1 00:00:04,120 --> 00:00:07,160 Speaker 1: Get in touch with technology with tech Stuff from how 2 00:00:07,200 --> 00:00:13,800 Speaker 1: stuff works dot com. Hey there, and welcome to tech Stuff. 3 00:00:13,840 --> 00:00:16,439 Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer and 4 00:00:16,480 --> 00:00:20,840 Speaker 1: I love all things tech. And as I record this, 5 00:00:21,040 --> 00:00:24,840 Speaker 1: it is the week of well Halloween in the United States. 6 00:00:25,360 --> 00:00:32,360 Speaker 1: But on October Tuesday of this week eighteen, NASA chose 7 00:00:32,440 --> 00:00:36,680 Speaker 1: to retire the space telescope Kepler, which had been in 8 00:00:36,760 --> 00:00:41,320 Speaker 1: operation not continuously, but had been an operation since two 9 00:00:41,360 --> 00:00:44,239 Speaker 1: thousand nine. I say they retired it. They didn't have 10 00:00:44,320 --> 00:00:46,279 Speaker 1: much choice in the matter. The telescope had run out 11 00:00:46,280 --> 00:00:50,639 Speaker 1: of fuel and could no longer hold its orientation, which 12 00:00:50,720 --> 00:00:53,480 Speaker 1: is pretty important if you are using a telescope, any 13 00:00:53,520 --> 00:00:55,600 Speaker 1: kind of telescope. If you've ever used any sort of 14 00:00:55,640 --> 00:00:58,720 Speaker 1: magnification and you couldn't hold it's steady, you know that 15 00:00:58,800 --> 00:01:02,760 Speaker 1: it's not much use. But this mission was no failure. 16 00:01:03,000 --> 00:01:07,200 Speaker 1: It was actually the conclusion of a monumentally successful scientific mission. 17 00:01:07,720 --> 00:01:11,640 Speaker 1: The Kepler team projected a nominal mission lifetime of three years, 18 00:01:12,200 --> 00:01:15,039 Speaker 1: or maybe three and a half. The actual telescope was 19 00:01:15,080 --> 00:01:18,880 Speaker 1: able to continue its original mission objectives for an additional 20 00:01:19,040 --> 00:01:22,000 Speaker 1: year when it was first launched, and then Stuff started 21 00:01:22,040 --> 00:01:24,600 Speaker 1: breaking down. But I'm getting ahead of myself. So let's 22 00:01:24,600 --> 00:01:28,040 Speaker 1: start with the question what was Kepler's purpose? What was 23 00:01:28,080 --> 00:01:31,399 Speaker 1: it built to do? The simple answer is that it 24 00:01:31,480 --> 00:01:35,039 Speaker 1: was built to search the galaxy for the presence of 25 00:01:35,200 --> 00:01:39,560 Speaker 1: exo planets, in other words, planets outside of our own 26 00:01:39,680 --> 00:01:43,400 Speaker 1: Solar system, and that included looking for Earth like planets. 27 00:01:43,920 --> 00:01:46,640 Speaker 1: Scientists had very little information to go on to make 28 00:01:47,000 --> 00:01:51,120 Speaker 1: conclusions about how many stars out there might have planets. 29 00:01:51,240 --> 00:01:55,600 Speaker 1: Is it common, is it infrequent? You can't really draw 30 00:01:55,640 --> 00:01:58,800 Speaker 1: any other, you know, theories or or make any more 31 00:01:58,880 --> 00:02:03,000 Speaker 1: hypotheses until you get more information about how frequently planets 32 00:02:03,080 --> 00:02:06,760 Speaker 1: are a thing out there. And that's before you get 33 00:02:06,800 --> 00:02:09,680 Speaker 1: to the question of how many planets might be similar 34 00:02:09,720 --> 00:02:14,400 Speaker 1: to Earth, or, even more importantly, in our our grand 35 00:02:14,440 --> 00:02:17,160 Speaker 1: scheme of things, how many of those planets might be 36 00:02:17,240 --> 00:02:20,120 Speaker 1: in an orbit around their respective stars in what we 37 00:02:20,120 --> 00:02:23,800 Speaker 1: would call the h Z or habitable zone. So the 38 00:02:23,840 --> 00:02:28,160 Speaker 1: habitable zone, it's pretty self explanatory. It's the region surrounding 39 00:02:28,160 --> 00:02:32,400 Speaker 1: a star in which water could exist in its liquid 40 00:02:32,440 --> 00:02:35,280 Speaker 1: state if it were on a planet. So there's not 41 00:02:35,320 --> 00:02:38,840 Speaker 1: a single range we can give to describe the habitable zone. Right, 42 00:02:39,000 --> 00:02:43,240 Speaker 1: I can't just tell you it's x many millions of 43 00:02:43,280 --> 00:02:46,760 Speaker 1: miles away, And the reason for that is because there 44 00:02:46,800 --> 00:02:50,520 Speaker 1: are different kinds of stars. So to determine the habitable 45 00:02:50,639 --> 00:02:53,800 Speaker 1: zone of a star, first you have to ask yourself 46 00:02:53,800 --> 00:02:58,239 Speaker 1: the question, is this star old enough that any planets 47 00:02:58,240 --> 00:03:01,000 Speaker 1: that might be orbiting it would have been around long 48 00:03:01,120 --> 00:03:04,880 Speaker 1: enough to have time necessary for life to develop, because 49 00:03:04,919 --> 00:03:07,320 Speaker 1: it would probably take billions of years, So you want 50 00:03:07,320 --> 00:03:10,480 Speaker 1: to make sure that the solar system you're looking at 51 00:03:10,560 --> 00:03:13,440 Speaker 1: is actually old enough for that to have been a possibility. 52 00:03:13,639 --> 00:03:17,000 Speaker 1: On a similar note, the size of the star matters. 53 00:03:17,240 --> 00:03:21,680 Speaker 1: Larger stars have shorter lifespans than smaller stars. Generally speaking, 54 00:03:21,840 --> 00:03:25,239 Speaker 1: that's because stars with greater mass will burn through their 55 00:03:25,280 --> 00:03:29,840 Speaker 1: fuel more quickly than smaller stars. The process of fusion 56 00:03:30,200 --> 00:03:32,720 Speaker 1: will be at a much greater rate for a larger 57 00:03:32,760 --> 00:03:35,120 Speaker 1: star than it is for a smaller star. So if 58 00:03:35,160 --> 00:03:37,640 Speaker 1: you have a really big star, it may only live 59 00:03:37,680 --> 00:03:40,600 Speaker 1: to be a few million years old before it collapses 60 00:03:40,680 --> 00:03:43,200 Speaker 1: and explodes in a supernova. Now I know, a few 61 00:03:43,240 --> 00:03:45,640 Speaker 1: million years it's a long time for humans, but for 62 00:03:45,720 --> 00:03:49,560 Speaker 1: stars most stars, like the smaller ones, that's not long 63 00:03:49,600 --> 00:03:51,880 Speaker 1: at all. A star of the size of our sun 64 00:03:52,360 --> 00:03:56,840 Speaker 1: could stick around for maybe ten billion years the sun. 65 00:03:57,000 --> 00:04:01,480 Speaker 1: Our sun is currently around four point six billion years old, 66 00:04:01,520 --> 00:04:04,240 Speaker 1: so we got a bit. We got a minute or 67 00:04:04,280 --> 00:04:08,560 Speaker 1: two before it burns out, and honestly, before it would 68 00:04:08,560 --> 00:04:10,920 Speaker 1: burn out, there would be other things going on that 69 00:04:11,000 --> 00:04:14,040 Speaker 1: would be of immediate concern to us. But yeah, we 70 00:04:14,160 --> 00:04:17,679 Speaker 1: got billions of years before that happens. So really, big 71 00:04:17,720 --> 00:04:21,120 Speaker 1: stars are not good candidates for finding planets that might 72 00:04:21,160 --> 00:04:23,960 Speaker 1: have life on them, just because they probably haven't been 73 00:04:23,960 --> 00:04:27,960 Speaker 1: around long enough for life to develop. So small stars, well, 74 00:04:28,000 --> 00:04:30,560 Speaker 1: that gets tricky too if the star is too small. 75 00:04:30,720 --> 00:04:34,919 Speaker 1: The habitable zone overlaps a region wherein an orbiting planet 76 00:04:35,000 --> 00:04:40,120 Speaker 1: would be entitled lock with its star. So title lock 77 00:04:40,240 --> 00:04:43,919 Speaker 1: means the same side of the planet would always face 78 00:04:44,000 --> 00:04:47,560 Speaker 1: the star, and the opposite side would always face away 79 00:04:47,720 --> 00:04:49,800 Speaker 1: from the star, So one side of the planet would 80 00:04:49,839 --> 00:04:52,680 Speaker 1: always be bathed in starlight. The other side of the 81 00:04:52,720 --> 00:04:57,480 Speaker 1: planet would always be dark. So the side facing the 82 00:04:57,520 --> 00:05:00,600 Speaker 1: star would be too warm for liquid water or to exist. 