1 00:00:02,280 --> 00:00:04,800 This month we have a space spectacular. 2 00:00:10,920 --> 00:00:14,720 After over a decade of chasing a comet through the solar system, 3 00:00:14,720 --> 00:00:18,400 the space probe Rosetta finally reaches its target. 4 00:00:24,840 --> 00:00:27,840 And we'll be reporting from the European Space Agency's 5 00:00:27,840 --> 00:00:30,360 mission control in Germany. 6 00:00:30,360 --> 00:00:34,600 Rosetta is one of the most exciting and ambitious missions ever 7 00:00:34,600 --> 00:00:37,760 attempted, like something straight out of science fiction. 8 00:00:37,760 --> 00:00:40,040 There's a six billion kilometre journey, 9 00:00:40,040 --> 00:00:43,640 a rendezvous with a comet and then, if all goes well, 10 00:00:43,640 --> 00:00:47,480 a landing on the surface using harpoons and grappling hooks. 11 00:00:47,480 --> 00:00:50,960 It's a wonderful scientific mission but it is also a remarkable 12 00:00:50,960 --> 00:00:53,560 feat of engineering and I'm going to meet the people 13 00:00:53,560 --> 00:00:57,440 who are in control and find out how they're going to pull this off. 14 00:00:57,440 --> 00:01:00,240 And here in the UK, we'll be discovering why comets are 15 00:01:00,240 --> 00:01:04,680 so important to study and viewing one visible in our skies right now. 16 00:01:04,680 --> 00:01:07,120 Welcome to The Sky At Night. 17 00:01:33,720 --> 00:01:37,080 Welcome to the European Space Operations Centre 18 00:01:37,080 --> 00:01:39,880 mission control in Darmstadt, Germany. 19 00:01:39,880 --> 00:01:42,920 This is where Rosetta's most critical manoeuvres are planned 20 00:01:42,920 --> 00:01:44,720 and then carried out. 21 00:01:44,720 --> 00:01:47,240 We'll be getting a tour of the spacecraft itself 22 00:01:47,240 --> 00:01:49,800 and a look at the latest images from Rosetta 23 00:01:49,800 --> 00:01:52,320 which have given scientists one or two surprises. 24 00:01:52,320 --> 00:01:55,320 And I'm here at the Open University in Buckinghamshire, 25 00:01:55,320 --> 00:01:57,880 where one of the key instruments on the Rosetta lander 26 00:01:57,880 --> 00:02:01,440 was designed and built. We'll be finding out more about comets 27 00:02:01,440 --> 00:02:05,120 and how they're helping us unravel mysteries of Earth's past 28 00:02:05,120 --> 00:02:08,040 and maybe looking into the origins of life itself. 29 00:02:08,040 --> 00:02:13,040 And there's a comet visible right now in the night sky. 30 00:02:13,040 --> 00:02:15,880 Pete Lawrence will be showing you how to find it 31 00:02:15,880 --> 00:02:18,560 and how to take a great comet photo. 32 00:02:29,120 --> 00:02:32,240 Comets are probably one of the most spectacular 33 00:02:32,240 --> 00:02:35,280 and enigmatic objects we see in our night skies. 34 00:02:35,280 --> 00:02:37,720 For millennia they have caused us to wonder, 35 00:02:37,720 --> 00:02:40,080 "What are they and where do they come from?!" 36 00:02:42,360 --> 00:02:47,280 Even 1,000 years ago we recognised their distinctive shape. 37 00:02:47,280 --> 00:02:49,880 In the 11th century Bayeux Tapestry 38 00:02:49,880 --> 00:02:52,560 Halley's Comet is carefully stitched, 39 00:02:52,560 --> 00:02:54,800 showing three main parts to a comet. 40 00:02:54,800 --> 00:02:59,000 A solid nucleus surrounded by a halo, called a coma, 41 00:02:59,000 --> 00:03:01,280 and then a long streaming tail 42 00:03:05,040 --> 00:03:09,720 With the advent of photography comets have provided breathtaking images 43 00:03:09,720 --> 00:03:13,480 and revealed features that cannot be seen with the naked eye. 44 00:03:14,800 --> 00:03:17,720 Multiple tails are often revealed on photos. 45 00:03:19,160 --> 00:03:22,480 A very straight gas tail is caused by the solar wind 46 00:03:22,480 --> 00:03:27,040 ionising gases as they are given off, making them glow. 47 00:03:27,040 --> 00:03:30,480 It always points directly away from the sun. 48 00:03:31,880 --> 00:03:36,480 The more familiar diffused, often curved tail is made up of dust 49 00:03:36,480 --> 00:03:38,080 which streams behind the comet, 50 00:03:38,080 --> 00:03:40,800 which is also slightly deflected by the solar wind. 51 00:03:45,840 --> 00:03:49,640 Recently we've been able to get an even closer look at a comet. 52 00:03:49,640 --> 00:03:54,080 In 1986, space probe Giotto took these remarkable images 53 00:03:54,080 --> 00:03:57,120 as it flew past Halley's Comet. 