1 00:00:03,533 --> 00:00:06,533 So, Tammo Jan is also here in the audience. 2 00:00:06,733 --> 00:00:10,000 And of course, the people from Stockert. 3 00:00:10,000 --> 00:00:12,966 Before I start the presentation, I have something else to point out. 4 00:00:13,733 --> 00:00:16,733 This was yesterday. 5 00:00:33,266 --> 00:00:34,366 Okay, now we can get to business. 6 00:00:34,366 --> 00:00:37,000 Thank you for your patience. 7 00:00:37,000 --> 00:00:40,500 So, luckily, yesterday evening, the last presentation was about Dwingeloo. 8 00:00:40,500 --> 00:00:42,033 And now the first one is. 9 00:00:42,033 --> 00:00:44,533 So I can skip a few things and spend more time on the content. 10 00:00:44,533 --> 00:00:47,366 So this is the telescope in Dwingeloo. 11 00:00:47,366 --> 00:00:50,366 Tammo Jan already talked a bit yesterday about the history. 12 00:00:50,966 --> 00:00:54,266 So here you see actually somebody in the early days watching from the telescope 13 00:00:54,266 --> 00:00:57,766 and we can use it these days for all kinds of fun projects. 14 00:00:58,233 --> 00:00:59,733 So we do pulsars. 15 00:00:59,733 --> 00:01:02,300 You've seen that yesterday. We do hydrogen. 16 00:01:02,300 --> 00:01:05,700 We have done recombination lines. 17 00:01:05,700 --> 00:01:10,200 We have received Voyager and we received all kinds of other satellites. 18 00:01:11,633 --> 00:01:15,300 And that's all received interesting stuff, either satellite 19 00:01:15,300 --> 00:01:17,266 or radio astronomy. 20 00:01:17,266 --> 00:01:19,933 But and again, as Tammo Jan already mentioned yesterday, 21 00:01:19,933 --> 00:01:23,833 we also have a group of radio amateurs using the dish. 22 00:01:23,833 --> 00:01:29,200 Over here you see one of the volunteers, Jan van Muijlwijk, who was doing, moon bouncing, EME. 23 00:01:29,366 --> 00:01:33,400 So they send signals to the moon, and then it bounces back 24 00:01:33,400 --> 00:01:36,500 and they can communicate with people all over the world via the Moon. 25 00:01:36,866 --> 00:01:39,866 And the 25 meter dish is so strong 26 00:01:40,233 --> 00:01:43,033 that if you send the signal to the moon and you switch, 27 00:01:43,033 --> 00:01:46,366 to receive in two seconds, you actually hear your own voice coming back. 28 00:01:46,900 --> 00:01:48,066 That's actually what he's doing here. 29 00:01:48,066 --> 00:01:51,900 Together with a sound artist called Hainbach, they're making recordings 30 00:01:51,900 --> 00:01:56,066 of the echoes, from the moon, for artistic purposes. 31 00:01:57,300 --> 00:01:58,500 The interesting thing is when 32 00:01:58,500 --> 00:02:02,200 you send your voice to the moon and it comes back, it sounds distorted. 33 00:02:02,566 --> 00:02:05,566 So it's not very clear audio anymore. 34 00:02:05,733 --> 00:02:10,300 But you have something which is called fading. Frequency selective fading. 35 00:02:10,300 --> 00:02:13,900 So some of the frequencies are suppressed and some of them are amplified, 36 00:02:13,900 --> 00:02:16,833 and you get a really funny voice back. 37 00:02:16,833 --> 00:02:18,833 For them, that's a distortion because they want to communicate. 38 00:02:18,833 --> 00:02:21,266 So anything that degrades the signal is bad. 39 00:02:21,266 --> 00:02:24,400 For us, it's an opportunity because something happens on the moon 40 00:02:24,433 --> 00:02:27,466 that actually transforms that signal into this distorted signal. 41 00:02:27,833 --> 00:02:29,866 So that is information about the moon. 42 00:02:29,866 --> 00:02:32,733 And that is what this presentation is about. 43 00:02:32,733 --> 00:02:35,933 We have been doing this in many steps, and we've made a lot of mistakes around, 44 00:02:36,600 --> 00:02:38,800 in the path 45 00:02:38,800 --> 00:02:41,233 and I wanted to share a little bit of what we have done and what we 46 00:02:41,233 --> 00:02:42,066 have discovered. 47 00:02:44,066 --> 00:02:46,166 So we're not the first ones to do this. 48 00:02:46,166 --> 00:02:49,200 And there was also a bit in the history talk already, yesterday. 49 00:02:49,800 --> 00:02:54,733 This is the Arecibo dish, that's unfortunately broken now and not active anymore. 50 00:02:55,700 --> 00:02:58,466 But this has been used for radar, to planets. 51 00:02:58,466 --> 00:03:02,400 So they send the signal to Venus, the signal comes back, and from that signal, 52 00:03:02,400 --> 00:03:05,400 they could actually determine the rotation of Venus. 53 00:03:05,533 --> 00:03:07,233 Which is strange, because it's the only planet 54 00:03:07,233 --> 00:03:10,233 which is rotating in the other direction than the rest of the planets. 55 00:03:10,500 --> 00:03:12,600 But due to the atmosphere, you could not see that. 56 00:03:12,600 --> 00:03:14,500 So they actually had to determine it with radar. 57 00:03:14,500 --> 00:03:17,500 This is an article from the 60s. 58 00:03:17,566 --> 00:03:20,166 So a lot of this radar research has been done, 59 00:03:20,166 --> 00:03:23,233 in the 60s, and there are very interesting papers about this. 60 00:03:23,233 --> 00:03:26,300 And we can see maybe, maybe we can do this, maybe we can. 61 00:03:26,300 --> 00:03:27,800 But that was this challenge. 62 00:03:29,066 --> 00:03:35,300 More recent, until Arecibo was broken, it was used to make pictures of Venus. 63 00:03:35,300 --> 00:03:37,766 That's actually a radar map of Venus you see there. 64 00:03:37,766 --> 00:03:39,900 And they do it together with the Greenbank telescope. 65 00:03:39,900 --> 00:03:44,500 So Arecibo sends, Greenbank receives, and they get a picture of Venus like that. 66 00:03:44,800 --> 00:03:47,166 Or they can even see an asteroid. 67 00:03:47,166 --> 00:03:48,566 Now we are going to do the same thing. 68 00:03:48,566 --> 00:03:54,533 So we are Arecibo in Dwingeloo and Wolfgang is Greenbank. 69 00:03:54,533 --> 00:03:55,600 Not exactly the same. 70 00:03:55,600 --> 00:03:57,533 We don't have the amount of power they have. 71 00:03:57,533 --> 00:04:00,966 I mean, Arecibo had something like 1.5MW to transmit. 72 00:04:00,966 --> 00:04:02,600 We have something like 80W, 73 00:04:02,600 --> 00:04:05,766 so it's not the same league, but let's see how far we can get. 74 00:04:06,466 --> 00:04:09,200 Now, there are two interesting books on this topic. 