83 00:05:00,680 --> 00:05:02,440 Speaker 1: Most likely it would be it would just be too hot, 84 00:05:02,600 --> 00:05:07,320 Speaker 1: it would evaporate out and boil off. There's nothing out 85 00:05:07,320 --> 00:05:10,360 Speaker 1: there to say that water is absolutely necessary for all 86 00:05:10,480 --> 00:05:13,800 Speaker 1: kinds of life. We're going from a sample size of 87 00:05:13,920 --> 00:05:16,520 Speaker 1: one planet that we know of that has life on it, 88 00:05:16,920 --> 00:05:20,839 Speaker 1: So we're having to make a lot of assumptions here 89 00:05:20,920 --> 00:05:25,560 Speaker 1: that could ultimately be wrong. But assuming water is necessary, 90 00:05:26,440 --> 00:05:29,000 Speaker 1: very small stars and very big stars are not really 91 00:05:29,040 --> 00:05:33,680 Speaker 1: good candidates for planets that may support life. Now, there 92 00:05:33,680 --> 00:05:35,760 Speaker 1: are a lot of different ways to classify stars, but 93 00:05:35,839 --> 00:05:40,159 Speaker 1: the modern classification system is called the Morgan Keenan system 94 00:05:40,360 --> 00:05:44,839 Speaker 1: and that divides stars into spectral classes, which sources stars 95 00:05:44,839 --> 00:05:48,680 Speaker 1: into categories based on the spectrum of electromagnetic radiation that 96 00:05:48,720 --> 00:05:52,520 Speaker 1: the star emits. Using something like a prism, you can 97 00:05:52,560 --> 00:05:56,039 Speaker 1: look at this spectrum of visible light. So prisms break 98 00:05:56,120 --> 00:06:00,240 Speaker 1: up visible light into the different colors that you would see. 99 00:06:00,279 --> 00:06:02,840 Speaker 1: You know, you get the visible light coming at you 100 00:06:02,920 --> 00:06:05,440 Speaker 1: use a prism, and then you can actually see uh 101 00:06:05,480 --> 00:06:10,080 Speaker 1: the spectrum, the full spectrum of light. And this kind 102 00:06:10,120 --> 00:06:14,560 Speaker 1: of approach, you would have spectral lines interspersed through a 103 00:06:14,680 --> 00:06:17,200 Speaker 1: range of colors. It would be like little black bars 104 00:06:17,960 --> 00:06:21,760 Speaker 1: that would be throughout the spectrum. In eruptions in the spectrum, 105 00:06:21,760 --> 00:06:24,800 Speaker 1: if you if you will, those lines indicate the abundance 106 00:06:25,120 --> 00:06:29,920 Speaker 1: of certain elements and the type of element will UH 107 00:06:30,160 --> 00:06:32,400 Speaker 1: you can determine what type of element is by where 108 00:06:32,400 --> 00:06:36,839 Speaker 1: on the spectrum. Those spectral lines are mostly However, the 109 00:06:36,880 --> 00:06:41,039 Speaker 1: spectral lines correspond with the stars surface temperature, and the 110 00:06:41,040 --> 00:06:45,520 Speaker 1: classification of stars from hottest to coolest goes like this, 111 00:06:46,040 --> 00:06:51,880 Speaker 1: oh B A, F G K, M. Some people use 112 00:06:51,920 --> 00:06:55,280 Speaker 1: a handy mnemonic device to remember that, like, oh be 113 00:06:55,440 --> 00:07:00,599 Speaker 1: a fine guy, kiss me kind of sweet. If you 114 00:07:00,640 --> 00:07:03,599 Speaker 1: think about it, oh BI and A stars typically burn 115 00:07:03,680 --> 00:07:05,920 Speaker 1: out before the time we would expect it would take 116 00:07:05,960 --> 00:07:08,880 Speaker 1: for life to develop on orbiting planets, So those are 117 00:07:09,320 --> 00:07:13,360 Speaker 1: your larger, hotter stars. That leaves us with F, G, K, 118 00:07:13,800 --> 00:07:18,640 Speaker 1: and M stars as candidates for stars that might host 119 00:07:18,720 --> 00:07:23,600 Speaker 1: planets that could potentially support life. For low mass cooler stars, 120 00:07:23,880 --> 00:07:27,200 Speaker 1: the habitable zone will be closer in than if the 121 00:07:27,240 --> 00:07:30,120 Speaker 1: star were larger and hotter. So, in other words, you 122 00:07:30,160 --> 00:07:35,600 Speaker 1: have to have that perfect temperature or range of temperatures 123 00:07:35,720 --> 00:07:38,640 Speaker 1: for water to exist in liquid form on the surface 124 00:07:38,640 --> 00:07:41,200 Speaker 1: of the planet. So if a planet is too close 125 00:07:41,240 --> 00:07:43,800 Speaker 1: to its star, it's possibly going to be tidally locked, 126 00:07:43,800 --> 00:07:45,960 Speaker 1: and it's also gonna be too hot. If it's too 127 00:07:45,960 --> 00:07:48,640 Speaker 1: far away, it's going to be too cold. So a 128 00:07:48,720 --> 00:07:51,600 Speaker 1: planet must be in orbit around its respective star in 129 00:07:51,680 --> 00:07:54,560 Speaker 1: such a way that it is not in title lock. 130 00:07:54,960 --> 00:07:58,120 Speaker 1: It's not too close, it's not too far, it's not 131 00:07:58,240 --> 00:08:00,760 Speaker 1: too hot, it's not too cold. And for that reason 132 00:08:00,800 --> 00:08:03,400 Speaker 1: a lot of people have also started calling the habitable 133 00:08:03,480 --> 00:08:09,760 Speaker 1: zone the Goldilocks zone because it's just right. Okay, So 134 00:08:09,800 --> 00:08:13,360 Speaker 1: we have some ideas about planets that could in theory 135 00:08:13,400 --> 00:08:16,720 Speaker 1: support life if they fell into the habitable zone. It 136 00:08:16,800 --> 00:08:18,880 Speaker 1: doesn't mean that they definitely have life on them. We 137 00:08:18,960 --> 00:08:22,320 Speaker 1: cannot make that determination. All we could say is, well, 138 00:08:22,600 --> 00:08:25,480 Speaker 1: in theory, water could exist on that planet, and that's 139 00:08:25,520 --> 00:08:27,880 Speaker 1: the best we can say. So that's one thing, But 140 00:08:27,960 --> 00:08:31,000 Speaker 1: detecting planets in the first place is actually something else. 141 00:08:31,040 --> 00:08:33,440 Speaker 1: Just because we could say, in theory, if a planet 142 00:08:33,440 --> 00:08:36,440 Speaker 1: were to exist within this band of ranges around its star, 143 00:08:36,840 --> 00:08:39,000 Speaker 1: it might be able to support life, doesn't mean we've 144 00:08:39,000 --> 00:08:42,760 Speaker 1: actually found any planets, right. We have to figure out 145 00:08:42,800 --> 00:08:45,720 Speaker 1: how to do that. So we have really powerful telescopes 146 00:08:45,760 --> 00:08:48,959 Speaker 1: here on Earth, but that's not really gonna cut it. 147 00:08:49,559 --> 00:08:53,240 Speaker 1: Even with a telescope that has an enormous aperture several 148 00:08:53,280 --> 00:08:56,760 Speaker 1: meters across, the conditions are such that we're not going 149 00:08:56,800 --> 00:08:59,680 Speaker 1: to be able to directly image planets. They're just the 150 00:08:59,679 --> 00:09:03,040 Speaker 1: star are too far away. The distance between us and 151 00:09:03,120 --> 00:09:09,040 Speaker 1: nearby stars is enormous light years, and comparatively speaking, the 152 00:09:09,120 --> 00:09:12,800 Speaker 1: distance between a planet and its host star is nothing 153 00:09:12,840 --> 00:09:16,000 Speaker 1: at all. Right, a few million miles is nothing compared 154 00:09:16,040 --> 00:09:19,200 Speaker 1: to light years. So the light reflecting off a planet 155 00:09:19,559 --> 00:09:23,920 Speaker 1: would also be much much, much much less bright than 156 00:09:23,960 --> 00:09:26,520 Speaker 1: the light coming off of a star, like maybe a 157 00:09:26,559 --> 00:09:30,600 Speaker 1: billion times less bright. So if we're looking at a 158 00:09:30,640 --> 00:09:34,680 Speaker 1: star of comparable size and brightness to our Sun, then 159 00:09:34,720 --> 00:09:38,120 Speaker 1: the planet that orbits it it will end up reflecting 160 00:09:38,160 --> 00:09:40,400 Speaker 1: some light off of it, but it will be a 161 00:09:40,480 --> 00:09:43,000 Speaker 1: tiny fraction of the light that's coming from the Sun. 162 00:09:43,080 --> 00:09:46,800 Speaker 1: So our earth based telescopes would blur this light together 163 00:09:46,880 --> 00:09:49,320 Speaker 1: due to diffraction, and we wouldn't really be able to 164 00:09:49,320 --> 00:09:52,280 Speaker 1: tell the difference. We wouldn't be able to distinguish the 165 00:09:52,360 --> 00:09:56,280 Speaker 1: planet from the star, so direct observation with Earth based 166 00:09:56,280 --> 00:10:01,520 Speaker 1: telescopes is a non starter. However, we could look at 167 00:10:01,559 --> 00:10:04,560 Speaker 1: indirect ways to observe the presence of a planet or 168 00:10:04,600 --> 00:10:09,520 Speaker 1: to uh too, guess whether or not a planet is there. 