Speaker 1: Get technology with tech Stuff from dot Com. Hey there,
Speaker 1: and welcome to tech Stuff. I'm your host, Jonathan Strickland,
Speaker 1: and today I want to talk about an awesome spacecraft,
Speaker 1: the Kepler Telescope. I've talked about this on the Forward
Speaker 1: Thinking podcast, so if you've listened to Forward Thinking, you're
Speaker 1: gonna hear some stuff that you've probably heard before. Although
Speaker 1: this is really going to focus pun completely intended, let's
Speaker 1: be honest on just the Kepler Telescope. And the reason
Speaker 1: why I'm doing this in the first place is because
Speaker 1: in May, researchers with the Kepler Mission at NASA held
Speaker 1: a press conference in which they announced the largest number
Speaker 1: of exo planets verified ever at a single event, and
Speaker 1: that was one thousand, two eight four verified exo planets. Previously,
Speaker 1: from two thousand nine, up to that point, the mission
Speaker 1: had identified and verified four planets, so this announcement was
Speaker 1: more than doubling the number of exo planets verified. That's incredible.
Speaker 1: So an exo planet, just in case you don't know,
Speaker 1: is of course a planet that is orbiting another star,
Speaker 1: not the Sun, so it's planets in other star systems,
Speaker 1: solar systems that are light years away from US, and
Speaker 1: it was a really cool thing to hear about all
Speaker 1: these different exo planets that had just been verified. Um,
Speaker 1: what I thought was hilarious was leading up to this
Speaker 1: announcement you had several news outlets that were, uh, guessing
Speaker 1: what was going to happen. It was just it was
Speaker 1: just complete throw stuff against the wall and see what sticks.
Speaker 1: And there were quite a few that had guessed that
Speaker 1: NASA was going to announce that the Kepler mission had
Speaker 1: somehow discovered alien life. Now, once you hear how the
Speaker 1: Kepler telescope works and what it's meant to do, you
Speaker 1: will understand that's really not in the purview of the
Speaker 1: Kepler telescope. It is looking for planets that could potentially
Speaker 1: support life, but it doesn't have the capacity to actually
Speaker 1: detect life on those other planets unless someone sent aliens
Speaker 1: to Earth and they started messing with the Kepler telescope,
Speaker 1: in which case you could say it discovered life, but
Speaker 1: not through its primary mission. That did not happen. As
Speaker 1: far as I know, no aliens have been messing with
Speaker 1: the Kepler telescope. So let's talk about how this telescope
Speaker 1: works and this new verification method that the research team
Speaker 1: used to identify so many exo planets. What was it
Speaker 1: that sped up the process so dramatically as to more
Speaker 1: than double the number of confirmed exoplanets. Plus I'll talk
Speaker 1: a little bit about the new candidates for earthlike plants
Speaker 1: that might be capable of supporting life. So first, let's
Speaker 1: go way back. The Kepler telescope is named after Johann Kepler,
Speaker 1: and astronomer of the late sixteenth and early seventeen centuries.
Speaker 1: That's not the original name of the telescope, by the way,
Speaker 1: but more on that in a little bit. So Johann
Speaker 1: Kepler is most famous for discovering the three major laws
Speaker 1: of planetary motion, although at the time no one called
Speaker 1: them laws. It would take Newton and Newton's observations before
Speaker 1: that really started to become a thing. But law number
Speaker 1: one is that the planets move in elliptical orbits around
Speaker 1: the Sun. Law number two, the time it takes to
Speaker 1: traverse any arc of a planetary orbit is proportional to
Speaker 1: the area of the sector between the central body, for example,
Speaker 1: the Sun and the arc. So you can think of
Speaker 1: the two points along the arc the starting point in
Speaker 1: the endpoint of the arc as your your barriers on
Speaker 1: one side, the Sun being the third point. And what's
Speaker 1: not exactly a triangle because you have a herv line
Speaker 1: on a straight line on the ark side, the area
Speaker 1: within that that is proportional to the time it takes
Speaker 1: to traverse that arc. Essentially, what that tells you is
Speaker 1: that the further out you are from a star, the
Speaker 1: slower your orbit is going to be, and the closer
Speaker 1: and you are to a star, the faster your orbit
Speaker 1: is going to be. Also, there's a relationship between the
Speaker 1: square of a planet's periodic time and the cube of
Speaker 1: the radius of its orbit, which is also known as
Speaker 1: the harmonic law. That's law number three. Now, the Kepler
Speaker 1: mission all started out with a question, which was how
Speaker 1: frequent are other Earth sized planets in our galaxy the
Speaker 1: Milky Way? How common is that? Is the Earth a
Speaker 1: strange outlier that is one in a billion or one
Speaker 1: in ten billion, or or even more rare than that.