75 00:04:09,200 --> 00:04:11,666 The left book is from the 60s, and it shows 76 00:04:11,666 --> 00:04:14,333 you exactly all these experiments that that have been done. 77 00:04:15,300 --> 00:04:17,933 And the results and, and how they were done. 78 00:04:17,933 --> 00:04:19,666 So you can actually learn on how this is done. 79 00:04:19,666 --> 00:04:22,233 The right book is one of the more recent ones. 80 00:04:22,233 --> 00:04:25,600 And that shows the state of the art of planetary radar. 81 00:04:26,400 --> 00:04:27,700 Now, they’re both second hand books. 82 00:04:27,700 --> 00:04:29,866 And I just want to point out a few interesting things. 83 00:04:29,866 --> 00:04:34,200 The left book actually comes from the Royal Radar establishment here in the UK. 84 00:04:35,500 --> 00:04:38,966 Which in itself is already interesting, but this is also the site 85 00:04:39,300 --> 00:04:42,066 where they had two copies of the Dwingeloo telescope. 86 00:04:42,066 --> 00:04:45,300 So the people who used this book were actually using copies of our 87 00:04:45,300 --> 00:04:46,266 Dwingeloo telescope. 88 00:04:46,266 --> 00:04:48,533 One of them is still there. 89 00:04:48,533 --> 00:04:50,800 The other book, is even stranger. 90 00:04:50,800 --> 00:04:55,633 It comes from the from the Rutherford Appleton Laboratory over here. 91 00:04:56,033 --> 00:04:57,933 So I don't know why they threw this book away. 92 00:04:57,933 --> 00:05:00,633 This is the most recent book on radar astronomy. 93 00:05:00,633 --> 00:05:02,766 Why is it not in the library here with me? 94 00:05:02,766 --> 00:05:04,700 That's strange Anyhow, back to the topic. 95 00:05:06,000 --> 00:05:10,166 So for radar, we transmit something and we receive something back. 96 00:05:10,166 --> 00:05:13,166 So it's important to look at what is involved there. 97 00:05:13,400 --> 00:05:15,300 On the left we have the received power. 98 00:05:15,300 --> 00:05:17,566 This is the power we get back. 99 00:05:17,566 --> 00:05:20,666 It's proportial obviously to the power we transmit. 100 00:05:21,000 --> 00:05:23,100 The more power going out, the more power you get. 101 00:05:23,100 --> 00:05:26,100 But it's also dependent on the gain of the dish. 102 00:05:26,100 --> 00:05:29,100 So the bigger the dish, the bigger the signal you get back. 103 00:05:29,100 --> 00:05:30,333 And it’s also squared. 104 00:05:30,333 --> 00:05:33,566 So the gain really has a big influence on what you get back. 105 00:05:34,800 --> 00:05:37,033 It's dependent on the wavelength squared. 106 00:05:37,033 --> 00:05:39,400 And that looks a bit strange because it would suggests 107 00:05:39,400 --> 00:05:41,733 that with a larger wavelength you would get more signal back. 108 00:05:41,733 --> 00:05:43,066 It's the other way around. 109 00:05:43,066 --> 00:05:46,566 And that is because the gain of the dish is also dependent on the wavelength. 110 00:05:47,666 --> 00:05:50,766 The other one, sigma, is the size of the object. 111 00:05:50,766 --> 00:05:51,933 So the bigger it is, 112 00:05:51,933 --> 00:05:55,033 I mean an asteroid gives you much less reflection than the moon, for example. 113 00:05:55,966 --> 00:05:59,600 But the most important one is this one here. It's R to the fourth, 114 00:05:59,633 --> 00:06:02,633 which is the distance to the object to the fourth power. 115 00:06:02,966 --> 00:06:04,300 And this is our big enemy 116 00:06:04,300 --> 00:06:05,200 because there's nothing 117 00:06:05,200 --> 00:06:08,200 you can do to compensate for something that grows with the fourth power. 118 00:06:08,333 --> 00:06:13,066 So if things are further away, it gets extremely difficult to get an echo back. 119 00:06:14,033 --> 00:06:15,300 So the moon is easy. 120 00:06:15,300 --> 00:06:18,600 I mean, we know we can do it because our amateur radio amateurs are doing this. 121 00:06:18,900 --> 00:06:22,866 But getting further, this is really, really the limiting factor in all of this. 122 00:06:23,333 --> 00:06:24,866 There's no way you can get more power 123 00:06:24,866 --> 00:06:28,266 linearly to compensate for something that grows to the fourth. 124 00:06:29,200 --> 00:06:32,633 Okay, so this is how we do this in Dwingeloo. 125 00:06:33,066 --> 00:06:36,433 On the left, we have our SDR that we actually use to receive signals. 126 00:06:36,433 --> 00:06:37,466 So all these other projects 127 00:06:37,466 --> 00:06:40,366 are done with the SDR, but we also use it to transmit. 128 00:06:40,366 --> 00:06:44,733 Now we have a small amplifier that brings the level up to about one watt, 129 00:06:45,500 --> 00:06:49,033 and then we send it to the power amplifier 130 00:06:49,233 --> 00:06:52,233 the 120 watt power amplifier used by the radio amateurs. 131 00:06:52,766 --> 00:06:55,966 Then there's a cable going all the way back to the dish, 132 00:06:56,633 --> 00:06:58,500 up to the dish, to the feed. 133 00:06:58,500 --> 00:07:02,833 We lose a lot of signal in that cable, so we have an amplifier of 120W, 134 00:07:02,833 --> 00:07:07,266 but I think we get something like 80 out of the dish, which is not not that much. 135 00:07:08,000 --> 00:07:11,100 The other path is the receiver. 136 00:07:11,100 --> 00:07:12,900 And you see there's a relay there. 137 00:07:12,900 --> 00:07:16,200 And that's actually the downside of having both transmit 138 00:07:16,200 --> 00:07:17,833 and receive in the same dish. 139 00:07:17,833 --> 00:07:21,900 The relay has to be there to protect the receiver, otherwise you kill it. 140 00:07:22,600 --> 00:07:24,233 But it also affects your noise figure. 141 00:07:24,233 --> 00:07:27,466 So we are a little bit less sensitive, for example, than the Stockert telescope. 142 00:07:27,800 --> 00:07:29,400 Also because of this relay. 143 00:07:29,400 --> 00:07:33,100 So for radio astronomy this is bad. For this project, 144 00:07:33,466 --> 00:07:37,433 it's nice because now we can switch. 145 00:07:37,433 --> 00:07:39,066 So we do this with two telescopes. 146 00:07:39,066 --> 00:07:43,000 And the key here is that we have exactly the same SDR on both sides. 