169 00:10:10,600 --> 00:10:13,560 Speaker 1: So stars have a gravitational poll on their planets, but 170 00:10:13,640 --> 00:10:17,720 Speaker 1: planets also exert a gravitational poll on their host stars, 171 00:10:18,040 --> 00:10:20,800 Speaker 1: and as planets move through their orbits around the star, 172 00:10:21,080 --> 00:10:24,960 Speaker 1: they caused the star to wobble a little bit. The 173 00:10:25,000 --> 00:10:30,680 Speaker 1: center of this gravitational poll is likely within the the 174 00:10:31,080 --> 00:10:34,320 Speaker 1: diameter of the star itself, but it's not right at 175 00:10:34,320 --> 00:10:36,160 Speaker 1: the center of the star. So the star kind of 176 00:10:36,200 --> 00:10:39,600 Speaker 1: wiggles a little bit as the planets orbit around it. 177 00:10:40,440 --> 00:10:44,320 Speaker 1: So if you are able to detect this wobble, if 178 00:10:44,320 --> 00:10:48,400 Speaker 1: you're able to see it, then you could uh then 179 00:10:48,480 --> 00:10:52,120 Speaker 1: deduce that there's something in orbit around that star. We've 180 00:10:52,200 --> 00:10:56,440 Speaker 1: used this methodology to detect binary stars that were too 181 00:10:56,440 --> 00:10:59,679 Speaker 1: close together for our Earth based telescopes to differentiate between 182 00:10:59,720 --> 00:11:03,760 Speaker 1: the too. We call this the astrometric method of detecting 183 00:11:04,040 --> 00:11:08,880 Speaker 1: binary stars. But planets are much smaller than stars, so 184 00:11:09,120 --> 00:11:12,800 Speaker 1: the wobbles that are produced by planets are much smaller 185 00:11:12,840 --> 00:11:17,200 Speaker 1: than would be produced by binary star systems AUH. It 186 00:11:17,320 --> 00:11:20,880 Speaker 1: is the oldest methodology for searching for exoplanets, but for 187 00:11:20,960 --> 00:11:24,160 Speaker 1: many years no one could confirm that any wobbles they 188 00:11:24,160 --> 00:11:26,800 Speaker 1: were seeing actually meant there were planets in orbit around 189 00:11:26,800 --> 00:11:30,200 Speaker 1: those stars. That changed in the era of space telescopes. 190 00:11:30,280 --> 00:11:32,480 Speaker 1: That changed in the era of more advanced telescopes in 191 00:11:32,520 --> 00:11:36,000 Speaker 1: the nineties, but let's set that aside for now. The 192 00:11:36,080 --> 00:11:40,200 Speaker 1: Kepler telescope would be powerful enough to use an alternative 193 00:11:40,240 --> 00:11:43,760 Speaker 1: method to detect exo planets. This is the so called 194 00:11:44,120 --> 00:11:48,199 Speaker 1: transit method, and the transit method looks for indications that 195 00:11:48,280 --> 00:11:53,000 Speaker 1: a planet is moving between a star and Earth. That is, 196 00:11:53,080 --> 00:11:56,880 Speaker 1: it is transitting across the face of the star from 197 00:11:57,000 --> 00:12:00,240 Speaker 1: our perspective. Now, we would detect this by measure ring 198 00:12:00,400 --> 00:12:04,040 Speaker 1: the amount of light coming from the star. The planet 199 00:12:04,040 --> 00:12:06,200 Speaker 1: would still be too far away and too small for 200 00:12:06,280 --> 00:12:08,240 Speaker 1: us to see. It's not like we would see a 201 00:12:08,320 --> 00:12:11,920 Speaker 1: tiny black dot moving across the star. But what we 202 00:12:11,960 --> 00:12:14,880 Speaker 1: could do is measure exactly how much light are we 203 00:12:15,000 --> 00:12:18,000 Speaker 1: receiving from that star. And if we noticed that there 204 00:12:18,080 --> 00:12:21,040 Speaker 1: was a dip in the intensity of that light, it 205 00:12:21,040 --> 00:12:25,400 Speaker 1: would indicate that something had passed between the star and us, 206 00:12:25,880 --> 00:12:29,040 Speaker 1: that something had blocked some of that light from getting 207 00:12:29,120 --> 00:12:32,760 Speaker 1: at us. A dip that happens with regularity would indicate 208 00:12:32,800 --> 00:12:35,520 Speaker 1: that there is a planet in orbit around that star. 209 00:12:35,880 --> 00:12:40,280 Speaker 1: That if we're seeing every so often that little dip happened, 210 00:12:40,720 --> 00:12:42,720 Speaker 1: it would tell us, all right, there's something that's orbiting 211 00:12:42,720 --> 00:12:45,079 Speaker 1: the star. And every time it comes across, that's when 212 00:12:45,120 --> 00:12:48,240 Speaker 1: we see the dip, and that's why there's this gap 213 00:12:48,600 --> 00:12:52,959 Speaker 1: between dips. If it's regular, that is, if it were irregular, 214 00:12:53,120 --> 00:12:55,400 Speaker 1: we wouldn't necessarily know what the heck is going on, 215 00:12:55,600 --> 00:12:59,200 Speaker 1: unless maybe it was multiple planets that were in orbit 216 00:12:59,280 --> 00:13:04,040 Speaker 1: around the star. It would, however, require a very powerful 217 00:13:04,200 --> 00:13:07,000 Speaker 1: and very precise telescope, and not only that, it would 218 00:13:07,000 --> 00:13:10,400 Speaker 1: also require the planet's orbit around its star to be 219 00:13:10,440 --> 00:13:12,600 Speaker 1: in an alignment so it would actually pass between the 220 00:13:12,600 --> 00:13:14,480 Speaker 1: star and us. In other words, it would need to 221 00:13:14,480 --> 00:13:17,880 Speaker 1: be at the right angle. So if the orbit was 222 00:13:17,920 --> 00:13:21,520 Speaker 1: at a tilt from our perspective, if it were orbiting 223 00:13:21,520 --> 00:13:24,600 Speaker 1: its star, but in such a way that its pathway 224 00:13:24,640 --> 00:13:27,560 Speaker 1: did not cross between us and the star, we wouldn't 225 00:13:27,600 --> 00:13:31,840 Speaker 1: see any indication of it because the light woulden't dim, 226 00:13:31,880 --> 00:13:34,599 Speaker 1: you know, the light would still be coming straight at us. 227 00:13:34,600 --> 00:13:37,600 Speaker 1: So it requires a couple of different things for for 228 00:13:37,720 --> 00:13:40,360 Speaker 1: us to even pick it up. NASA started looking into 229 00:13:40,400 --> 00:13:43,240 Speaker 1: the possibility of using the transit method to detect planets 230 00:13:43,280 --> 00:13:45,840 Speaker 1: in the nineteen eighties, and one early step was a 231 00:13:45,840 --> 00:13:50,520 Speaker 1: workshop at the NASA Aims Research Center in high precision photometry. 232 00:13:50,880 --> 00:13:55,319 Speaker 1: Photometry is the science of the measurement of intensity of light. 233 00:13:55,679 --> 00:13:57,520 Speaker 1: That's what I was talking about earlier, about measuring how 234 00:13:57,600 --> 00:14:01,040 Speaker 1: much light is coming to you. That's using photometry. That 235 00:14:01,120 --> 00:14:04,440 Speaker 1: science has been around for a bit. And you know, 236 00:14:04,480 --> 00:14:06,760 Speaker 1: it's obvious that not everything that emits light does so 237 00:14:06,880 --> 00:14:10,360 Speaker 1: at the same intensity. Right, Some things are brighter than others, 238 00:14:10,400 --> 00:14:13,600 Speaker 1: some things are dimmer than others. Light isn't just on 239 00:14:13,960 --> 00:14:19,000 Speaker 1: or off. There's a magnitude associated with it. Quantifying magnitude 240 00:14:19,840 --> 00:14:23,440 Speaker 1: was really tricky. I have more to say about photometry 241 00:14:23,560 --> 00:14:25,880 Speaker 1: and its history in just a second, but first let's 242 00:14:25,880 --> 00:14:36,120 Speaker 1: take a quick break to thank our sponsor. Okay, we're 243 00:14:36,200 --> 00:14:38,080 Speaker 1: back now. One day I'm going to have to do 244 00:14:38,240 --> 00:14:42,520 Speaker 1: a full episode about photometry. The history of photometry is fascinating. 