hello and welcome to what's new in aerospace we're here in the moving
beyond Earth gallery of the Smithsonian National Air and Space Museum here in
Washington DC today with us as our guests we have an astrophysicist from
NASA Ames dr. Ruslan Belikov who will be talking to us about the direct imaging
of exoplanets and where we go next in studying exoplanets but before we get to
that one of our educators Genovia of domestic a discovery station from here
in the museum that demonstrates how we've discovered most of the exoplanets
that we know of today yes this activity demonstrates the transit method of just
of detecting exoplanets so what we have here is a model of a solar system you'll
notice there's a star in the middle and planets that go around it and could
represent our own solar system but in this case we're talking about planets
around other stars and how we can find them one method is using the transit
method this over here represents a telescope it represents the Kepler space
telescope which like this device here is a light sensor it measures the amount of
light it sees over time as it looks at this star and you'll notice that as the
planets go around this solar system happens to be lined up so that the
planets are coming exactly between the star and the telescope which enables us
to use the transit method over here on this screen we'll show a graph of data
coming from this telescope where we have the amount of light over time so let's
start collecting data and see how the amount of light seen over time from this
telescope is changing so here's the level of light that that the sensor is
seeing and you'll notice as the planets go around the star that there are dips
in the level of light that is being seen there that's actually caused by the
planets going between the star and the telescope blocking a small amount of the
light and the sensitive sensitive enough detector
can actually detect that slight drop in the amount of light the bigger that the
the bigger the planet the bigger the depth let me start this again and well
I'm gonna predict that we'll see a medium sized dip right now that's when
the medium sized planet went between the star and the telescope here's a big dip
from the Big Planet so the bigger the dip the bigger the planet and the time
between the dips tells you how far the how long it takes the planets to go
around the star which tells you how far they are from their stars and thus
whether they might be nearby and hot or far from their stars and cool all right
Thank You Genevieve and just to tell our viewers that this transiting exoplanet
discovery station is something that you can see and interact with if you come to
the museum and educators like Genevieve will help you to understand and get
excited about concepts like exoplanets and and what we're learning about them
everyday so thank you and thank you Russ for being with us here today so so this
is the transiting method of discovering exoplanets and that you know it's pretty
incredible that we've gone during our lifetimes from wondering whether there
might be exoplanets out there to now having discovered thousands of them and
knowing that that's just the beginning so so what's next on the horizon that's
like a great question and maybe we can go to the first slide so but the transit
method that generally you've nicely demonstrated is one of the current
indirect methods of detecting exoplanets and I would say it it's generated a big
wave of extra client discoveries in in this decade spearheaded by the Kepler
mission now which you can see here and there are also several other missions
that have done have done Kepler discoveries soon but it one possible
next big wave of X applying discoveries might come from actually taking pictures
of exoplanets and that's what my be happening in the next decade or two
for example NASA is planning a mission called w first which among other things
would do direct imaging of exoplanets it would also do something called
microlensing exoplanet science and then in the 2030s NASA is studying mission
concepts that would not only directly image our planet but also directly image
potentially habitable planets and start looking for life on them there there
ground-based efforts as well you can see some of them here that have or planning
to directly image exoplanets so it seems like you know in the next few decades
you'll be seeing a lot of pictures of exoplanets and actually some exoplanets
have already been imaged you can see on Genevieve's
plot here is this is what the signal that the transit method gives you from
from an exoplanet I am these pictures or videos rather show you what taking an
actual picture of a planet looks like and I should point out that these
planets are very large and very far from the star so they're the easiest ones
that we've detected so far I and the community is now developing instruments
and looking forward to detecting potentially habitable planets and taking
pictures of potentially habitable planets I am those are harder to do
because they would be much closer to the store than these planets you can see
that an Earth orbit for scale would be here and it would be much dimmer but
here's what a earth-like planet would look like you can see a pale blue dot or
orbiting a star compared to an actual int so this is a simulated image and
this is an actual image of our Earth taken by the Voyager spacecraft from the
edge of the solar system see a pale blue dot suspended in something so to just to
summarize the next or one of the most exciting
next steps that I feel in this field is to obtain an image like this of another
