Who are you? We are from Mars, don't be afraid. We have children just like you on Mars. Human beings have contemplated whether life exists beyond
Earth for thousands of years. Ancient one of Mars I call upon you. It's thought that there's a possibility that simple microbial life might exist within our solar system, but not advanced complex life. Doesn't mean it doesn't exist, it just means we don't expect to find it, largely because the conditions for life elsewhere in the solar system appear to be extremely hostile to such life. But since the early 90s, technology has allowed
us to locate planets outside of our solar system. They're known as exoplanets
and planet-hunting telescopes like Kepler and TESS, have discovered roughly
4,000 of them and counting. So we now understand
that majority of stars will have planets. So planets are ubiquitous. And because we just reach that sensitivity that is allowing us to
detect those exoplanets, this field is evolving very rapidly. And while they're too far away to send a probe to even
the closest exoplanets, a team at NASA's Jet Propulsion Laboratory has been developing a method more powerful than any telescope ever built. It'll be able to give us
a close-up look at planets and other objects thousands
of light-years away, find worlds that are similar to Earth, and maybe even discover
signs of intelligent life. So that's what the Earth
people call a city? How primitive. Look at all those buildings above ground. And it will be amazing discovery, first of all to see that we are not alone and how life evolved in that system. So it's an enormous step in our sort of philosophical understanding who we are and where we go. Powerful telescopes, like
the Hubble Space Telescope, Spitzer, Herschel and Keck Observatory have photographed objects very far away. This galaxy called The Sombrero Galaxy is 28 million light-years from Earth. But even though known
exoplanets are as close as four light-years, these
are the best images we have. All we really get are just
these tiny little blobs. They just look like fuzzy, little points of light orbiting some
distance from the star. So we don't really see anything
that looks like a planet. In fact, if we didn't know
any better we might think that it was just a very very faint star, when in fact it's a very
very large planet reflecting the starlight off of it. And of the 4,000 discovered exoplanets, only about 50 of them have been imaged. So basically it's really really hard to image an exoplanet? It's really hard, but not impossible. And that's why we're aiming
to do that, you know, that's why we're trying
to make that happen, but you're right, it's very difficult, it's certainly is not
beyond our capabilities or won't be beyond our capabilities. The majority of exoplanets are found using the transit method, a tiny dip in a star's
brightness when a planet passes or transits in front of it. And it's that telltale drop off in light, especially when it repeats
over several cycles that tells us that this
is caused by a planet, orbiting the star making regular transits across its surface. Another common method is looking at slight shifts
in the motion of a star when there's a planet orbiting it. This is known as the radial
velocity or wobble method. The planet exerts gravity on the star. So what happens is that as the
planet comes around the star, the star also kind of comes around the system's center of mass. And so the star has to move. Although both of these methods allow planetary scientists
to make predictions like the basic mass, size,
whether it's rocky or gaseous, and distance to its host star, it doesn't allow us to see it. In the best case scenario, the light can be analyzed
with modern telescopes to give hints as to whether
the planet is habitable. How can we even tell that
a planet is habitable just by a fuzzy blob? We certainly cannot. So the goal with these telescopes
is not to actually show us what the planet looks like, but it would allow us to
analyze the light coming from the planet. The spectrum of light coming from the planet can be analyzed to reveal the chemical
components of its atmosphere, a much easier feat than
getting a real life image. That's because in comparison to a galaxy, exoplanets are dark and tiny. Planets just reflect light
from their host star. So even though a planet may only be a few dozen
light-years down the road, our chances of seeing it are much less than seeing a bright
star that's even farther or a bright galaxy that's
billions of light-years away. It's just the nature of
the luminosities involved. Even with the upcoming James Webb Space Telescope, which will be the most powerful
space telescope ever built, the images won't give you
much more than fuzzy blobs. What we want is an image where
you can see color variations that distinguish oceans,
continents, vegetation, and even see lights at night. That can determine not
just if it's habitable, but show proof of advanced life. But to image an Earth-sized exoplanet, that's a hundred light years