245 00:14:42,560 --> 00:14:44,400 Speaker 1: It actually it dates all the way back to the 246 00:14:44,400 --> 00:14:48,200 Speaker 1: ancient Greeks and Romans. But obviously, by the time we're 247 00:14:48,200 --> 00:14:51,960 Speaker 1: talking about the the events that would lead into the 248 00:14:51,960 --> 00:14:54,760 Speaker 1: development of the Kepler telescope, NASA was looking into something 249 00:14:54,760 --> 00:14:57,440 Speaker 1: a little more sophisticated than what the ancients were capable 250 00:14:57,440 --> 00:15:02,640 Speaker 1: of doing. Now, during the workshop on photometry, the group 251 00:15:02,760 --> 00:15:06,960 Speaker 1: had several goals they wanted to achieve. One was determine 252 00:15:07,040 --> 00:15:12,440 Speaker 1: which astronomical problems would benefit by increased photometric precision. So 253 00:15:13,320 --> 00:15:16,200 Speaker 1: we've got this technology, if we make it better, what 254 00:15:16,360 --> 00:15:18,520 Speaker 1: could we use it to do? What would it be 255 00:15:18,600 --> 00:15:21,440 Speaker 1: good for? Another was to get a handle on what 256 00:15:21,600 --> 00:15:25,200 Speaker 1: the current level of precision was with the latest equipment, 257 00:15:25,280 --> 00:15:27,720 Speaker 1: So not just what would it be good for if 258 00:15:27,760 --> 00:15:30,080 Speaker 1: we made it better, but how good is it right now? 259 00:15:31,000 --> 00:15:33,760 Speaker 1: Another goal was to identify any of the things that 260 00:15:33,760 --> 00:15:37,480 Speaker 1: would limit the precision of photometry, so what stands in 261 00:15:37,520 --> 00:15:40,920 Speaker 1: our way of making this technology better? And finally, the 262 00:15:41,000 --> 00:15:44,200 Speaker 1: last goal was to make recommendations to overcome or sidestep 263 00:15:44,400 --> 00:15:48,320 Speaker 1: any of those limitations. The workshop was considered a success, 264 00:15:48,520 --> 00:15:51,400 Speaker 1: and that led to a second workshop that was held 265 00:15:51,440 --> 00:15:56,000 Speaker 1: in NASA Commission to study to determine if a multi 266 00:15:56,120 --> 00:16:01,520 Speaker 1: channel photometer built on silicon photo diodes would be practical, 267 00:16:02,040 --> 00:16:05,480 Speaker 1: and the researchers found that such photometers were incredibly precise, 268 00:16:06,040 --> 00:16:08,400 Speaker 1: but they would also have to be super cooled down 269 00:16:08,400 --> 00:16:12,640 Speaker 1: to less than negative one degrees celsius or negative three 270 00:16:13,360 --> 00:16:17,800 Speaker 1: degrees fahrenheit, the temperature of liquid nitrogen. In other words, Now, 271 00:16:17,840 --> 00:16:20,280 Speaker 1: since I'm gonna do an episode about photometry in the future, 272 00:16:20,280 --> 00:16:23,000 Speaker 1: I'm going to skip a deep explanation of how those 273 00:16:23,000 --> 00:16:26,280 Speaker 1: devices work for now. Just know that they are all 274 00:16:26,320 --> 00:16:33,280 Speaker 1: about quantifying the intensity of light that is hitting them. 275 00:16:33,520 --> 00:16:36,440 Speaker 1: So let's go back to our history lesson leading up 276 00:16:36,480 --> 00:16:41,040 Speaker 1: to the Kepler telescope. In the early NASA officials were 277 00:16:41,080 --> 00:16:44,880 Speaker 1: considering a suite of new missions for the organization to pursue. 278 00:16:45,240 --> 00:16:47,520 Speaker 1: Some of them were aimed at getting a more comprehensive 279 00:16:47,600 --> 00:16:50,960 Speaker 1: understanding of our own Solar system, but some were meant 280 00:16:50,960 --> 00:16:54,840 Speaker 1: to search for planets outside of our immediate neighborhood. One 281 00:16:54,840 --> 00:16:58,600 Speaker 1: of those proposed missions got the name free SIP or 282 00:16:58,840 --> 00:17:02,480 Speaker 1: f R E s I P, which stood for Frequency 283 00:17:02,640 --> 00:17:07,040 Speaker 1: of Earth size Inner Planets. Like all the proposed missions, 284 00:17:07,359 --> 00:17:10,760 Speaker 1: the team had to outline the scientific and technical requirements 285 00:17:10,800 --> 00:17:13,520 Speaker 1: to complete mission objectives, as well as how much they 286 00:17:13,640 --> 00:17:17,800 Speaker 1: estimated it would cost, and a proposed schedule and management plan. 287 00:17:18,800 --> 00:17:21,520 Speaker 1: Free SIP would land on the chopping block. It would 288 00:17:21,520 --> 00:17:24,760 Speaker 1: not make it through in that initial round, and in 289 00:17:24,840 --> 00:17:28,360 Speaker 1: nine two there just wasn't sufficient evidence that the technical 290 00:17:28,400 --> 00:17:31,400 Speaker 1: equipment would be sensitive enough to pick up the transit 291 00:17:31,440 --> 00:17:34,159 Speaker 1: of a distant planet and yet also be able to 292 00:17:34,200 --> 00:17:37,960 Speaker 1: filter out noise. So what NASA HQ was saying was 293 00:17:38,680 --> 00:17:41,320 Speaker 1: this is it's not that your idea doesn't have merit, 294 00:17:41,359 --> 00:17:43,960 Speaker 1: it's that we cannot be certain that the equipment you 295 00:17:44,000 --> 00:17:46,920 Speaker 1: would use would actually achieve the goals, and we don't 296 00:17:46,960 --> 00:17:49,520 Speaker 1: want to spend millions of dollars on something that ultimately 297 00:17:49,560 --> 00:17:53,200 Speaker 1: doesn't work. The scientific community still felt that the objective 298 00:17:53,280 --> 00:17:58,000 Speaker 1: was worth pursuing, so in nineteen scientists organized another workshop 299 00:17:58,200 --> 00:18:02,119 Speaker 1: called Astrophysical Science with a space born photometric telescope in 300 00:18:02,240 --> 00:18:07,040 Speaker 1: mountain View, California. More specifically, not just mountain View, California, 301 00:18:07,280 --> 00:18:11,080 Speaker 1: this event took place at SETI Headquarters cet IS the 302 00:18:11,160 --> 00:18:16,919 Speaker 1: Search for Extra Terrestrial Intelligence. Also in NASA announced the 303 00:18:16,920 --> 00:18:21,280 Speaker 1: initiation of Discovery class missions. Now that's a category of 304 00:18:21,320 --> 00:18:24,440 Speaker 1: missions that are supposed to be complementary to the larger 305 00:18:24,600 --> 00:18:27,879 Speaker 1: missions that NASA pursus. So these are supposed to be 306 00:18:27,920 --> 00:18:32,600 Speaker 1: smaller and therefore also less expensive than the bigger missions. 307 00:18:33,320 --> 00:18:37,240 Speaker 1: The Frecept team would resubmit their proposal as a Discovery 308 00:18:37,280 --> 00:18:41,280 Speaker 1: class mission, but then NASA ultimately rejected that second attempt, 309 00:18:41,960 --> 00:18:44,359 Speaker 1: and the reason they gave was that they felt that 310 00:18:44,400 --> 00:18:47,960 Speaker 1: the mission as described would be too expensive to qualify 311 00:18:48,080 --> 00:18:52,560 Speaker 1: as a Discovery class mission. In a team of scientists 312 00:18:52,600 --> 00:18:55,919 Speaker 1: at the University of Geneva announced that they had discovered 313 00:18:55,960 --> 00:19:00,080 Speaker 1: an exo planet in the constellation Pegasus. This exo and 314 00:19:00,119 --> 00:19:04,680 Speaker 1: it got the designation fifty one pegasie B. The team 315 00:19:04,760 --> 00:19:08,960 Speaker 1: had used the so called Wobble method radial velocity method 316 00:19:09,160 --> 00:19:12,840 Speaker 1: to detect this planet, and that helped fuel interest in 317 00:19:12,840 --> 00:19:17,960 Speaker 1: the search for more exoplanets in the free SIP team 318 00:19:17,960 --> 00:19:21,640 Speaker 1: had yet another chance to propose a flight mission, and 319 00:19:21,720 --> 00:19:24,800 Speaker 1: this time they made a really big adjustment to their proposal. 320 00:19:24,840 --> 00:19:28,200 Speaker 1: Actually they made two big adjustments. It's just that one 321 00:19:28,240 --> 00:19:32,639 Speaker 1: of them was perhaps more important and more key to 322 00:19:32,880 --> 00:19:36,560 Speaker 1: getting approval, and that was changing the parameters of the mission. 323 00:19:36,840 --> 00:19:41,080 Speaker 1: The original proposal required putting a spacecraft in a lagrange orbit. 