Pele blue dot similar to our earth so in the demonstration that Genevieve showed
us you know we can see that with the transit method you can tell the size of
a planet you can tell the distance it's orbiting from the star you can get an
idea of what planets are in the habitable zone but what can you learn
from direct imaging that we are not learning from the transit method of
discovering these planets yeah absolutely so there are two key things
one is that direct imaging allows you to in fear you with a powerful enough
instrument to detect planets in any star system regardless of whether the planets
are crossing the star or not and as you can see from from this demonstration if
you were to tilt the system and in space systems are have random tilt then
planets may not cross between the star and your telescope and then you wouldn't
see it and so with direct imaging you you can
detect planets even if they don't cross the star and and that allows you to
detect planets around pretty much any nearby star and the second thing is is
it also allows you to do something called spectroscopy which is a way to
determine the composition of a planet and whether it has oxygen and water and
so on and start looking for life the transit method also allows you to do
that but again if you want to find life around all the nearby stars regardless
of whether they transit or not then direct imaging is the only technology we
know that can do that wow that's great I want to remind our audience that after
we finish our discussion up here we will be taking questions from the audience so
you know in a few minutes when we get to that point if folks want to line up at
the microphone then you know dr. Bell cough we'll be happy to answer your
questions and also if you're watching this on Facebook live or on the
live stream and you want to send a question via that method we'll also be
taking your online questions so tell me a little bit about the technology that
you and your colleagues at Ames are working on it's called a coronagraph
that's right and so how are you developing that and
how is that gonna work all right well let me move to the next slides and let's
see there we go so as you know Matt as you said we're working on the
coronagraph but let me also highlight an alternative
way of doing that which is a star shade and so there are two methods or branches
of methods to take pictures of exoplanets one which is conceptually
very simple to understand is you just fly a shield called a star shade in
front of your telescope to block the star and then you can see a planet the
other one is called a coronagraph which is where instead of flying a shield
outside the telescope you block the star inside the telescope and there are
advantages and disadvantages of both methods I happen to work on on this one
although we do some working with star shades as well but the idea behind the
coronagraph is that you have a series of optics
inside your telescope like a mask and other optics and a deformable mirror to
block the star and also to block diffraction which is ripples from from
light that that light generates when it when it enters the telescope and which
is brighter than your client so you have to remove it in order to see the planet
all right and so that's in at a high level at least that's how it works and
and this is a kind of an image you would get from this instrument where you see
all this light and diffraction from the star and all these masks and objects
allow you to remove light from the star in some region and
see the faint planets that are hiding in the glare of starlight so with the
coronagraph I mean it sounds like it's a very
technically sophisticated operation how are you testing that and developing it
and how are you proving that it will work so we have a lab at NASA Ames and
also there are labs at many universities and in particular JPL also has has a
nice lab testing these technologies and so let's see if I can wanted nice yeah
there we go so our lab is is one of several and this
is what some of the people in our lab and we actually have two labs that is
one of them in the background by the way you see a Kepler test demo that's going
to be at the Smithsonian I understand yeah we're working on collecting it from
from your lab to clear up some space for you there yes
but going back to to your question how are we testing us so we we can't really
test our instruments with ground-based telescopes because the problems and
challenges associated with with the atmosphere they're different from the
challenges in space but what we what we can do in lab is we can create a star
with laser or star light with lasers and then pass it through a prototype of our
coronagraph our instrument on an optical bench and then operate it as if we were
doing it in space and then and then see if we can suppress the Starlight to a
level that allows us to see planets and so once we can suppress it enough to
where we can see planets and repeat the test in vacuum that's when we know that
we can put it on a telescope launch it yeah now I remember when I
visited you in your lab that it's a very sensitive setup that you've got it can
even detect tidal forces between the moon and the earth right it yes
yeah it's it's amazing and in fact Eduardo who couldn't be here today has
just done an experiment where which was so sensitive that he could see a signal
from the moon passing by and so the the level of precision that we need to
achieve with these types of instruments is incredible and it's equally
incredible that we actually can achieve this level of precision so and
