WEBVTT - How the Kepler Telescope Works 0:00:04.240 --> 0:00:12.320 Get technology with tech Stuff from dot Com. Hey there, 0:00:12.400 --> 0:00:15.800 and welcome to tech Stuff. I'm your host, Jonathan Strickland, 0:00:16.200 --> 0:00:20.000 and today I want to talk about an awesome spacecraft, 0:00:20.079 --> 0:00:24.000 the Kepler Telescope. I've talked about this on the Forward 0:00:24.000 --> 0:00:26.720 Thinking podcast, so if you've listened to Forward Thinking, you're 0:00:26.720 --> 0:00:29.640 gonna hear some stuff that you've probably heard before. Although 0:00:29.680 --> 0:00:33.520 this is really going to focus pun completely intended, let's 0:00:33.560 --> 0:00:37.320 be honest on just the Kepler Telescope. And the reason 0:00:37.360 --> 0:00:39.559 why I'm doing this in the first place is because 0:00:39.680 --> 0:00:43.960 in May, researchers with the Kepler Mission at NASA held 0:00:43.960 --> 0:00:46.560 a press conference in which they announced the largest number 0:00:46.640 --> 0:00:51.720 of exo planets verified ever at a single event, and 0:00:51.800 --> 0:00:57.280 that was one thousand, two eight four verified exo planets. Previously, 0:00:57.720 --> 0:01:00.480 from two thousand nine, up to that point, the mission 0:01:00.520 --> 0:01:05.440 had identified and verified four planets, so this announcement was 0:01:05.480 --> 0:01:10.679 more than doubling the number of exo planets verified. That's incredible. 0:01:11.400 --> 0:01:13.200 So an exo planet, just in case you don't know, 0:01:13.360 --> 0:01:16.040 is of course a planet that is orbiting another star, 0:01:16.240 --> 0:01:19.880 not the Sun, so it's planets in other star systems, 0:01:19.880 --> 0:01:24.640 solar systems that are light years away from US, and 0:01:25.240 --> 0:01:28.000 it was a really cool thing to hear about all 0:01:28.040 --> 0:01:32.279 these different exo planets that had just been verified. Um, 0:01:32.600 --> 0:01:35.560 what I thought was hilarious was leading up to this 0:01:35.600 --> 0:01:42.480 announcement you had several news outlets that were, uh, guessing 0:01:42.720 --> 0:01:44.720 what was going to happen. It was just it was 0:01:44.760 --> 0:01:48.279 just complete throw stuff against the wall and see what sticks. 0:01:48.320 --> 0:01:50.840 And there were quite a few that had guessed that 0:01:51.000 --> 0:01:55.280 NASA was going to announce that the Kepler mission had 0:01:55.320 --> 0:01:59.480 somehow discovered alien life. Now, once you hear how the 0:01:59.560 --> 0:02:02.200 Kepler telescope works and what it's meant to do, you 0:02:02.240 --> 0:02:06.320 will understand that's really not in the purview of the 0:02:06.400 --> 0:02:09.800 Kepler telescope. It is looking for planets that could potentially 0:02:09.840 --> 0:02:14.600 support life, but it doesn't have the capacity to actually 0:02:14.600 --> 0:02:19.280 detect life on those other planets unless someone sent aliens 0:02:19.280 --> 0:02:22.040 to Earth and they started messing with the Kepler telescope, 0:02:22.040 --> 0:02:24.760 in which case you could say it discovered life, but 0:02:24.840 --> 0:02:28.640 not through its primary mission. That did not happen. As 0:02:28.680 --> 0:02:31.480 far as I know, no aliens have been messing with 0:02:31.480 --> 0:02:37.320 the Kepler telescope. So let's talk about how this telescope 0:02:37.320 --> 0:02:41.600 works and this new verification method that the research team 0:02:41.680 --> 0:02:44.760 used to identify so many exo planets. What was it 0:02:45.240 --> 0:02:48.840 that sped up the process so dramatically as to more 0:02:48.880 --> 0:02:53.360 than double the number of confirmed exoplanets. Plus I'll talk 0:02:53.400 --> 0:02:56.400 a little bit about the new candidates for earthlike plants 0:02:56.440 --> 0:03:00.560 that might be capable of supporting life. So first, let's 0:03:00.560 --> 0:03:05.520 go way back. The Kepler telescope is named after Johann Kepler, 0:03:05.960 --> 0:03:09.720 and astronomer of the late sixteenth and early seventeen centuries. 