324 00:19:41,320 --> 00:19:44,440 Speaker 1: Now that's a position in space where the combined gravitational 325 00:19:44,480 --> 00:19:48,199 Speaker 1: forces of two large bodies equal the centrivigal force of 326 00:19:48,240 --> 00:19:52,600 Speaker 1: a body that's in that position between the two or 327 00:19:52,640 --> 00:19:55,320 Speaker 1: around the two. So the two large bodies in the 328 00:19:55,359 --> 00:19:58,400 Speaker 1: case that we care about are the Earth and the Sun. 329 00:19:59,080 --> 00:20:03,440 Speaker 1: So there are five lagrange points that are in that 330 00:20:03,560 --> 00:20:08,320 Speaker 1: vicinity around the Sun and Earth. They have designations that 331 00:20:08,400 --> 00:20:11,480 Speaker 1: go from L one up to L five, So L 332 00:20:11,560 --> 00:20:15,879 Speaker 1: one lagrange orbit is at a point between Earth and 333 00:20:15,920 --> 00:20:18,679 Speaker 1: the Sun. It's much closer to the Earth than the 334 00:20:18,720 --> 00:20:22,760 Speaker 1: Sun because gravity depends upon mass and distance, and the 335 00:20:22,800 --> 00:20:25,919 Speaker 1: Earth is much less massive than the Sun, so you 336 00:20:25,920 --> 00:20:27,760 Speaker 1: need to get closer if you want to have all 337 00:20:27,800 --> 00:20:30,680 Speaker 1: that stuff kind of balance out. L two is actually 338 00:20:30,760 --> 00:20:34,520 Speaker 1: located behind Earth with respect to the Sun, so in 339 00:20:34,520 --> 00:20:39,080 Speaker 1: an orbit that's uh, that's further out from the Sun 340 00:20:39,200 --> 00:20:42,080 Speaker 1: than Earth is. L three is actually on the opposite 341 00:20:42,160 --> 00:20:45,520 Speaker 1: side of the Sun from where the Earth is. L 342 00:20:45,600 --> 00:20:48,119 Speaker 1: four and L five are in effect at an orbit 343 00:20:48,200 --> 00:20:52,640 Speaker 1: sixty degrees ahead and sixty degrees behind the Earth, respectively. 344 00:20:52,840 --> 00:20:56,760 Speaker 1: In its orbit. Now, a satellite at L one would 345 00:20:56,800 --> 00:20:59,880 Speaker 1: have an unobstructed view of the Sun, and that's why 346 00:20:59,880 --> 00:21:03,640 Speaker 1: we put the solar in Heliospheric Observatory there. A satellite 347 00:21:03,640 --> 00:21:06,400 Speaker 1: at ALL two would have a view of deep space, 348 00:21:06,520 --> 00:21:08,760 Speaker 1: and it would be shaded from the Sun because it 349 00:21:08,760 --> 00:21:10,879 Speaker 1: would be in the shadow of Earth. That's where the 350 00:21:10,960 --> 00:21:15,520 Speaker 1: James Webb Space Telescope will eventually be. These orbits require 351 00:21:15,560 --> 00:21:18,760 Speaker 1: a lot of adjustments to keep a satellite stable, otherwise 352 00:21:18,760 --> 00:21:21,040 Speaker 1: they would drift out of orbit and move into a 353 00:21:21,040 --> 00:21:25,280 Speaker 1: collision course with a celestial body like the Sun, for example, 354 00:21:25,760 --> 00:21:28,240 Speaker 1: Moving a telescope into one of those orbits and keeping 355 00:21:28,240 --> 00:21:30,800 Speaker 1: it there would have required a lot more fuel and 356 00:21:30,880 --> 00:21:34,879 Speaker 1: thus added expense to the mission. So this new proposal 357 00:21:35,240 --> 00:21:39,560 Speaker 1: for what was originally called Free SIP suggested putting the 358 00:21:39,560 --> 00:21:42,960 Speaker 1: telescope in a normal solar or orbit rather than on 359 00:21:43,040 --> 00:21:46,320 Speaker 1: a grange orbit, and that brought the cost down significantly, 360 00:21:46,320 --> 00:21:48,960 Speaker 1: and the mission also got a new name. This was 361 00:21:49,000 --> 00:21:52,480 Speaker 1: the second big change, and that new name was Kepler, 362 00:21:52,680 --> 00:21:57,440 Speaker 1: after Johannes Kepler, the seventeenth century German astronomer. The mission 363 00:21:57,600 --> 00:22:02,359 Speaker 1: still did not get greenlit at that time, however, then 364 00:22:02,720 --> 00:22:05,760 Speaker 1: they tried again and they got turned down again. The 365 00:22:05,800 --> 00:22:09,040 Speaker 1: team were told they needed to demonstrate the photometry system 366 00:22:09,080 --> 00:22:11,680 Speaker 1: they had in mind would actually be sufficient to pick 367 00:22:11,760 --> 00:22:15,080 Speaker 1: up the transit of a planet across its star. So 368 00:22:15,160 --> 00:22:17,800 Speaker 1: they built a testing facility at the Aimes Research Center 369 00:22:18,040 --> 00:22:21,080 Speaker 1: and they began running more than a hundred fifty simulations 370 00:22:21,119 --> 00:22:24,160 Speaker 1: to prove that their system would actually work. In two 371 00:22:24,200 --> 00:22:29,320 Speaker 1: thousand one, NASA officials finally gave approval to Kepler. This 372 00:22:29,400 --> 00:22:32,040 Speaker 1: was the fifth proposal for that mission, and it was 373 00:22:32,119 --> 00:22:37,120 Speaker 1: designated as the tenth Discovery Class mission. For nearly a decade, 374 00:22:37,200 --> 00:22:40,959 Speaker 1: engineers and scientists got to work building the actual telescope. 375 00:22:41,000 --> 00:22:43,399 Speaker 1: I'll talk more about how it worked in just a moment, 376 00:22:43,440 --> 00:22:47,520 Speaker 1: but the telescope launched on March sixth, two thousand nine. 377 00:22:47,920 --> 00:22:50,600 Speaker 1: It was on top of a three stage Delta two 378 00:22:50,680 --> 00:22:53,480 Speaker 1: rocket that's what was used as the launch vehicle, and 379 00:22:53,560 --> 00:22:55,879 Speaker 1: more than a month would go by once it reached 380 00:22:55,880 --> 00:22:59,359 Speaker 1: its orbit before it would take the first image of 381 00:22:59,400 --> 00:23:02,879 Speaker 1: a small patch of sky. It was a small patch 382 00:23:02,880 --> 00:23:06,200 Speaker 1: of sky which was occupied by part of the constellation Sicknus, 383 00:23:06,280 --> 00:23:09,959 Speaker 1: the Swan and Lyra or a liar, also known as 384 00:23:10,000 --> 00:23:14,120 Speaker 1: the harp. There's a term for this moment when a 385 00:23:14,160 --> 00:23:17,960 Speaker 1: space telescope like this sends back its first image, and 386 00:23:18,040 --> 00:23:21,439 Speaker 1: it's called first light, which I think is kind of cool. Also, 387 00:23:22,119 --> 00:23:25,119 Speaker 1: it had the equivalent of a lens cap. It's a 388 00:23:25,119 --> 00:23:28,080 Speaker 1: a very very large lens cap because the telescope has 389 00:23:28,160 --> 00:23:31,200 Speaker 1: quite a large opening at one end, but that had 390 00:23:31,240 --> 00:23:34,520 Speaker 1: to be jettisoned first before any images could be sent back. Obviously, 391 00:23:34,520 --> 00:23:37,600 Speaker 1: otherwise you just get if you've ever taken a picture 392 00:23:37,600 --> 00:23:39,600 Speaker 1: with a camera that still had a lens cap on, 393 00:23:40,080 --> 00:23:42,600 Speaker 1: you know, what you get, you get pitch black darkness. 394 00:23:43,960 --> 00:23:47,159 Speaker 1: That same little small patch of sky. By the way, 395 00:23:47,280 --> 00:23:50,440 Speaker 1: while it is a tiny, tiny portion of the overall 396 00:23:50,560 --> 00:23:53,679 Speaker 1: night sky, it's home to around four and a half 397 00:23:53,920 --> 00:23:58,600 Speaker 1: million stars. Kepler's job was to monitor around a hundred 398 00:23:58,600 --> 00:24:02,879 Speaker 1: seventy thousand of the stars simultaneously, So its job was 399 00:24:02,920 --> 00:24:05,800 Speaker 1: just to monitor the brightness of those stars and look 400 00:24:05,840 --> 00:24:11,840 Speaker 1: for tiny variations in their luminosity, regular ones, periodic dips 401 00:24:12,000 --> 00:24:15,760 Speaker 1: in their luminosity, which would indicate an exoplanet in transit. 402 00:24:16,760 --> 00:24:20,800 Speaker 1: On January four, the Kepler team announced that the telescope 403 00:24:20,800 --> 00:24:24,160 Speaker 1: had detected five planets. They had gone through the data 404 00:24:24,560 --> 00:24:27,199 Speaker 1: and they had found enough convincing data to say that 405 00:24:27,240 --> 00:24:30,880 Speaker 1: in those five cases, they're certainly appeared to be planets 406 00:24:30,880 --> 00:24:34,040 Speaker 1: in orbit around their respective stars, and they had exciting 407 00:24:34,119 --> 00:24:38,600 Speaker 1: names like Kepler four B, Kepler five B, Kepler six B, 408 00:24:38,920 --> 00:24:41,840 Speaker 1: Kepler seven B, and Kepler eight B. They fell into 409 00:24:41,920 --> 00:24:45,760 Speaker 1: a class of planets called hot jupiters. Now, these are 410 00:24:45,800 --> 00:24:48,359 Speaker 1: planets that are of a similar size to Jupiter in 411 00:24:48,400 --> 00:24:51,440 Speaker 1: our Solar system. That's the biggest Planet's got a diameter 412 00:24:51,560 --> 00:24:54,479 Speaker 1: that's eleven times greater than Earth's. Technically you could fit 413 00:24:54,520 --> 00:24:59,000 Speaker 1: about one thousand three earths inside a single jupiter. So 414 00:24:59,040 --> 00:25:02,240 Speaker 1: what makes them hot, Well, it's that these planets are 415 00:25:02,240 --> 00:25:06,879 Speaker 1: relatively close to their parents stars. The orbits are very short. 