the the reason we need our instruments to be so kind of exquisitely accurate
and precise is because the brightness difference between an earth and a
sunlight star is about 10 billion so you have to for every 10 billion
you know photons from the star you get to 1 billion of one photon from from an
earth-like planet so you really needs to make sure everything works very
precisely to remove the Starlight so once you have the technology developed
where do you begin where do you want to start looking for a
habitable exoplanet well my favorite star is Alpha Centauri which is the
closest star to us actually the closest sun-like star by a wide margin and so I
that's that's where I would like to look but also all the nearby stars I think
make excellent targets all right and so there's a there's a video here that
shows you a star field that you would see from from the east coast and all the
highlighted stars there are stars around which we know that there are planets but
you also may see little dots that are not highlighted and you might see that
there many more that then highlighted stars which means
there are many stars in our neighborhood around which statistically there should
be planets but we just haven't found them either because they're not
transiting or because the planets are too small like most of earth-like
planets are small and/or much smaller than the ones we found already and are
challenging to find so even though we found you know close to four thousand
planets now as you can see here you know that's cleanest filled with highlighted
stars there there are many stars nearby around which there should be potentially
habitable planets but but there aren't and also I I think we want to search the
entire galaxy I mean in the far future and you can see that the highlighted
stars are clustered in our galactic neighborhood but the galaxy is huge and
even though we found four thousand planets there or you know roughly
speaking there are hundreds of billions of stars in our galaxy and we know that
there should be more planets than stars which means they're many hundreds of
billions of planets expected to be in our galaxy alone and perhaps as many as
a hundred billion potentially habitable worlds many of which are yet to be found
so starting with our you know immediate your nearest stars and then expanding
further guys what I would like to see happen Wow
so potentially you know many many habitable worlds out there what will
what do you think will happen once we discover our first habitable world or
our first candidate for a habitable world sure so and it's interesting that
you say candidate for a habitable world because the direct imaging by itself and
just if you take a picture it doesn't tell you if the client is habitable or
not but it enables you to just get rasca P and let's see there we go
so spectroscopy is essentially looking at the brightness of a planet or
brightness of anything really as you change the wavelength of light or the
color and encoded in in this brightness variation versus wavelength or a
spectrum I is a is a signature of what a planet's atmosphere is composed of and
if you look at the spectrum of a Venus Earth and Mars you can see that you know
Mars has carbon dioxide Venus has carbon dioxide but not water or oxygen but
earth has obvious signature signatures of Earth and water so if we were to
treat earth like an exoplanet or or all three of these as exit points it would
be obvious that Earth has oxygen and water and Mars and Venus do not at least
not nearly as a Bunton I and on earth oxygen is caused by life and it's it's
possible to create oxygen without life but the the methods you know to do that
so you have to kind of think of somewhat contrived explanations of how to do that
so detecting atmospheric oxygen and water
on an exoplanet would be suggestive of life which isn't incredible because you
know you would think you have to go to planets to detect life but perhaps not
perhaps you can do it remotely and in in our lifetimes we we could potentially do
it and figure out if life is abundant or not however the way I see this
proceeding as many things attempt to happen in science is that
there will never be a kind of smoking gun or at least not not at first
evidence of life we would find suggestive signatures oxygen methane
water and and even those so you know could would start probably as marginal
detection and then the signal-to-noise would build up and then perhaps over a
decade or decades evidence will build up to where the scientific community will
say okay yes this planet does indeed have life or the answer might come back
to most planets or old planets do not have life and life is rare so look look
at Mars for example we've spent decades debating whether Mars has life or not
and whether Mars has microbes on it or not and that answers the question stone
not closed and I expect the same thing to happen with the VEX appliance but
what an exciting adventure it is to be contemplating these questions and to be
on the verge of beginning to answer them and even though there's not going to be
a clear you know smoking gun anytime soon I think just the process itself is
fascinating and it's it's incredible to be in the generation that's that's doing
that's answering these questions so you'd be pretty excited if we found
signs of habitability on a planet at our nearest neighbor Alpha Centauri right
but I think a lot of people would wonder you know okay once that decade or so of
scientific debate is over and we've decided that yes there is probably life
on that planet what would we do next I mean how would we get there what would