away at a decent quality, 1000 by 1000 pixels, you would need a telescope that is 90,000 kilometers in diameter, seven times larger than Earth. And even if it were made of
a super lightweight material, it would still weigh about
a trillion kilograms. In other words, it's not possible. What we need to do instead
is rather than think about even building a telescope, we need to think about using nature itself as a kind of telescope. And luckily nature gives
us a way to do that. This was discovered by Albert Einstein, and it's the idea that mass or gravity can bend the path of light. As long as that can happen,
then we can in theory, go to where all those light rays that are being bent by a mass converges, and we can take an image. This is called gravitational lensing. As long as we can choose the
right place to put a telescope, we could in principle,
look back toward the sun, image the gravitational lens
from a distant exoplanet, and for the first time, we would actually be
able to see continents. We'd be able to see the
oceans and map the coastlines of a Earth-sized planet, maybe
a hundred light-years away. This is a very different
approach to making images with a telescope that we
could build here on Earth, but it may in fact be the
only way that we'd be able to directly image the
surface of another planet. It may sound like science fiction, but we've actually observed
this phenomenon before. When light from a distant galaxy is behind a massive foreground object, from our perspective on Earth, the mass of that foreground
object bends space time, creating gravity and bending
the light around that object. This forms a ring called an Einstein ring. To visually demonstrate this, you can use a wine
glass to act as the lens or a foreground object and a light bulb that can act as the source. If we the observer
looked through the center of the base of the wine
glass, we see a ring of light. And in theory, we could
use computer software to decode that ring of light
back into its original state. If you replace the wine glass
with the sun to bend the light and send a telescope, now the observer, to the point where the light converges, you could then take images of the ring and put it back together using software. The sun is massive enough that it will amplify whatever
you're pointing it at, by a factor of a hundred billion, just like an astronomically
massive telescope. That's why a team of scientists
led by Slava Turyshev at NASA's Jet Propulsion Laboratory are proposing a solar
gravitational lens mission. Flying a small telescope to
the solar gravitational lens will allow us to study those
objects in very fine details and confirm the presence of life, and study the evolution
of life on that exoplanet. There are a few challenges
though, for this to work, the telescope will need to be positioned past the convergence point at
around 650 astronomical units or AU from the Sun. One AU equals the distance
from the Earth to the Sun. Neptune is at 30 AU for example. And Voyager 1, the farthest manmade object that was launched in the 70s, is currently at about 150 AU. So we have thought about how
we can reach those distances, what technology do we have? And essentially we realized
that using chemical propulsion is very challenging because
the fastest velocity we were able to achieve
with chemical propulsion was achieved with the New
Horizons mission to Pluto and New Horizons was able to reach roughly three
astronomical units per year. With this velocity, it
will take us a lot of time to get to solar gravity lens. So, we realized that solar sailing offers a unique alternative. With solar sailing we are
using the solar photons, solar light to gain a
very significant momentum that will push our sail
craft to very high velocity. Solar sailing has been successfully demonstrated by The Planetary Society, NASA and the Japanese
Aerospace Exploration Agency. If done in a way that Slava
and his team are proposing, which involves flying close to the Sun, the telescope will reach speeds
of roughly 25 AU per year. So with those velocities, we will be able to
reach solar gravity lens within I would say 20 to 25 years. That's the only way to do this. The next challenge is
once you get to 650 AU, there's no slowing down. But this is where they get a lucky break. It doesn't have just a single focal point, it has a focal line. If you fly a spacecraft
towards the focal region of the solar gravity lens,
we don't have to stop. Moving along that focal
line will still benefit from that large amplification. Another challenge, which current telescopes also
face when imaging exoplanets, is that you have to point the telescope at a very bright object,
in this case the Sun. This creates a glare which needs to somehow be blocked out in order to see the planet. We will use a very interesting technique called a coronograph. So the, or star shade, the large instrument
that is, has to be flown in front of our telescope in space, and that coronagraph will allow us to block the light from the parent star. And suddenly the very faint