147 00:07:43,800 --> 00:07:46,800 Because now we need to look at the timing and the frequency 148 00:07:46,800 --> 00:07:48,600 and everything that that we get back. 149 00:07:48,600 --> 00:07:51,600 We need to make sure that the two sides are completely in sync. 150 00:07:51,833 --> 00:07:55,500 Now, these SDR have all kind of delays and offsets and whatnot as well, 151 00:07:55,866 --> 00:07:58,366 but they are exactly the same on the both sides. 152 00:07:58,366 --> 00:08:00,300 And that's really important. 153 00:08:00,300 --> 00:08:03,966 So we have a set of tools that also Tammo Jan mentioned yesterday 154 00:08:04,666 --> 00:08:08,066 that we can use to record and to send data. 155 00:08:08,400 --> 00:08:12,200 So we have a file with some kind of signal in it that we transmit. 156 00:08:12,733 --> 00:08:15,433 And then we get the echoes back into SigMF files, 157 00:08:15,433 --> 00:08:17,433 that's the format to save IQ. 158 00:08:17,433 --> 00:08:20,900 And on that format, on those files, we do our analysis. 159 00:08:21,500 --> 00:08:23,266 In Stockert, we have exactly the same set up. 160 00:08:23,266 --> 00:08:25,933 Only there we receive. 161 00:08:25,933 --> 00:08:29,933 And interestingly we get two files in Stockert because Stockert has 162 00:08:30,966 --> 00:08:33,833 a horizontal and a vertical antenna in the feed. 163 00:08:33,833 --> 00:08:36,833 So later on we can also look at polarization. 164 00:08:37,200 --> 00:08:38,400 Now we can point at anything. 165 00:08:38,400 --> 00:08:40,433 But we start with the moon. 166 00:08:40,433 --> 00:08:43,333 But we can also point at Venus and do exactly the same thing. 167 00:08:43,333 --> 00:08:45,700 Let's see what happens. 168 00:08:45,700 --> 00:08:47,633 So this is how it works. 169 00:08:47,633 --> 00:08:50,000 This is a six second recording. 170 00:08:50,000 --> 00:08:51,900 This is actually Dwingeloo to Dwingeloo. 171 00:08:51,900 --> 00:08:54,533 So this is just our own telescope. 172 00:08:54,533 --> 00:08:57,533 We start the signal with the transmission at one second. 173 00:08:58,433 --> 00:09:00,233 And you see here this is a CW. 174 00:09:00,233 --> 00:09:03,000 So it's just a carrier, just a single tone that we're sending. 175 00:09:03,000 --> 00:09:06,200 Not any modulation. Because the signal is so strong, 176 00:09:06,600 --> 00:09:09,700 you see it completely overloading and you see a lot of images, etc. 177 00:09:09,700 --> 00:09:10,633 Ignore this. 178 00:09:10,633 --> 00:09:13,700 Anything that happens here is just pure overload of the system. 179 00:09:14,600 --> 00:09:18,233 But over here we calculate when we will receive the signal back. 180 00:09:19,100 --> 00:09:23,000 And you see that there's a nice, echo coming back from the moon. 181 00:09:23,033 --> 00:09:27,133 So the signal you see here in this part is actually returned from the moon. 182 00:09:28,200 --> 00:09:31,166 What you also see, it's a bit difficult, maybe, but there's a little offset. 183 00:09:31,166 --> 00:09:35,933 So the signal is not exactly at the same frequency as that we transmitted. 184 00:09:35,933 --> 00:09:37,533 And you also see there's a bit of fading. 185 00:09:37,533 --> 00:09:40,533 You see a few spots where the signal completely disappears. 186 00:09:40,900 --> 00:09:43,900 Well this is this fading that I talked about. 187 00:09:44,200 --> 00:09:47,200 The other interesting thing is that you see these green bands here. 188 00:09:48,033 --> 00:09:50,566 This is basically when the relay switches. 189 00:09:50,566 --> 00:09:53,566 So just before we transmit we protect the receiver. 190 00:09:53,833 --> 00:09:56,966 And because the receiver is protected with a 50 ohm resistor, 191 00:09:56,966 --> 00:10:00,366 the noise is actually higher than the noise of the sky. 192 00:10:00,366 --> 00:10:05,033 So your noise goes up when you switch the antenna off. 193 00:10:06,300 --> 00:10:08,800 So this is what we can transmit and receive. 194 00:10:08,800 --> 00:10:10,233 And now we can start analyzing it. 195 00:10:10,233 --> 00:10:11,800 So this is the the moon. 196 00:10:11,800 --> 00:10:14,866 So this is the the the movement of the moon. 197 00:10:15,700 --> 00:10:20,600 So from our perspective the moon has a certain speed towards us. 198 00:10:20,600 --> 00:10:24,600 And there are three components that are participating or contributing to that. 199 00:10:25,266 --> 00:10:28,100 First of all the orbit of the moon is not completely circular. 200 00:10:28,100 --> 00:10:31,200 So at some point it's moving a little bit more away or towards us. 201 00:10:31,900 --> 00:10:36,000 The axis of the rotation of the moon is not completely aligned with the, 202 00:10:36,733 --> 00:10:38,100 plane of the orbit. 203 00:10:38,100 --> 00:10:40,633 Those are really small effects. So we're going to ignore those. 204 00:10:40,633 --> 00:10:43,266 The big effect is simply our own rotation. 205 00:10:43,266 --> 00:10:45,933 And when the moon is rising, we are moving towards it. 206 00:10:45,933 --> 00:10:48,000 When it's descending, we are moving away. 207 00:10:48,000 --> 00:10:51,466 And that gives a Doppler. Also, because the moon is not a point, 208 00:10:52,100 --> 00:10:55,466 but it has a size, there are differences. 209 00:10:55,466 --> 00:10:58,500 So the left side of the moon has a slightly different speed to us 210 00:10:58,500 --> 00:11:01,700 than the right side of the moon, and that's a difference we can measure. 211 00:11:01,700 --> 00:11:03,733 So we have a big Doppler offset. 212 00:11:03,733 --> 00:11:06,733 But also the Doppler is not the same for all the points on the moon. 213 00:11:07,133 --> 00:11:10,600 So if we look at the same data as the other graph. 214 00:11:11,100 --> 00:11:12,966 But now we plotted in the spectrum. 215 00:11:12,966 --> 00:11:16,900 So this was the frequency we expected our signal back at. 216 00:11:17,266 --> 00:11:18,533 And you see it's widened. 217 00:11:18,533 --> 00:11:21,600 So we started it as a pure tone which basically has 218 00:11:21,600 --> 00:11:23,866 no width, so let's say one hertz. 