0:03:10.240 --> 0:03:12.399 That's not the original name of the telescope, by the way, 0:03:12.400 --> 0:03:14.840 but more on that in a little bit. So Johann 0:03:14.919 --> 0:03:18.239 Kepler is most famous for discovering the three major laws 0:03:18.280 --> 0:03:21.280 of planetary motion, although at the time no one called 0:03:21.320 --> 0:03:25.680 them laws. It would take Newton and Newton's observations before 0:03:25.720 --> 0:03:30.080 that really started to become a thing. But law number 0:03:30.120 --> 0:03:33.919 one is that the planets move in elliptical orbits around 0:03:33.960 --> 0:03:36.520 the Sun. Law number two, the time it takes to 0:03:36.600 --> 0:03:40.840 traverse any arc of a planetary orbit is proportional to 0:03:40.880 --> 0:03:44.640 the area of the sector between the central body, for example, 0:03:44.800 --> 0:03:47.760 the Sun and the arc. So you can think of 0:03:47.800 --> 0:03:50.160 the two points along the arc the starting point in 0:03:50.200 --> 0:03:53.560 the endpoint of the arc as your your barriers on 0:03:53.560 --> 0:03:57.600 one side, the Sun being the third point. And what's 0:03:57.640 --> 0:04:00.480 not exactly a triangle because you have a herv line 0:04:00.480 --> 0:04:03.600 on a straight line on the ark side, the area 0:04:03.680 --> 0:04:08.280 within that that is proportional to the time it takes 0:04:08.320 --> 0:04:12.280 to traverse that arc. Essentially, what that tells you is 0:04:12.280 --> 0:04:14.720 that the further out you are from a star, the 0:04:14.760 --> 0:04:18.680 slower your orbit is going to be, and the closer 0:04:18.680 --> 0:04:21.159 and you are to a star, the faster your orbit 0:04:21.240 --> 0:04:24.760 is going to be. Also, there's a relationship between the 0:04:24.839 --> 0:04:28.400 square of a planet's periodic time and the cube of 0:04:28.440 --> 0:04:31.080 the radius of its orbit, which is also known as 0:04:31.120 --> 0:04:35.160 the harmonic law. That's law number three. Now, the Kepler 0:04:35.200 --> 0:04:38.400 mission all started out with a question, which was how 0:04:38.520 --> 0:04:42.560 frequent are other Earth sized planets in our galaxy the 0:04:42.600 --> 0:04:47.320 Milky Way? How common is that? Is the Earth a 0:04:47.440 --> 0:04:51.960 strange outlier that is one in a billion or one 0:04:52.000 --> 0:04:55.560 in ten billion, or or even more rare than that. 0:04:55.600 --> 0:04:59.039 We had no way of knowing. Now that particular space 0:04:59.080 --> 0:05:02.200 based tell us cope, the Kepler telescope tries to answer 0:05:02.240 --> 0:05:05.719 this question by looking for planets using what is called 0:05:05.720 --> 0:05:10.719 the transit method. Now, this method was proposed a few 0:05:10.760 --> 0:05:16.040 times leading up to nineteen one, when Frank Rosenblatt really 0:05:16.839 --> 0:05:20.279 went strong with the idea. He suggested the transit method 0:05:20.320 --> 0:05:24.960 for detecting satellites orbiting other stars. And technically, the way 0:05:25.000 --> 0:05:27.600 this works is that you look at a star and 0:05:27.640 --> 0:05:30.720 you measure the amount of light coming to Earth from 0:05:30.760 --> 0:05:34.000 that star, and you look for any variations and that 0:05:34.120 --> 0:05:38.360 any dimming of that light. Now, if a planet were 0:05:38.480 --> 0:05:42.120 to pass between that star and the Earth, you would 0:05:42.160 --> 0:05:46.359 expect the light from that star to dim a tiny amount, 0:05:47.200 --> 0:05:49.599 and that if you were able to detect that difference, 0:05:50.040 --> 0:05:53.280 and you were able to observe that this happens regularly 0:05:54.040 --> 0:05:56.760 over the course of a given amount of time, you 0:05:56.800 --> 0:05:59.320 could come to the conclusion that what you have seen 0:06:00.080 --> 0:06:03.800 is in fact a planet passing between its host star 0:06:04.080 --> 0:06:07.680 and the Earth. This is what we call transit when 0:06:07.720 --> 0:06:11.799 we see from our perspective a planet crossing its star. 0:06:13.080 --> 0:06:18.000 Now we're looking at the planet making its progress across 0:06:18.040 --> 0:06:21.360 its star in the course of that planet's year. So 0:06:21.480 --> 0:06:24.320 if it's close to the same distance from its