54 00:03:57,120 --> 00:04:00,760 In the past 30 years there have been a number of missions 55 00:04:00,760 --> 00:04:02,400 that have flown past comets. 56 00:04:02,400 --> 00:04:04,800 And what they've discovered is a central nucleus 57 00:04:04,800 --> 00:04:07,120 one to ten kilometres wide. 58 00:04:07,120 --> 00:04:11,040 Comets also are surprisingly black due to the high carbon content. 59 00:04:11,040 --> 00:04:14,120 The carbon is mixing with ice and rock, 60 00:04:14,120 --> 00:04:15,960 and as the comet approaches the sun, 61 00:04:15,960 --> 00:04:20,720 that ice vaporises, producing a coma and the glorious comet's tail. 62 00:04:22,160 --> 00:04:24,760 The tail can be very long indeed. 63 00:04:24,760 --> 00:04:29,240 Comet Hyakutake's was about 360 million miles long 64 00:04:29,240 --> 00:04:31,720 when it appeared in 1996. 65 00:04:33,240 --> 00:04:36,560 When the Earth passes through the remains of a comet's tail, 66 00:04:36,560 --> 00:04:39,720 the result is an often spectacular meteor shower 67 00:04:39,720 --> 00:04:43,520 as dust particles burn up in the Earth's upper atmosphere. 68 00:04:48,360 --> 00:04:52,200 It's only when comets approach the sun closely enough to become active 69 00:04:52,200 --> 00:04:55,000 and brightly lit that they become visible to us. 70 00:04:56,560 --> 00:04:59,760 To date we've detected over 4,000 comets 71 00:04:59,760 --> 00:05:02,520 but we know that there are billions more out there. 72 00:05:02,520 --> 00:05:05,600 We think they're the leftover detritus of the formation 73 00:05:05,600 --> 00:05:09,080 of the solar system, some 4.5 billion years ago. 74 00:05:09,080 --> 00:05:12,320 And, as such, we can use them as tiny time capsules, 75 00:05:12,320 --> 00:05:15,480 giving us a window into our distant past. 76 00:05:18,320 --> 00:05:21,640 Now we hope to get an unprecedented view of a comet, 77 00:05:21,640 --> 00:05:25,640 the snappily named 67P/Churyumov-Gerasimenko, 78 00:05:25,640 --> 00:05:27,800 was discovered in 1969 79 00:05:27,800 --> 00:05:31,160 and it's what is known as one of the Jupiter family comets, 80 00:05:31,160 --> 00:05:34,560 as they have been swung into their orbits by Jupiter's gravity. 81 00:05:35,680 --> 00:05:39,440 Picked from obscurity, it has become a scientific celebrity 82 00:05:39,440 --> 00:05:42,080 as the target for the Rosetta mission. 83 00:05:44,560 --> 00:05:47,800 And with Rosetta approaching it, we're beginning to get images 84 00:05:47,800 --> 00:05:51,280 of the comet for the first time and it's throwing up some big surprises. 85 00:05:51,280 --> 00:05:55,480 Chris is in Germany, looking at the latest images hot off the press. 86 00:05:57,040 --> 00:06:00,720 Letting me loose in ESA's mission control is a bit like letting 87 00:06:00,720 --> 00:06:03,640 a child loose in a sweet shop. 88 00:06:10,400 --> 00:06:12,120 Here, look what I've found. 89 00:06:12,120 --> 00:06:15,640 This is a model of Rosetta and it's completely accurate. 90 00:06:15,640 --> 00:06:19,040 The real thing weighed 2.9 tonnes on launch, 91 00:06:19,040 --> 00:06:22,560 this one's not quite that big but you can see these long solar panels 92 00:06:22,560 --> 00:06:25,400 which in real life are 32 metres long. 93 00:06:25,400 --> 00:06:29,440 They need to be that size to capture the faint light of the sun and so 94 00:06:29,440 --> 00:06:33,320 that Rosetta can be powered all the way out in the outer solar system. 95 00:06:33,320 --> 00:06:36,080 It's got this beautiful communications antenna here. 96 00:06:36,080 --> 00:06:39,560 This can point towards Earth so it can send its signals back to us 97 00:06:39,560 --> 00:06:41,880 and then, on the back, all of the instruments. 98 00:06:41,880 --> 00:06:45,320 This is the side that will face the comet. You can see here 99 00:06:45,320 --> 00:06:49,240 in particular the two cameras of the OSIRIS imaging system. 100 00:06:49,240 --> 00:06:51,800 Those will provide the scientific images 101 00:06:51,800 --> 00:06:54,880 and they'll help us select a landing site for Philae. 102 00:06:54,880 --> 00:06:59,160 This is the little lander that will somehow touch down on the comet. 