219 00:11:23,866 --> 00:11:25,066 And we get it back. 220 00:11:25,066 --> 00:11:27,466 And now it's something like nine hertz. 221 00:11:27,466 --> 00:11:29,000 So different parts of the moon 222 00:11:29,000 --> 00:11:32,500 have reflected the signal at a different frequency back to us. 223 00:11:32,966 --> 00:11:34,733 And that's information 224 00:11:34,733 --> 00:11:38,433 because we can make a calculation of the moon on how it will reflect. 225 00:11:39,000 --> 00:11:42,533 And you see that we can predict it reflects at nine hertz. 226 00:11:43,633 --> 00:11:46,633 Eight Hertz actually on the edge at this moment. 227 00:11:46,633 --> 00:11:49,633 Now, this is exactly how they discovered the rotation of Venus. 228 00:11:50,000 --> 00:11:51,100 We do it the other way around 229 00:11:51,100 --> 00:11:54,633 so we know how the rotation works, and then we predict how it will look like 230 00:11:55,366 --> 00:11:58,366 they did it the other way they received this graph. 231 00:11:58,600 --> 00:12:01,600 And then they would know what the rotation of Venus is. 232 00:12:02,133 --> 00:12:05,133 So we can already, replicate that for the moon. 233 00:12:05,933 --> 00:12:08,133 But there's no time information yet. 234 00:12:08,133 --> 00:12:12,166 When we send a tone, every cycle of the tone is exactly the same. 235 00:12:12,166 --> 00:12:15,166 So I have no idea about distance. 236 00:12:15,966 --> 00:12:18,666 And that's interesting because we have already seen 237 00:12:18,666 --> 00:12:20,166 that the left side of the moon 238 00:12:20,166 --> 00:12:23,133 and the right side of the moon send back a different frequency. 239 00:12:23,133 --> 00:12:25,933 So they have a different Doppler. 240 00:12:25,933 --> 00:12:31,133 So we have lines over the moon that have the same Doppler, coming back to us. 241 00:12:31,133 --> 00:12:34,133 And those lines are in this picture vertical. 242 00:12:34,500 --> 00:12:39,333 But also the front of the moon reflects the signal first. 243 00:12:39,500 --> 00:12:42,500 So the first reflection you get is from the front of the moon. 244 00:12:42,733 --> 00:12:45,733 The deeper parts of the moon will reflect later. 245 00:12:45,733 --> 00:12:47,333 So we also have time information. 246 00:12:47,333 --> 00:12:50,066 Now the time information is in a circle. 247 00:12:50,066 --> 00:12:52,633 So on this circle all the information 248 00:12:52,633 --> 00:12:55,633 will get back to us exactly at the same time. 249 00:12:55,700 --> 00:12:57,166 And then you see there’s an intersect. 250 00:12:57,166 --> 00:13:01,800 So every point on the moon has a certain delay and it has a certain Doppler. 251 00:13:02,233 --> 00:13:05,400 And that is what we're going to use to actually make a map of the planet. 252 00:13:06,100 --> 00:13:08,766 There's one unfortunate thing you see, point A 253 00:13:08,766 --> 00:13:11,766 and B, they have exactly the same Doppler and the same delay. 254 00:13:12,133 --> 00:13:16,866 So you will see later two parts of the moon will be folded over each other. 255 00:13:17,600 --> 00:13:20,266 This is called Doppler delay mapping. 256 00:13:20,266 --> 00:13:22,966 And this is the the principle behind it. 257 00:13:25,000 --> 00:13:26,900 Again we're not the first ones to do this. 258 00:13:26,900 --> 00:13:29,100 This is all done in the 60s. 259 00:13:29,100 --> 00:13:32,100 Which is nice to repeat, of course, with a telescope from, from the 50s. 260 00:13:32,500 --> 00:13:34,800 This is the first time they did it. 261 00:13:34,800 --> 00:13:37,800 And what they used here is a very short pulse. 262 00:13:38,066 --> 00:13:41,966 So the moon has a depth in light-time of around 11 milliseconds. 263 00:13:42,333 --> 00:13:45,333 So they make a pulse of something like 50 microseconds. 264 00:13:45,333 --> 00:13:47,400 And then you first see the reflection from the front, 265 00:13:47,400 --> 00:13:50,733 and then you see the deeper parts of the moon reflecting back. 266 00:13:51,333 --> 00:13:54,100 It works really well if you have a two megawatt transmitter, 267 00:13:54,100 --> 00:13:56,866 it does not work so well if you have an 80 Watt transmitter. 268 00:13:56,866 --> 00:13:59,866 So we can not do this, we will simply see nothing. 269 00:14:00,466 --> 00:14:04,333 But, time has progressed and we have computers, 270 00:14:04,333 --> 00:14:07,333 so we can do a lot of stuff that could not do in the 60s. 271 00:14:07,900 --> 00:14:10,800 They wish they would have been able to, but they couldn't. 272 00:14:10,800 --> 00:14:13,033 So here what we do is pulse compression. 273 00:14:13,033 --> 00:14:17,033 So instead of sending a very short pulse, I put all our power in that one pulse. 274 00:14:17,300 --> 00:14:20,833 We spread the pulse over time, and later on you will see that together with Stockert 275 00:14:20,933 --> 00:14:22,566 we could spread it even over 60 seconds. 276 00:14:23,933 --> 00:14:25,133 We send a sequence. 277 00:14:25,133 --> 00:14:28,700 So here you see a few pluses and minuses. This is what they call a Barker code. 278 00:14:29,466 --> 00:14:33,500 And the property of the Barker code is that if you align it with itself 279 00:14:34,233 --> 00:14:37,233 it will add up to seven in this case. 280 00:14:37,233 --> 00:14:39,300 So all the bits will perfectly align. 281 00:14:39,300 --> 00:14:42,666 And you get all the power of these seven bits in one point. 282 00:14:43,233 --> 00:14:47,700 And it doesn't align at all, it gives you zero or almost zero if there’s a difference between them. 283 00:14:48,300 --> 00:14:51,100 So we can use this to actually measure the the distance, 284 00:14:51,100 --> 00:14:54,400 because we can align these things and see exactly when they match. 285 00:14:54,700 --> 00:14:57,700 Then we get all the power back at that point, 286 00:14:58,300 --> 00:15:00,933 and we know the distance and we have much more power 287 00:15:00,933 --> 00:15:03,300 because now we can spread the power over time. 288 00:15:03,300 --> 00:15:07,133 So our 80 Watts we can do times 60 if we do it over 60 seconds. 