host 0:06:24.400 --> 0:06:27.680 star as the Earth is from the Sun, you have 0:06:27.720 --> 0:06:30.960 to wait a long time to verify that that in 0:06:31.040 --> 0:06:34.440 fact is what you saw, especially if you want to 0:06:34.560 --> 0:06:39.480 truly verify it and and get a few periodic uh 0:06:39.640 --> 0:06:43.600 instances of that dimming. And if it has, if it's 0:06:43.640 --> 0:06:47.640 a star that has multiple planets alone that same orbital plane, 0:06:48.120 --> 0:06:51.919 then that's going to cause some confusion too. But by 0:06:51.960 --> 0:06:55.160 by seeing the amount of light that has been dimmed, 0:06:56.200 --> 0:07:00.400 and by detecting how long it takes the this dimming 0:07:00.480 --> 0:07:03.560 to change back to normal, you can start to make 0:07:03.680 --> 0:07:08.640 some conclusions like how big the planet must be, how 0:07:08.720 --> 0:07:11.000 quickly it travels tells you a bit about its orbit. 0:07:11.360 --> 0:07:14.320 It tells you also by that orbit, how close it 0:07:14.360 --> 0:07:16.880 is to its home star. As long as you know 0:07:16.920 --> 0:07:19.280 information about the home star, then you can start to 0:07:19.320 --> 0:07:22.560 make guesses as to how hot the planet is or 0:07:22.600 --> 0:07:26.160 how cold it might be. And this is how you 0:07:26.200 --> 0:07:30.600 start to draw some conclusions about the nature of that planet. 0:07:31.120 --> 0:07:36.040 Ultimately looking for planets that are similar to size, uh 0:07:36.920 --> 0:07:40.120 similar to Earth size, I should say, and similar to 0:07:40.240 --> 0:07:42.560 distance from its host star as the Earth is to 0:07:42.600 --> 0:07:45.400 the Sun. The reason for that is we know that 0:07:46.120 --> 0:07:50.360 if the planet is about two times the size of 0:07:50.360 --> 0:07:53.960 Earth or smaller, it's probably going to have gravity that 0:07:54.160 --> 0:07:59.400 is uh amenable to life as we know it. It's 0:07:59.440 --> 0:08:02.360 gonna probably be a rocky planet as opposed to a 0:08:02.400 --> 0:08:06.320 gas giant. That's also important. It's probably gonna be at 0:08:06.360 --> 0:08:09.640 a temperature that will allow liquid water to be on 0:08:09.680 --> 0:08:12.600 the planet. And since life as we know it depends 0:08:12.680 --> 0:08:16.480 upon the presence of liquid water, that's what we're looking for. 0:08:16.640 --> 0:08:18.800 Keeping in mind that there is the possibility there could 0:08:18.800 --> 0:08:22.560 be life out there in the galaxy that doesn't depend 0:08:22.680 --> 0:08:25.560 upon liquid water. But we have a sample size of 0:08:25.680 --> 0:08:29.240 one planet with life on it, so we have to 0:08:29.320 --> 0:08:32.520 draw our conclusions based upon the limited information we have. 0:08:33.160 --> 0:08:37.400 So assuming that water is in fact necessary for life, 0:08:37.520 --> 0:08:41.640 we need to find other planets that could potentially have 0:08:41.840 --> 0:08:46.520 water on them. So that's kind of guiding the principles 0:08:46.600 --> 0:08:52.800 behind looking for planets through the transit method. But it's 0:08:52.960 --> 0:08:56.960 really really hard to do. Now, let's get back to 0:08:57.080 --> 0:08:59.720 to Frank Rosenblatt for a second. He wasn't just famous 0:08:59.760 --> 0:09:04.200 for suggesting this astronomical approach. He wasn't known as a 0:09:04.240 --> 0:09:08.080 great astronomer. He was actually better known as a leading 0:09:08.160 --> 0:09:12.120 expert in the field of artificial intelligence, particularly in the 0:09:12.240 --> 0:09:18.360 areas of recognizing visual patterns and speech recognition, So that 0:09:18.440 --> 0:09:22.320 was his specific forte. He was really working with computers 0:09:22.360 --> 0:09:26.080 so that they could recognize visual patterns, they could recognize 0:09:26.120 --> 0:09:29.080 when you what you are saying when you talk to them. 0:09:29.120 --> 0:09:32.800 And these are fields that today are really coming into 0:09:32.800 --> 0:09:35.599 their own with stuff like Google's Deep Dream, where it 0:09:35.920 --> 0:09:39.320 starts to recognize patterns even if patterns aren't really in 0:09:39.360 --> 0:09:42.920 the picture. It really enhances that and looks for patterns 0:09:43.200 --> 0:09:46.800 in in the in ways that are really interesting and trippy. 