416 00:25:07,119 --> 00:25:09,280 Speaker 1: Compared to an Earth year, a year on one of 417 00:25:09,280 --> 00:25:12,159 Speaker 1: those planets might only take three or four Earth days. 418 00:25:12,760 --> 00:25:15,680 Speaker 1: So every imagine that every three or four days you've 419 00:25:15,720 --> 00:25:19,919 Speaker 1: gone through an entire year. That is uh the equivalent 420 00:25:20,000 --> 00:25:24,240 Speaker 1: of these planets years um. It made it easier to 421 00:25:24,280 --> 00:25:27,639 Speaker 1: detect because they were big planets, so they had a 422 00:25:27,720 --> 00:25:29,960 Speaker 1: big impact on the amount of light that was hitting 423 00:25:30,080 --> 00:25:35,680 Speaker 1: the Kepler telescope, so you could see the indication very clearly. 424 00:25:36,040 --> 00:25:38,840 Speaker 1: And because they were so close to their parents stars, 425 00:25:39,080 --> 00:25:42,800 Speaker 1: it happened so frequently that you could keep that you 426 00:25:42,800 --> 00:25:44,959 Speaker 1: could actually make predictions of when you would see the 427 00:25:45,080 --> 00:25:48,960 Speaker 1: next dip, and if in fact a dip occurred when 428 00:25:48,960 --> 00:25:52,640 Speaker 1: you predicted it, it would be a strong support that yes, 429 00:25:52,680 --> 00:25:55,679 Speaker 1: there is a very large planet that's in orbit around 430 00:25:55,720 --> 00:26:02,040 Speaker 1: that star. So the telescope was very successful. It was 431 00:26:02,359 --> 00:26:04,800 Speaker 1: indicating that there were bodies or in orbit around other 432 00:26:04,840 --> 00:26:08,479 Speaker 1: stars and other solar systems. It wasn't measuring the wobble 433 00:26:08,560 --> 00:26:11,679 Speaker 1: is just measuring the light and it was showing that 434 00:26:11,760 --> 00:26:15,960 Speaker 1: this method actually had a lot of validity to it. Now, 435 00:26:16,080 --> 00:26:18,960 Speaker 1: in our next segment, I will go into a little 436 00:26:19,000 --> 00:26:22,359 Speaker 1: bit about how Kepler actually worked and what else it 437 00:26:22,440 --> 00:26:26,960 Speaker 1: discovered in its lifetime out in space. But first let's 438 00:26:26,960 --> 00:26:37,280 Speaker 1: take a quick break to thank our sponsor. The Kepler 439 00:26:37,320 --> 00:26:41,760 Speaker 1: telescope looked like a cylinder, probably about twice as tall 440 00:26:41,760 --> 00:26:45,880 Speaker 1: as your typical person, so fairly large telescope. It had 441 00:26:45,920 --> 00:26:49,280 Speaker 1: solar panels along the sun facing side of the satellite, 442 00:26:49,280 --> 00:26:52,320 Speaker 1: so it would generate electricity that would be used to 443 00:26:52,359 --> 00:26:56,320 Speaker 1: power various parts of the telescope. It also had an 444 00:26:56,359 --> 00:27:00,200 Speaker 1: angled opening. It was essentially a sunshade that would the 445 00:27:00,240 --> 00:27:02,600 Speaker 1: Sun's light from interfering with the light the telescope was 446 00:27:02,600 --> 00:27:04,600 Speaker 1: trying to pick up from distant stars. You didn't want 447 00:27:04,600 --> 00:27:09,919 Speaker 1: to have interference there, otherwise the sensors inside the telescope 448 00:27:10,160 --> 00:27:13,159 Speaker 1: would just be registering the Sun rather than the stars 449 00:27:13,160 --> 00:27:16,080 Speaker 1: it was looking for. To keep Kepler pointed at the 450 00:27:16,160 --> 00:27:20,160 Speaker 1: right patch of sky, the telescope had four reaction wheels. 451 00:27:20,280 --> 00:27:23,359 Speaker 1: I guess technically it still has four reaction wheels, just 452 00:27:23,520 --> 00:27:27,159 Speaker 1: there's nothing to power them anymore. Uh. These were motorized 453 00:27:27,200 --> 00:27:30,840 Speaker 1: components that could cause Kepler to move in the opposite 454 00:27:30,840 --> 00:27:34,080 Speaker 1: direction of the spinning of each wheel, and the wheels 455 00:27:34,080 --> 00:27:37,520 Speaker 1: could spend really fast, like around a thousand to four 456 00:27:37,560 --> 00:27:41,399 Speaker 1: thousand revolutions per minute. The wheels were a known point 457 00:27:41,560 --> 00:27:46,440 Speaker 1: of vulnerability as well. The the group knew that the 458 00:27:46,480 --> 00:27:50,960 Speaker 1: wheels had failed on other spacecraft. After a while, but 459 00:27:51,960 --> 00:27:55,480 Speaker 1: they also realized that they needed components that would help 460 00:27:55,560 --> 00:27:59,639 Speaker 1: keep the budget down for Kepler, and eventually, once it 461 00:27:59,720 --> 00:28:02,680 Speaker 1: got to the point where they were really worried about 462 00:28:02,720 --> 00:28:05,879 Speaker 1: their reliability, it was a bit too late, so the 463 00:28:05,960 --> 00:28:09,439 Speaker 1: vulnerability would become a true thorn in the side of 464 00:28:09,480 --> 00:28:12,000 Speaker 1: the group in two thousand twelve. That's when one of 465 00:28:12,040 --> 00:28:16,159 Speaker 1: the four wheels failed. A second wheel would fail in 466 00:28:16,200 --> 00:28:19,399 Speaker 1: two thousand thirteen, and the kepler needed at least three 467 00:28:19,400 --> 00:28:23,000 Speaker 1: working wheels to maintain its orientation that way, So in 468 00:28:23,080 --> 00:28:26,280 Speaker 1: two thousand thirteen, the primary mission for Kepler came to 469 00:28:26,320 --> 00:28:30,119 Speaker 1: an end. The aperture on the telescope measured nearly a 470 00:28:30,200 --> 00:28:35,000 Speaker 1: meter in diameter. The light detection comes from an array 471 00:28:35,119 --> 00:28:39,520 Speaker 1: of forty two camera sensors, which collectively acted like a 472 00:28:39,640 --> 00:28:43,680 Speaker 1: ninety five megapixel camera. Now specifically, the camera sensors were 473 00:28:43,760 --> 00:28:47,120 Speaker 1: c c d s, or charge couple devices. Each one 474 00:28:47,200 --> 00:28:50,800 Speaker 1: measured fifty by twenty five millimeters in size, and each 475 00:28:50,800 --> 00:28:54,120 Speaker 1: one had a resolution of twenty two hundred by one thousand, 476 00:28:54,240 --> 00:28:57,560 Speaker 1: twenty four pixels. The c c d s wouldn't record 477 00:28:57,560 --> 00:29:00,920 Speaker 1: information from stars below a certain lumina that would limit 478 00:29:00,960 --> 00:29:03,400 Speaker 1: the amount of data being fed back to NASA. Essentially, 479 00:29:03,400 --> 00:29:05,720 Speaker 1: they were saying, you know, some of these stars are 480 00:29:05,760 --> 00:29:09,040 Speaker 1: so faint that it doesn't make sense for us to 481 00:29:09,160 --> 00:29:11,560 Speaker 1: track them because we're not getting enough data to be 482 00:29:11,600 --> 00:29:14,520 Speaker 1: able to reliably say, oh, this represents a depth in 483 00:29:14,560 --> 00:29:17,800 Speaker 1: that light. On January ten, two thousand eleven, just a 484 00:29:17,840 --> 00:29:20,400 Speaker 1: bit more than a year after NASA had announced the 485 00:29:20,480 --> 00:29:24,000 Speaker 1: first five planets discovered by Kepler, the agency had a 486 00:29:24,040 --> 00:29:27,000 Speaker 1: new announcement, which was that the telescope had discovered the 487 00:29:27,120 --> 00:29:32,040 Speaker 1: first unquestionably rocky planet orbiting a distant star. This one 488 00:29:32,400 --> 00:29:36,080 Speaker 1: became a Kepler ten B. Later that year, NASA would 489 00:29:36,080 --> 00:29:39,080 Speaker 1: reveal that Kepler had found a planet that the team 490 00:29:39,080 --> 00:29:43,120 Speaker 1: would designate Kepler sixteen B. This one was special, and 491 00:29:43,160 --> 00:29:46,680 Speaker 1: that it was a planet in a double star system, 492 