Speaker 1: We had no way of knowing. Now that particular space
Speaker 1: based tell us cope, the Kepler telescope tries to answer
Speaker 1: this question by looking for planets using what is called
Speaker 1: the transit method. Now, this method was proposed a few
Speaker 1: times leading up to nineteen one, when Frank Rosenblatt really
Speaker 1: went strong with the idea. He suggested the transit method
Speaker 1: for detecting satellites orbiting other stars. And technically, the way
Speaker 1: this works is that you look at a star and
Speaker 1: you measure the amount of light coming to Earth from
Speaker 1: that star, and you look for any variations and that
Speaker 1: any dimming of that light. Now, if a planet were
Speaker 1: to pass between that star and the Earth, you would
Speaker 1: expect the light from that star to dim a tiny amount,
Speaker 1: and that if you were able to detect that difference,
Speaker 1: and you were able to observe that this happens regularly
Speaker 1: over the course of a given amount of time, you
Speaker 1: could come to the conclusion that what you have seen
Speaker 1: is in fact a planet passing between its host star
Speaker 1: and the Earth. This is what we call transit when
Speaker 1: we see from our perspective a planet crossing its star.
Speaker 1: Now we're looking at the planet making its progress across
Speaker 1: its star in the course of that planet's year. So
Speaker 1: if it's close to the same distance from its host
Speaker 1: star as the Earth is from the Sun, you have
Speaker 1: to wait a long time to verify that that in
Speaker 1: fact is what you saw, especially if you want to
Speaker 1: truly verify it and and get a few periodic uh
Speaker 1: instances of that dimming. And if it has, if it's
Speaker 1: a star that has multiple planets alone that same orbital plane,
Speaker 1: then that's going to cause some confusion too. But by
Speaker 1: by seeing the amount of light that has been dimmed,
Speaker 1: and by detecting how long it takes the this dimming
Speaker 1: to change back to normal, you can start to make
Speaker 1: some conclusions like how big the planet must be, how
Speaker 1: quickly it travels tells you a bit about its orbit.
Speaker 1: It tells you also by that orbit, how close it
Speaker 1: is to its home star. As long as you know
Speaker 1: information about the home star, then you can start to
Speaker 1: make guesses as to how hot the planet is or
Speaker 1: how cold it might be. And this is how you
Speaker 1: start to draw some conclusions about the nature of that planet.
Speaker 1: Ultimately looking for planets that are similar to size, uh
Speaker 1: similar to Earth size, I should say, and similar to
Speaker 1: distance from its host star as the Earth is to
Speaker 1: the Sun. The reason for that is we know that
Speaker 1: if the planet is about two times the size of
Speaker 1: Earth or smaller, it's probably going to have gravity that
Speaker 1: is uh amenable to life as we know it. It's
Speaker 1: gonna probably be a rocky planet as opposed to a
Speaker 1: gas giant. That's also important. It's probably gonna be at
Speaker 1: a temperature that will allow liquid water to be on
Speaker 1: the planet. And since life as we know it depends
Speaker 1: upon the presence of liquid water, that's what we're looking for.
Speaker 1: Keeping in mind that there is the possibility there could
Speaker 1: be life out there in the galaxy that doesn't depend
Speaker 1: upon liquid water. But we have a sample size of
Speaker 1: one planet with life on it, so we have to
Speaker 1: draw our conclusions based upon the limited information we have.
Speaker 1: So assuming that water is in fact necessary for life,
Speaker 1: we need to find other planets that could potentially have
Speaker 1: water on them. So that's kind of guiding the principles
Speaker 1: behind looking for planets through the transit method. But it's
Speaker 1: really really hard to do. Now, let's get back to
Speaker 1: to Frank Rosenblatt for a second. He wasn't just famous
Speaker 1: for suggesting this astronomical approach. He wasn't known as a
Speaker 1: great astronomer. He was actually better known as a leading
Speaker 1: expert in the field of artificial intelligence, particularly in the
Speaker 1: areas of recognizing visual patterns and speech recognition, So that
Speaker 1: was his specific forte. He was really working with computers
Speaker 1: so that they could recognize visual patterns, they could recognize
Speaker 1: when you what you are saying when you talk to them.
Speaker 1: And these are fields that today are really coming into
Speaker 1: their own with stuff like Google's Deep Dream, where it
Speaker 1: starts to recognize patterns even if patterns aren't really in
Speaker 1: the picture. It really enhances that and looks for patterns
Speaker 1: in in the in ways that are really interesting and trippy.
Speaker 1: And speech recognition, which we're all using to some degree
Speaker 1: these days, um often with the personal digital assistance that
Speaker 1: are popping up all over the place. Now here's the problem.