0:09:46.920 --> 0:09:50.200 And speech recognition, which we're all using to some degree 0:09:50.280 --> 0:09:54.240 these days, um often with the personal digital assistance that 0:09:54.280 --> 0:09:57.480 are popping up all over the place. Now here's the problem. 0:09:57.640 --> 0:10:02.680 Rosenblatt's suggested approach as not practical at the time in 0:10:02.720 --> 0:10:07.760 the early seventies. We just lacked the technological sophistication necessary 0:10:07.840 --> 0:10:10.960 to detect and analyze such a very tiny change in 0:10:11.000 --> 0:10:14.920 a star's brightness. If we were looking for an Earth 0:10:15.120 --> 0:10:20.160 sized planet at a distance similar to what Earth is 0:10:20.240 --> 0:10:24.640 from our sun, we're talking about a reduction of one 0:10:24.800 --> 0:10:28.560 ten the brightness of a star, and that dimming lasts 0:10:28.640 --> 0:10:32.800 between two and sixteen hours, so that's not a lot 0:10:32.840 --> 0:10:36.680 of time, and it's certainly not a big difference in brightness. 0:10:36.679 --> 0:10:38.800 You have to have a very sensitive instrument in order 0:10:38.800 --> 0:10:40.560 to be able to pick that up, and that just 0:10:40.600 --> 0:10:44.400 didn't exist in nineteen seventy one. Now, we also have 0:10:44.440 --> 0:10:46.160 to keep in mind that stars tend to be much 0:10:46.280 --> 0:10:49.599 much bigger than planets. For example, the Sun's diameter is 0:10:49.640 --> 0:10:52.160 a hundred and nine times greater than the Earth's diameter, 0:10:52.760 --> 0:10:56.400 and because of that, that's why, with the distances involved 0:10:56.440 --> 0:10:59.360 and the size is involved, it's such a tiny change 0:10:59.360 --> 0:11:02.960 in the brightness of the star. However, NASA began to 0:11:03.000 --> 0:11:05.720 explore how they might be able to use the transit 0:11:05.800 --> 0:11:09.960 method to detect exoplanets in a practical way. Back in 0:11:11.480 --> 0:11:14.640 they were essentially laying out the requirements necessary to detect 0:11:14.640 --> 0:11:18.480 planets with a reasonable amount of confidence. A conference that 0:11:18.520 --> 0:11:22.200 they held on High precision photometry acted as the launching 0:11:22.280 --> 0:11:27.680 ground figuratively speaking for discussions about a space based telescope 0:11:27.720 --> 0:11:31.400 designed to detect a transitting planet. The idea being that 0:11:31.880 --> 0:11:36.120 in space there would be less uh noise in the 0:11:36.280 --> 0:11:40.440 signal to noise ratio you could get it outside the atmosphere. 0:11:40.920 --> 0:11:44.400 The effects of the atmosphere would not be an impediment 0:11:44.559 --> 0:11:47.800 to a space telescope, and it would be more likely 0:11:47.840 --> 0:11:52.479 to pick up something as tiny as this change in brightness. 0:11:53.240 --> 0:11:57.360 So in two NASA proposed new missions to look into 0:11:57.400 --> 0:12:00.559 the possibility of life in our galaxy, and the first 0:12:00.600 --> 0:12:03.640 concept that came up with was called the Frequency of 0:12:03.720 --> 0:12:08.200 Earth Size Inner Planets or FRESIP f R E s 0:12:08.240 --> 0:12:13.319 I P. But that proposal was rejected largely because there 0:12:13.400 --> 0:12:16.240 was doubt at the time that our technological sophistication had 0:12:16.240 --> 0:12:19.840 actually reached a level sufficient to detect any transitting planets 0:12:19.840 --> 0:12:22.920 of Earth like size. So, in other words, if we 0:12:23.000 --> 0:12:25.280 had gone forward with it, we would have built a 0:12:25.320 --> 0:12:28.640 tool that was not up to the task of actually 0:12:28.640 --> 0:12:30.480 doing what was supposed to do, and we would have 0:12:30.520 --> 0:12:34.840 wasted millions of dollars in the process, not something NASA 0:12:34.840 --> 0:12:38.720 could easily afford to do now. Two years later, in 0:12:40.400 --> 0:12:44.880 a team proposed FRESIP again with a space based telescope 0:12:44.920 --> 0:12:48.959 in lagrange orbit, but again