00:29:46,720 --> 00:29:49,320 Speaker 1: which always makes me think of tattooing in the Star 493 00:29:49,360 --> 00:29:53,080 Speaker 1: Wars series with the two sons at sunset, and at 494 00:29:53,080 --> 00:29:57,960 Speaker 1: the tail end of two thousand eleven, NASA announced Kepler 495 00:29:58,160 --> 00:30:00,480 Speaker 1: twenty two B. That was the first plant to be 496 00:30:00,560 --> 00:30:04,680 Speaker 1: found in the habitable zone around its respective star, and 497 00:30:04,760 --> 00:30:07,840 Speaker 1: it has a diameter that's about twice the size of Earth's, 498 00:30:08,040 --> 00:30:10,960 Speaker 1: so it's a bigger planet than ours is. In two 499 00:30:10,960 --> 00:30:15,040 Speaker 1: thousand thirteen, after the second reaction wheel failure, the team 500 00:30:15,240 --> 00:30:17,280 Speaker 1: worked had to work on coming up with a way 501 00:30:17,800 --> 00:30:21,360 Speaker 1: to still use the telescope without being able to use 502 00:30:21,400 --> 00:30:25,040 Speaker 1: the intended method to keep its orientation to make sure 503 00:30:25,040 --> 00:30:28,640 Speaker 1: it was pointed in the right way. Meanwhile, researchers were 504 00:30:28,640 --> 00:30:32,600 Speaker 1: discovering more exoplanets as they were pouring over all the 505 00:30:32,680 --> 00:30:35,320 Speaker 1: data that Kepler had gathered in its operations, and that 506 00:30:35,360 --> 00:30:38,360 Speaker 1: would continue on for a couple of years. Just because 507 00:30:38,400 --> 00:30:42,120 Speaker 1: the telescope wasn't in current operation didn't mean it wasn't 508 00:30:42,320 --> 00:30:47,440 Speaker 1: providing really useful data for people to pursue, because they 509 00:30:47,480 --> 00:30:49,640 Speaker 1: could actually go through all the stuff that already been 510 00:30:49,640 --> 00:30:52,280 Speaker 1: collected and look for more signs of it. In May 511 00:30:52,320 --> 00:30:55,800 Speaker 1: two thousand fourteen, the Kepler Telescope would start a new 512 00:30:55,840 --> 00:30:59,520 Speaker 1: mission called K two. In this mission. The team would 513 00:30:59,560 --> 00:31:04,120 Speaker 1: rely upon sunlight, which actually does exert pressure. That's the 514 00:31:04,160 --> 00:31:08,040 Speaker 1: actually the working principle behind things like solar sales, and 515 00:31:08,360 --> 00:31:11,440 Speaker 1: they used the sunlight to help keep the Kepler pointed 516 00:31:11,480 --> 00:31:14,320 Speaker 1: in the right direction. Now, that would mean the telescope 517 00:31:14,360 --> 00:31:17,800 Speaker 1: would have to look at around four different sections of 518 00:31:17,800 --> 00:31:21,800 Speaker 1: sky every year, every three months or so, it would 519 00:31:21,920 --> 00:31:26,520 Speaker 1: change its orientation just because they could not keep it 520 00:31:26,680 --> 00:31:30,120 Speaker 1: pointed at the exact same patch all year round while 521 00:31:30,160 --> 00:31:34,280 Speaker 1: relying upon sunlight to study it. But it did mean 522 00:31:34,280 --> 00:31:37,440 Speaker 1: that the telescope could keep operating. It just wouldn't look 523 00:31:37,440 --> 00:31:40,400 Speaker 1: at the same thousand stars all year round. Instead, it 524 00:31:40,440 --> 00:31:44,840 Speaker 1: was more like half a million stars in total throughout 525 00:31:44,880 --> 00:31:48,240 Speaker 1: the year. But then keep in mind if you're looking 526 00:31:48,280 --> 00:31:52,160 Speaker 1: at different patches of stars every three months or so. 527 00:31:53,040 --> 00:31:57,000 Speaker 1: If you aren't, if it's not timed out the same 528 00:31:57,000 --> 00:32:01,240 Speaker 1: way as a planet transitting its own parents star, you 529 00:32:01,280 --> 00:32:03,440 Speaker 1: don't get any more data from that, right you may 530 00:32:03,560 --> 00:32:05,560 Speaker 1: it may be that you look away just as something 531 00:32:05,600 --> 00:32:08,920 Speaker 1: interesting happens, which is the story of my life. I 532 00:32:08,960 --> 00:32:13,520 Speaker 1: should just title my autobiography I wasn't looking. Over the years, 533 00:32:13,880 --> 00:32:17,840 Speaker 1: the information from Kepler kept providing researchers with more evidence 534 00:32:17,880 --> 00:32:23,480 Speaker 1: of exoplanets and other interesting phenomena. So in data suggested 535 00:32:23,520 --> 00:32:26,960 Speaker 1: that a rocky planet orbiting a white dwarf star was 536 00:32:27,000 --> 00:32:30,560 Speaker 1: actually being pulled apart as its solar system was kind 537 00:32:30,560 --> 00:32:34,600 Speaker 1: of dying. In two thousand sixteen, some interesting information showed 538 00:32:34,800 --> 00:32:38,760 Speaker 1: odd fluctuations in a particular stars brightness, which led some 539 00:32:38,800 --> 00:32:43,880 Speaker 1: people to theorize that perhaps some alien civilization had built 540 00:32:43,920 --> 00:32:47,520 Speaker 1: a mega structure around that star. It was far more 541 00:32:47,600 --> 00:32:50,040 Speaker 1: likely than the fluctuations were caused by a dust cloud, 542 00:32:50,080 --> 00:32:53,080 Speaker 1: but it was still a super cool thing. In the 543 00:32:53,120 --> 00:32:56,600 Speaker 1: spring of twenty six NASA announced that the team had 544 00:32:56,600 --> 00:33:00,880 Speaker 1: found one thousand, two hundred new exo planet's after reviewing 545 00:33:00,960 --> 00:33:04,040 Speaker 1: Kepler data, And that was a huge announcement, and all 546 00:33:04,080 --> 00:33:07,080 Speaker 1: of these were from that original mission of Kepler, not 547 00:33:07,120 --> 00:33:09,800 Speaker 1: the K two mission. This was still from its first run. 548 00:33:10,400 --> 00:33:14,000 Speaker 1: In twenty seventeen, NASA producer report that stated Kepler had 549 00:33:14,040 --> 00:33:19,040 Speaker 1: detected four thousand, thirty four potential planets in its original mission, 550 00:33:19,400 --> 00:33:23,680 Speaker 1: with two thousand, three hundred thirty five planets confirmed now. Originally, 551 00:33:23,720 --> 00:33:26,480 Speaker 1: the team estimated that about thirty of those planets were 552 00:33:26,480 --> 00:33:30,280 Speaker 1: likely close to Earth's size and were of a rocky nature. 553 00:33:30,760 --> 00:33:35,360 Speaker 1: Further examination, however, tempered our expectations a bit reduced that 554 00:33:35,440 --> 00:33:40,040 Speaker 1: number somewhere down between two and twelve. In two thousand eighteen, 555 00:33:40,400 --> 00:33:44,720 Speaker 1: the power of crowdsourcing in science was proven again when 556 00:33:44,760 --> 00:33:48,720 Speaker 1: an Australian car mechanic discovered a planet system that had 557 00:33:48,760 --> 00:33:52,600 Speaker 1: at least four Neptune sized planets in it. He had 558 00:33:52,600 --> 00:33:55,000 Speaker 1: taken the data from the K two mission and had 559 00:33:55,040 --> 00:33:59,120 Speaker 1: gone through it meticulously. NASA would end up confirming his 560 00:33:59,240 --> 00:34:01,920 Speaker 1: find and also the scientists who were looking into it 561 00:34:01,960 --> 00:34:05,600 Speaker 1: discovered that the planet actually had a fifth or the 562 00:34:06,000 --> 00:34:08,560 Speaker 1: star rather had a fifth planet in its system. So 563 00:34:09,040 --> 00:34:13,960 Speaker 1: cool stuff. On April eighteen, two eighteen, the Transiting Exo 564 00:34:13,960 --> 00:34:18,799 Speaker 1: Planet Survey Satellite or Tests launched into orbit. This is 565 00:34:18,880 --> 00:34:22,520 Speaker 1: Kepler's successor. It's going to be looking for planets using 566 00:34:22,560 --> 00:34:27,080 Speaker 1: the transit method, much like Kepler did. On October eighteen, 567 00:34:27,719 --> 00:34:30,759 Speaker 1: NASA essentially pulled the plug on Kepler. Now it could 568 00:34:30,800 --> 00:34:33,560 Speaker 1: no longer operate as it run out of fuel that 569 00:34:33,719 --> 00:34:36,920 Speaker 1: needed to help stabilize its position. It was too wobbly. 