Speaker 1: Rosenblatt's suggested approach as not practical at the time in
Speaker 1: the early seventies. We just lacked the technological sophistication necessary
Speaker 1: to detect and analyze such a very tiny change in
Speaker 1: a star's brightness. If we were looking for an Earth
Speaker 1: sized planet at a distance similar to what Earth is
Speaker 1: from our sun, we're talking about a reduction of one
Speaker 1: ten the brightness of a star, and that dimming lasts
Speaker 1: between two and sixteen hours, so that's not a lot
Speaker 1: of time, and it's certainly not a big difference in brightness.
Speaker 1: You have to have a very sensitive instrument in order
Speaker 1: to be able to pick that up, and that just
Speaker 1: didn't exist in nineteen seventy one. Now, we also have
Speaker 1: to keep in mind that stars tend to be much
Speaker 1: much bigger than planets. For example, the Sun's diameter is
Speaker 1: a hundred and nine times greater than the Earth's diameter,
Speaker 1: and because of that, that's why, with the distances involved
Speaker 1: and the size is involved, it's such a tiny change
Speaker 1: in the brightness of the star. However, NASA began to
Speaker 1: explore how they might be able to use the transit
Speaker 1: method to detect exoplanets in a practical way. Back in
Speaker 1: they were essentially laying out the requirements necessary to detect
Speaker 1: planets with a reasonable amount of confidence. A conference that
Speaker 1: they held on High precision photometry acted as the launching
Speaker 1: ground figuratively speaking for discussions about a space based telescope
Speaker 1: designed to detect a transitting planet. The idea being that
Speaker 1: in space there would be less uh noise in the
Speaker 1: signal to noise ratio you could get it outside the atmosphere.
Speaker 1: The effects of the atmosphere would not be an impediment
Speaker 1: to a space telescope, and it would be more likely
Speaker 1: to pick up something as tiny as this change in brightness.
Speaker 1: So in two NASA proposed new missions to look into
Speaker 1: the possibility of life in our galaxy, and the first
Speaker 1: concept that came up with was called the Frequency of
Speaker 1: Earth Size Inner Planets or FRESIP f R E s
Speaker 1: I P. But that proposal was rejected largely because there
Speaker 1: was doubt at the time that our technological sophistication had
Speaker 1: actually reached a level sufficient to detect any transitting planets
Speaker 1: of Earth like size. So, in other words, if we
Speaker 1: had gone forward with it, we would have built a
Speaker 1: tool that was not up to the task of actually
Speaker 1: doing what was supposed to do, and we would have
Speaker 1: wasted millions of dollars in the process, not something NASA
Speaker 1: could easily afford to do now. Two years later, in
Speaker 1: a team proposed FRESIP again with a space based telescope
Speaker 1: in lagrange orbit, but again a committee determined the price
Speaker 1: would be similar to that of the Hubble, which was
Speaker 1: incredibly expensive and also had been a black eye on
Speaker 1: NASA because when the Hubble launched, it launched with a
Speaker 1: defect that later had to be corrected in space. A
Speaker 1: team had to be sent up to make some tweaks
Speaker 1: to the Hubble. Space telescope so that it would be
Speaker 1: perform more closely to what it was supposed to do
Speaker 1: because one of its mirrors was not right at any rate,
Speaker 1: they didn't want to involve a you know, I didn't
Speaker 1: want to invest in a big time project that was
Speaker 1: unproven um, especially after the Hubble issue, so they rejected
Speaker 1: the proposal. By the way, in case you're wondering what
Speaker 1: a lagrange orbit is, that refers to five specific orbits
Speaker 1: around the Sun. In two of the orbits L one
Speaker 1: and L two, a spacecraft would orbit the Sun either
Speaker 1: just inside the Earth's orbit or just outside the Earth's orbit. So,
Speaker 1: in other words, if you were to look top down,
Speaker 1: you would have a spacecraft that would be just inside
Speaker 1: of the Earth orbit moving at the same speed, or
Speaker 1: one just outside the Earth orbit, moving at the same
Speaker 1: speed as the Earth around the Sun. And you might think, well,
Speaker 1: how is that possible? Because earlier you mentioned if you're
Speaker 1: closer in to the star you move faster, and if
Speaker 1: you're further out from the star, you move slower. So
Speaker 1: how would spacecraft keep up with the Earth. The answer
Speaker 1: is gravity. Earth's gravitational pull would be enough to hold
Speaker 1: the spacecraft in that orbit. That Lagrange orbit, and you
Speaker 1: could do this. You might want to do this for
Speaker 1: lots of reasons. If it's on the inside of the
Speaker 1: Earth's orbit, you could do it to study the Sun
Speaker 1: as it faces Earth. If you did outside the RS orbit,
Speaker 1: you could look away from the Earth out into the
Speaker 1: outer Solar System and not have the Earth in the
Speaker 1: way when you're studying those planets. Um There's also another one.
