WEBVTT 0 00:00:00.320 --> 00:00:02.120 Andrew Dunkley: Hello again. Thank you for joining us on 1 00:00:02.120 --> 00:00:04.360 another episode of Space Nuts. This is a Q 2 00:00:04.360 --> 00:00:06.640 and A edition where we take audience 3 00:00:06.720 --> 00:00:08.760 questions, we write them on a piece of paper 4 00:00:08.760 --> 00:00:11.640 and then we throw it in the bin. Or we 5 00:00:11.640 --> 00:00:14.500 could answer them. We'll do the latter. Uh, 6 00:00:14.500 --> 00:00:17.040 we got questions about ultra hot 7 00:00:17.040 --> 00:00:19.680 Jupiters. We've also got questions about, 8 00:00:19.980 --> 00:00:22.920 uh, reusing spent rocket fuel. How would 9 00:00:22.920 --> 00:00:25.920 you do that? That is the question. And 10 00:00:26.320 --> 00:00:29.040 wow, how about this one? Uh, some conspiracy 11 00:00:29.040 --> 00:00:31.280 with the Artemis 2 mission 12 00:00:31.910 --> 00:00:34.630 being fake. We'll deal with all of that on 13 00:00:34.630 --> 00:00:36.790 this episode of space nuts. 14 00:00:36.950 --> 00:00:39.430 Generic: 15 seconds. Guidance is internal. 15 00:00:39.750 --> 00:00:42.390 10, 9. Ignition 16 00:00:42.390 --> 00:00:43.120 sequence start. 17 00:00:43.120 --> 00:00:44.319 Jonti Horner: Uh, space nuts. 18 00:00:44.396 --> 00:00:47.391 Generic: 5, 4, 3, 2, 1. 3, 4, 5, 19 00:00:47.468 --> 00:00:49.350 5, 4, 3, 2', 1. 20 00:00:49.430 --> 00:00:50.550 Jonti Horner: Space nuts. 21 00:00:50.630 --> 00:00:52.470 Generic: Astronauts report. It feels good. 22 00:00:53.670 --> 00:00:56.230 Andrew Dunkley: And joining us to try and sort all that out 23 00:00:56.230 --> 00:00:58.710 is Jonty Horner, professor of Astrophysics at 24 00:00:58.710 --> 00:01:01.390 the University of Southern Queensland. 25 00:01:01.390 --> 00:01:02.190 Jonty, hello. 26 00:01:02.190 --> 00:01:03.270 Jonti Horner: Good afternoon. How are you? 27 00:01:04.290 --> 00:01:07.010 Andrew Dunkley: I'm, um, all right. Um, please forgive me if 28 00:01:07.010 --> 00:01:09.090 there's some background noise. There's a 29 00:01:09.090 --> 00:01:11.970 gardener working, uh, just out the front, and 30 00:01:12.050 --> 00:01:13.850 he's, uh, doing a fabulous job. But he's 31 00:01:13.850 --> 00:01:15.970 using that kind of equipment that you would, 32 00:01:16.080 --> 00:01:18.610 um, you know, demolish a building with. 33 00:01:19.250 --> 00:01:22.090 So, uh, it's, um, it's making 34 00:01:22.090 --> 00:01:24.730 quite a noise. But, um, I've got my filter 35 00:01:24.730 --> 00:01:26.490 turned on, so hopefully it'll just keep it 36 00:01:26.490 --> 00:01:27.010 blocked out. 37 00:01:27.010 --> 00:01:28.690 Jonti Horner: Oh, it's amazing just how well these things 38 00:01:28.690 --> 00:01:31.130 work. I use this microphone in front of me 39 00:01:31.130 --> 00:01:32.650 for my teaching. I've had a number of 40 00:01:32.650 --> 00:01:35.170 occasions where the dog has decided that I'm 41 00:01:35.170 --> 00:01:36.550 painting too much attention to my students 42 00:01:36.550 --> 00:01:38.590 and not enough to her. And it's got quite 43 00:01:38.590 --> 00:01:40.310 vocal about that lying just behind me here 44 00:01:40.310 --> 00:01:41.830 next to her fire at the minute, keeping her 45 00:01:41.830 --> 00:01:44.390 really happy. And they say, no, we can't hear 46 00:01:44.390 --> 00:01:46.070 anything. It's amazing how well it can filter 47 00:01:46.070 --> 00:01:47.070 out the background noise. 48 00:01:47.470 --> 00:01:50.430 Andrew Dunkley: Yeah, the technology is amazing today. It's 49 00:01:50.430 --> 00:01:53.390 like the telescope technology that exists now 50 00:01:53.390 --> 00:01:56.110 where you can filter out light pollution. 51 00:01:56.830 --> 00:01:59.470 I don't know how that works, but, uh, it's 52 00:01:59.470 --> 00:02:02.300 quite incredible these days. Works really 53 00:02:02.300 --> 00:02:04.100 well. I want to answer some questions. 54 00:02:04.500 --> 00:02:05.140 Jonti Horner: Of course. 55 00:02:05.940 --> 00:02:08.940 Andrew Dunkley: All right, let's start with David, who's on 56 00:02:08.940 --> 00:02:11.700 the Sunshine coast in Queensland, Australia. 57 00:02:12.420 --> 00:02:14.960 David: G', day, David from the sunny coast again. I, 58 00:02:14.960 --> 00:02:17.820 uh, just had a question regarding the, uh, 59 00:02:17.820 --> 00:02:20.340 ultra hot Jupiter article from the latest, 60 00:02:20.520 --> 00:02:22.610 uh, podcast. Um, 61 00:02:23.460 --> 00:02:25.300 in the conversation, Fred Watson, uh, 62 00:02:25.580 --> 00:02:28.520 mentioned that, uh, the belief is 63 00:02:28.520 --> 00:02:31.480 that stars and their surrounding planets all 64 00:02:31.480 --> 00:02:34.120 form from the same, uh, disc of material. 65 00:02:34.720 --> 00:02:37.360 Um, I just had a question regarding the 66 00:02:37.360 --> 00:02:40.240 material. Um, you know, we tend to 67 00:02:40.240 --> 00:02:43.240 think of stars as Helium or hydrogen or both, 68 00:02:43.540 --> 00:02:46.240 um, and everything else as metals. And we 69 00:02:46.240 --> 00:02:49.080 believe those metals formed within stars, 70 00:02:49.220 --> 00:02:50.360 uh, due to the 71 00:02:51.800 --> 00:02:54.750 fusion burning. Um, where then 72 00:02:54.830 --> 00:02:57.790 does this material come from in the disc to 73 00:02:57.790 --> 00:03:00.030 form a star and its planets? Is that from 74 00:03:00.510 --> 00:03:02.910 material from. Do we believe it's material 75 00:03:02.910 --> 00:03:05.830 from another star or, um, is there some 76 00:03:05.830 --> 00:03:08.150 other process going on? Thanks very much for 77 00:03:08.150 --> 00:03:10.350 the show. Awesome. See you guys. 78 00:03:10.510 --> 00:03:12.830 Andrew Dunkley: See you, David. Thank you very much. Um, that 79 00:03:12.830 --> 00:03:14.430 sounds like it's right up your alley. 80 00:03:14.910 --> 00:03:17.190 Jonti Horner: It is. It's a good film to start off with. 81 00:03:17.190 --> 00:03:19.960 Sah. Uh, you're right. The 82 00:03:19.960 --> 00:03:22.760 material that forms a star and its planets 83 00:03:23.400 --> 00:03:25.720 has been contributed to by many previous 84 00:03:25.800 --> 00:03:28.160 stars. If you imagine after the Big Bang, the 85 00:03:28.160 --> 00:03:31.000 universe was hydrogen and helium and a tiny 86 00:03:31.000 --> 00:03:32.520 little bit of other stuff, but it really was 87 00:03:32.520 --> 00:03:35.200 barely any, which meant that a generation of 88 00:03:35.200 --> 00:03:37.160 stars formed that were pretty much just 89 00:03:37.160 --> 00:03:39.000 hydrogen and helium and very little else. 90 00:03:39.640 --> 00:03:41.840 Those stars in the early universe, there's 91 00:03:41.840 --> 00:03:43.440 some speculation that they may have been, 92 00:03:43.440 --> 00:03:46.400 including mega megastars, much 93 00:03:46.400 --> 00:03:48.440 bigger than something called the Eddington 94 00:03:48.440 --> 00:03:51.260 Limit, which is a maximum size a 95 00:03:51.260 --> 00:03:53.700 stable star can form, um, because of how 96 00:03:53.700 --> 00:03:55.500 dense the universe was at the time, how much 97 00:03:55.500 --> 00:03:57.580 material there was. So speculation of stars 98 00:03:57.580 --> 00:04:00.180 up to several thousand solar mass. Those 99 00:04:00.180 --> 00:04:02.860 stars lived fast, died young, put 100 00:04:02.860 --> 00:04:05.300 material back out into the cosmos. So they, 101 00:04:05.380 --> 00:04:07.540 when they died, they locked some of the stuff 102 00:04:07.540 --> 00:04:09.020 up in the remnants to the left, whether 103 00:04:09.020 --> 00:04:11.100 that's a black hole, a neutron star, a white 104 00:04:11.100 --> 00:04:14.100 dwarf, whatever. But the material that was 105 00:04:14.100 --> 00:04:16.300 flung outwards to form planetary nebulae, 106 00:04:16.300 --> 00:04:19.020 supernova remnants, disperses into the 107 00:04:19.020 --> 00:04:21.860 wider galaxy. So what's happening over 108 00:04:22.400 --> 00:04:24.800 the aeons of time since the Milky Way formed 109 00:04:25.280 --> 00:04:28.240 is that stars are born, live and 110 00:04:28.320 --> 00:04:31.000 die. And when they die, they pollute the 111 00:04:31.000 --> 00:04:33.920 cosmos. Stars of different masses throughout 112 00:04:33.920 --> 00:04:35.800 different things. But what that means is that 113 00:04:35.800 --> 00:04:37.880 you gradually get more and more heavy 114 00:04:37.880 --> 00:04:40.640 elements introduced into the galaxy. 115 00:04:41.520 --> 00:04:44.280 And, um, that goes to basically contributing 116 00:04:44.280 --> 00:04:46.120 to the composition of the gas and dust that 117 00:04:46.120 --> 00:04:48.680 floats around in our galaxy. If you go out, 118 00:04:48.680 --> 00:04:50.120 particularly this time of year in the 119 00:04:50.120 --> 00:04:52.960 Southern Hemisphere. But if you go out on any 120 00:04:52.960 --> 00:04:54.480 night of the year where you can see the Milky 121 00:04:54.480 --> 00:04:56.400 Way, you'll see that in the band of the Milky 122 00:04:56.400 --> 00:04:58.000 Way, there are dark patches as well as 123 00:04:58.000 --> 00:05:00.840 glowing bits. The dark patches are not 124 00:05:00.840 --> 00:05:02.680 places where there is a lack of stars, but 125 00:05:02.680 --> 00:05:04.480 rather they're places where you've got huge 126 00:05:04.480 --> 00:05:07.200 clouds of gas and dust that are opaque, that 127 00:05:07.200 --> 00:05:09.000 are blocking the light from stars that are 128 00:05:09.000 --> 00:05:11.520 more distant from reaching us. So they look 129 00:05:11.520 --> 00:05:14.120 dark in the same way that a cloud blocking 130 00:05:14.120 --> 00:05:16.400 the sun will look dark in the daytime. It's 131 00:05:16.400 --> 00:05:19.370 blocking light from beyond. These clouds 132 00:05:19.370 --> 00:05:21.330 can be vast and they're made of gas and dust 133 00:05:21.410 --> 00:05:24.170 and ice, mainly hydrogen and 134 00:05:24.170 --> 00:05:26.690 helium, but lots of other stuff. And that 135 00:05:26.690 --> 00:05:29.650 other stuff will vary from one cloud to the 136 00:05:29.650 --> 00:05:32.170 next to some degree, based on what it has 137 00:05:32.170 --> 00:05:34.250 been polluted with. You'll have to some 138 00:05:34.250 --> 00:05:36.130 degree a stirring, a pollution of the galaxy 139 00:05:36.130 --> 00:05:37.850 that gives you a background increase in the 140 00:05:37.850 --> 00:05:40.130 amount of metals. But you'll also get local 141 00:05:40.130 --> 00:05:42.690 variation. We see all