light from the exoplanet may present itself. So it's a challenging technique because the brightness mismatch. Fortunately, coronagraphs are being
developed and in use on many planet-hunting telescopes, including the upcoming
James Webb Space Telescope. Finally, the telescope will be limited to choosing a single target since changing the angle by just a degree, could mean propelling it
billions of kilometers in the lateral direction. Usually people when talking
about solar gravity lens there is a significant limit, because we currently are limited
by propulsion capability. So we can think that we can fly only towards one target essentially. And so, I think about
solar gravity lens mission, it's like any planetary exploration. If you fly towards a Saturn, we're studying the
whole set of satellites, the whole formula of satellites
around Saturn with Cassini. If you fly around Jupiter with Galileo, we're studying multiple
satellites of Jupiter. With the solar gravity lens,
flying towards a Trappist we can study every planet in that system. The Trappist system is a star with seven planets orbiting it, three of which are in the
theoretical habitable zone. The sweet spot for a planet
to possess liquid water on its surface and possibly support life. Pointing the telescope
at the Trappist system could be a solution for
looking at multiple planets since they orbit the same star. Another way they're looking
to solve this is to build the telescopes cheaply
and send many of them. These are just a few of the hurdles that Slava and his team face, but none of them are out of reach. And what we realize is that
most of those technologies already exist. Some of them in a very high
technology readiness level, some of them are yet to reach a very reasonable
technology readiness level, but all of them exist
in one form or another. Most of this technology is being developed
alongside other projects that need to get far out into
interstellar space cheaply, and in a reasonable amount of time. So ultimately we will transfer those engineering developments to allow us to explore further, more,
at a very affordable cost. Solar gravity lens is
our ultimate goal so far, but looking at this we realize that there are plenty
of synergistic efforts within exploration community
and who benefits from them, who benefit from those efforts
and we invite our colleagues and friends to join us to
look at those technologies, how we can use those
technologies in the near term, how those technologies will benefit us in the next, five, 10 years. Slava and his team
received phase III funding from the NASA Innovative
Advanced Concepts Program, and are developing methods
to reconstruct the image from an Einstein ring, as well as building instrument prototypes. They hope to launch their
technology demonstration mission in the next three to five years. So as of now, if you
could choose one target for the solar gravitational lens, what would you choose and why? Oh man, only one? Let's take a picture of
our closest neighbor, so the Proxima, right? So Proxima b, it's our neighbor. The closer the exoplanet
is, the larger its image and therefore the more detail
we will be able to see. The closest star to our solar
system, Proxima Centauri is only 4.2 light years away, and it has at least one, but probably two planets orbiting it. I would love to use the SGL on that to see what the planetary system
next door looks like. It's possible that once
we get a close-up look at our nearest neighboring solar system, we'll be able to find
out once and for all, whether we're alone or at the very least, get a detailed image of an
exoplanet for the first time. Slava and his team hope to
launch their first mission to image an exoplanet in
the next 12 to 15 years. So it's only in a short
40 years from today, you and I may discuss
the images of, you know, life present on a different exoplanet. And this is how the childhood dream may realize for many of us. So now we will have a clear understanding, yes we are not alone and oh by the way, our life is excellent. Or maybe we just have a
confirmation that those aliens use, you know, carbon fuel
as stupidly as we do. Or maybe they come up
with something excellent and we'll learn from them. But anyway, I think it's
exciting opportunity for us to step above our daily
lives and think about what our universe will
tell us about ourselves. So, while we're never gonna solve every problem on Earth,
we can solve most of them. And in addition to reducing
the pain of life on Earth, we can also increase the excitement of being alive in the first place. And that's what missions like
the solar gravitational lens and these next generation
of space telescopes are allowing us to do. And there's something just
fundamentally essential about learning about our
real true place in the cosmos and understanding how it works.
My favorite thing is that (because of the way Reddit displays movies) is that it looks like an eye.
https://i.imgur.com/wEkEE6H.jpg