Speaker 1: L three Lagrange orbit, is on the opposite side of
Speaker 1: the Sun from the Earth, essentially following more or less
Speaker 1: the same orbital path as the Earth. This is a
Speaker 1: great way to see the far side of the Sun
Speaker 1: while the Earth is in its normal location. So if
Speaker 1: you wanted to study the far side of the Sun,
Speaker 1: you could do that and look for solar activity. Then
Speaker 1: there's L four and L five, which are sixty degrees
Speaker 1: separated either before or after the Earth's orbit. But enough
Speaker 1: about that. Those are the Lagrange orbits, the idea being
Speaker 1: that when you play something in there, it tends to
Speaker 1: be pretty stable. But NASA had determined that putting something
Speaker 1: into one of those orbits would be really expensive. Uh
Speaker 1: So eventually they came to the conclusion that perhaps they
Speaker 1: would want to just put the Kepler telescope in an
Speaker 1: orbit around the Sun in its own orbit, not a
Speaker 1: lagrange orbit. Meanwhile, engineers started to experiment with charge coupled
Speaker 1: device sensors to see if they could be made to
Speaker 1: detect tiny changes in light, and lab experiments with c
Speaker 1: c ds proved that they were a pretty good candidate
Speaker 1: for this. So let's talk about c c ds for
Speaker 1: a second. They're designed to move an electrical charge, typically
Speaker 1: in a way that allows a device to convert the
Speaker 1: electrical charge into something else, like a digital value, and
Speaker 1: C c D image sensors are important in digital imaging,
Speaker 1: particularly for highly sensitive imaging, such as with very low
Speaker 1: levels of light. Now you can find digital cameras with
Speaker 1: c c ds, but many also use or rather instead
Speaker 1: they'll use active pixel sensors or the seamost c MOSS
Speaker 1: c m O S sensors. And it used to be
Speaker 1: that there was a noticeable gap in quality, that c
Speaker 1: c D s were demonstrably much higher quality than c
Speaker 1: MOSS sensors. These days, that gap is much more narrow,
Speaker 1: it's not as uh as blatant as it used to be.
Speaker 1: So we've seen the technology of one start to catch
Speaker 1: up to the technology of the other. Within the c
Speaker 1: c D, you have millions of tiny light sensitive squares
Speaker 1: called photo sites, and each photosite corresponds to an individual
Speaker 1: pixel in the final image. It uses the photoelectric effect.
Speaker 1: It turned photons into electrons. That's actually an oversimplification. It
Speaker 1: really uses photons to energize electrons push them into higher
Speaker 1: energy bands, and that is the key to how CCTs work. Essentially,
Speaker 1: photons raise the energy level of electrons from low energy
Speaker 1: valence bands to high energy conduction bands, and each photo
Speaker 1: site has a positively charged capacitor when the photon converts
Speaker 1: that electron when it adds that energy to an electron,
Speaker 1: the electron is then attracted to the positively charged capacitor
Speaker 1: and the number of photons that penetrated the CCD affects
Speaker 1: the voltage that this creates, and that voltage is then
Speaker 1: converted into a digital signal. The whole array is actually
Speaker 1: cooled through a series of heat pipes that run through
Speaker 1: an external radiator, so they're actually rading the heat directly
Speaker 1: out into space. So as this generates heat, they just
Speaker 1: vent that off into space and it keeps the whole
Speaker 1: thing cool enough for it to operate without overheating and
Speaker 1: causing any problems. Now in six two years later. So
Speaker 1: remember this was first proposed in ninety two and rejected,
Speaker 1: ninety four, rejected, nine proposed again, and at this point
Speaker 1: they started to make some changes. One of those was
Speaker 1: decided to put the telescope into a solar orbit rather
Speaker 1: than a lagrange orbit. It was also the point where
Speaker 1: they renamed the project Kepler, after the astronomer we talked
Speaker 1: about earlier. But this proposal was also rejected. This time
Speaker 1: is because no one at that point had proven that
Speaker 1: a telescope could simultaneously observe thousands of stars. One of
Speaker 1: the big selling points of the Kepler telescope is that
Speaker 1: has a very wide field of view and can keep
Speaker 1: an eye on a hundred thousand stars simultaneously. But NASA
Speaker 1: budget oh overseers were saying, no one's proved that you
Speaker 1: could do this yet, so researchers went to work on
Speaker 1: a prototype photometer to prove it could be done. In
Speaker 1: nine seven, they had finished building that prototype photometer and
Speaker 1: in they demonstrated that it could observe six thousand stars
Speaker 1: in a single field of view and generate data that
Speaker 1: could then be analyzed. The results of this project were
Speaker 1: published in a paper in n SO nine, seven years
Speaker 1: after the initial proposal. It's proposed yet again, and it
Speaker 1: got rejected yet again. So why was it rejected this time? Well,
Speaker 1: it was rejected on the grounds that there was no
Speaker 1: evidence the photometer would be precise enough to find Earth
Speaker 1: sized planets that could also operate in orbit in the
Speaker 1: presence of noise. So now the argument was, all right,