289 00:15:08,233 --> 00:15:10,233 So this trick we're going to use, we have something 290 00:15:10,233 --> 00:15:12,466 much more advanced than this. 291 00:15:12,466 --> 00:15:14,033 I'll show you later on. 292 00:15:14,033 --> 00:15:15,766 And now it looks like this picture. 293 00:15:15,766 --> 00:15:19,433 So it's the same, six seconds. We transmit from Dwingeloo. 294 00:15:19,433 --> 00:15:23,500 Again, pure overload on this side. We're completely saturating everything. 295 00:15:23,500 --> 00:15:27,266 But here you see a signal coming back, and you see there’s structure now in this signal.. 296 00:15:27,266 --> 00:15:30,266 And this is what we're going to use. 297 00:15:30,533 --> 00:15:34,800 So now we compare that signal coming back with the original signal. 298 00:15:35,100 --> 00:15:36,133 And we're going to shift it. 299 00:15:36,133 --> 00:15:38,833 And we're going to find where we get a peak. 300 00:15:38,833 --> 00:15:42,633 And you see very nicely over here that now we get a huge peak 301 00:15:42,800 --> 00:15:49,866 exactly at the moment that the front of the moon starts echoing our signal. 302 00:15:49,866 --> 00:15:53,666 You also see that we get signals echoed from later points. 303 00:15:54,100 --> 00:15:55,966 Because of this code that we use, 304 00:15:55,966 --> 00:16:00,100 we can actually distinguish the first echo from the echo that comes a millisecond later 305 00:16:00,100 --> 00:16:01,700 or two milliseconds later. 306 00:16:01,700 --> 00:16:06,366 So now we can measure where on the moon a certain reflection is coming from. 307 00:16:07,200 --> 00:16:08,966 Now this is key to what we're going to do. 308 00:16:10,166 --> 00:16:14,266 And I don't have enough time to fully explain how this works. 309 00:16:14,266 --> 00:16:18,200 What we use is a Zadoff-Chu sequence, and I'm pretty sure we are the first ones 310 00:16:18,200 --> 00:16:21,233 ever to use a Zadff-Chu sequence for making pictures of the moon. 311 00:16:21,233 --> 00:16:22,566 This is quite modern. 312 00:16:22,566 --> 00:16:25,833 This is used in 5G, for example, for synchronization between your phone 313 00:16:25,833 --> 00:16:29,233 and your base station and we use it for the moon echo. 314 00:16:29,600 --> 00:16:31,966 It works the same way as this Barker codes. 315 00:16:31,966 --> 00:16:34,700 The code only aligns if you align it with itself. 316 00:16:34,700 --> 00:16:35,966 You get all the power back. 317 00:16:35,966 --> 00:16:37,900 If you shift it, you get zero. 318 00:16:37,900 --> 00:16:39,566 So it's really useful. 319 00:16:39,566 --> 00:16:42,566 But it's much more efficient because the binary code 320 00:16:42,566 --> 00:16:45,333 only uses one axis of freedom. 321 00:16:45,333 --> 00:16:48,500 And in the transmission we have with the I and the Q signal, 322 00:16:48,500 --> 00:16:52,566 we have actually two axes. So we can use both. 323 00:16:52,566 --> 00:16:55,333 The signal looks like this. You might think it looks like a chirp, 324 00:16:55,333 --> 00:16:57,433 which is almost correct because it's related to the chirp, 325 00:16:57,433 --> 00:17:00,000 but you see that they actually overlap. 326 00:17:00,000 --> 00:17:03,600 And again, I don't have the time to dive into this, in more detail. 327 00:17:05,066 --> 00:17:07,000 It almost sounds too good to be true. 328 00:17:07,000 --> 00:17:10,133 And that's indeed the case because there's one problem and that's called ambiguity. 329 00:17:11,300 --> 00:17:13,800 Because if you have a frequency translation. 330 00:17:13,800 --> 00:17:17,200 So basically a Doppler, at some point, your frequency 331 00:17:17,200 --> 00:17:20,200 translation and your time translation for sequence become the same thing. 332 00:17:20,600 --> 00:17:23,600 So you get points that you cannot distinguish anymore. 333 00:17:23,966 --> 00:17:26,966 And if you see how that maps, this is what we transmit. 334 00:17:27,433 --> 00:17:30,300 We would expect a single point there at zero, zero, 335 00:17:30,300 --> 00:17:32,466 but we actually get multiple points. 336 00:17:32,466 --> 00:17:36,366 The only trick we now need to do is to make sure that our return, our moon, 337 00:17:36,700 --> 00:17:41,900 will not overlap with one of the fake points, but we have that under control. 338 00:17:41,933 --> 00:17:44,966 We've made a few mistakes on the early echoes, but now we can do this 339 00:17:45,566 --> 00:17:47,566 and then we get to the result. 340 00:17:47,566 --> 00:17:49,766 So this is what we can do between our sites. 341 00:17:49,766 --> 00:17:55,033 This is only a single echo between Dwingeloo and Stockport 342 00:17:55,466 --> 00:17:58,466 that was transmitted for 60s. 343 00:17:59,033 --> 00:18:00,533 And in this picture we can see a lot. 344 00:18:00,533 --> 00:18:02,500 First of all we see again the Doppler. 345 00:18:02,500 --> 00:18:05,533 So we see the width of the moon in Doppler. 346 00:18:05,800 --> 00:18:10,033 We also see the depth of the moon now in time. 347 00:18:10,033 --> 00:18:14,166 So these lines I have plotted where exactly I expect to be the zero point. 348 00:18:14,166 --> 00:18:16,800 So this is why we Doppler compensate for everything 349 00:18:16,800 --> 00:18:19,800 and where I expect the moon, to end. 350 00:18:19,800 --> 00:18:23,300 So you can see that we can actually see all the way to the edge of the moon. 351 00:18:24,166 --> 00:18:26,433 You already start seeing a few of the craters, 352 00:18:26,433 --> 00:18:27,633 which have a different echo, 353 00:18:27,633 --> 00:18:29,700 so they have a stronger echo than some of the other parts. 354 00:18:29,700 --> 00:18:32,933 But most of the energy that comes back to us sits here. 355 00:18:33,033 --> 00:18:36,033 Almost all of it sits in this really small part. 356 00:18:38,033 --> 00:18:42,500 This takes very accurate equipment and also accurate clocks. 357 00:18:42,500 --> 00:18:47,600 The points you see here are something like 50 millihertz in accuracy. 358 00:18:48,066 --> 00:18:50,400 So it takes really accurate clocks to make this work. 359 00:18:50,400 --> 00:18:54,100 And also accurate calculations to find these lines. 360 00:18:56,133 --> 00:18:58,766 So now we have this working. 