a committee determined the price 0:12:49.000 --> 0:12:51.200 would be similar to that of the Hubble, which was 0:12:51.440 --> 0:12:55.880 incredibly expensive and also had been a black eye on 0:12:56.040 --> 0:12:59.440 NASA because when the Hubble launched, it launched with a 0:12:59.520 --> 0:13:03.880 defect that later had to be corrected in space. A 0:13:04.160 --> 0:13:07.440 team had to be sent up to make some tweaks 0:13:07.480 --> 0:13:10.520 to the Hubble. Space telescope so that it would be 0:13:10.640 --> 0:13:13.719 perform more closely to what it was supposed to do 0:13:15.000 --> 0:13:18.920 because one of its mirrors was not right at any rate, 0:13:19.480 --> 0:13:22.880 they didn't want to involve a you know, I didn't 0:13:22.920 --> 0:13:25.200 want to invest in a big time project that was 0:13:25.280 --> 0:13:31.560 unproven um, especially after the Hubble issue, so they rejected 0:13:31.600 --> 0:13:34.240 the proposal. By the way, in case you're wondering what 0:13:34.280 --> 0:13:38.280 a lagrange orbit is, that refers to five specific orbits 0:13:38.320 --> 0:13:41.600 around the Sun. In two of the orbits L one 0:13:41.640 --> 0:13:44.640 and L two, a spacecraft would orbit the Sun either 0:13:44.760 --> 0:13:48.599 just inside the Earth's orbit or just outside the Earth's orbit. So, 0:13:48.640 --> 0:13:50.800 in other words, if you were to look top down, 0:13:51.559 --> 0:13:55.200 you would have a spacecraft that would be just inside 0:13:55.320 --> 0:13:59.080 of the Earth orbit moving at the same speed, or 0:13:59.160 --> 0:14:01.440 one just outside the Earth orbit, moving at the same 0:14:01.440 --> 0:14:04.640 speed as the Earth around the Sun. And you might think, well, 0:14:04.640 --> 0:14:07.040 how is that possible? Because earlier you mentioned if you're 0:14:07.080 --> 0:14:10.840 closer in to the star you move faster, and if 0:14:10.880 --> 0:14:12.800 you're further out from the star, you move slower. So 0:14:12.840 --> 0:14:16.360 how would spacecraft keep up with the Earth. The answer 0:14:16.400 --> 0:14:20.800 is gravity. Earth's gravitational pull would be enough to hold 0:14:20.840 --> 0:14:25.440 the spacecraft in that orbit. That Lagrange orbit, and you 0:14:25.480 --> 0:14:28.000 could do this. You might want to do this for 0:14:28.080 --> 0:14:29.840 lots of reasons. If it's on the inside of the 0:14:29.840 --> 0:14:34.600 Earth's orbit, you could do it to study the Sun 0:14:34.920 --> 0:14:38.840 as it faces Earth. If you did outside the RS orbit, 0:14:38.880 --> 0:14:41.520 you could look away from the Earth out into the 0:14:41.560 --> 0:14:43.760 outer Solar System and not have the Earth in the 0:14:43.760 --> 0:14:48.000 way when you're studying those planets. Um There's also another one. 0:14:48.120 --> 0:14:51.560 L three Lagrange orbit, is on the opposite side of 0:14:51.600 --> 0:14:56.400 the Sun from the Earth, essentially following more or less 0:14:56.400 --> 0:14:59.560 the same orbital path as the Earth. This is a 0:14:59.600 --> 0:15:02.200 great way to see the far side of the Sun 0:15:02.520 --> 0:15:07.360 while the Earth is in its normal location. So if 0:15:07.360 --> 0:15:10.720 you wanted to study the far side of the Sun, 0:15:11.160 --> 0:15:14.440 you could do that and look for solar activity. Then 0:15:14.440 --> 0:15:17.240 there's L four and L five, which are sixty degrees 0:15:17.320 --> 0:15:21.440 separated either before or after the Earth's orbit. But enough 0:15:21.480 --> 0:15:24.000 about that. Those are the Lagrange orbits, the idea being 0:15:24.000 --> 0:15:25.680 that when you play something in there, it tends to 0:15:25.680 --> 0:15:28.800 be pretty stable. But NASA had determined that putting something 0:15:28.880 --> 0:15:32.800 into one of those orbits would be really expensive. Uh 0:15:32.880 --> 0:15:36.400 So eventually they came to the conclusion that perhaps they 0:15:36.400 --> 0:15:39.560 would want to just put the Kepler telescope in an 0:15:39.680 --> 0:15:42.440 orbit around the Sun in its own orbit, not a 0:15:42.520 --> 0:15:47.200 lagrange orbit. Meanwhile, engineers started to experiment with charge