Speaker 1: you've shown that it's precise enough to detect a planet,
Speaker 1: but maybe un Earth sized one, because those are particularly small,
Speaker 1: they're not the size of a gas giant. Uh So
Speaker 1: we need to prove that, and we aren't sure that
Speaker 1: if you're in space, you will be able to differentiate
Speaker 1: a planet passing between Earth and its host star or
Speaker 1: just some random piece of space debris that happens to
Speaker 1: pass between a star and Earth, until you can prove
Speaker 1: that we're not giving you any moneys. So the engineers
Speaker 1: built another test bed and they proved that the Kepler
Speaker 1: telescope could operate satisfactorily even within noise, that their analysis
Speaker 1: would be able to differentiate between false positives and the
Speaker 1: real thing. So two thousand rolls around and the Kepler
Speaker 1: gets proposed one more time, and this time it's selected
Speaker 1: as one of three proposals out of a total of
Speaker 1: twenty six to compete ver NASSA approval, So it then
Speaker 1: goes on to compete with the other two projects. And
Speaker 1: essentially this is the way NASA works. They have teams
Speaker 1: proposed different UH potential missions and then they whittle that
Speaker 1: down to a group of finalists and then they say
Speaker 1: fight it out, convince us to fund your project. And
Speaker 1: sometimes only one project gets funded, and that was the
Speaker 1: case for Kepler, and in two thousand one it won
Speaker 1: the right to be funded. It became Discovery Mission number ten.
Speaker 1: So the Kepler Telescope is a discovery spacecraft by that definition.
Speaker 1: The actual work on the mission began in two thousand two,
Speaker 1: and that started with orders placed for the detectors for
Speaker 1: those c c D s and the telescope was completed
Speaker 1: and launched UH and it was launched on March six,
Speaker 1: two thousand nine, and went into space around its solar orbit.
Speaker 1: So here's some stats about the Kepler tell lescope and
Speaker 1: the Kepler spacecraft. The diameter of the photometer is just
Speaker 1: shy of a meter. It's point nine five meters in diameter.
Speaker 1: Which is about three ft. The camera has a ninety
Speaker 1: five megapixel array. So your typical smartphone has an eight
Speaker 1: to maybe thirteen megapixel camera on it. This one is
Speaker 1: a nine five megapixel camera, and it can continuously monitor
Speaker 1: the brightness of more than one hundred thousand stars simultaneously.
Speaker 1: The field of view is thirty three thousand times greater
Speaker 1: than that of the Hubble Space telescope, so it's looking
Speaker 1: at a pretty wide range of space. Keep in mind,
Speaker 1: the Milky Way galaxy has a hundred billion stars in it,
Speaker 1: so a hundred thousand is nothing. It's it's a tiny
Speaker 1: little drop in an enormous bucket. Let's talk about the
Speaker 1: spacecraft though. The Kepler spacecraft is two point seven meters
Speaker 1: in diameter, that's about nine ft. It's four point seven
Speaker 1: meters tall, that's about fifteen point three feet, and it
Speaker 1: weighed one thousand, fifty two point four kilograms or two thousand,
Speaker 1: three hundred twenty point one pounds at the time of launch.
Speaker 1: Why is it just the time of launch, Well, part
Speaker 1: of that weight was taken up by fuel hydrazine propellant,
Speaker 1: which it has used some of since it was launched.
Speaker 1: There was eleven point seven kilograms of fuel at that point,
Speaker 1: so that makes a difference. Also the fact that it's
Speaker 1: in space hard to weigh things in space. You can
Speaker 1: talk about mass, but weight not as relevant. It generates
Speaker 1: electricity with one hundred nine point eight square feet or
Speaker 1: about ten point two square meters of solar panels. Now
Speaker 1: those solar panels can provide one thousand, one hundred watts
Speaker 1: of electrical current. The space cars also has a twenty
Speaker 1: amp hour lithium ion battery that's a rechargeable battery, so
Speaker 1: when it's generating excess electri city, it charges the battery
Speaker 1: and UH and everything can continue to be powered. Once
Speaker 1: it launched, it became part of the Exoplanet Exploration Program Office,
Speaker 1: part of the Jet Propulsion Laboratory, so it's been shifted
Speaker 1: from one group in NASA to another one to actually
Speaker 1: manage the mission. So basically, the way the Kepler works,
Speaker 1: it has more than a hundred thousand stars in its
Speaker 1: view and it can detect these very tiny fluctuations in
Speaker 1: the light from those stars. Typically, up until recently, we
Speaker 1: just had to keep those stars under observation for a
Speaker 1: really long time to see if that fluctuation would repeat
Speaker 1: at regular intervals, and it wasn't just something passing between
Speaker 1: us and the star. And that was how we would
Speaker 1: go from a signal that was a potential planet to
Speaker 1: a verified planet. It also explains why, over the course
Speaker 1: of several years, we were only able to verify n
Speaker 1: exo planets with a whole bunch of candidates that maybe
Speaker 1: or exo planets, but we're not sure, so we can't
Speaker 1: call them that. But then you had this May tenth
Speaker 1: announcement of one thousand two four exo planets. So what changed?