we do well so getting there of course is
you know very interesting and fascinating and I think the gist
detecting planets by themselves even even without thinking about you know how
to get there would already be a huge milestone for our civilization because
it would answer fundamental questions about how common life is whether we are
alone and so on which humans have been answering asking for thousands of years
and just just standing on the verge of answering these questions is pretty
amazing yeah but in terms of getting there I think that if we know that there
potential potentially habitable planets and if we know there's actual real
estate around other stars I think that would provide a much greater incentive
for developing technologies to go there and perhaps it's not going to happen in
our lifetimes or even for centuries or even a thousand years I think that
having the long-term goal of going there and having the human race expanding to
the Stars is something that's pretty amazing to dream about oh yeah it's very
exciting now I've got one just one last question and then we're gonna take some
questions from the audience just a reminder that if you do have a question
please line up at the microphone over here behind this distinguished gentleman
so my last question for you is you know really on behalf of maybe younger
audience members or someone watching online who's thinking about you know how
exciting this this field is and the next 10 20 30 years of work how do you get
into this field what do you suggest for a young budding scientist or you know
maybe tell us a little bit about how you got into this field yep well this is a
very personal question for me because I have two daughters an eight year old and
a three year olds here's my eight year old when she was a few years younger I
and I would say that the the most important thing is to encourage offer
for parents to encourage interests in in science in their kids and I'm you know
very grateful to my parents for encouraging me to work hard and
having me you know do a lot of nothing and science when I was a kid that kind
of led me to to around today and I'm trying to repeat that with with my
daughter's yeah I and you know not not pushing too hard it's it's also very
important not to push them to where they start hating it but I think more
specifically getting a firm foundation in mathematics and in physics is
possibly the the most important thing to do because that then could propel you to
to anything you want to do in science or in engineering yeah so make sure that
you get the foundations down great well we're running low on time but I think we
might have time for one quick question hi I'm David Devore can I work here at
the Museum and I can't think of a more profound question than the one you are
treating and I think most for me most meaningful thing you said was just to
know that life exists out there let other people worry about getting there
or having them get here but my question to you is much more mundane and it deals
with the coronagraph itself of course know that coronagraphs been around for
40 50 60 years now and mainly for the son being able to look at the atmosphere
of the Sun but in your coronagraph you're using an occulting device inside
the optical system is that right and I'm wondering why you decided to do it that
way but also I'm curious about the rubber mirror and not only what a rubber
mirror is but what is that going to be in the vehicle that you send into space
or is that just for testing it on the ground yeah so excellent questions so
regarding the the first question why do it inside rather than outside if you
were to block the star outside I'll scope the star shade that that you
you would have to fly would have to be bounced in the tens of thousands of
kilometers away from your telescope and the reason for that is that the angle
between the star and the planet is very small as opposed to the the Sun where
the angle is like half a degree but that the angle between a star and appliance
is measured like hundreds of milliseconds so because the angle is so
much smaller that means that you have to have your outside you know coronagraph
or star shade very far away and that presents you know challenges which are
not insurmountable there's excellent technology development going on but and
you know I it it also means that the alternative of putting the blocker
inside the telescope is also attractive on your second part of the question the
rubber mirror is as you call it so it's actually not made of rubber it's it's an
actual mirror it just happens to be deformable and the reason that we we
need something like that is because we cannot manufacture technology doesn't
exist to manufacture optics no no optics to the degree of precision
that we need but we can make a mirror that we can you know an adaptive mirror
that we can deform to compensate for any errors in manufacturing or misalignment
you know during launch and so on - then I get us the precision that we need to
remove starlight all right thank you thank you for that question and thank
you dr. Belikov for joining us today on this program and thank you to our
sponsor Boeing so once again thank you for joining us here at what's new in
aerospace here in the moving beyond Earth gallery at the Smithsonian
National Air and Space Museum we hope you'll tune in to another one of our
programs and also you know as I said before come and see us come in and enjoy
the museum and also all of the stuff that we have online for you
enjoy at home so thanks again
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