570 00:34:37,480 --> 00:34:40,359 Speaker 1: It was just not going to provide reliable information. So 571 00:34:40,520 --> 00:34:43,520 Speaker 1: it will remain in its orbit. It's safely away from Earth, 572 00:34:44,280 --> 00:34:47,680 Speaker 1: but it will be defunct. Out in space, tests, which 573 00:34:47,719 --> 00:34:51,440 Speaker 1: is more powerful than Kepler was, is expected to detect 574 00:34:51,520 --> 00:34:56,200 Speaker 1: perhaps more than twenty thousand new exo planets, and Kepler 575 00:34:56,239 --> 00:34:58,480 Speaker 1: has given us a lot to think about. Before Kepler, 576 00:34:59,000 --> 00:35:02,600 Speaker 1: we didn't really know how common exo planets were. It 577 00:35:02,640 --> 00:35:05,320 Speaker 1: could be that they were really really rare. But Kepler 578 00:35:05,400 --> 00:35:10,240 Speaker 1: discovered hundreds of multiplanet systems in a few small patches 579 00:35:10,280 --> 00:35:14,880 Speaker 1: of sky. So extrapolating from that information, we can estimate 580 00:35:15,320 --> 00:35:20,480 Speaker 1: that there are possibly hundreds of billions of planets in 581 00:35:20,480 --> 00:35:24,040 Speaker 1: our galaxy alone. Though to be fair, we don't actually 582 00:35:24,080 --> 00:35:26,759 Speaker 1: know how many stars are in the Milky Way Galaxy, 583 00:35:27,160 --> 00:35:29,600 Speaker 1: we can estimate it. We think it's somewhere between one 584 00:35:30,000 --> 00:35:33,160 Speaker 1: billion and four hundred billion. So even if we are 585 00:35:33,280 --> 00:35:35,920 Speaker 1: being conservative we say a hundred billion, And even if 586 00:35:35,960 --> 00:35:39,960 Speaker 1: we say that only a tiny fraction of the exo 587 00:35:40,000 --> 00:35:43,600 Speaker 1: planets out there are earth like and in a habitable 588 00:35:43,680 --> 00:35:47,480 Speaker 1: zone around the respective stars, you're still talking about hundreds 589 00:35:47,520 --> 00:35:52,080 Speaker 1: of millions of planets that might possibly support life in 590 00:35:52,120 --> 00:35:56,000 Speaker 1: the Milky Way galaxy. Future telescopes will give us more 591 00:35:56,000 --> 00:36:00,480 Speaker 1: information about those exo planets. Visiting one, however, is going 592 00:36:00,520 --> 00:36:05,080 Speaker 1: to take a lot longer. The closest exoplanet orbiting in 593 00:36:05,080 --> 00:36:08,680 Speaker 1: the habitable zone of its star is Proxima Centauri B. 594 00:36:09,560 --> 00:36:13,759 Speaker 1: That's orbiting the red dwarf star Proxima Centauri. And just 595 00:36:13,840 --> 00:36:18,120 Speaker 1: to be clear, Kepler did not discover Proxima B. That 596 00:36:18,200 --> 00:36:22,600 Speaker 1: planet was discovered by the European Southern Observatory using the 597 00:36:22,680 --> 00:36:25,840 Speaker 1: radial velocity method, you know, the good old Wobbli method. 598 00:36:26,480 --> 00:36:29,600 Speaker 1: That star, however, is the closest star to our Sun, 599 00:36:29,960 --> 00:36:33,760 Speaker 1: but closest is a relative term. It's still four point 600 00:36:33,880 --> 00:36:37,560 Speaker 1: two light years away. Now, that means it takes more 601 00:36:37,600 --> 00:36:41,719 Speaker 1: than four years for light from that star to reach us. 602 00:36:42,280 --> 00:36:45,360 Speaker 1: The spacecraft we have designed so far in the history 603 00:36:45,440 --> 00:36:49,160 Speaker 1: of space travel, in in all of human history, they 604 00:36:49,160 --> 00:36:53,400 Speaker 1: travel significantly slower than the speed of light. And obviously 605 00:36:53,400 --> 00:36:55,279 Speaker 1: we can't get matter up to the speed of light 606 00:36:55,600 --> 00:37:00,200 Speaker 1: because matter has mass, So getting to this destination would 607 00:37:00,239 --> 00:37:03,800 Speaker 1: take a really long time. However, one company called Breakthrough 608 00:37:03,800 --> 00:37:08,440 Speaker 1: Initiatives has proposed a plan that would do it sort of. 609 00:37:09,000 --> 00:37:12,879 Speaker 1: They plan to launch small, unmanned spacecraft that they call 610 00:37:13,000 --> 00:37:18,239 Speaker 1: star chips. These tiny spacecraft would use light sales for propulsion, 611 00:37:18,400 --> 00:37:22,440 Speaker 1: so light sales or solar sales use pressure from photons. 612 00:37:22,880 --> 00:37:24,640 Speaker 1: Photons don't have a mass, but they do have a 613 00:37:24,680 --> 00:37:28,040 Speaker 1: relativistic mass, which means they have momentum, which means when 614 00:37:28,080 --> 00:37:31,640 Speaker 1: they hit against something, they transfer momentum to it. So 615 00:37:31,719 --> 00:37:36,200 Speaker 1: you can actually accelerate a spacecraft by having photons bounce 616 00:37:36,360 --> 00:37:40,520 Speaker 1: off a solar sale. It does take a while to 617 00:37:40,680 --> 00:37:43,200 Speaker 1: get up to a pretty fast speed, but you're under 618 00:37:43,280 --> 00:37:47,839 Speaker 1: constant acceleration, so while the acceleration isn't so dramatic, you're 619 00:37:47,840 --> 00:37:51,799 Speaker 1: not going like zero two, you know, point to five 620 00:37:51,840 --> 00:37:54,759 Speaker 1: the speed of light in in five seconds. It takes 621 00:37:54,800 --> 00:37:57,600 Speaker 1: a long time to get up to speed, but according 622 00:37:57,680 --> 00:38:02,440 Speaker 1: to the company, the StarCraft they have designed will eventually 623 00:38:02,480 --> 00:38:05,799 Speaker 1: reach a top speed of about twenty that of the 624 00:38:05,840 --> 00:38:08,960 Speaker 1: speed of light, so they would get to Proxima B 625 00:38:09,280 --> 00:38:12,719 Speaker 1: in around twenty years or so. Then you have to 626 00:38:12,800 --> 00:38:16,359 Speaker 1: tack on another four years for the information they were 627 00:38:16,400 --> 00:38:19,800 Speaker 1: sending back to get to us, So twenty four twenty 628 00:38:19,880 --> 00:38:23,879 Speaker 1: five years from the time that those are launched and 629 00:38:23,960 --> 00:38:27,040 Speaker 1: they start heading toward Proxima B before we would find 630 00:38:27,080 --> 00:38:31,799 Speaker 1: anything out about it. But still pretty exciting, and the 631 00:38:31,840 --> 00:38:35,440 Speaker 1: search for exoplants continues Kepler is done, but it has 632 00:38:35,480 --> 00:38:38,439 Speaker 1: served us well. It has given us a lot more 633 00:38:38,440 --> 00:38:42,560 Speaker 1: information and told us that planets are way more plentiful 634 00:38:43,080 --> 00:38:46,279 Speaker 1: than we might have hoped. Whether or not planets in 635 00:38:46,320 --> 00:38:49,759 Speaker 1: the habitable zone are more plentiful, that still remains to 636 00:38:49,760 --> 00:38:52,880 Speaker 1: be seen. We're gonna have to really do a careful 637 00:38:52,880 --> 00:38:57,359 Speaker 1: study with using multiple lines of inquiry to make that determination. 638 00:38:57,760 --> 00:39:00,880 Speaker 1: But it's really exciting stuff. I hope you guys enjoyed 639 00:39:00,920 --> 00:39:04,080 Speaker 1: this episode. If you have any suggestions for me, any 640 00:39:04,160 --> 00:39:06,640 Speaker 1: questions or anything like that, you can go on over 641 00:39:06,680 --> 00:39:09,440 Speaker 1: to tech Stuff podcast dot com. That's the website for 642 00:39:09,480 --> 00:39:11,359 Speaker 1: the series. You can learn more about the show there, 643 00:39:11,400 --> 00:39:13,879 Speaker 1: and you can find the ways to contact me. Don't 644 00:39:13,920 --> 00:39:17,200 Speaker 1: forget to go to te public dot com slash tech stuff. 645 00:39:17,239 --> 00:39:20,120 Speaker 1: That's where you'll find all of our merchandise. Make sure 646 00:39:20,120 --> 00:39:22,160 Speaker 1: you check that out. We're gonna have some new designs 647 00:39:22,160 --> 00:39:25,439 Speaker 1: in there real soon, so check back see if there's 648 00:39:25,440 --> 00:39:27,680 Speaker 1: anything that catches your fancy. Maybe there's something you want 649 00:39:27,680 --> 00:39:31,160 Speaker 1: as a stocking stuffer for the holidays. Every purchase you 650 00:39:31,160 --> 00:39:33,359 Speaker 1: make goes to help the show. We greatly appreciate it, 651 00:39:33,760 --> 00:39:42,400 Speaker 1: and I will talk to you again really soon for 652 00:39:42,480 --> 00:39:44,800 Speaker 1: more on this and thousands of other topics because it 653 00:39:44,880 --> 00:39:55,800 Speaker 1: how stuff works. Dot com