coupled 0:15:47.320 --> 0:15:49.600 device sensors to see if they could be made to 0:15:49.680 --> 0:15:53.760 detect tiny changes in light, and lab experiments with c 0:15:53.880 --> 0:15:56.280 c ds proved that they were a pretty good candidate 0:15:56.320 --> 0:15:59.480 for this. So let's talk about c c ds for 0:15:59.520 --> 0:16:03.600 a second. They're designed to move an electrical charge, typically 0:16:03.640 --> 0:16:05.720 in a way that allows a device to convert the 0:16:05.720 --> 0:16:09.400 electrical charge into something else, like a digital value, and 0:16:09.600 --> 0:16:13.440 C c D image sensors are important in digital imaging, 0:16:13.440 --> 0:16:17.280 particularly for highly sensitive imaging, such as with very low 0:16:17.400 --> 0:16:20.160 levels of light. Now you can find digital cameras with 0:16:20.240 --> 0:16:24.160 c c ds, but many also use or rather instead 0:16:24.200 --> 0:16:28.680 they'll use active pixel sensors or the seamost c MOSS 0:16:28.760 --> 0:16:32.280 c m O S sensors. And it used to be 0:16:32.440 --> 0:16:35.200 that there was a noticeable gap in quality, that c 0:16:35.320 --> 0:16:39.240 c D s were demonstrably much higher quality than c 0:16:39.440 --> 0:16:43.520 MOSS sensors. These days, that gap is much more narrow, 0:16:44.080 --> 0:16:47.720 it's not as uh as blatant as it used to be. 0:16:48.680 --> 0:16:51.280 So we've seen the technology of one start to catch 0:16:51.360 --> 0:16:53.880 up to the technology of the other. Within the c 0:16:54.040 --> 0:16:57.720 c D, you have millions of tiny light sensitive squares 0:16:57.800 --> 0:17:02.720 called photo sites, and each photosite corresponds to an individual 0:17:02.800 --> 0:17:07.119 pixel in the final image. It uses the photoelectric effect. 0:17:07.200 --> 0:17:11.760 It turned photons into electrons. That's actually an oversimplification. It 0:17:11.800 --> 0:17:15.800 really uses photons to energize electrons push them into higher 0:17:16.359 --> 0:17:21.600 energy bands, and that is the key to how CCTs work. Essentially, 0:17:21.640 --> 0:17:24.399 photons raise the energy level of electrons from low energy 0:17:24.480 --> 0:17:28.040 valence bands to high energy conduction bands, and each photo 0:17:28.080 --> 0:17:32.359 site has a positively charged capacitor when the photon converts 0:17:32.960 --> 0:17:35.800 that electron when it adds that energy to an electron, 0:17:36.119 --> 0:17:39.280 the electron is then attracted to the positively charged capacitor 0:17:39.840 --> 0:17:43.120 and the number of photons that penetrated the CCD affects 0:17:43.160 --> 0:17:46.959 the voltage that this creates, and that voltage is then 0:17:47.000 --> 0:17:50.919 converted into a digital signal. The whole array is actually 0:17:50.920 --> 0:17:54.439 cooled through a series of heat pipes that run through 0:17:54.480 --> 0:17:58.760 an external radiator, so they're actually rading the heat directly 0:17:58.800 --> 0:18:02.159 out into space. So as this generates heat, they just 0:18:02.440 --> 0:18:04.879 vent that off into space and it keeps the whole 0:18:04.920 --> 0:18:08.040 thing cool enough for it to operate without overheating and 0:18:08.080 --> 0:18:13.879 causing any problems. Now in six two years later. So 0:18:13.960 --> 0:18:17.040 remember this was first proposed in ninety two and rejected, 0:18:17.160 --> 0:18:21.520 ninety four, rejected, nine proposed again, and at this point 0:18:21.520 --> 0:18:23.600 they started to make some changes. One of those was 0:18:24.080 --> 0:18:26.600 decided to put the telescope into a solar orbit rather 0:18:26.680 --> 0:18:29.760 than a lagrange orbit. It was also the point where 0:18:29.760 --> 0:18:33.120 they renamed the project Kepler, after the astronomer we talked 0:18:33.119 --> 0:18:38.000 about earlier. But this proposal was also rejected. This time 0:18:38.440 --> 0:18:40.480 is because no one at that point had proven that 0:18:40.520 --> 0:18:45.359 a telescope could simultaneously observe thousands of stars. One of 0:18:45.400 --> 0:18:47.840 the big selling points of the Kepler telescope is that 0:18:47.920 --> 0:18:51.480 has a very