Speaker 1: How could we potentially do that? They actually the researchers
Speaker 1: had analyzed four thousand, three hundred two potential signals, these
Speaker 1: candidate planets, and out of those four thousand, three hundred
Speaker 1: two they decided that one thousand two Night four should
Speaker 1: be verified as actual exo planets because they had a
Speaker 1: greater than certainty that they were in fact planets and
Speaker 1: not some anomaly or impostor as they called them. This
Speaker 1: is pretty phenomenal, right, this is Night the fact that
Speaker 1: they could more than double them. Uh. They also had
Speaker 1: said that there were another one thousand, three hundred seven
Speaker 1: signals that have a better than fifty chance of actually
Speaker 1: being a planet, but those would require more research and
Speaker 1: observation before ASSA would go so far as to say, yeah,
Speaker 1: here are some. These will also join the list of
Speaker 1: verified planets and are very high threshold. To call a
Speaker 1: signal a planet, it had to be greater than certainty.
Speaker 1: So that's pretty incredible, much higher standards than I have.
Speaker 1: I'd be cool with now. As a throwback, the first
Speaker 1: Earth size planet that Kepler telescope found in a potential
Speaker 1: habitable zone, also known as the Goldilocks zone, was Kepler
Speaker 1: one eight six f UH, and the Goldilocks zone that's
Speaker 1: what we think. That's the band of orbits we think
Speaker 1: would be UH would be amenable for life to exist,
Speaker 1: for water to exist in liquid form. The Goldilocks zone
Speaker 1: is dependent upon lots of stuff like the not just
Speaker 1: how close you are to the host star, but how
Speaker 1: old is that host star. You know, if it's an
Speaker 1: older star that's burned out a lot of its energy,
Speaker 1: it's a cooler star. So you have to be closer
Speaker 1: to the to the star in order to get enough
Speaker 1: energy to support life as we know it. So it's
Speaker 1: depend upon a lot of factors. In the case of
Speaker 1: Kepler one six f the host star is older than
Speaker 1: our son, it is more red, and it's cooler. And
Speaker 1: this also means that if there is in fact life
Speaker 1: on Kepler six F, it probably looks different from life
Speaker 1: on our planet. It's receiving a lot of red wavelength
Speaker 1: photons coming in, which could mean that the plants themselves
Speaker 1: might look very different. They might be big red plants
Speaker 1: all over F or it could be a barren waste land.
Speaker 1: We don't know. We have no way of telling yet.
Speaker 1: We can just make some guesses based upon the age
Speaker 1: of the star, the size of the star, the distance
Speaker 1: that we estimate the planet is from that star, those
Speaker 1: sort of things. Those are the kind of things that
Speaker 1: we can kind of start to draw some basic guesses around.
Speaker 1: But there's still guesses until we can develop some other
Speaker 1: means of really looking at these distant planets. Now, out
Speaker 1: of all the one thousand two four planets announced by
Speaker 1: this research team, nine of those are considered potentially habitable,
Speaker 1: meaning that they are relatively the same size as Earth
Speaker 1: or no greater than two times the size of Earth,
Speaker 1: and within their host stars Goldilocks zone. Now, what's really
Speaker 1: cool is to look at how they determined this, Like
Speaker 1: what was the way that they verified these planets and
Speaker 1: they used a probabilistic approach, meaning what is the probability
Speaker 1: that any given signal is in fact a planet? Essentially,
Speaker 1: they were looking at two main factors. How much does
Speaker 1: a single transit signal resemble what we would expect from
Speaker 1: a transitting planet, so does it look like what a
Speaker 1: planet would look like when passing in front of a star.