of this 142 00:05:42.690 --> 00:05:44.750 incidentally in the Earth and the solar 143 00:05:44.750 --> 00:05:47.270 system. There are suggestions that the solar 144 00:05:47.270 --> 00:05:49.190 system, when it was young, when it was 145 00:05:49.190 --> 00:05:51.950 forming, was polluted by a nearby supernova 146 00:05:51.950 --> 00:05:53.750 that injected a lot of very short lived 147 00:05:53.750 --> 00:05:56.550 radioactive aluminium isotopes that 148 00:05:56.550 --> 00:05:58.830 accelerated the degree of melting you got in 149 00:05:58.830 --> 00:06:01.070 the rocky objects. There's a signature there 150 00:06:01.070 --> 00:06:04.070 of a radioisotope that is so short 151 00:06:04.070 --> 00:06:05.670 lived, there shouldn't really have been any 152 00:06:05.670 --> 00:06:07.750 of it around, unless a supernova exploded 153 00:06:07.750 --> 00:06:10.150 nearby to pollute our disc, giving us a 154 00:06:10.150 --> 00:06:12.430 slightly unusual composition. There is also 155 00:06:12.430 --> 00:06:15.250 an argument that the Earth is richer 156 00:06:15.250 --> 00:06:17.770 in gold than it should be, because 157 00:06:18.650 --> 00:06:20.890 sometime between 10 and 100 million years 158 00:06:20.890 --> 00:06:22.970 before the formation of the Earth, 10,000 159 00:06:22.970 --> 00:06:25.770 light years from where we formed, two neutron 160 00:06:25.770 --> 00:06:27.930 stars collided, polluting the universe with 161 00:06:27.930 --> 00:06:30.529 gold. And some of that gold made its way into 162 00:06:30.529 --> 00:06:32.330 the disc that formed the solar system, got 163 00:06:32.330 --> 00:06:33.970 incorporated into the Earth. And that's why 164 00:06:33.970 --> 00:06:35.890 we are a particularly good place for 165 00:06:35.890 --> 00:06:38.210 Goldfinger to, uh, have his little layer. 166 00:06:38.210 --> 00:06:39.690 We've got more gold than normal. 167 00:06:40.480 --> 00:06:40.760 Andrew Dunkley: Yeah. 168 00:06:40.760 --> 00:06:42.560 Jonti Horner: What this all means is that those giant 169 00:06:42.560 --> 00:06:45.280 clouds of gas and dust in space can be truly 170 00:06:45.280 --> 00:06:47.480 vast. When they get nudged and start to 171 00:06:47.480 --> 00:06:49.840 collapse, they'll fragment in their interiors 172 00:06:50.000 --> 00:06:52.600 to form a cluster of stars, a number of 173 00:06:52.600 --> 00:06:54.640 stars, which form from the little denser 174 00:06:54.640 --> 00:06:56.160 bits. It's like driving through a fog bank. 175 00:06:56.319 --> 00:06:58.440 Fog banks are never one uniform density. 176 00:06:58.440 --> 00:06:59.960 There's denser patches and less dense 177 00:06:59.960 --> 00:07:02.680 patches. A denser patch in one of these 178 00:07:02.680 --> 00:07:04.320 clouds will collapse under its own gravity. 179 00:07:04.720 --> 00:07:07.120 And so you'll get lots of stars forming. As 180 00:07:07.120 --> 00:07:09.120 that material collapses in, it collapses down 181 00:07:09.120 --> 00:07:11.280 to form a disc around that young protostar 182 00:07:11.280 --> 00:07:13.860 that's forming. And the star and the 183 00:07:13.860 --> 00:07:16.100 disc are made of the same material. They're 184 00:07:16.100 --> 00:07:18.500 forming from the same material. All that 185 00:07:18.500 --> 00:07:20.580 material that was in the cloud from which 186 00:07:20.580 --> 00:07:22.260 they're formed, which has been polluted over 187 00:07:22.260 --> 00:07:24.900 many generations of stars, cooking the 188 00:07:24.900 --> 00:07:27.780 books to give the composition that is uniform 189 00:07:27.780 --> 00:07:30.740 across that star system. What happens then is 190 00:07:30.740 --> 00:07:32.980 that the star forms from everything, so it 191 00:07:32.980 --> 00:07:35.660 ends up very rich in hydrogen and helium. 192 00:07:35.980 --> 00:07:37.740 Because even after all that pollution and all 193 00:07:37.740 --> 00:07:40.100 that evolution, hydrogen and helium still 194 00:07:40.100 --> 00:07:43.070 make up something like between 98 and 99% of 195 00:07:43.070 --> 00:07:45.710 all atoms in the universe. So the star is 196 00:07:45.710 --> 00:07:47.470 going to be primarily hydrogen and helium 197 00:07:47.630 --> 00:07:50.390 with a thin veneer of everything else. In 198 00:07:50.390 --> 00:07:52.230 other words, the abundance of material in the 199 00:07:52.230 --> 00:07:54.590 star is going to be very nearly 200 00:07:54.590 --> 00:07:57.510 identical to the disc. Star will end 201 00:07:57.510 --> 00:08:00.310 up being very, very, very slightly enriched 202 00:08:00.310 --> 00:08:03.270 in the heavier elements, because from 203 00:08:03.270 --> 00:08:04.910 the disc, particularly when the disc is 204 00:08:04.910 --> 00:08:07.390 cleared, there will be some infall of rocky 205 00:08:07.390 --> 00:08:09.430 and icy objects like the Kreutz sun, grazing 206 00:08:09.430 --> 00:08:11.830 comets, we see that fall into the star and 207 00:08:11.830 --> 00:08:13.610 pollute it further. But that' very, very 208 00:08:13.610 --> 00:08:16.010 small effect compared to the overall mass of 209 00:08:16.010 --> 00:08:18.610 the star. The planets form in the 210 00:08:18.610 --> 00:08:20.890 disc in the main 211 00:08:21.290 --> 00:08:23.130 form through a process we call core 212 00:08:23.130 --> 00:08:24.730 accretion. There are some suggestions that 213 00:08:24.730 --> 00:08:26.810 some of the most massive stars can form 214 00:08:26.810 --> 00:08:29.370 through a process of instability. And those 215 00:08:29.930 --> 00:08:32.850 planets and binary stars would form with a 216 00:08:32.850 --> 00:08:34.490 more stellar composition, I.e. lots of 217 00:08:34.490 --> 00:08:36.730 hydrogen, helium. But most planets 218 00:08:37.210 --> 00:08:39.490 will form by initially growing a core of 219 00:08:39.490 --> 00:08:42.200 solid material, because when you have a low, 220 00:08:42.200 --> 00:08:44.009 uh, mass, you can't capture gas, 221 00:08:44.889 --> 00:08:47.249 and so therefore your composition will be 222 00:08:47.249 --> 00:08:49.289 dominated by the solid material, not the 223 00:08:49.289 --> 00:08:51.689 gases. So that's why the Earth doesn't have 224 00:08:51.689 --> 00:08:54.129 free hydrogen and helium. We simply don't 225 00:08:54.129 --> 00:08:56.169 have enough mass to capture those gases and 226 00:08:56.169 --> 00:08:59.169 hold onto them. So even though 99% of all 227 00:08:59.169 --> 00:09:01.089 atoms in the protoplanetary disc were 228 00:09:01.089 --> 00:09:02.929 hydrogen and helium, we didn't get any of 229 00:09:02.929 --> 00:09:05.169 them, other than the old tiny little atom 230 00:09:05.169 --> 00:09:07.809 that was captured in a cage of other 231 00:09:07.809 --> 00:09:10.009 compounds called clathrate, 232 00:09:10.860 --> 00:09:12.700 that was captured in a mineral effectively. 233 00:09:13.500 --> 00:09:15.460 So we barely got any of those materials 234 00:09:15.460 --> 00:09:17.020 because we couldn't hold onto them. We formed 235 00:09:17.020 --> 00:09:19.700 out of the solid stuff. The further you are 236 00:09:19.700 --> 00:09:21.660 from the star, the colder it is, so the more 237 00:09:21.660 --> 00:09:23.340 different things can be solid rather than 238 00:09:23.340 --> 00:09:24.900 gas, which is where we get the idea of the 239 00:09:24.900 --> 00:09:27.180 ice line. If you're far enough from the star, 240 00:09:27.820 --> 00:09:30.660 water can be solid, can be ice, and then 241 00:09:30.660 --> 00:09:32.620 suddenly you've got a lot more solid material 242 00:09:32.860 --> 00:09:34.620 because water's about the most common 243 00:09:34.620 --> 00:09:36.700 compound there is, almost it's the most 244 00:09:36.700 --> 00:09:38.420 common atom, hydrogen, and the third most 245 00:09:38.420 --> 00:09:39.860 common atom, oxygen. And you put them 246 00:09:39.860 --> 00:09:42.280 together and you've got water. So beyond the 247 00:09:42.280 --> 00:09:43.880 ice line, you've got a lot more solid, and 248 00:09:43.880 --> 00:09:46.480 you can form planets much quicker, which is 249 00:09:46.480 --> 00:09:48.800 why we think Jupiter and Saturn got so big so 250 00:09:48.800 --> 00:09:50.960 quickly. They had a lot to feed on. And 251 00:09:50.960 --> 00:09:52.960 eventually they got massive enough that their 252 00:09:52.960 --> 00:09:54.600 gravity was strong enough to hold onto the 253 00:09:54.600 --> 00:09:56.280 hydrogen and helium around them and devour 254 00:09:56.280 --> 00:09:58.280 it. So they are 255 00:09:59.480 --> 00:10:01.800 in composition much more similar to the sun 256 00:10:01.800 --> 00:10:03.320 than the, uh, Earth. Is because they have all 257 00:10:03.320 --> 00:10:05.880 that hydrogen and helium, but they are still 258 00:10:05.880 --> 00:10:08.420 richer in solid material than the sun 259 00:10:08.820 --> 00:10:11.740 because at their core, there was all the 260 00:10:11.740 --> 00:10:13.740 solid material needed to build up before they 261 00:10:13.740 --> 00:10:16.260 could gather the hydrogen and helium. So they 262 00:10:16.260 --> 00:10:18.100 started with more solids. Effectively. 263 00:10:19.140 --> 00:10:21.220 The Earth doesn't really have the hydrogen 264 00:10:21.220 --> 00:10:23.180 and helium. So all of the objects in our 265 00:10:23.180 --> 00:10:25.700 solar system will have the same composition 266 00:10:25.700 --> 00:10:28.700 as the sun in terms of the balance between 267 00:10:28.700 --> 00:10:30.820 carbon and nitrogen and iron and all these 268 00:10:30.820 --> 00:10:33.700 elements, except for where they weren't able 269 00:10:33.700 --> 00:10:36.060 to capture those elements because they 270 00:10:36.060 --> 00:10:38.180 weren't massive enough. So the Earth doesn't 271 00:10:38.180 --> 00:10:39.880 have the same composition as the sun in terms 272 00:10:39.880 --> 00:10:42.600 of hydrogen and helium, but it does in terms 273 00:10:42.600 --> 00:10:45.200 of iron, nickel, all those things, 274 00:10:45.360 --> 00:10:47.160 the balance between iron and nickel and 275 00:10:47.160 --> 00:10:48.920 carbon and all the rest of it are all in the 276 00:10:48.920 --> 00:10:51.840 same ratios as the sun, um, to an 277 00:10:51.840 --> 00:10:54.080 incredibly high precision. And that's because 278 00:10:54.080 --> 00:10:56.480 we all formed from the same material that 279 00:10:56.480 --> 00:10:58.080 quite rightly was mentioned in the question 280 00:10:58.080 --> 00:11:00.560 was delivered by past generation of stars 281 00:11:00.560 --> 00:11:02.000 that had lived and died. And that's where the 282 00:11:02.000 --> 00:11:03.840 whole concept that we are stardust comes 283 00:11:03.840 --> 00:11:05.920 from. It's the idea that all the atoms that 284 00:11:05.920 --> 00:11:07.760 we need to make us, us, other than the 285 00:11:07.760 --> 00:11:10.240 hydrogen atoms, were cooked in the furnaces 286 00:11:10.240 --> 00:11:12.490 of stars long de. All the carbon, the 287 00:11:12.490 --> 00:11:15.050 nitrogen, the oxygen, the phosphorus, all 288 00:11:15.050 --> 00:11:16.570 those wonderful things, calcium, that 289 00:11:16.570 --> 00:11:18.970 contributes to our bones are all stardust 290 00:11:18.970 --> 00:11:20.770 from stars that died long before the solar 291 00:11:20.770 --> 00:11:21.650 system formed. 