361 00:18:58,766 --> 00:18:59,000 Oh yeah. 362 00:18:59,000 --> 00:19:02,333 First of all we were doing this and then somebody pointed out to me 363 00:19:02,333 --> 00:19:04,833 oh you're not the first doing this with the telescope. 364 00:19:04,833 --> 00:19:09,733 So Pieter-Tjerk de Boer in 2011 already did the same thing. 365 00:19:09,733 --> 00:19:13,500 This was even more of a challenge because he used the radio amateur equipment. 366 00:19:13,500 --> 00:19:14,533 So he has to do this via 367 00:19:14,533 --> 00:19:17,800 the audio channel of the radio amateurs, which was really challenging. 368 00:19:18,400 --> 00:19:20,100 But he had a very similar picture. 369 00:19:20,100 --> 00:19:23,966 But you also see how far we have progressed since 2011, 370 00:19:24,133 --> 00:19:28,033 which is really the equipment, because Pieter-Tjerk did really smart things, 371 00:19:28,033 --> 00:19:31,033 but he was just limited by the equipment. 372 00:19:34,633 --> 00:19:37,333 We can do this at multiple frequencies. 373 00:19:37,333 --> 00:19:42,633 These example were all done at 23cm because that's where we have the most power. 374 00:19:42,633 --> 00:19:45,766 We also can do this at seventy centimeters with UHF. 375 00:19:45,900 --> 00:19:50,366 But then you have much less resolution in the Doppler because of the longer wavelengths. 376 00:19:50,366 --> 00:19:54,033 Or we can do it at S-band, but it in S-band we don't have enough power. 377 00:19:54,300 --> 00:19:55,200 So that's very limited. 378 00:19:57,033 --> 00:19:59,933 I already mentioned you could see those craters, 379 00:19:59,933 --> 00:20:02,800 and there's something really interesting here, which is, 380 00:20:02,800 --> 00:20:05,966 a benefit of using the Stocker telescope is that they have two polarizations. 381 00:20:06,500 --> 00:20:10,133 So the received signal, if you send a right hand polarized 382 00:20:10,133 --> 00:20:13,666 signal to the moon and it reflects back, you get a left hand polarized signal back. 383 00:20:13,666 --> 00:20:15,733 That's what the radio amateurs do. 384 00:20:15,733 --> 00:20:21,500 But you also get what they call the diffuse reflection. 385 00:20:21,766 --> 00:20:23,733 You also get a bit of RHCP back. 386 00:20:23,733 --> 00:20:27,033 It's not as strong, but it's especially the features. 387 00:20:27,033 --> 00:20:31,166 So basically, the moon is not a perfect sphere, but all the things that stick out 388 00:20:31,166 --> 00:20:34,633 and small hills, etc., they reflect in a certain different way. 389 00:20:34,933 --> 00:20:38,100 So the left picture is the one with the most power, 390 00:20:38,666 --> 00:20:40,633 but the right picture has less power and it. 391 00:20:40,633 --> 00:20:46,066 But you actually start much better seeing the features. 392 00:20:48,000 --> 00:20:49,766 If we look at the power, we 393 00:20:49,766 --> 00:20:53,466 see that the blue one, which is basically the normal reflection, is very strong. 394 00:20:53,966 --> 00:20:56,466 The orange one is weaker. 395 00:20:56,466 --> 00:20:58,733 But it has more information in it. 396 00:20:58,733 --> 00:21:02,633 If we look at the polarization on the difference basically between the two, 397 00:21:03,133 --> 00:21:06,766 and we compare that with the book from the 1960s, you can actually see 398 00:21:06,766 --> 00:21:10,166 that we can perfectly replicate what they have measured back then. 399 00:21:12,366 --> 00:21:14,066 Now basically this is where we stand today. 400 00:21:14,066 --> 00:21:17,233 This is the, let's say the state of the art as we are today. 401 00:21:17,566 --> 00:21:20,566 We need to do need to do more measurements. 402 00:21:20,733 --> 00:21:23,966 But this looks quite impressive, especially on this screen, I must admit. 403 00:21:25,100 --> 00:21:27,600 And also here I can switch 404 00:21:27,600 --> 00:21:30,600 between the left and the right hand polarization. 405 00:21:39,233 --> 00:21:45,133 So the RHCP has more detail and the LHSP has more power. 406 00:21:45,133 --> 00:21:48,133 The combination, of course, is the most interesting. 407 00:21:49,700 --> 00:21:53,800 And now this is, by the way, a combination of a lot of bounces. 408 00:21:53,833 --> 00:21:59,800 So this is 11 times 30 seconds between Dwingeloo and Stockert. 409 00:21:59,800 --> 00:22:02,666 Now it almost looks like this is a photo of the Moon. 410 00:22:03,066 --> 00:22:05,633 And that's very misleading. And we did this on purpose. 411 00:22:05,633 --> 00:22:09,400 We gave it a little bit of a round form so you would get the idea it’s a photo 412 00:22:09,400 --> 00:22:12,400 but it really isn't. 413 00:22:12,466 --> 00:22:16,866 The thing is, as I said in the beginning about this delay Doppler, there’s ambiguity. 414 00:22:16,866 --> 00:22:18,600 You have two points on the moon 415 00:22:18,600 --> 00:22:21,600 that map to a single point in this picture that you are seeing. 416 00:22:22,466 --> 00:22:26,533 So over here you see again the same measurement we have done. 417 00:22:26,533 --> 00:22:33,600 Over here you see how we think it should look based on a known map of the moon. 418 00:22:33,800 --> 00:22:36,500 And you see two colors here blue and green. 419 00:22:36,500 --> 00:22:40,066 And the blue is the northern hemisphere and the green is the southern 420 00:22:40,466 --> 00:22:41,266 or the other way around. 421 00:22:42,266 --> 00:22:48,400 You see very nicely, for example, this crater here, you see, that's showing up over here. 422 00:22:48,900 --> 00:22:51,633 What we have not done yet, and that's the next step 423 00:22:51,633 --> 00:22:55,800 is to map from left to right so we can actually unwrap this. 424 00:22:55,800 --> 00:22:57,433 But we need multiple measurements. 425 00:22:57,433 --> 00:23:00,433 We need this to change. 426 00:23:00,500 --> 00:23:03,500 How that works: This is a nice animation that Tammo Jan made 427 00:23:07,433 --> 00:23:09,766 So this is how we view the moon 428 00:23:09,766 --> 00:23:12,900 compared to the the axis of the of the telescope. 429 00:23:13,233 --> 00:23:19,400 And on the left, you see how the two halves map. 430 00:23:24,500 --> 00:23:27,900 So you see that actually the bottom one is rotating to the left. 431 00:23:28,233 --> 00:23:30,600 The top one is rotating to the right. 