Speaker 1: And then also what is the likelihood that that particular
Speaker 1: signal could have been caused by an impostor? And you
Speaker 1: take these two ideas into account and you try to
Speaker 1: figure out what is the likelihood that we have and
Speaker 1: a real legitimate hit here. One of the people associated
Speaker 1: with this mission, Timothy Morton, who's an associate research scholar
Speaker 1: at Princeton University, calculate the probability that any given transit
Speaker 1: signal is actually a planet. Uh by using this and
Speaker 1: and essentially you've got numbers between zero and one, and
Speaker 1: only the results that were as close to one as
Speaker 1: possible better than in fact were kept and verified as
Speaker 1: a planet. Now, the big advantage of this approach is
Speaker 1: that it can be applied to many signals simultaneously. Instead
Speaker 1: of having to continuously review the data of a single
Speaker 1: signal and look for those replicable results. You could take
Speaker 1: this approach and apply it across multiple planets all at
Speaker 1: the same time and see which one's come out at
Speaker 1: greater than certainty. Or as Morton said, if you drop
Speaker 1: a few large crumbs on the floor, you can pick
Speaker 1: those up one by one, but if you spell a
Speaker 1: whole bag of tiny crumbs, you're gonna need a broom.
Speaker 1: And the statistical analysis approach is their broom. So we've
Speaker 1: got out of all the different planets found, about five
Speaker 1: fifty of the one hundred and eighty four were announced
Speaker 1: on May, about five fifty of them might be rocky
Speaker 1: planets like Earth, and out of those only nine are
Speaker 1: considered to occupy the habitable zone. And he might think, well,
Speaker 1: that's a really small number. Nine how many were there before?
Speaker 1: The answer was twelve, So there were a dozen discovered
Speaker 1: before this announcement. Nine more added to it, for a
Speaker 1: total of twenty one. There are several others that are
Speaker 1: possible candidates for rocky like planets that could be in
Speaker 1: the Goldilocks zone, but they don't meet that criteria of yet,
Speaker 1: so they have not been verified. There has just been
Speaker 1: twenty one verified planets that are of rocky most likely
Speaker 1: anyway rocky consistency and in that Goldilocks zone. So this
Speaker 1: is also we gotta remember based on that assumption that
Speaker 1: liquid water is ne necessary prerequisite. If it's not, then
Speaker 1: obviously we could be looking at lots of different plants
Speaker 1: that could potentially support life, might not be life that
Speaker 1: we would recognize. However, so the kepler, as awesome as
Speaker 1: it is, cannot detect all the exoplanets orbiting stars. If
Speaker 1: the planet orbit isn't at the right angle from our perspective,
Speaker 1: from the kepler's perspective, it won't detect any dimming. In
Speaker 1: other words, if there's a planet crossing that star, but
Speaker 1: it's at an angle that does not go in front
Speaker 1: of the star from our perspective, the star doesn't dim,
Speaker 1: we don't see any change in that, and the kepler
Speaker 1: can't detect it. So how many plants are actually passing
Speaker 1: at the correct angle for kepler to detect them well.
Speaker 1: The probability of such a thing is determined by the
Speaker 1: diameter of the star divided by the diameter of the orbit,
Speaker 1: which for a planet the size of Earth orbiting a
Speaker 1: star similar to the Sun eventually gives you a point
Speaker 1: five pc chance of detecting that signal. Being at the
Speaker 1: right angle to detect that signal point five half a
Speaker 1: percent chance of detecting the signal in the first place.
Speaker 1: Bigger plants have a better probability because they are more
Speaker 1: likely to at least pass over a star partially to
Speaker 1: you know, they have fewer angles where you won't see
Speaker 1: anything at all, So a much bigger planet like something
Speaker 1: like Jupiter could be closer to a ten pc chance.
Speaker 1: So it's entirely possible, and even probable in fact, that
Speaker 1: what we have detected is just a tiny fraction of
Speaker 1: what is actually out there, even just with the one
Speaker 1: hundred thousand or so stars we've looked at, more like
Speaker 1: a hundred fifty thousand. But even though we've looked at
Speaker 1: a hundred fifty thousand stars and we've detected so many
Speaker 1: of these exoplanets so far, there could be a lot
Speaker 1: more that we just can't see because of the angle.
Speaker 1: And then you take into account we're looking at a
Speaker 1: hundred thousand out of a hundred billion, and the mind
Speaker 1: really starts to boggle. We realize that the frequency of
Speaker 1: planets around other stars is much greater than we anticipated,
Speaker 1: and that we even maybe looking at more planets in
Speaker 1: the Milky Way than there are stars. So if you
Speaker 1: have a hundred billion stars and there's more in a
Speaker 1: hundred billion planets, you think, wow, the odds of you know,
Speaker 1: the chances that there is another planet within our galaxy
Speaker 1: that could potentially support life are pretty good. It may
Speaker 1: not be anywhere close to us. It may be on
Speaker 1: the other side of the Milky Way galaxy from where
Speaker 1: we are, but the chances are pretty good that there's
Speaker 1: at least some other planets within our own galaxy, let
Speaker 1: alone the universe, which is filled with billions of galaxies.