292 00:11:23.010 --> 00:11:25.730 Andrew Dunkley: There you are, David. Um, a very 293 00:11:26.050 --> 00:11:28.690 good, uh, answer. That pretty m. Well, nails 294 00:11:28.690 --> 00:11:30.930 it. I like the bit about there being more 295 00:11:30.930 --> 00:11:33.050 gold on Earth than there probably would be in 296 00:11:33.050 --> 00:11:33.770 other places. 297 00:11:33.770 --> 00:11:35.930 So that's. That was a lucky break for us. 298 00:11:35.930 --> 00:11:38.850 Jonti Horner: Absolutely. So useful for a 299 00:11:38.850 --> 00:11:40.370 lot of the technology we use. Not just for 300 00:11:40.370 --> 00:11:42.690 those who are sparkly, bangly things, but, 301 00:11:42.850 --> 00:11:45.590 you know, there's a lot of those rarer type 302 00:11:45.590 --> 00:11:48.430 things that are so vital to our technological 303 00:11:48.430 --> 00:11:50.790 growth that are all linked to our ancient 304 00:11:50.790 --> 00:11:51.310 heritage. 305 00:11:52.110 --> 00:11:54.590 Andrew Dunkley: Yeah, yeah. Um, well, 306 00:11:54.750 --> 00:11:56.190 there's gold, there's lithium. 307 00:11:57.470 --> 00:11:59.230 There's just so many of them. But we've got a 308 00:11:59.230 --> 00:12:00.750 lithium mine just down the road from us, 309 00:12:00.750 --> 00:12:01.030 actually. 310 00:12:01.030 --> 00:12:03.750 Jonti Horner: And that lithium, probably all primordial, 311 00:12:03.750 --> 00:12:05.310 the lithium in the universe, is almost 312 00:12:05.310 --> 00:12:07.950 certainly, almost all leftovers from the Big 313 00:12:07.950 --> 00:12:08.350 Bang. 314 00:12:09.640 --> 00:12:12.560 Andrew Dunkley: Wow, that's interesting. There you go, 315 00:12:12.560 --> 00:12:14.240 David, thanks for the question. Lovely to 316 00:12:14.240 --> 00:12:15.960 hear from you. Hope all is well on the 317 00:12:15.960 --> 00:12:18.760 Sunshine Coast. This is Space Nuts with 318 00:12:18.760 --> 00:12:21.680 Andrew Dunkley and Jonty Horner, A 319 00:12:21.680 --> 00:12:22.600 Q and A Edition. 320 00:12:25.480 --> 00:12:26.880 Generic: Roger, your lab is right here. 321 00:12:26.880 --> 00:12:28.360 David: Also Space Nuts. 322 00:12:28.840 --> 00:12:31.320 Andrew Dunkley: And we're with Professor Jonty Horner today 323 00:12:31.320 --> 00:12:34.120 with Fred Watson away. Uh, let's Go to our, 324 00:12:34.190 --> 00:12:37.080 uh, next question. Jonty, this one comes from 325 00:12:37.320 --> 00:12:37.720 Mark. 326 00:12:38.380 --> 00:12:40.660 Mark: Hi, it's Mark from Sunny Siddlesham in the 327 00:12:40.660 --> 00:12:42.900 uk. I've eventually plugged up the courage to 328 00:12:42.900 --> 00:12:45.780 send in an audio question, so here goes. You 329 00:12:45.780 --> 00:12:48.020 quite often mention water ice and the 330 00:12:48.020 --> 00:12:50.340 possibility of turning this into rocket fuel. 331 00:12:50.340 --> 00:12:52.940 So my what do you think? Sort of question is, 332 00:12:53.260 --> 00:12:55.700 when you use hydrogen and oxygen as a rocket 333 00:12:55.700 --> 00:12:57.980 fuel, it must turn back into water ice in 334 00:12:57.980 --> 00:13:00.060 space. So do you think it would be possible 335 00:13:00.140 --> 00:13:02.740 to collect it and reuse it through the rocket 336 00:13:02.740 --> 00:13:05.060 engine, again massively reducing the amount 337 00:13:05.060 --> 00:13:07.010 of fuel you would need to carry for an 338 00:13:07.010 --> 00:13:09.970 extended journey, say, to Mars? I've sort of 339 00:13:09.970 --> 00:13:12.810 drawn up an idea, but what do you think? Once 340 00:13:12.810 --> 00:13:15.130 again, keep up the great work, Mark from the 341 00:13:15.130 --> 00:13:15.410 uk. 342 00:13:16.290 --> 00:13:18.450 Andrew Dunkley: Thank you, Mark. It's an interesting idea. 343 00:13:18.930 --> 00:13:21.010 My, uh, first thought when I 344 00:13:21.729 --> 00:13:24.010 first heard the question was, um, 345 00:13:24.690 --> 00:13:27.610 how would you collect it? That 346 00:13:27.610 --> 00:13:28.930 might be the first challenge. 347 00:13:29.090 --> 00:13:30.410 Jonti Horner: That would be a bit of a challenge. I mean, 348 00:13:30.410 --> 00:13:32.090 the thing is, your exhaust is being pushed 349 00:13:32.090 --> 00:13:34.050 out of the bucket, the rocket, at very high 350 00:13:34.050 --> 00:13:36.970 speed in a very dispersed form. Now the 351 00:13:36.970 --> 00:13:38.590 rocket's going forward because you're 352 00:13:38.590 --> 00:13:40.350 throwing the things out the back. You've got 353 00:13:40.350 --> 00:13:43.350 the momentum, um, being transferred and it's 354 00:13:43.350 --> 00:13:46.030 equivalent, I guess, to you. The way I'd 355 00:13:46.030 --> 00:13:48.190 visualise this is imagining, again, sitting 356 00:13:48.190 --> 00:13:50.750 on an ice rink on a wheelie chair. So you've 357 00:13:50.750 --> 00:13:53.630 got no friction whatsoever, really slippy and 358 00:13:53.630 --> 00:13:55.430 you're holding, Normally, I'd just say one 359 00:13:55.430 --> 00:13:56.990 medicine ball, but instead imagine that 360 00:13:56.990 --> 00:13:59.710 you're holding a big bag of short puts. You 361 00:13:59.710 --> 00:14:01.510 throw a short put away from you and you'll 362 00:14:01.510 --> 00:14:03.070 recall in the other direction. You throw 363 00:14:03.070 --> 00:14:04.510 another short put and you'll speed up and 364 00:14:04.510 --> 00:14:06.190 you'll move in the opposite direction to the 365 00:14:06.190 --> 00:14:08.740 direction your short puts are going. So 366 00:14:08.740 --> 00:14:10.100 that's how you'll work. And that's 367 00:14:10.100 --> 00:14:11.340 essentially what you're doing with the 368 00:14:11.340 --> 00:14:13.100 rocket. You're pushing material out of the 369 00:14:13.100 --> 00:14:15.140 back and you're moving the opposite way, 370 00:14:15.460 --> 00:14:17.500 because overall, the momentum is conserved 371 00:14:17.500 --> 00:14:19.220 between the stuff going one way and you going 372 00:14:19.220 --> 00:14:21.940 the other. The problem with the 373 00:14:21.940 --> 00:14:24.420 rocket itself capturing its own exhaust, 374 00:14:24.420 --> 00:14:27.100 pumping it back in and reusing it, is 375 00:14:27.100 --> 00:14:29.140 then you're taking that momentum and bringing 376 00:14:29.140 --> 00:14:30.420 it back to you, which means you're getting 377 00:14:30.420 --> 00:14:31.900 pulled back towards it and you'll end up 378 00:14:31.900 --> 00:14:34.870 having gone nowhere to some degree. 379 00:14:34.870 --> 00:14:36.710 So imagine now that situation with the short 380 00:14:36.710 --> 00:14:39.590 puts on the I shrink, but 381 00:14:39.590 --> 00:14:42.030 instead you've got a really efficient bungee 382 00:14:42.030 --> 00:14:43.630 cord, so that when you throw them away, they 383 00:14:43.630 --> 00:14:45.910 bounce back and you catch them again. What'll 384 00:14:45.910 --> 00:14:47.390 Happen is as they're moving away from you, 385 00:14:47.390 --> 00:14:49.230 you'll wheel away from them. And then as they 386 00:14:49.230 --> 00:14:50.670 get pulled back towards you, you get pulled 387 00:14:50.670 --> 00:14:51.950 back towards them and you end up where you 388 00:14:51.950 --> 00:14:54.870 started from. Here will know a little bit of 389 00:14:54.870 --> 00:14:56.710 change due to friction and loss of energy and 390 00:14:56.710 --> 00:14:59.700 stuff like that. So the problem I'd have 391 00:14:59.700 --> 00:15:01.700 with this suggestion is not actually the idea 392 00:15:01.700 --> 00:15:03.820 of capturing and reusing the fuel. 393 00:15:04.330 --> 00:15:06.340 Um, I think that will be hard because the 394 00:15:06.340 --> 00:15:08.260 fuel will get so dispersed, so water will be 395 00:15:08.260 --> 00:15:09.900 scattered out there. It's just easier to go 396 00:15:09.900 --> 00:15:12.260 get a big lump of ice from somewhere than try 397 00:15:12.260 --> 00:15:14.180 and pick up individual water molecules or 398 00:15:14.180 --> 00:15:16.500 small grains of ice disperse over a large 399 00:15:16.500 --> 00:15:19.300 area. But the idea of being able to capture 400 00:15:19.300 --> 00:15:21.300 it from the same rocket and reuse it would 401 00:15:21.300 --> 00:15:23.060 get you into this problem of having to pull 402 00:15:23.060 --> 00:15:25.460 back material that you've pushed away, which 403 00:15:25.460 --> 00:15:27.220 means you'd be pulling yourself back to where 404 00:15:27.220 --> 00:15:29.700 you started from. So you can't get away, I 405 00:15:29.700 --> 00:15:32.180 think, from that momentum issue there. 406 00:15:32.580 --> 00:15:34.460 So I think it's two different things. I think 407 00:15:34.460 --> 00:15:37.420 if you had the ability to, instead of using 408 00:15:37.420 --> 00:15:39.380 hydrogen and oxygen as a fuel and burning 409 00:15:39.380 --> 00:15:42.100 them to be water, you can instead have a 410 00:15:42.100 --> 00:15:44.660 rocket fired powered by firing 411 00:15:44.660 --> 00:15:47.460 pellets of water out of the back. You could 412 00:15:47.460 --> 00:15:49.620 fire them at a target that captures them, um, 413 00:15:50.020 --> 00:15:52.380 collect them and reuse those pellets for 414 00:15:52.380 --> 00:15:53.860 something else. But that target will get 415 00:15:53.860 --> 00:15:56.020 pushed around by the arriving water pellets. 