wide field of view and can keep 0:18:51.560 --> 0:18:57.240 an eye on a hundred thousand stars simultaneously. But NASA 0:18:58.600 --> 0:19:02.119 budget oh overseers were saying, no one's proved that you 0:19:02.160 --> 0:19:04.520 could do this yet, so researchers went to work on 0:19:04.520 --> 0:19:08.879 a prototype photometer to prove it could be done. In 0:19:08.960 --> 0:19:12.960 nine seven, they had finished building that prototype photometer and 0:19:12.960 --> 0:19:16.879 in they demonstrated that it could observe six thousand stars 0:19:16.880 --> 0:19:19.080 in a single field of view and generate data that 0:19:19.119 --> 0:19:22.240 could then be analyzed. The results of this project were 0:19:22.280 --> 0:19:28.520 published in a paper in n SO nine, seven years 0:19:28.520 --> 0:19:34.760 after the initial proposal. It's proposed yet again, and it 0:19:34.840 --> 0:19:41.359 got rejected yet again. So why was it rejected this time? Well, 0:19:41.840 --> 0:19:43.719 it was rejected on the grounds that there was no 0:19:43.800 --> 0:19:46.960 evidence the photometer would be precise enough to find Earth 0:19:47.080 --> 0:19:50.399 sized planets that could also operate in orbit in the 0:19:50.400 --> 0:19:55.000 presence of noise. So now the argument was, all right, 0:19:55.200 --> 0:19:59.240 you've shown that it's precise enough to detect a planet, 0:19:59.480 --> 0:20:02.439 but maybe un Earth sized one, because those are particularly small, 0:20:02.480 --> 0:20:06.920 they're not the size of a gas giant. Uh So 0:20:07.040 --> 0:20:09.240 we need to prove that, and we aren't sure that 0:20:09.320 --> 0:20:12.000 if you're in space, you will be able to differentiate 0:20:12.080 --> 0:20:17.800 a planet passing between Earth and its host star or 0:20:18.280 --> 0:20:21.280 just some random piece of space debris that happens to 0:20:21.320 --> 0:20:25.840 pass between a star and Earth, until you can prove 0:20:25.960 --> 0:20:30.119 that we're not giving you any moneys. So the engineers 0:20:30.119 --> 0:20:34.159 built another test bed and they proved that the Kepler 0:20:34.200 --> 0:20:40.040 telescope could operate satisfactorily even within noise, that their analysis 0:20:40.359 --> 0:20:44.480 would be able to differentiate between false positives and the 0:20:44.560 --> 0:20:47.960 real thing. So two thousand rolls around and the Kepler 0:20:48.000 --> 0:20:51.119 gets proposed one more time, and this time it's selected 0:20:51.119 --> 0:20:53.439 as one of three proposals out of a total of 0:20:53.480 --> 0:20:58.280 twenty six to compete ver NASSA approval, So it then 0:20:58.359 --> 0:21:01.480 goes on to compete with the other two projects. And 0:21:01.600 --> 0:21:05.560 essentially this is the way NASA works. They have teams 0:21:05.640 --> 0:21:10.679 proposed different UH potential missions and then they whittle that 0:21:10.800 --> 0:21:14.480 down to a group of finalists and then they say 0:21:14.520 --> 0:21:19.760 fight it out, convince us to fund your project. And 0:21:20.480 --> 0:21:24.040 sometimes only one project gets funded, and that was the 0:21:24.080 --> 0:21:27.359 case for Kepler, and in two thousand one it won 0:21:27.480 --> 0:21:32.440 the right to be funded. It became Discovery Mission number ten. 0:21:33.560 --> 0:21:37.639 So the Kepler Telescope is a discovery spacecraft by that definition. 0:21:38.080 --> 0:21:41.240 The actual work on the mission began in two thousand two, 0:21:41.600 --> 0:21:45.119 and that started with orders placed for the detectors for 0:21:45.240 --> 0:21:49.040 those c c D s and the telescope was completed 0:21:49.240 --> 0:21:52.200 and launched UH and it was launched on March six, 0:21:52.240 --> 0:21:56.919 two thousand nine, and went into space around its solar orbit. 0:21:57.240 --> 0:22:00.600 So here's some stats about the Kepler tell lescope and 0:22:00.640 --> 0:22:04.920 the Kepler spacecraft. The diameter of the photometer is just 0:22:05.119 --> 0:22:08.760 shy of a meter. It's point nine five meters in diameter. 