
exploring the icy moons this also turns
out to be a pretty good book and so I
will stop here
guess we have time for questions
Oh any time for questions including a
few that appear that they're gonna come
from online as well yes okay so I have
to repeat the question for the online
audience can the Hubble be turned back
on Earth to look for the same sort of
things we might be looking for on Europa
the short answer is no Hubble is
actually designed to avoid looking down
on Earth for logical reasons but there
are other satellites whose missions are
to look down on Earth
so there are as a whole suite of Earth
observing satellites now I don't know
the details of whether they would have
all of the sensing equipment to be able
to look for life but I did that is not
that is one of the few things Hubble
cannot do is turn turn around and look
at and look at hers we're here that's
actually some okay so the question is
does the is does the effect of the tidal
forcing of the or the tidal heating of
Europa coincide with where you see the
plumes and in fact I just read a paper
on that and I think the answer is no
that is that is what in fact Enceladus
is locked but Europa is not so I think
that's one of the other pieces of
evidence that we're not looking at
exactly the same thing in the green
sweater there yes
when the bottom I think you said it was
100 when it comes I would be like a 94
degrees Kelvin no cuz you only see it on
you only have a little bit of 100
degrees Celsius as it comes out and then
it'll cool and remember the ice is a
hundred meters is a hundred kilometers
thick so the the surface of Europa so
the question is is the temperature on
the surface of Europa fluid and the
answer is I'm not sure because it well
you know sometimes Europe is facing the
Sun so it's gonna have a little more
insulation I think overall if we go back
and look at those beautiful images let's
go back and look at the numbers let's do
the numbers so what you see here is that
you see it's roughly about eighty to
ninety degrees Kelvin with a little bit
maybe getting up 230 so I don't know if
that means it's constantly changing but
I think it's pretty constrained
obviously when it's facing the Sun it's
gonna be a little hotter right yeah your
image on the right is it says the marked
is daytime and this is daytime and this
is nighttime here so night so that
there's probably a 30 degree change
between the daytime and the nighttime I
don't I don't know that means fluid okay
so over here in the black two
so generally then what is the theory
behind why's there's a certain only a
certain area where we're seeing so the
question is what is our understanding of
why we only see the plumes in one
location yeah good question that's what
we're trying to understand actually and
isn't that what one of the things your
rope or clipper would be able to under
Europa clipper we'll be able to probe a
little better so there's like there was
a question earlier and so doing the
comparison between Europa and say some
of the other moons not quite seeing a
direct analog particularly with
Enceladus so it is a it is an open
question and yes having a mission
actually go there and get really close
and personal would be a wonderful thing
right so there was a question on line
let me just interrupt with that that was
sort of related to the Europa clipper
they were wondering what all right so
they they recognized that like that yes
you have to go survey what would be the
timescale for a lander mission is what
they were asking I mean like when would
that happen yes if Europa clipper went
up next next decade would there be the
several people on line were very
concerned that we need to be able to
measure the water on Europa before they
died yeah how old are they and where do
they live I think it's likely within my
my my lifetime okay and I would hope in
20 years
all right so we'll just call it decades
okay yeah yeah it's not it's not gonna
happen next decade but I think in the
30s would be a reason oh yeah there are
there are people on the on the team that
not me because I'm sort of a you know
lower-level type player in this but
there are people there who have been who
are very active in in talking to NASA
about that okay as you the question is
house Cassini flew through the plumes of
Enceladus and made some measurements of
the of the chemistry and the so the
question is if you went through the
plumes of Europa what would that
chemistry look like I'm not actually
sure I know the answer to that I think
it would depend on well you'd want to
see some evidence for example like
hydrogen compounds sulfate compounds
maybe iron compounds but I don't know
the quantity offhand would it matter
that much that Enceladus is sort of a
medium sized moon whereas Europa is a
large moon you're opening one of the
seven large moons Enceladus is just one
of the medium-size moons
I think those two and then in addition
the cool thing would be to find the
bacteria
all right in the back up there we knew
that there were was like when Europe
what would the implication be for
because there's life in the solar system
I think it certainly opens up the
definition of the habitable zone so so
the question is what is what is the
implication if life were found on Europe
but what is the implication for life in
the universe in in general so I'm going
to back that up a little bit which is
that on earth wherever there is the
possibility of life there is life so
life is very tenacious and there just
but just take that you know the basic
definition of life organic
an organism that can replicate and eats
and poops that's the basic definition of
life and moves it maybe moves around a
little bit if there's life on Europa
that tells you that you don't need to
have direct starlight whether its
sunlight or or that to provide the
energy and that's a little different
because that's one of the difficulties
is on earth is knowing exactly when you
know you're no longer dependent on
sunlight so if you're in the bottom of
the ocean with the in the trenches is
the hydrothermal vents and so forth you
know you're not getting a lot of
sunlight down there at all so that's a
possibility so then when people talk
about looking for extraterrestrial
planets and looking for evidence of life
there's a whole discussion of what's
considered the habitable zone hours some
people call it the Goldilocks you may
have heard of it as the Goldilocks a
factor which is where now you're looking
at but there you're looking at things
like what could be an earth as we know
as we know Earth if there's life on
Europa what that tells us I think is
that the definition of a habitable zone
you could have one for planets but you
might also need to sort of think about
all the conditions that are necessary
going back to the basics of energy and
chemistry that are necessary so I think
it opens it up I think it also makes it
much harder to well if you're looking
for moons around Jupiter and extra
terrestrial planets you'd make an
exoplanets it's it's a more difficult to
find but I think it would imply that
it's probably more prevalent this is now
my personal opinion it's more prevalent
than we might otherwise have expected
it's a long-winded answer to a short
question all right other questions Peter
so the question is could there be
another source of heat like
radioactivity from the core probably but
you know these let's say these form
four-and-a-half billion years ago four
billion years ago I don't think it would
be enough I think you would definitely
need the tidal heating to to keep that
ocean liquid some of the numbers I've
seen like six to ten times the amount of
water on earth it's a huge amount of
water hey was there a question in the
back there other questions no I I think
it's possible
it's probably less likely yes
tardigrades are very tenacious and they
are very tough they're really hard to
to do away with I mean they're using in
school in school labs all the time
because of that so they they do have a
chance at Rd and lots of places on earth
and they can survive cosmic radiation
but they are multicellular yeah you if
you don't know about tardigrades you
might want to look them up my son at one
of the science centers we went to spent
about half an hour reading about the
tardigrades and it's really cool
target grades are used for in a lot of
astrobiology labs when they when they
teach astrobiology because it's one of
those life forms that is very tough and
it you can subject it to all sorts of
conditions they're everywhere
okay questions you've had one more I
just want to see if there's any others
before okay back to you the physical
relationship so to speak the gravitation
so the so the question is the fact that
Jupiter is a gas is a gaseous planet
yeah because that effect in the
gravitational relationship between the
planet
and it's mmm because of the density yes
yes it's yes or no because if it's just
gravity then mass is more important than
the density so it's a total mass but the
fact that it has an atmosphere and has a
magnetic field so you start seeing
interactions of the magnetic field with
Jupiter with its with its um plus the
the aurora which are you know it's a
it's a chemical reactor not a camel it's
a physical reaction so either you're
getting particles thrown into the
magnetic field so that will that will
affect so you could you can get
sputtering for example on the surface of
the of the moon's that's when material
gets bombarded and then gets but gets
some sort of scraped off so the answer
is yes to both okay Herman okay
come in one last question I don't think
so no all right so thank you all for
coming on next month may 1st
gravitational wave astronomy with Annie
Fructis
let's give Suzanna one more big hand