416 00:15:56.340 --> 00:15:57.860 So you'd want to be clever with that and 417 00:15:57.860 --> 00:15:59.420 you'd need to continually change its orbit 418 00:15:59.420 --> 00:16:02.410 and stuff. So in theory, potentially, you 419 00:16:02.410 --> 00:16:04.090 could gather the fuel for use on another 420 00:16:04.090 --> 00:16:06.930 rocket without it being the rocket you're 421 00:16:06.930 --> 00:16:09.210 flying that gathers that fuel. But in 422 00:16:09.210 --> 00:16:11.210 reality, you're dispersing over such a large 423 00:16:11.210 --> 00:16:14.210 area that unfortunately, it wouldn't be that 424 00:16:14.210 --> 00:16:15.850 practical anyway. Especially when we've got 425 00:16:15.850 --> 00:16:17.930 just huge lumps of ice floating around 426 00:16:17.930 --> 00:16:19.330 anyway. I mean, you and I have both been 427 00:16:19.330 --> 00:16:21.690 photographing a beautiful lump of ice flying 428 00:16:21.690 --> 00:16:23.610 through the solar system. There we go in the 429 00:16:23.610 --> 00:16:26.370 background. That's enough fuel for 430 00:16:26.530 --> 00:16:28.410 missions forevermore. If we were to go and 431 00:16:28.410 --> 00:16:30.610 mine there, and that's a lot more efficient 432 00:16:30.610 --> 00:16:33.170 to mine one big comet or 433 00:16:33.570 --> 00:16:36.090 asteroid for water ice or mine the moon for 434 00:16:36.090 --> 00:16:38.370 water ice, then try and catch it when it's 435 00:16:38.370 --> 00:16:40.490 dispersed, I think. So it's a really good 436 00:16:40.490 --> 00:16:43.250 idea. It's really good thinking. But it's 437 00:16:43.250 --> 00:16:44.530 something that wouldn't work. I think that's 438 00:16:44.530 --> 00:16:45.490 the way I'd view it. 439 00:16:47.010 --> 00:16:49.230 Andrew Dunkley: It'd be very complicated. And as you said, 440 00:16:49.230 --> 00:16:51.490 um, trying to capture it in the ship, you're 441 00:16:51.650 --> 00:16:53.330 actually propelling would be 442 00:16:53.330 --> 00:16:56.210 counterproductive. Using another 443 00:16:56.610 --> 00:16:59.410 spaceship to capture the ice after it's been 444 00:16:59.410 --> 00:17:02.300 expelled, uh, would be difficult because it 445 00:17:02.300 --> 00:17:04.340 would spread out too far. But then you're 446 00:17:04.340 --> 00:17:06.700 using the same technology 447 00:17:07.020 --> 00:17:09.820 to chase the ice that's been spent already 448 00:17:10.700 --> 00:17:13.340 and spending more to get the ice back. So it, 449 00:17:13.500 --> 00:17:15.580 yeah, It's a catch 22. It's just going to 450 00:17:15.580 --> 00:17:18.460 keep going around and around. So um, 451 00:17:19.020 --> 00:17:21.980 it makes it a little bit difficult. Uh, Mark, 452 00:17:21.980 --> 00:17:24.980 but, uh, thanks for your question, that 453 00:17:24.980 --> 00:17:26.860 was a fun one actually. But, uh, yeah, 454 00:17:26.960 --> 00:17:29.910 um, yeah, I like the way people 455 00:17:29.910 --> 00:17:32.310 think. But I, uh, suppose just to expand on 456 00:17:32.310 --> 00:17:35.310 it a bit, um, there's going to come a 457 00:17:35.310 --> 00:17:37.590 time where using those kinds of fuels 458 00:17:37.590 --> 00:17:39.310 probably won't be necessary. They're 459 00:17:39.310 --> 00:17:41.350 developing all sorts of different kinds of 460 00:17:41.430 --> 00:17:44.390 engine technology, uh, everything 461 00:17:44.390 --> 00:17:46.950 from solar sails to scramjets, and 462 00:17:48.630 --> 00:17:50.390 they don't use that kind of fuel. 463 00:17:50.390 --> 00:17:52.030 Jonti Horner: There's all sorts of things you could do. I 464 00:17:52.030 --> 00:17:54.510 mean again, going back to the Bobiverse, 465 00:17:54.510 --> 00:17:55.990 which I mentioned before, the Van Neumann 466 00:17:55.990 --> 00:17:58.820 probes going through, they used kind of um, 467 00:17:58.820 --> 00:18:01.030 ram scoots essentially initially in the book 468 00:18:01.030 --> 00:18:03.030 set. They then move on to other kind of 469 00:18:03.030 --> 00:18:05.630 speculative sci fi things. But initially the 470 00:18:05.630 --> 00:18:08.150 idea of having a fusion drive where you scoop 471 00:18:08.150 --> 00:18:10.070 up hydrogen atoms and turn them into helium 472 00:18:10.070 --> 00:18:12.630 and push them out the back where in front of 473 00:18:12.630 --> 00:18:14.870 you you deploy a big thing that gathers the 474 00:18:14.870 --> 00:18:16.510 hydrogen you're moving through. This is also 475 00:18:16.510 --> 00:18:18.750 what they did in Tau Zero by Poole Anderson 476 00:18:18.910 --> 00:18:20.550 is you know, you're moving really quickly, 477 00:18:20.550 --> 00:18:22.550 you gather hydrogen from in front of you and 478 00:18:22.550 --> 00:18:24.430 compress it like a ramjet effectively. 479 00:18:25.480 --> 00:18:26.920 There's all these kind of things, but they 480 00:18:26.920 --> 00:18:29.760 will all, unless we get to truly sci fi 481 00:18:29.760 --> 00:18:32.040 type things like warp driver albatier drives 482 00:18:32.040 --> 00:18:34.800 or whatever, which require physics to be 483 00:18:34.800 --> 00:18:36.360 somewhat different than how we can only 484 00:18:36.360 --> 00:18:39.240 understand it. You still have 485 00:18:39.800 --> 00:18:42.680 either a source of propellant which you 486 00:18:42.680 --> 00:18:44.720 then get rid of out the back one way or the 487 00:18:44.720 --> 00:18:47.720 other, or with solar sails you're using 488 00:18:47.880 --> 00:18:50.840 the stellar wind and that pushes you away. 489 00:18:51.460 --> 00:18:54.300 Um, people who are sailors can probably tell 490 00:18:54.300 --> 00:18:55.940 you a lot more about the complexity of how 491 00:18:55.940 --> 00:18:57.620 you can tack into the wind and move across 492 00:18:57.620 --> 00:18:59.460 the wind. But the wind, the solar wind is 493 00:18:59.460 --> 00:19:02.380 incredibly tenuous compared to the wind in 494 00:19:02.380 --> 00:19:03.900 the Earth's atmosphere. So you need a very, 495 00:19:03.900 --> 00:19:06.460 very big sail. And I think that will be 496 00:19:06.460 --> 00:19:08.540 somewhat limiting. If you were wanting to do, 497 00:19:09.180 --> 00:19:11.660 I guess, Star wars style dogfight manoeuvres, 498 00:19:11.660 --> 00:19:13.620 you wouldn't do that with a solar sail. So 499 00:19:13.620 --> 00:19:15.660 people will pick the right technology for the 500 00:19:15.660 --> 00:19:17.220 kind of mission that they want. And that was 501 00:19:17.220 --> 00:19:19.980 where the dawn mission which went to Ceres 502 00:19:20.300 --> 00:19:22.260 and um, Juno in the asteroid belt was really 503 00:19:22.260 --> 00:19:24.120 interesting because it used an ion drive 504 00:19:25.080 --> 00:19:27.920 where it was using I think ionised xenon. And 505 00:19:27.920 --> 00:19:30.760 um, that kind of drive achieves a much, 506 00:19:30.760 --> 00:19:33.280 much lower thrust but can operate for much 507 00:19:33.280 --> 00:19:35.080 much longer time. So it's very energy 508 00:19:35.080 --> 00:19:38.080 efficient um, but it wouldn't be any good for 509 00:19:38.080 --> 00:19:39.480 getting off the surface of the Earth. But 510 00:19:39.480 --> 00:19:41.400 it's very, very good for cruising around the 511 00:19:41.400 --> 00:19:43.720 solar system when you're not in a rush. And 512 00:19:43.720 --> 00:19:45.440 so what will happen is I think different 513 00:19:45.440 --> 00:19:48.080 people will have different types of drives 514 00:19:48.080 --> 00:19:50.600 for different types of scenario 515 00:19:51.650 --> 00:19:53.010 and choose the one that works best. 516 00:19:53.970 --> 00:19:56.290 Andrew Dunkley: Yeah but to get off the planet at the moment 517 00:19:56.610 --> 00:19:59.610 you need rockets. There's no real 518 00:19:59.610 --> 00:20:01.890 other technology that will get you out there. 519 00:20:01.970 --> 00:20:04.930 I know they've been trying um, sort 520 00:20:04.930 --> 00:20:07.730 of catapult technology uh, which 521 00:20:08.240 --> 00:20:11.050 um, could deploy satellites in the 522 00:20:11.050 --> 00:20:13.730 future. I um, think 523 00:20:13.810 --> 00:20:15.610 you'd need to be in the right place on the 524 00:20:15.610 --> 00:20:18.010 planet to take advantage of the um, rotation 525 00:20:18.010 --> 00:20:20.150 of the Earth so that you don't have to like 526 00:20:20.150 --> 00:20:22.150 you couldn't do it too far away from the 527 00:20:22.150 --> 00:20:25.020 equator, that kind of thing. But um, 528 00:20:25.020 --> 00:20:27.910 at the moment uh, yeah the um, standard 529 00:20:27.910 --> 00:20:30.710 old rocket engine is uh, the best option at 530 00:20:30.710 --> 00:20:31.150 the moment. 531 00:20:31.580 --> 00:20:33.950 Jonti Horner: Um, part of where the refuelling station idea 532 00:20:33.950 --> 00:20:36.390 around uh, the moon comes from which is if 533 00:20:36.390 --> 00:20:38.030 you have to take your fuel with you, you're 534 00:20:38.030 --> 00:20:39.430 carrying a lot of extra weight so you've got 535 00:20:39.430 --> 00:20:41.590 to burn extra fuel to carry that fuel which 536 00:20:41.590 --> 00:20:43.070 means you're carrying extra weight so you've 537 00:20:43.070 --> 00:20:44.910 got to take even more fuel to burn um, to 538 00:20:44.910 --> 00:20:46.310 carry the weight of the fuel you're carrying 539 00:20:46.310 --> 00:20:48.710 to carry the extra fuel. And so uh, it 540 00:20:48.710 --> 00:20:50.630 becomes very inefficient very quickly. So if 541 00:20:50.630 --> 00:20:52.850 instead you can small launches from Earth and 542 00:20:52.850 --> 00:20:54.650 then refuel once you're beyond the Earth, 543 00:20:54.890 --> 00:20:57.290 that's a lot more effective. And the other 544 00:20:57.290 --> 00:20:58.860 thing that people have suggested long term 545 00:20:58.860 --> 00:21:01.410 um, as a solution to get things off the Earth 546 00:21:01.410 --> 00:21:03.290 more cheaply are things like space elevators 547 00:21:04.010 --> 00:21:06.690 which are ah, probably still far science 548 00:21:06.690 --> 00:21:08.890 fiction. I don't, don't think we have the 549 00:21:08.890 --> 00:21:10.650 material science to do that nor the political 550 00:21:10.730 --> 00:21:12.810 will. I mean putting that in perspective, 551 00:21:12.810 --> 00:21:14.570 just saw the announcement this week that the 552 00:21:14.730 --> 00:21:17.450 vast inland rail project that was happening 553 00:21:17.770 --> 00:21:20.010 in Australia is no longer happening because 554 00:21:20.010 --> 00:21:22.090 it got too expensive and it's taken too long. 555 00:21:22.490 --> 00:21:24.270 And if we can't build a railway between 556 00:21:24.270 --> 00:21:26.590 Melbourne and Brisbane, it's going to be 557 00:21:26.590 --> 00:21:29.430 really hard to build an elevator between low 558 00:21:29.430 --> 00:21:31.510 Earth orbit, well between the Earth's surface 559 00:21:31.670 --> 00:21:33.910 geostationary orbit and the same distance 560 00:21:33.910 --> 00:21:36.630 beyond for the counterweight. Yeah, 561 00:21:36.870 --> 00:21:38.790 So I don't see it happening anytime soon. 562 00:21:39.349 --> 00:21:41.670 Andrew Dunkley: We can't even get a tunnel under the Blue 563 00:21:41.670 --> 00:21:43.590 Mountains between the west and Sydney. 