432 00:23:30,600 --> 00:23:34,233 So if we do another measurement where these craters are in a different position, 433 00:23:34,566 --> 00:23:37,733 then we can start trying to make a map. So that is work to do. 434 00:23:37,733 --> 00:23:39,733 This is basically where we currently stand. 435 00:23:40,766 --> 00:23:43,200 One more interesting thing is this one. 436 00:23:43,200 --> 00:23:46,300 This is what the radio amateurs experience, which is the fading. 437 00:23:46,966 --> 00:23:49,966 So here we have a movie of the short term. 438 00:23:49,966 --> 00:23:51,800 So this is basically real time 439 00:23:51,800 --> 00:23:54,333 where on the moon your reflection is coming from. 440 00:23:54,333 --> 00:23:57,333 And you see some really interesting points that move around. 441 00:23:57,766 --> 00:24:00,766 And this is the thing that distorts your your audio. 442 00:24:01,333 --> 00:24:05,633 But it's really funny to see it as a movie. 443 00:24:07,833 --> 00:24:08,666 It takes a bit longer. 444 00:24:08,666 --> 00:24:11,666 This is like, like a minute, but I think you get the idea. 445 00:24:12,300 --> 00:24:14,700 If you do this for a minute and you integrate, 446 00:24:14,700 --> 00:24:16,533 then actually this all disappears 447 00:24:16,533 --> 00:24:19,466 and it looks a little bit like the picture that Jocelyn was showing yesterday 448 00:24:19,466 --> 00:24:22,800 of the pool with the the waves in it and the light. 449 00:24:23,066 --> 00:24:24,166 This is a very similar. 450 00:24:26,100 --> 00:24:30,600 I need to move on looking at time. 451 00:24:31,200 --> 00:24:33,066 Now, the moon was easy. 452 00:24:33,066 --> 00:24:34,766 We can do nice things, but this was very close, 453 00:24:34,766 --> 00:24:37,266 so the question is, how far can we get now? 454 00:24:37,266 --> 00:24:38,233 This is Venus. 455 00:24:38,233 --> 00:24:40,566 Venus is the next easiest target. 456 00:24:40,566 --> 00:24:44,833 And this is the orbit from Venus as seen from the Earth. 457 00:24:44,833 --> 00:24:47,100 So the Earth is in the middle here. This is how they in the Middle Ages 458 00:24:47,100 --> 00:24:50,100 thought that the universe was looking like, 459 00:24:50,133 --> 00:24:53,500 and you see that every one year and seven months it's very close to us. 460 00:24:53,500 --> 00:24:55,266 And remember the R to the fourth. 461 00:24:55,266 --> 00:24:58,300 So we can only do this when Venus is very close to us. 462 00:24:59,066 --> 00:25:02,300 And, what was it, last year, it was very close to the. 463 00:25:02,300 --> 00:25:05,300 So we had an opportunity to try this out. 464 00:25:05,433 --> 00:25:08,666 You also see from our point of view, it's very close to the sun. 465 00:25:08,700 --> 00:25:10,833 It's in the line with the sun, which makes sense 466 00:25:10,833 --> 00:25:13,433 because it's actually moving in between us and the sun. 467 00:25:13,433 --> 00:25:16,433 So if you look from the Dwingeloo telescope, which is pointed at Venus, 468 00:25:16,433 --> 00:25:18,866 you see how awfully close it is to the sun. 469 00:25:18,866 --> 00:25:26,033 Luckily, our, beam is quite small, so it is an issue, but we can do it. 470 00:25:26,666 --> 00:25:28,266 Same setup as last time. 471 00:25:28,266 --> 00:25:31,333 The only difference is now we put the amplifier in the front end 472 00:25:31,666 --> 00:25:35,566 so up in the dish, and it's a one kilowatt amplifier, 473 00:25:35,566 --> 00:25:38,566 because this was the only way to make it work. 474 00:25:39,000 --> 00:25:41,166 That's very tricky to do. 475 00:25:41,166 --> 00:25:43,566 Here, you see us going up with the elevator. 476 00:25:43,566 --> 00:25:45,766 That's the picture Tammo Jan didn't show yesterday. 477 00:25:45,766 --> 00:25:48,766 So here you see the elevator being used. 478 00:25:49,800 --> 00:25:52,800 And here you see us up, at the front end. 479 00:25:52,833 --> 00:25:54,500 And here you see the one kilowatt 480 00:25:54,500 --> 00:25:57,500 amplifier, which we're going to move all the way into the back there. 481 00:25:58,300 --> 00:26:01,300 You might wonder where all the heat is going from the one kilowatt. 482 00:26:02,233 --> 00:26:03,366 We didn't think about that. 483 00:26:03,366 --> 00:26:05,266 So we'll get back to that point. 484 00:26:07,200 --> 00:26:09,766 I'm going to speed up a little bit. 485 00:26:09,766 --> 00:26:12,900 With Venus, accurate calculations become really important. 486 00:26:12,900 --> 00:26:15,166 I mean, the signal is away for five minutes. 487 00:26:15,166 --> 00:26:18,166 You're transmitting for five minutes, and then you're listening for five minutes. 488 00:26:18,400 --> 00:26:20,233 So in the meantime, Venus has moved. 489 00:26:20,233 --> 00:26:22,966 So you really need to take all the geometry into account. 490 00:26:22,966 --> 00:26:26,266 The Doppler going out and the Doppler going back is not the same thing. 491 00:26:26,266 --> 00:26:28,500 So you need very accurate calculations. 492 00:26:28,500 --> 00:26:32,333 Luckily, there's a very nice toolkit from, JPL called SPICE 493 00:26:32,666 --> 00:26:33,900 that does all of that for you. 494 00:26:33,900 --> 00:26:36,900 All these pictures from the moon you saw before were all made with which SPICE. 495 00:26:37,166 --> 00:26:41,033 So it's complicated, but actually there's a toolkit that can do all of that. 496 00:26:41,466 --> 00:26:44,266 So we calculate exactly the Doppler but also the Doppler rate. 497 00:26:44,266 --> 00:26:47,266 So how fast is the Doppler changing over the five minutes. 498 00:26:47,266 --> 00:26:48,733 And we correct for all of that. 499 00:26:48,733 --> 00:26:51,733 That's the only way to detect our signal. 500 00:26:52,200 --> 00:26:54,966 This is a simulation made by here by Cees. 501 00:26:54,966 --> 00:26:57,300 On the left you see again the Doppler we expect 502 00:26:57,300 --> 00:27:00,933 this is the power where we expect it to be reflected from Venus. 503 00:27:01,300 --> 00:27:04,666 And on the right you see the Doppler delay map that we expect. 