0:22:08.840 --> 0:22:12.679 Which is about three ft. The camera has a ninety 0:22:12.800 --> 0:22:18.760 five megapixel array. So your typical smartphone has an eight 0:22:18.800 --> 0:22:21.840 to maybe thirteen megapixel camera on it. This one is 0:22:21.840 --> 0:22:26.359 a nine five megapixel camera, and it can continuously monitor 0:22:26.440 --> 0:22:30.040 the brightness of more than one hundred thousand stars simultaneously. 0:22:31.720 --> 0:22:34.600 The field of view is thirty three thousand times greater 0:22:34.680 --> 0:22:38.199 than that of the Hubble Space telescope, so it's looking 0:22:38.240 --> 0:22:42.760 at a pretty wide range of space. Keep in mind, 0:22:42.760 --> 0:22:46.600 the Milky Way galaxy has a hundred billion stars in it, 0:22:46.680 --> 0:22:50.640 so a hundred thousand is nothing. It's it's a tiny 0:22:50.720 --> 0:22:54.600 little drop in an enormous bucket. Let's talk about the 0:22:54.600 --> 0:22:57.919 spacecraft though. The Kepler spacecraft is two point seven meters 0:22:57.920 --> 0:23:01.240 in diameter, that's about nine ft. It's four point seven 0:23:01.240 --> 0:23:04.800 meters tall, that's about fifteen point three feet, and it 0:23:04.920 --> 0:23:08.800 weighed one thousand, fifty two point four kilograms or two thousand, 0:23:08.800 --> 0:23:11.840 three hundred twenty point one pounds at the time of launch. 0:23:12.800 --> 0:23:15.680 Why is it just the time of launch, Well, part 0:23:15.680 --> 0:23:19.720 of that weight was taken up by fuel hydrazine propellant, 0:23:20.000 --> 0:23:23.360 which it has used some of since it was launched. 0:23:23.920 --> 0:23:27.760 There was eleven point seven kilograms of fuel at that point, 0:23:27.840 --> 0:23:30.920 so that makes a difference. Also the fact that it's 0:23:30.920 --> 0:23:33.760 in space hard to weigh things in space. You can 0:23:33.800 --> 0:23:39.000 talk about mass, but weight not as relevant. It generates 0:23:39.000 --> 0:23:43.040 electricity with one hundred nine point eight square feet or 0:23:43.040 --> 0:23:47.120 about ten point two square meters of solar panels. Now 0:23:47.160 --> 0:23:50.600 those solar panels can provide one thousand, one hundred watts 0:23:50.720 --> 0:23:54.320 of electrical current. The space cars also has a twenty 0:23:54.400 --> 0:23:58.040 amp hour lithium ion battery that's a rechargeable battery, so 0:23:58.359 --> 0:24:01.800 when it's generating excess electri city, it charges the battery 0:24:02.040 --> 0:24:06.640 and UH and everything can continue to be powered. Once 0:24:06.680 --> 0:24:11.199 it launched, it became part of the Exoplanet Exploration Program Office, 0:24:11.240 --> 0:24:15.160 part of the Jet Propulsion Laboratory, so it's been shifted 0:24:15.200 --> 0:24:18.080 from one group in NASA to another one to actually 0:24:18.160 --> 0:24:22.560 manage the mission. So basically, the way the Kepler works, 0:24:22.640 --> 0:24:24.840 it has more than a hundred thousand stars in its 0:24:24.920 --> 0:24:27.879 view and it can detect these very tiny fluctuations in 0:24:27.880 --> 0:24:32.879 the light from those stars. Typically, up until recently, we 0:24:32.960 --> 0:24:35.600 just had to keep those stars under observation for a 0:24:35.600 --> 0:24:39.080 really long time to see if that fluctuation would repeat 0:24:39.160 --> 0:24:42.840 at regular intervals, and it wasn't just something passing between 0:24:42.960 --> 0:24:46.680 us and the star. And that was how we would 0:24:46.720 --> 0:24:50.639 go from a signal that was a potential planet to 0:24:50.760 --> 0:24:53.600 a verified planet. It also explains why, over the course 0:24:53.600 --> 0:24:56.800 of several years, we were only able to verify n 0:24:57.520 --> 0:25:00.640 exo planets with a whole bunch of candidates that maybe 0:25:00.760 --> 0:25:03.480 or exo planets, but we're not sure, so we can't 0:25:03.520 --> 0:25:06.360 call them that. But then you had this May tenth 0:25:06.400 --> 0:25:10.840 announcement of one thousand two four exo planets. So what changed? 0:25:10.920 --> 0:25:15.680 How could we potentially do that? They actually the researchers 0:25:15.760 --> 0:25:20.000 had analyzed four thousand, three hundred two potential signals, these 0:25:20.040 --> 0:25:23.679