564 00:21:44.370 --> 00:21:47.350 Uh, and that's despite the fact 565 00:21:47.350 --> 00:21:49.990 that that road is currently closed due to 566 00:21:50.070 --> 00:21:52.990 a structural failure in Victoria Pass. 567 00:21:52.990 --> 00:21:55.930 The old convict bridge, that's, uh, 200 568 00:21:55.930 --> 00:21:58.530 years old or something, or 150 years old. And 569 00:21:58.610 --> 00:22:01.170 it's finally given up the ghost. And so 570 00:22:01.170 --> 00:22:02.210 they've closed the road. 571 00:22:02.210 --> 00:22:05.210 It's. You know, people have been screaming 572 00:22:05.210 --> 00:22:08.130 for a tunnel for decades. And, 573 00:22:08.370 --> 00:22:11.329 um, no politicians willing to spend the 574 00:22:11.329 --> 00:22:12.770 money because there aren't enough people. 575 00:22:13.090 --> 00:22:14.570 Bottom line is there aren't enough people 576 00:22:14.570 --> 00:22:17.290 living west of the mountains to make it worth 577 00:22:17.290 --> 00:22:17.890 your vote. 578 00:22:18.930 --> 00:22:20.050 Jonti Horner: Really. What it comes down. 579 00:22:20.370 --> 00:22:21.490 Andrew Dunkley: That's what it comes down to. 580 00:22:21.490 --> 00:22:23.290 Jonti Horner: Reminds me of the old episode of the Simpsons 581 00:22:23.290 --> 00:22:24.890 when I was a kid with the kind of argument 582 00:22:24.890 --> 00:22:26.450 about books for the kids or something. 583 00:22:26.530 --> 00:22:28.730 There's the two people at the front room 584 00:22:28.730 --> 00:22:30.850 basically shouting, but our children, but 585 00:22:30.850 --> 00:22:33.410 taxes. But our children, but taxes. And it's 586 00:22:33.490 --> 00:22:35.090 this whole thing of everybody wants it, but 587 00:22:35.090 --> 00:22:36.210 nobody wants to pay for it. 588 00:22:36.770 --> 00:22:39.450 Andrew Dunkley: Exactly, yes. Uh, a tunnel under the Blue 589 00:22:39.450 --> 00:22:41.650 Mounds would be wonderful, though. Although, 590 00:22:41.710 --> 00:22:44.490 um, some. Some of the arguments against it 591 00:22:44.490 --> 00:22:46.130 are, uh. Well, it'll only save you 15 592 00:22:46.210 --> 00:22:48.210 minutes. I think it'd probably save you more. 593 00:22:48.370 --> 00:22:50.370 Gets pretty log jammed up over that mountain. 594 00:22:50.370 --> 00:22:52.450 Jonti Horner: We have those arguments about the Toowoomba 595 00:22:52.450 --> 00:22:54.080 bypass, and that's been a godsend. 596 00:22:54.550 --> 00:22:57.350 Andrew Dunkley: I mean, yeah, I used it last, uh, year. Yeah, 597 00:22:57.350 --> 00:22:58.110 it's fantastic. 598 00:22:58.110 --> 00:22:59.990 Jonti Horner: It fell apart and bits fell onto it because 599 00:22:59.990 --> 00:23:02.230 they contracted fairly cheaply. 600 00:23:02.590 --> 00:23:04.950 Um, but that has saved about half an hour 601 00:23:04.950 --> 00:23:06.870 from my trip down to Brisbane when I go to 602 00:23:06.870 --> 00:23:08.790 the airport and stuff because I don't have to 603 00:23:08.790 --> 00:23:10.790 go through Toowoomba and all the freight 604 00:23:10.790 --> 00:23:12.430 companies use it even though the tolls are 605 00:23:12.430 --> 00:23:15.350 quite high. Because the tolls being high is a 606 00:23:15.350 --> 00:23:16.790 lot better than the wear and tear on their 607 00:23:16.790 --> 00:23:18.150 vehicles coming up the old road into 608 00:23:18.150 --> 00:23:19.550 Toowoomba and having to stop at all the 609 00:23:19.550 --> 00:23:21.730 traffic lights and stuff. So it works out 610 00:23:21.730 --> 00:23:23.410 deeper for them. It's better for the 611 00:23:23.410 --> 00:23:25.010 Toowoomba council because they're having to 612 00:23:25.010 --> 00:23:26.450 repair less potholes and they have less 613 00:23:26.450 --> 00:23:28.490 accidents. And it's one of those things where 614 00:23:28.490 --> 00:23:29.930 it was a little controversial when it was 615 00:23:29.930 --> 00:23:32.650 being built, but since it's there, it's been 616 00:23:32.650 --> 00:23:34.770 a godsend. And I'd like to think that some of 617 00:23:34.770 --> 00:23:36.290 these big infrastructure projects would be 618 00:23:36.290 --> 00:23:38.330 the same. And I mean, a space elevator would 619 00:23:38.330 --> 00:23:40.850 be wonderful, but, you know, gonna be hard to 620 00:23:40.850 --> 00:23:42.530 persuade people to commit to building it, 621 00:23:42.530 --> 00:23:43.730 even when we get the technology. 622 00:23:43.810 --> 00:23:46.410 Andrew Dunkley: I think, uh, wait till there are 623 00:23:46.410 --> 00:23:48.930 orbiting hotels that'll change everything. 624 00:23:49.170 --> 00:23:52.030 You wait and see. Might be 625 00:23:52.030 --> 00:23:54.870 waiting a while. Um, thanks, Mark. Lovely to 626 00:23:54.870 --> 00:23:55.350 hear from you. 627 00:23:55.350 --> 00:23:58.270 This is Space Nuts with Andrew Dunkley and 628 00:23:58.270 --> 00:23:59.670 Professor Jonty Horner. 629 00:24:04.150 --> 00:24:05.190 Jonti Horner: Space Nuts. 630 00:24:05.350 --> 00:24:08.070 Andrew Dunkley: One more question, uh, Jonty. And this one 631 00:24:08.150 --> 00:24:10.230 comes from Paul. 632 00:24:10.630 --> 00:24:12.430 Joe: G', day, Fred Watson and Andrew. Paul here 633 00:24:12.430 --> 00:24:15.190 from Sunnybridge, Vegas. I have 634 00:24:15.190 --> 00:24:17.830 a question and a dirty secret that 635 00:24:18.150 --> 00:24:19.590 I need to confess. 636 00:24:21.510 --> 00:24:24.270 So I was on this Flat Earth group on 637 00:24:24.270 --> 00:24:27.110 Facebook. Yes, I know, I know. Uh, anyway, 638 00:24:27.270 --> 00:24:30.150 this guy provided some AI information 639 00:24:30.710 --> 00:24:33.710 which was absolutely correct to 640 00:24:33.710 --> 00:24:36.670 contend that there is no way that the Artemis 641 00:24:36.670 --> 00:24:38.670 mission could have ever caught up to the 642 00:24:38.670 --> 00:24:40.390 Earth because the Earth travels a hell of a 643 00:24:40.390 --> 00:24:43.190 lot faster than that little spaceship. 644 00:24:43.830 --> 00:24:46.710 I pointed out that they didn't need to 645 00:24:47.120 --> 00:24:49.160 catch up to the Earth at all. They just 646 00:24:49.160 --> 00:24:51.960 needed to point themselves to where it was 647 00:24:51.960 --> 00:24:54.000 going to be and then splash down, 648 00:24:54.880 --> 00:24:57.280 land safely, and be 649 00:24:57.360 --> 00:24:59.200 applauded by everybody except for the Flat 650 00:24:59.200 --> 00:25:02.200 Earthers like him, uh, who are absolutely 651 00:25:02.200 --> 00:25:04.800 incensed at the moment about 652 00:25:05.120 --> 00:25:07.760 how it's all fake, as per, uh, usual. 653 00:25:08.080 --> 00:25:11.000 Anyway, I told him 654 00:25:11.000 --> 00:25:13.440 that if he really wanted a better answer, 655 00:25:13.520 --> 00:25:15.480 exact answer, he really needed to talk to an 656 00:25:15.480 --> 00:25:18.080 astrophysicist. So my second question 657 00:25:18.580 --> 00:25:21.060 is. Well, my first question is, was I on the 658 00:25:21.060 --> 00:25:23.460 right track? And my second question is, 659 00:25:24.340 --> 00:25:26.980 are there any astrophysicists or any websites 660 00:25:26.980 --> 00:25:29.460 out there that can give us an animation 661 00:25:30.020 --> 00:25:32.980 of the Earth going around 662 00:25:32.980 --> 00:25:35.860 the sun that also has, uh, the 663 00:25:35.860 --> 00:25:38.420 animated version of the Artemis going around 664 00:25:38.420 --> 00:25:40.580 the moon so that we can see the whole thing 665 00:25:40.580 --> 00:25:43.460 in context in terms of the solar system, or 666 00:25:43.460 --> 00:25:45.300 at least our area of the solar system system. 667 00:25:45.720 --> 00:25:48.700 Uh, it's not going to convince him, I'm sure, 668 00:25:48.700 --> 00:25:51.540 but I think it'd be pretty cool to see 669 00:25:51.540 --> 00:25:54.300 something like that. Anyway, thanks very 670 00:25:54.300 --> 00:25:56.720 much, gentlemen, for the show, as always. Um, 671 00:25:56.720 --> 00:25:59.580 look forward to it every week and catch you 672 00:25:59.580 --> 00:25:59.940 later. 673 00:26:00.340 --> 00:26:01.140 Jonti Horner: Have a good one. 674 00:26:01.300 --> 00:26:04.100 Andrew Dunkley: You too, Paul. Thank you. If only we had 675 00:26:04.100 --> 00:26:06.980 an astrophysicist somewhere nearby. 676 00:26:07.300 --> 00:26:09.700 Jonty, any I know 677 00:26:10.420 --> 00:26:12.020 was directing the question to Fred Watson, 678 00:26:12.020 --> 00:26:13.860 but he asked for an 679 00:26:13.860 --> 00:26:15.060 astrophysicist. 680 00:26:15.300 --> 00:26:17.560 Jonti Horner: Yeah. We are legion, for we are many. There's 681 00:26:17.560 --> 00:26:19.680 plenty of us around. It, uh, was always a 682 00:26:19.680 --> 00:26:22.160 thing when I was at uni of what title you use 683 00:26:22.160 --> 00:26:23.680 for what you're studying would depend on how 684 00:26:23.680 --> 00:26:25.200 bothered you were about the conversation. 685 00:26:25.200 --> 00:26:27.320 Because if, you know, if I told someone I was 686 00:26:27.320 --> 00:26:30.040 studying physics, said very quickly, exit 687 00:26:30.040 --> 00:26:31.600 stage left, if I told them I was doing 688 00:26:31.600 --> 00:26:33.320 astronomy, they'd stay and chat. And if I 689 00:26:33.320 --> 00:26:34.960 told them I was doing astrophysics, they'd 690 00:26:34.960 --> 00:26:37.720 just look a little bit scared. Um, but I was 691 00:26:37.720 --> 00:26:38.400 doing all three. 692 00:26:39.040 --> 00:26:41.760 This is an interesting one. I mean, 693 00:26:42.870 --> 00:26:45.440 people like the flat Earthers are difficult. 