Speaker 1: And suddenly you think, there's no way that we're the
Speaker 1: only life forms in the universe. That's just not statistically plausible.
Speaker 1: Is it possible? Well, I mean, technically I guess so,
Speaker 1: but it's certainly not not plausible. It's more likely that
Speaker 1: there's life on lots of other planets. Whether it's evolved
Speaker 1: life that is intelligent, that's another matter. Whether it's life
Speaker 1: that is anywhere remotely close to us where we would
Speaker 1: ever have an opportunity to discover it through communication, that's
Speaker 1: highly debatable. Uh, it's quite possible that any any life
Speaker 1: that's that advanced is so far away from us that
Speaker 1: we haven't had enough time to pass for any communication
Speaker 1: generated by that civilization to get to us, because I
Speaker 1: remember that stuff has to travel at the speed of light.
Speaker 1: That's as fast as you can go barring some huge
Speaker 1: change in physics, and so if you are thousands of
Speaker 1: light years away, it's going to take thousands of years
Speaker 1: from the generation of a signal for it to get
Speaker 1: to its destination. And by then the milk has gone bad,
Speaker 1: and that shopping list that the aliens gave us is
Speaker 1: not really going to do anyone any good. The party
Speaker 1: is over, but still it's really exciting to think about
Speaker 1: what the Kepler telescope has done. Now, keep in mind
Speaker 1: this is very different from other types of telescopes. There
Speaker 1: are other ways of detecting the potential for exoplanets. One
Speaker 1: of those is to look at stars and look to
Speaker 1: see if they are moving at all, like if there's
Speaker 1: a little jiggle, which could indicate that there is a
Speaker 1: gravitational pull upon that star, and that in turn can
Speaker 1: indicate that there is a planet in orbit around the
Speaker 1: start and the planet's gravitational pull in the star is
Speaker 1: causing it to move just a little bit, and that
Speaker 1: we can detect that. That's another way of detecting at
Speaker 1: least the potential of an exo planet in that star's orbit,
Speaker 1: but it's different obviously from the transit method. And then
Speaker 1: there are ways where we can look at planets to
Speaker 1: try and determine what are they made of, and we
Speaker 1: usually use a spectroscopy for that, where we we take
Speaker 1: the light reflected off of a planet and we analyze
Speaker 1: that light and we break it down into the various wavelengths,
Speaker 1: and then we start to make very educated guesses about
Speaker 1: the types of elements that are present on that particular planet.
Speaker 1: Even so, this is still largely working from very educated guesses,
Speaker 1: uh so educated that you could argue they are they
Speaker 1: are as good as fact, at least in some cases.
Speaker 1: But you have to keep in mind there's still there's
Speaker 1: still a tiny room for error. So that about wraps
Speaker 1: it up for the Kepler Telescope. It has served us well.
Speaker 1: It's primary mission is over um. We will continue to
Speaker 1: look at the data from the Kepler Telescope for many
Speaker 1: more years, but the actual data gathering portion of the
Speaker 1: Kepler's life is over. There are other telescopes that we're
Speaker 1: planning on launching that will continue this work. It will
Speaker 1: either be looking for similar planets to what Kepler was
Speaker 1: looking for or different style planets. But we're just getting started,
Speaker 1: and the hope is that we will eventually be able
Speaker 1: to draw some very firm conclusions about the presence of
Speaker 1: life within our galaxy, and this could just be the
Speaker 1: first step toward that. So while a lot of those
Speaker 1: news outlets were perhaps being a bit optimistic about the
Speaker 1: announcement of the discovery of alien life, it is true
Speaker 1: that this is a step toward making such a discovery,
Speaker 1: and it may be many, many, many more decades before
Speaker 1: we're able to say, yes, we've detected the presence of
Speaker 1: life on another planet. But it's through work like the
Speaker 1: Kepler mission that will get there. So this is a
Speaker 1: really cool science and technology story, and I just wanted
Speaker 1: to touch on that because I loved that announcement. I
Speaker 1: actually listened to it live while they were talking about
Speaker 1: and it was just really cool to hear a group
Speaker 1: of engineers and scientists talk about their life's work with
Speaker 1: such passion. So, guys, if you have suggestions for future
Speaker 1: episodes of Tech Stuff or you've got questions or comments
Speaker 1: or anything like that. Maybe you've got a suggest stution
Speaker 1: for a future guest host or an interview subject. Let
Speaker 1: me know. Send me an email. The address is tech
Speaker 1: stuff at how stuff works dot com, or drop me
Speaker 1: a line on Facebook or Twitter. The handle at both
Speaker 1: of those is tech stuff hs W and I will
Speaker 1: talk to you again really soon. For more on this
Speaker 1: and bousands of other topics. Is it how stuff works
Speaker 1: dot com