504 00:27:04,666 --> 00:27:07,066 This was the goal. Like how far can we get. 505 00:27:08,200 --> 00:27:12,733 Luckily, because Venus’ rotation is slow and it's also retrograde, 506 00:27:12,733 --> 00:27:17,000 so it's moving against its own moving around the sun, which means 507 00:27:17,000 --> 00:27:21,066 that the Doppler from Venus coming towards us is partly canceled by the fact 508 00:27:21,066 --> 00:27:24,966 that Venus rotates the other way around, so the Doppler is really low. 509 00:27:24,966 --> 00:27:26,766 We had like eight hertz on the moon, 510 00:27:26,766 --> 00:27:30,066 but we have within one hertz most of the signal, 511 00:27:30,066 --> 00:27:33,033 half of the signal is within one hertz, which is really useful 512 00:27:33,033 --> 00:27:35,866 because that gives us a lot more sensitivity. 513 00:27:35,866 --> 00:27:39,466 Now we had two hours to do this experiment, and we had fully automated it. 514 00:27:39,466 --> 00:27:41,566 And we started with four times in CW. 515 00:27:41,566 --> 00:27:43,300 So that's a tone, just a carrier. 516 00:27:43,300 --> 00:27:48,100 And then we had all these interesting signals with radar wave forms in them. 517 00:27:48,433 --> 00:27:51,833 But as you can see, after the first four: failed. 518 00:27:52,633 --> 00:27:56,566 We completely melted the amplifier in the front-end. 519 00:27:56,566 --> 00:27:59,200 So unfortunately, we never got to these other ones. 520 00:27:59,200 --> 00:28:00,133 You can see it's busy. 521 00:28:00,133 --> 00:28:02,000 We're very happy here because the first time 522 00:28:02,000 --> 00:28:04,766 you see the one kilowatt going out of the transmitter. 523 00:28:04,766 --> 00:28:07,266 Here we were still laughing. 524 00:28:09,066 --> 00:28:10,866 And, these are the results. 525 00:28:10,866 --> 00:28:12,900 So we managed to do this four times. 526 00:28:12,900 --> 00:28:16,100 If I split all the measurements out you have Dwingeloo and Stockert, 527 00:28:16,166 --> 00:28:19,166 and Dwingeloo to Dwingeloo 528 00:28:19,533 --> 00:28:23,333 And you see that, actually, in the individual five minutes reflections, 529 00:28:23,500 --> 00:28:26,700 We can see Venus, even in a single measurement. 530 00:28:27,166 --> 00:28:28,666 You also see that on Dwingeloo, 531 00:28:28,666 --> 00:28:31,666 the performance is lower and it's completely disappearing. 532 00:28:31,800 --> 00:28:35,966 Maybe this had to do with the heating up of the whole front-end, we don't really know. 533 00:28:36,166 --> 00:28:41,700 If we combine these things, we see that we have an overall detection of more than ten sigma, 534 00:28:41,700 --> 00:28:44,633 which is a really, really strong, detection of the Venus signal. 535 00:28:44,633 --> 00:28:47,633 So we succeeded in getting something back from Venus. 536 00:28:47,700 --> 00:28:50,466 You can also see there's no information in here. 537 00:28:50,466 --> 00:28:52,500 So we just see it's there. 538 00:28:52,500 --> 00:28:56,733 We don't have enough signal to make a delay-Doppler map of Venus. 539 00:28:56,733 --> 00:29:00,066 So there's no way we can actually make this nice map 540 00:29:00,066 --> 00:29:01,666 that we have of the moon of Venus. 541 00:29:03,333 --> 00:29:06,333 Here's another one to prove that it's a real signal from Venus. 542 00:29:06,500 --> 00:29:11,733 This looks like a plot made for the pulsars. 543 00:29:12,400 --> 00:29:14,933 If we shift in frequency, we lose it. 544 00:29:14,933 --> 00:29:17,733 And if we have the frequency rate, we lose it. 545 00:29:17,733 --> 00:29:22,500 Just to prove that we're really seeing the signal as we expected, there. 546 00:29:22,500 --> 00:29:24,733 Okay, this is the melted amplifier. 547 00:29:24,733 --> 00:29:27,233 So we destroyed that one kilowatt. 548 00:29:27,233 --> 00:29:29,900 It was repaired later on, so no issues there. 549 00:29:29,900 --> 00:29:32,500 The question is, is this the best we can do? 550 00:29:32,500 --> 00:29:34,966 So can we go further? 551 00:29:34,966 --> 00:29:36,166 Quick answer: no. 552 00:29:36,166 --> 00:29:38,466 If you look at next one from Venus. 553 00:29:38,466 --> 00:29:41,466 So Venus is at zero dBm. 554 00:29:41,666 --> 00:29:43,366 Mars is already 20 dB lower. 555 00:29:43,366 --> 00:29:45,533 Well, there was clearly not a 20 dB margin. 556 00:29:45,533 --> 00:29:48,500 So with the current set setup, Venus we can do 557 00:29:48,500 --> 00:29:51,600 and there's another one, later next year, 558 00:29:52,766 --> 00:29:56,600 Which we will try again, but things like Mars etc., are out of our reach. 559 00:29:57,300 --> 00:30:00,500 The other one was I started with the pictures of the asteroid. 560 00:30:00,900 --> 00:30:03,666 We really want to make a moving, picture of an asteroid 561 00:30:03,666 --> 00:30:07,200 with our two telescopes, but, no, that's not going to happen either. 562 00:30:07,933 --> 00:30:11,000 We simply don't have the power and the dishes to to make it work. 563 00:30:12,300 --> 00:30:14,700 So, as I said, this was work by a lot of people. 564 00:30:14,700 --> 00:30:17,700 Of course, the full teams at Dwingeloo and Stockert, because, 565 00:30:18,200 --> 00:30:20,400 you need a lot of people to keep the telescope running 566 00:30:20,400 --> 00:30:22,200 and to make everything work, 567 00:30:22,200 --> 00:30:26,000 Jan van Muijlwijk, who knows a lot about the amplifiers and the whole setup for EME. 568 00:30:26,666 --> 00:30:31,066 Daniel Estévez did an independent analysis of our Venus data, which was really nice. 569 00:30:31,066 --> 00:30:33,166 And we learned a few new things from that. 570 00:30:33,166 --> 00:30:38,366 Pete Syckoff came up with the idea for the the picture of the fading, the movie. 571 00:30:38,366 --> 00:30:42,266 And we also cooperated with Nathaniel Fairfield on Venus. 572 00:30:42,266 --> 00:30:45,266 So there is input from a lot of people in it. 573 00:30:45,800 --> 00:30:48,000 But I think we have nice results and of more to come. 574 00:30:48,000 --> 00:30:50,766 Next time, I really hope we can show you a map of the moon, 575 00:30:50,766 --> 00:30:54,433 where we have unfolded those two halves. 576 00:30:54,433 --> 00:30:55,566 And that’s it.