694 00:26:45.440 --> 00:26:45.480 David: Ah. 695 00:26:46.070 --> 00:26:48.950 Jonti Horner: Because there is no amount of truth, no 696 00:26:48.950 --> 00:26:51.030 amount of evidence that you can put before 697 00:26:51.030 --> 00:26:52.630 people who are convinced that they've been 698 00:26:52.630 --> 00:26:55.550 lied to, um, other than talking to 699 00:26:55.550 --> 00:26:57.590 them gently about it. And it's like 700 00:26:58.070 --> 00:26:59.990 discussions of climate change I've had in the 701 00:26:59.990 --> 00:27:02.070 past with people who argue climate change 702 00:27:02.070 --> 00:27:04.790 isn't real. Arguing and fighting with people 703 00:27:05.110 --> 00:27:07.510 over this doesn't win hearts and minds. It 704 00:27:07.510 --> 00:27:09.390 just gets them more entrenched. But talking 705 00:27:09.390 --> 00:27:11.650 to them about it and talking about why we 706 00:27:11.650 --> 00:27:14.010 think something is the case, this is our 707 00:27:14.010 --> 00:27:17.010 evidence, this is what it is. That can 708 00:27:17.010 --> 00:27:18.570 be a little bit more fruitful, I guess, but 709 00:27:18.570 --> 00:27:19.890 it is really challenging. I mean, especially 710 00:27:19.890 --> 00:27:21.490 given that we had a beautiful eclipse of the 711 00:27:21.490 --> 00:27:23.730 moon just a few months ago, where you can see 712 00:27:23.730 --> 00:27:25.450 that the shadow of the Earth is round. 713 00:27:27.930 --> 00:27:30.410 Andrew Dunkley: And that's the big argument. If the Earth was 714 00:27:30.410 --> 00:27:33.130 flat, the shadow at some stage would be 715 00:27:33.130 --> 00:27:35.530 just a line across the Moon. 716 00:27:35.530 --> 00:27:38.500 Jonti Horner: We'd see the elephants in the turtle. Um, 717 00:27:38.960 --> 00:27:40.480 the other thing is, if the Earth was flat, 718 00:27:40.480 --> 00:27:41.960 the cats would have pushed everything off the 719 00:27:41.960 --> 00:27:44.800 edge by now. Yes, yes, 720 00:27:44.880 --> 00:27:47.640 that's the other one. But, uh, in terms of 721 00:27:47.640 --> 00:27:50.160 Artemis, at the end of the day, 722 00:27:50.640 --> 00:27:53.240 we know it happened because we saw it. You 723 00:27:53.240 --> 00:27:56.040 know, I was over in Europe at the 724 00:27:56.040 --> 00:27:58.800 time, and, um, my colleagues at UNISQ were 725 00:27:58.800 --> 00:28:00.680 happily sharing their own little footage of 726 00:28:00.680 --> 00:28:02.840 the spacecraft that they got from our 727 00:28:02.840 --> 00:28:05.600 telescopes. They have no reason to lie. 728 00:28:05.760 --> 00:28:08.560 They have no vested interest in this. It's 729 00:28:08.560 --> 00:28:09.960 not like they're secretly on the payroll of 730 00:28:09.960 --> 00:28:12.880 NASA, ignoring the fact that if it was faked, 731 00:28:13.440 --> 00:28:15.560 Russia and China will be racing to tell 732 00:28:15.560 --> 00:28:17.840 everybody because that will be the best PR 733 00:28:17.840 --> 00:28:20.120 victory ever. You know, I mean, it's the same 734 00:28:20.120 --> 00:28:22.720 with the Moon landings in, uh, 1969. 735 00:28:23.280 --> 00:28:25.040 Did anybody really, really think that the 736 00:28:25.040 --> 00:28:26.600 Russians would have stayed quiet if there was 737 00:28:26.600 --> 00:28:28.000 a sniff of it being faked? 738 00:28:28.960 --> 00:28:31.040 Andrew Dunkley: In fact, my great grandmother 739 00:28:32.510 --> 00:28:34.590 always thought the Apollo landings were 740 00:28:34.590 --> 00:28:37.390 faked. Uh, she absolutely refused 741 00:28:37.470 --> 00:28:40.150 to believe it. But she grew up in an era 742 00:28:40.150 --> 00:28:42.430 before flight, so 743 00:28:43.070 --> 00:28:46.070 I can understand why she would 744 00:28:46.070 --> 00:28:47.550 think that, but she just thought it was all 745 00:28:47.550 --> 00:28:50.150 just some sort of publicity stunt. But I 746 00:28:50.150 --> 00:28:51.710 don't remember what they might have been 747 00:28:52.190 --> 00:28:53.550 trying to get publicity for, 748 00:28:53.550 --> 00:28:54.910 Jonti Horner: because they beat the Russians. I mean, 749 00:28:54.910 --> 00:28:56.110 that's what it was to them. I'll beat the 750 00:28:56.110 --> 00:28:58.190 Soviets as it was then, have been pulled up 751 00:28:58.190 --> 00:28:58.910 on that a couple of times. 752 00:28:58.910 --> 00:29:00.750 Andrew Dunkley: It was definitely a big PR, um, 753 00:29:00.750 --> 00:29:03.370 Jonti Horner: exercise in that regard. Uh, a former 754 00:29:03.370 --> 00:29:05.250 PhD student who worked with me, Jake Clark, 755 00:29:05.250 --> 00:29:08.250 Dr. Jack Clark, now M, gave a wonderful talk 756 00:29:08.250 --> 00:29:10.890 a couple of times about the 757 00:29:10.970 --> 00:29:13.330 moon landings in 1969 and why they couldn't 758 00:29:13.330 --> 00:29:14.770 have been faked because we couldn't afford 759 00:29:14.770 --> 00:29:17.610 it. Talking about faking it with the 760 00:29:17.610 --> 00:29:19.209 technology we had at the time would have 761 00:29:19.209 --> 00:29:20.610 actually been more expensive than going 762 00:29:20.610 --> 00:29:23.570 there. Um, which is fairly compelling 763 00:29:23.570 --> 00:29:25.170 for me. I mean, there's always a joke that, 764 00:29:25.170 --> 00:29:26.970 you know, yeah, the moon landings were always 765 00:29:26.970 --> 00:29:28.410 going to be faked, but they hired Stanley 766 00:29:28.410 --> 00:29:29.850 Kubrick to direct and he was such a 767 00:29:29.850 --> 00:29:31.290 perfectionist that they demanded that they do 768 00:29:31.290 --> 00:29:32.740 it on site. Um, 769 00:29:34.970 --> 00:29:37.920 um, with Artemis 2, there 770 00:29:38.080 --> 00:29:40.800 is abundant evidence that it really happened. 771 00:29:41.440 --> 00:29:43.000 You could, with a small telescope or 772 00:29:43.000 --> 00:29:44.440 binoculars, go outside and see the 773 00:29:44.440 --> 00:29:46.920 spacecraft. And I mean, you can't fake that. 774 00:29:46.920 --> 00:29:48.320 It's not like we're beaming thoughts into 775 00:29:48.320 --> 00:29:49.880 your head. And if you think we are, you can 776 00:29:49.880 --> 00:29:51.440 wear some tinfoil. That's all good. 777 00:29:52.250 --> 00:29:54.920 Um, in terms of the 778 00:29:54.920 --> 00:29:56.840 argument that the Earth is going too quick 779 00:29:56.840 --> 00:29:59.670 for this thing to catch up, that is 780 00:30:00.470 --> 00:30:03.350 in the kindest interpretation of it, that 781 00:30:03.350 --> 00:30:06.190 is allowing common sense 782 00:30:06.190 --> 00:30:08.590 based on your understanding of how day to day 783 00:30:08.590 --> 00:30:10.870 life works, interfere with 784 00:30:11.590 --> 00:30:13.390 looking at how things would move through 785 00:30:13.390 --> 00:30:15.710 space. I can see why you would get to that. 786 00:30:15.710 --> 00:30:18.230 If you think about a small child running 787 00:30:18.230 --> 00:30:20.070 along with a model of Artemis in the hand and 788 00:30:20.070 --> 00:30:22.110 a Ferrari driving down the motorway, or 789 00:30:22.110 --> 00:30:23.990 insert the make of car driving down the 790 00:30:23.990 --> 00:30:26.360 motorway at 100 kilometres an hour, the child 791 00:30:26.360 --> 00:30:27.840 is not going to catch the thing because 792 00:30:27.840 --> 00:30:30.180 they're not quick enough. And there are, uh, 793 00:30:30.240 --> 00:30:32.120 limits on how fast a child can run and how 794 00:30:32.120 --> 00:30:33.640 fast the car can move to do with air 795 00:30:33.640 --> 00:30:36.240 resistance. It's 796 00:30:36.480 --> 00:30:39.000 however, almost similar to saying, you know, 797 00:30:39.000 --> 00:30:41.160 I can't throw a ball up in the air and catch 798 00:30:41.160 --> 00:30:43.640 it because I'm Moving at over 1000 kilometres 799 00:30:43.640 --> 00:30:45.800 an hour around the Earth. So I'm moving too 800 00:30:45.800 --> 00:30:48.520 fast to catch up with that ball. Doesn't work 801 00:30:48.520 --> 00:30:49.960 like that because me and the ball are both 802 00:30:49.960 --> 00:30:52.560 moving at 1000 kilometres per hour. And so 803 00:30:52.560 --> 00:30:54.560 it's a relative speed between us that 804 00:30:54.560 --> 00:30:57.080 matters. So the Earth is going around the sun 805 00:30:57.080 --> 00:30:59.120 at about 30 kilometres a second. That's 806 00:30:59.280 --> 00:31:02.280 demonstrably true. Artemis moving 807 00:31:02.280 --> 00:31:05.040 in orbit around the Earth is moving around 808 00:31:05.040 --> 00:31:07.280 the sun at 30 kilometres a second with the 809 00:31:07.280 --> 00:31:09.400 Earth. It's falling with the Earth. Uh, so 810 00:31:09.400 --> 00:31:11.360 it's a relative speed that matters. 811 00:31:12.080 --> 00:31:12.640 Andrew Dunkley: Yeah. 812 00:31:12.640 --> 00:31:14.880 Jonti Horner: Now, if I went above the Earth, onto the 813 00:31:14.880 --> 00:31:17.440 space station, but instead of orbiting the, 814 00:31:17.440 --> 00:31:19.400 uh, Earth and falling with things, I was able 815 00:31:19.400 --> 00:31:22.310 to use rockets to stand still. Or I had 816 00:31:22.390 --> 00:31:24.910 an imaginary hovering platform of doom that 817 00:31:24.910 --> 00:31:26.630 wasn't moving. I'm, um, out of the 818 00:31:26.630 --> 00:31:28.870 atmosphere. If I threw a ball up in the air, 819 00:31:29.110 --> 00:31:30.550 it would move away from the Earth and the 820 00:31:30.550 --> 00:31:31.910 Earth's gravity would slow it down and pull 821 00:31:31.910 --> 00:31:33.470 it back, and it'd fall back down to me just 822 00:31:33.470 --> 00:31:35.190 the same as how it does on the ground. 823 00:31:36.310 --> 00:31:39.230 Now, if I was in orbit around the Earth and 824 00:31:39.230 --> 00:31:40.630 I was stood on the International Space 825 00:31:40.630 --> 00:31:42.670 Station and I tossed the ball upward, it 826 00:31:42.670 --> 00:31:44.270 would actually start moving on a different 827 00:31:44.270 --> 00:31:45.710 orbit around the Earth. So while it would 828 00:31:45.710 --> 00:31:47.510 move up, away from me and it would move down, 829 00:31:47.830 --> 00:31:49.790 it'd be going around the Earth on an orbit 830 00:31:49.790 --> 00:31:51.510 that takes slightly longer to go around the 831 00:31:51.510 --> 00:31:52.940 Earth than I do. So it also fall behind, 832 00:31:53.010 --> 00:31:54.850 behind. And that would look like wind 833 00:31:54.850 --> 00:31:57.290 resistance. But it's actually just a quirk of 834 00:31:57.290 --> 00:31:59.730 orbital mechanics in that I've put it onto a 835 00:31:59.730 --> 00:32:02.610 different orbit, um, because we are both 836 00:32:02.610 --> 00:32:05.290 falling at the time I let go of it. So if we 837 00:32:05.290 --> 00:32:07.370 imagine our flat Earther jumped off a cliff, 838 00:32:07.370 --> 00:32:09.410 and I'm not encouraging them to please do not 839 00:32:09.410 --> 00:32:11.930 do this, but imagine one jumps off a cliff 840 00:32:11.930 --> 00:32:14.090 while holding one of the shot puts from the 841 00:32:14.090 --> 00:32:16.370 previous answer without it being on a bungee 842 00:32:16.370 --> 00:32:18.930 cord. And they let go of the shot put, but 843 00:32:18.930 --> 00:32:20.890 the shot put will fall with them at the same 844 00:32:20.890 --> 00:32:23.810 speed. It won't move away from them and come 845 00:32:23.810 --> 00:32:26.330 back. It will accelerate downwards in exactly 846 00:32:26.330 --> 00:32:28.330 the same way that they do. And, uh, they'll 847 00:32:28.330 --> 00:32:30.970 only diverge once air resistance takes 848 00:32:30.970 --> 00:32:33.210 effect, depending on which of them feels more 849 00:32:33.210 --> 00:32:33.970 air resistance. 850 00:32:35.090 --> 00:32:37.210 Andrew Dunkley: It's the Galileo experiment, isn't it? 851 00:32:37.210 --> 00:32:39.010 Jonti Horner: So if you're on the space station, you throw 852 00:32:39.010 --> 00:32:40.530 a tennis ball up in the air. Ah, you're both 853 00:32:40.530 --> 00:32:42.050 actually falling, but you've changed the 854 00:32:42.050 --> 00:32:43.450 speed the tennis ball's falling, so it'll 855 00:32:43.450 --> 00:32:45.610 move away from you and not appear to come 856 00:32:45.610 --> 00:32:47.790 back because you're both still falling. 857 00:32:48.590 --> 00:32:50.630 The reason all this is relevant to Artemis is 858 00:32:50.630 --> 00:32:53.020 Artemis boosted off towards the Moon at, uh, 859 00:32:53.110 --> 00:32:55.630 a speed that was not greater than the escape 860 00:32:55.630 --> 00:32:57.950 velocity from the Earth. It was a speed that 861 00:32:57.950 --> 00:33:00.120 was high enough to get to the Moon. And, uh, 862 00:33:00.150 --> 00:33:01.830 the moon steered it around and flung it back 863 00:33:01.830 --> 00:33:04.030 towards the Earth. But then it fell towards 864 00:33:04.030 --> 00:33:06.830 the Earth under Earth's gravity, moving 865 00:33:06.990 --> 00:33:09.910 with insufficient sideward speed that as 866 00:33:09.910 --> 00:33:11.630 it fell towards the Earth, it would miss us. 867 00:33:12.340 --> 00:33:13.740 It instead was going to hit us. And they 868 00:33:13.740 --> 00:33:15.300 controlled it with rockets and stuff so that 869 00:33:15.300 --> 00:33:16.780 it entered in a controlled rather than 870 00:33:16.780 --> 00:33:19.740 uncontrolled fashion. What matters is 871 00:33:19.740 --> 00:33:21.260 not the speed the Earth's moving around the 872 00:33:21.260 --> 00:33:23.300 sun, or the speed the sun's moving around our 873 00:33:23.300 --> 00:33:25.020 galaxy, or the speed that the galaxy is 874 00:33:25.020 --> 00:33:27.899 moving through space. All that matters is the 875 00:33:27.899 --> 00:33:29.620 difference in speed between the Earth and the 876 00:33:29.620 --> 00:33:32.060 object, because they're moving together. This 877 00:33:32.060 --> 00:33:34.540 thing's speed was at no time greater than the 878 00:33:34.540 --> 00:33:36.900 escape velocity of the Earth, so it could 879 00:33:36.900 --> 00:33:38.960 never fall away from the Earth and never come 880 00:33:38.960 --> 00:33:40.480 back. It was always going to go up and then 881 00:33:40.480 --> 00:33:43.200 come down again. Unless they use rockets to 882 00:33:43.200 --> 00:33:44.880 boost it into an orbit around the moon to 883 00:33:44.880 --> 00:33:46.880 shed some of that energy, which they didn't. 884 00:33:46.880 --> 00:33:48.720 They instead slingshot it around the moon to 885 00:33:48.720 --> 00:33:51.560 come back. All of that is perfectly 886 00:33:51.560 --> 00:33:53.600 rational and straightforward given our 887 00:33:53.600 --> 00:33:55.920 understanding of physics. But it doesn't 888 00:33:55.920 --> 00:33:58.400 necessarily fit your common sense, because 889 00:33:58.400 --> 00:34:00.480 you think about throwing a ball out of the 890 00:34:00.480 --> 00:34:02.240 window of your car while your car's doing 100 891 00:34:02.240 --> 00:34:03.600 kilometres an hour and the ball will fall 892 00:34:03.600 --> 00:34:06.360 behind you and never catch you up. And so 893 00:34:06.360 --> 00:34:09.029 a lot of the arguments that 894 00:34:09.029 --> 00:34:11.469 flat Earth, uh, believers or other people in 895 00:34:11.469 --> 00:34:14.309 that kind of situation are making good faith 896 00:34:14.709 --> 00:34:16.869 are, uh, built on a faulty groundwork 897 00:34:17.829 --> 00:34:20.629 where the common sense of how they understand 898 00:34:20.709 --> 00:34:22.749 the world to work is not applicable to the 899 00:34:22.749 --> 00:34:25.080 situation they're applying it in. Um, 900 00:34:25.669 --> 00:34:27.909 and that's true of things like, you know, the 901 00:34:27.909 --> 00:34:30.589 oceans are flat. If you put a spirit level on 902 00:34:30.589 --> 00:34:32.109 them, they're flat. Well, it's actually that 903 00:34:32.109 --> 00:34:33.429 they're curved, but they're curved at such 904 00:34:33.429 --> 00:34:35.429 small level that locally they look flat. 905 00:34:36.299 --> 00:34:37.979 It's a subtle difference, but it's one that's 906 00:34:37.979 --> 00:34:39.299 easy to miss because it's hard to get your 907 00:34:39.299 --> 00:34:40.379 head around those distances. 908 00:34:41.259 --> 00:34:43.099 In terms of the animations. I just did a 909 00:34:43.099 --> 00:34:45.739 quick Google search for Artemis animation of 910 00:34:45.739 --> 00:34:48.219 orbit, and there's some beautiful. The first 911 00:34:48.219 --> 00:34:51.059 hit is a NASA flight with an annotated and 912 00:34:51.059 --> 00:34:53.779 animated path. There's a few YouTube videos, 913 00:34:53.779 --> 00:34:56.299 there is a Reddit link with an interactive 3D 914 00:34:56.299 --> 00:34:59.259 animation. There's a lot of 915 00:34:59.339 --> 00:35:01.579 little YouTube short videos that pop up 916 00:35:02.190 --> 00:35:04.590 which are not to scale, because if you make 917 00:35:04.590 --> 00:35:06.150 things to scale, the sun and the Earth and 918 00:35:06.150 --> 00:35:08.310 the Moon are points that are one pixel 919 00:35:08.310 --> 00:35:11.150 across. And, um, the spaceship is a point 920 00:35:11.150 --> 00:35:12.550 that is a pixel across as well, because 921 00:35:12.550 --> 00:35:15.540 nothing can be smaller than a pixel. Um, 922 00:35:15.540 --> 00:35:17.260 there is a fabulous thing, incidentally, and, 923 00:35:17.260 --> 00:35:18.990 um, I'm gonna see if I can find it, see if 924 00:35:18.990 --> 00:35:19.630 it's still there. 925 00:35:21.630 --> 00:35:23.830 There's this great thing called if the Moon 926 00:35:23.830 --> 00:35:26.540 were Only One Pixel. Um, 927 00:35:26.590 --> 00:35:29.150 it is. I'm gonna see if the website still 928 00:35:29.150 --> 00:35:30.830 works, because this is one of the great 929 00:35:30.830 --> 00:35:32.390 things on the Internet. Here we go. I'm gonna 930 00:35:32.390 --> 00:35:35.150 Drop it into the chat window. This, um, 931 00:35:35.390 --> 00:35:37.830 was an effort somebody made many, many, long, 932 00:35:37.830 --> 00:35:39.470 long years ago. I'll put this into the public 933 00:35:39.470 --> 00:35:41.910 chat, which never gets used. There we go. To 934 00:35:41.910 --> 00:35:44.310 visualise the scale of the solar system, 935 00:35:44.870 --> 00:35:47.670 if you made the moon one pixel across, 936 00:35:47.670 --> 00:35:49.590 so the Earth will then be two or three pixels 937 00:35:49.590 --> 00:35:52.510 across, you can, when you get bored of 938 00:35:52.510 --> 00:35:54.070 scrolling, you can click Play. But if you 939 00:35:54.070 --> 00:35:55.750 open that up and then you scroll to the right 940 00:35:55.750 --> 00:35:58.070 to explore, you move along 941 00:35:58.630 --> 00:36:00.870 and then you've got the scale. One pixel is 942 00:36:00.870 --> 00:36:03.790 3,500 kilometres, so the sun is a fairly big 943 00:36:03.790 --> 00:36:06.430 blob. And you scroll to the right from the 944 00:36:06.430 --> 00:36:08.550 sun and you've got a distance at the bottom. 945 00:36:08.870 --> 00:36:10.670 Scroll to the right a long way. We've gone 10 946 00:36:10.670 --> 00:36:12.429 million kilometres. This is this fabulous 947 00:36:12.429 --> 00:36:14.630 visualisation to let you see how big 948 00:36:15.110 --> 00:36:15.910 things are. 949 00:36:16.550 --> 00:36:17.750 Andrew Dunkley: Oh, isn't that clever? 950 00:36:17.830 --> 00:36:20.710 Jonti Horner: How fast light travels. You can click, um. 951 00:36:20.870 --> 00:36:23.800 That's slow. It's fabulous. Now what 952 00:36:23.800 --> 00:36:26.240 you can do is you can skip through. 953 00:36:26.640 --> 00:36:29.200 I need to find where there was a way to skip 954 00:36:29.200 --> 00:36:31.280 to the Earth. Yes, at the top. Skip to the 955 00:36:31.280 --> 00:36:33.200 Earth, goes whiz, whiz, whiz, whiz, whiz. 956 00:36:33.200 --> 00:36:34.960 Really quick, goes past Venus, comes to the 957 00:36:34.960 --> 00:36:37.720 Earth and the Moon. If the moon is one pixel, 958 00:36:37.720 --> 00:36:39.880 the earth is only two or three and you get 959 00:36:39.880 --> 00:36:42.400 the scale of them 8.3 light minutes out from 960 00:36:42.400 --> 00:36:44.640 the sun. And think how far you've got to 961 00:36:44.640 --> 00:36:47.520 scroll to get there. Think with that moon 962 00:36:47.520 --> 00:36:49.400 being a single pixel, how far it is from the 963 00:36:49.400 --> 00:36:52.230 Earth. This is why none of those animations 964 00:36:52.230 --> 00:36:55.190 have things to scale, because you wouldn't 965 00:36:55.190 --> 00:36:56.830 see the spacecraft, you wouldn't see the 966 00:36:56.830 --> 00:36:57.950 Earth and the moon, they wouldn't look 967 00:36:57.950 --> 00:37:00.270 pretty. So the caution there is that, uh, the 968 00:37:00.270 --> 00:37:02.390 animations that you see, even the beautiful 969 00:37:02.390 --> 00:37:05.310 NASA ones that show the flight path, are, 970 00:37:05.310 --> 00:37:07.150 ah, not to scale. And, um, that can be 971 00:37:07.150 --> 00:37:09.590 misleading. That can also 972 00:37:10.390 --> 00:37:12.110 add to some of the arguments that this is 973 00:37:12.110 --> 00:37:14.310 fake, because people say, well, the Earth and 974 00:37:14.310 --> 00:37:15.430 the Moon are much smaller than that and 975 00:37:15.430 --> 00:37:16.790 they're much further apart. Uh, that looks 976 00:37:16.790 --> 00:37:19.790 wrong. Um, so it's worth being explicit 977 00:37:19.790 --> 00:37:22.110 that these are, these visualisations are, um, 978 00:37:22.120 --> 00:37:25.040 definitively not to scale. Um, the one, 979 00:37:25.040 --> 00:37:26.800 incidentally, that was linked on the Reddit 980 00:37:26.800 --> 00:37:29.240 page looks like the dots for Earth and Moon 981 00:37:29.240 --> 00:37:30.880 actually are more to scale. So I'll just drop 982 00:37:30.880 --> 00:37:33.280 that one in as well. Not sure how this works, 983 00:37:33.280 --> 00:37:34.720 I've not really played with it. But you can 984 00:37:34.720 --> 00:37:36.240 drag the orbits around, you can move them 985 00:37:36.240 --> 00:37:38.520 back and forward in time, you can see the in 986 00:37:38.520 --> 00:37:41.360 and out of plane stuff and you can move the 987 00:37:41.360 --> 00:37:43.280 visualisation around even with the background 988 00:37:43.280 --> 00:37:45.760 stars, which is quite nice. Um, so that's 989 00:37:45.760 --> 00:37:47.360 worth a play as well. And that looks a bit 990 00:37:47.360 --> 00:37:49.880 more to scale. And there's lots of things you 991 00:37:49.880 --> 00:37:52.840 can play with, but fundamentally we 992 00:37:52.840 --> 00:37:55.360 could see it. The hardest part for me, about 993 00:37:55.840 --> 00:37:57.840 the small number of people who have argued 994 00:37:57.840 --> 00:37:59.840 that the Artemis mission didn't happen, 995 00:38:00.800 --> 00:38:02.480 is that it's something that anybody on the 996 00:38:02.480 --> 00:38:03.920 planet could see, so long as they owned a 997 00:38:03.920 --> 00:38:06.280 binoculars or a telescope. You could have 998 00:38:06.280 --> 00:38:07.400 pointed somewhere and you could see the 999 00:38:07.400 --> 00:38:10.040 capsule moving there if you really wanted. At 1000 00:38:10.040 --> 00:38:12.000 any time when the moon was above the horizon, 1001 00:38:12.640 --> 00:38:13.760 you could track it round. 1002 00:38:15.970 --> 00:38:17.730 Andrew Dunkley: And if you've got good enough gear, you can 1003 00:38:17.730 --> 00:38:19.490 actually look at the moon and see 1004 00:38:20.370 --> 00:38:23.290 the landing positions of some 1005 00:38:23.290 --> 00:38:25.570 of the Apollos. If you've got the gear. 1006 00:38:25.570 --> 00:38:26.850 Jonti Horner: If you've got the gear, I mean, that's kind 1007 00:38:26.850 --> 00:38:28.570 of spice athlete level. But what you can do 1008 00:38:28.570 --> 00:38:31.250 if you've got slightly less of the gear is 1009 00:38:31.410 --> 00:38:33.730 bounce laser pulses 1010 00:38:34.130 --> 00:38:36.290 off the retroreflectors that the astronauts 1011 00:38:36.290 --> 00:38:38.690 left at those sites and measure the distance 1012 00:38:38.690 --> 00:38:41.380 to the moon and measure its recession to an 1013 00:38:41.380 --> 00:38:43.300 incredible precision. And we can only do that 1014 00:38:43.300 --> 00:38:44.740 because people went to the moon. 1015 00:38:46.580 --> 00:38:48.660 Andrew Dunkley: Yeah, absolutely. 1016 00:38:50.660 --> 00:38:53.060 I remember the day that Neil 1017 00:38:53.060 --> 00:38:55.370 Armstrong stepped on the moon. I was, um, 1018 00:38:55.370 --> 00:38:56.420 sent home from school. 1019 00:38:59.380 --> 00:39:01.300 It's one of the strongest memories of my 1020 00:39:01.300 --> 00:39:03.510 childhood. I was seven years old and, uh, 1021 00:39:03.510 --> 00:39:06.380 I'll never forget it. It was, um, quite 1022 00:39:06.380 --> 00:39:08.680 an extraordinary thing in human history. 1023 00:39:09.080 --> 00:39:09.760 Inspirational. 1024 00:39:09.760 --> 00:39:12.600 Jonti Horner: I mean, I, I'm not old enough to have ever 1025 00:39:12.600 --> 00:39:14.200 seen anybody walk on the moon. I'm hoping 1026 00:39:14.200 --> 00:39:16.400 that'll change. But the generation of 1027 00:39:16.400 --> 00:39:19.084 astronomers who are 15, 1028 00:39:19.156 --> 00:39:21.560 20 years older than me, who were old enough 1029 00:39:21.560 --> 00:39:23.320 to see the moon landings and take them in, 1030 00:39:24.360 --> 00:39:25.960 so many people were inspired to become 1031 00:39:25.960 --> 00:39:28.720 scientists and engineers by that. We got a 1032 00:39:28.720 --> 00:39:31.680 whole generation of people across 1033 00:39:31.680 --> 00:39:34.080 the sciences, across the engineering subjects 1034 00:39:34.080 --> 00:39:37.070 that changed the world, who were all inspired 1035 00:39:37.070 --> 00:39:39.550 by seeing people walk on the moon. 1036 00:39:40.190 --> 00:39:42.110 And, um, it's kind of exciting to me, even 1037 00:39:42.110 --> 00:39:43.830 ignoring the signs, even ignoring the 1038 00:39:43.830 --> 00:39:45.510 technology, that we're going to get that 1039 00:39:45.510 --> 00:39:46.990 experience again in the coming years. If we 1040 00:39:46.990 --> 00:39:48.470 go back there, there'll be a whole new 1041 00:39:48.470 --> 00:39:50.590 generation who will change the world. All 1042 00:39:50.590 --> 00:39:52.710 inspired by those people touching down and 1043 00:39:52.710 --> 00:39:53.390 seeing it happen. 1044 00:39:54.190 --> 00:39:57.190 Andrew Dunkley: Yes, yes. I was very lucky to meet one 1045 00:39:57.190 --> 00:40:00.110 of them. Uh, Buzz Aldrin, um, some years ago, 1046 00:40:00.110 --> 00:40:03.030 came here because they built a Reutt 1047 00:40:03.030 --> 00:40:05.830 Flyer at a place called Narrowmine, just up 1048 00:40:05.830 --> 00:40:08.250 the road from here, 40 kilomet, and they took 1049 00:40:08.250 --> 00:40:10.970 it out for a fly and he came for the 1050 00:40:10.970 --> 00:40:13.650 occasion and, uh, gave A wonderful 1051 00:40:13.650 --> 00:40:16.290 speech and a, uh, handful of us in the media 1052 00:40:16.290 --> 00:40:18.930 got to interview him afterwards in a, in a 1053 00:40:18.930 --> 00:40:21.610 hangar at the same time as a helicopter 1054 00:40:21.610 --> 00:40:22.730 decided to take off. 1055 00:40:23.130 --> 00:40:24.250 Jonti Horner: That sounds about right. 1056 00:40:24.410 --> 00:40:26.970 Andrew Dunkley: He famously, you know what? You just, you 1057 00:40:26.970 --> 00:40:27.730 just go with it. 1058 00:40:27.730 --> 00:40:30.050 Jonti Horner: Oh, he very famously gave very short shrift 1059 00:40:30.050 --> 00:40:31.730 to people who told him that he'd not been to 1060 00:40:31.730 --> 00:40:32.170 the moon. 1061 00:40:32.570 --> 00:40:35.500 Andrew Dunkley: Oh, I know. Uh, Ah, yeah, I did 1062 00:40:35.500 --> 00:40:38.340 actually raise that question, but gee, it was 1063 00:40:38.340 --> 00:40:39.700 such an interesting answer. 1064 00:40:41.060 --> 00:40:42.180 Yeah, fabulous. 1065 00:40:42.230 --> 00:40:44.940 Um, Paul, great question, really 1066 00:40:44.940 --> 00:40:46.580 enjoyed that one and I, 1067 00:40:48.740 --> 00:40:51.370 I can understand your frustration, but, um, 1068 00:40:51.370 --> 00:40:53.540 maybe just avoid those Facebook pages, 1069 00:40:54.390 --> 00:40:56.540 um, because you can't, you just can't save 1070 00:40:56.540 --> 00:40:58.940 them, my friend. Uh, but good to hear from 1071 00:40:58.940 --> 00:41:00.540 you. Uh, if you've got questions for us, 1072 00:41:00.540 --> 00:41:02.420 please send them in. Uh, you can do that via 1073 00:41:02.420 --> 00:41:04.980 our website, space nutspodcast.com or 1074 00:41:04.980 --> 00:41:07.680 spacenut. You can also 1075 00:41:08.080 --> 00:41:09.920 visit us on social media. We've got the 1076 00:41:09.920 --> 00:41:11.800 official Space Nuts Facebook page and the 1077 00:41:11.800 --> 00:41:14.160 official. What's, uh, the 1078 00:41:14.480 --> 00:41:17.120 Instagram page. Uh, we've also got the 1079 00:41:17.280 --> 00:41:19.880 user group on Facebook, um, the 1080 00:41:19.880 --> 00:41:22.720 podcast group, uh, uh, which is 1081 00:41:22.720 --> 00:41:25.680 all. It's a lot of fun. It's where people who 1082 00:41:25.680 --> 00:41:28.440 listen get together, swap photos of stuff 1083 00:41:28.440 --> 00:41:30.890 they've taken in space and ask, uh, 1084 00:41:31.160 --> 00:41:34.080 questions. And, uh, it is a really good 1085 00:41:34.080 --> 00:41:37.040 group. So the Space Nuts podcast group on 1086 00:41:37.040 --> 00:41:39.820 Facebook book very much worth, uh, joining 1087 00:41:39.820 --> 00:41:42.420 that one as well and hope you'll join us 1088 00:41:42.420 --> 00:41:44.620 again real soon. And thank you to Johnny 1089 00:41:44.620 --> 00:41:46.580 Horner for filling in for Fred Watson for the 1090 00:41:46.580 --> 00:41:49.380 last month or so. It's been fantastic and 1091 00:41:49.380 --> 00:41:51.190 hopefully we can get that photography, uh, 1092 00:41:51.860 --> 00:41:53.660 special off the ground and get you back and 1093 00:41:53.660 --> 00:41:56.060 have a chat about astrophotography. Jonty, 1094 00:41:56.060 --> 00:41:57.140 that would be a real good one. 1095 00:41:57.140 --> 00:41:58.540 Jonti Horner: Fingers crossed. That would be awesome. 1096 00:41:59.500 --> 00:42:01.660 Andrew Dunkley: Yeah. All right, catch you soon. Thank you so 1097 00:42:01.660 --> 00:42:01.670 much. 1098 00:42:01.670 --> 00:42:03.340 Jonti Horner: M m. Take care. Thank you very much. 1099 00:42:04.260 --> 00:42:05.780 Andrew Dunkley: Professor Johnty Horner, professor of 1100 00:42:05.780 --> 00:42:07.780 Astrophysics at the University of Southern 1101 00:42:07.780 --> 00:42:09.700 Queensland, filling, uh, in for Fred Watson. 1102 00:42:09.700 --> 00:42:12.700 Fred Watson should be back, uh, next week 1103 00:42:12.700 --> 00:42:15.420 or later this week. I can't get my head 1104 00:42:15.420 --> 00:42:18.100 around when it'll be. It's a time slip thing. 1105 00:42:18.630 --> 00:42:20.820 Uh, but, uh, yeah, thanks to Jonty for 1106 00:42:20.820 --> 00:42:22.980 filling in and thanks to Huw in the studio, 1107 00:42:22.980 --> 00:42:25.780 who couldn't be with us today because he's 1108 00:42:25.780 --> 00:42:28.460 fake. Boom, boom. And from me, Andrew 1109 00:42:28.460 --> 00:42:30.020 Dunkley. Thanks for your company. We'll see 1110 00:42:30.020 --> 00:42:31.910 you on the next episode of Space Nuts. 1111 00:42:32.380 --> 00:42:32.580 Jonti Horner: Bye. 1112 00:42:32.580 --> 00:42:32.940 Andrew Dunkley: Bye. 1113 00:42:34.140 --> 00:42:36.340 Jonti Horner: You've been listening to the Space Nuts 1114 00:42:36.340 --> 00:42:39.340 podcast, available at 1115 00:42:39.340 --> 00:42:41.340 Apple Podcasts, Spotify, 1116 00:42:41.500 --> 00:42:44.260 iHeartRadio or your favourite podcast 1117 00:42:44.260 --> 00:42:45.980 player. You can also stream on 1118 00:42:45.980 --> 00:42:47.660 demand@bytes.um com 1119 00:42:47.979 --> 00:42:50.060 Andrew Dunkley: this has been another quality podcast 1120 00:42:50.060 --> 00:42:51.870 production from bytes.com 1121 00:42:51.870 --> 00:42:53.710 um.