103 00:07:03,040 --> 00:07:07,440 On August 6th Rosetta went into orbit around the comet and so now 104 00:07:07,440 --> 00:07:11,040 those cameras are providing vital images to help the team 105 00:07:11,040 --> 00:07:12,920 choose their landing spot. 106 00:07:12,920 --> 00:07:16,120 But, as Dr Holger Sierks shows me, 107 00:07:16,120 --> 00:07:19,920 those images have provided quite a surprise already. 108 00:07:19,920 --> 00:07:22,920 The early images taken, yes, the beginning of July 109 00:07:22,920 --> 00:07:26,720 when it had just barely started to resolve were a surprise 110 00:07:26,720 --> 00:07:30,560 and it looks like two bodies sticking together, 111 00:07:30,560 --> 00:07:33,160 - so that was quite obvious right from the beginning. - Yes. 112 00:07:33,160 --> 00:07:34,880 The first days in early July. 113 00:07:34,880 --> 00:07:37,920 The most recent ones I've seen make it look a bit like a rubber duck 114 00:07:37,920 --> 00:07:40,640 or something like that, or at least a small head on a body. 115 00:07:40,640 --> 00:07:43,840 Is that because it's two bodies that have stuck together 116 00:07:43,840 --> 00:07:46,320 or could this shape have appeared some other way? 117 00:07:46,320 --> 00:07:48,200 I like the rubber duck a lot. 118 00:07:48,200 --> 00:07:50,520 We don't know it yet. 119 00:07:50,520 --> 00:07:54,120 That is a surprise and we'll have to work to find out why 120 00:07:54,120 --> 00:07:56,240 the body looks like this. 121 00:07:56,240 --> 00:07:58,840 It could be two pieces right from the beginning, 122 00:07:58,840 --> 00:08:02,880 it could also be a bigger block that just had 123 00:08:02,880 --> 00:08:08,080 some eruptions sideways and just carved like the shape we see. 124 00:08:08,080 --> 00:08:10,480 So, the duck, if that's what we're calling it, 125 00:08:10,480 --> 00:08:13,320 - is about three kilometres across, something like that. - Yes. 126 00:08:13,320 --> 00:08:17,040 It must make planning what you're going to do with Rosetta harder, and 127 00:08:17,040 --> 00:08:20,960 that planning depends on the images that your cameras are providing. 128 00:08:20,960 --> 00:08:24,280 - It makes planning harder but also more fascinating. - Yes. 129 00:08:24,280 --> 00:08:29,760 And we are now in the process of laying out the mapping sequences. 130 00:08:29,760 --> 00:08:31,880 Yes, and the rest of the mission depends on 131 00:08:31,880 --> 00:08:34,200 - the quality of those maps as well? - Yes. 132 00:08:34,200 --> 00:08:37,120 And we will also remap because the shape is going to change. 133 00:08:37,120 --> 00:08:42,080 We'll watch it on the way in, so to the closest point to the sun, 134 00:08:42,080 --> 00:08:45,160 so we'll see the activity rise and the comet be more 135 00:08:45,160 --> 00:08:48,000 and more active and then die out again, 136 00:08:48,000 --> 00:08:52,080 calm down. We know that the comet is releasing dust 137 00:08:52,080 --> 00:08:56,960 and we want to study these areas where the activity is formed, 138 00:08:56,960 --> 00:08:58,880 where dust has moved away, 139 00:08:58,880 --> 00:09:03,600 and so why is it happening here in this area and not in others? 140 00:09:03,600 --> 00:09:07,200 The physics of comets is not well understood. 141 00:09:07,200 --> 00:09:11,280 So the immediate task for OSIRIS is to produce a three-dimensional map 142 00:09:11,280 --> 00:09:14,240 of the surface. Can you show us how far you've got with that? 143 00:09:14,240 --> 00:09:16,480 I can show you the current state. 144 00:09:16,480 --> 00:09:18,920 Just looking here at the shape model here, 145 00:09:18,920 --> 00:09:23,120 it's hard to understand where you would safely put down this lander. 146 00:09:23,120 --> 00:09:26,560 Is the obvious thing to go for this big flat face here? 147 00:09:26,560 --> 00:09:30,560 - That seems safest to me. - Yes, that is very obvious. 148 00:09:30,560 --> 00:09:34,240 The tricky thing is the sun is coming up 149 00:09:34,240 --> 00:09:38,960 so if you project the illumination condition into November you'll see 150 00:09:38,960 --> 00:09:43,480 that it's not so favourable on the large side, on this bottom side. 151 00:09:43,480 --> 00:09:45,120 You don't want to land in the dark. 152 00:09:45,120 --> 00:09:48,600 And you don't want to land in the dark so landing will be a challenge. 153 00:09:48,600 --> 00:09:52,800 I think that we'll do a good job, I am convinced about this, 154 00:09:52,800 --> 00:09:58,960 and find a good spot, perhaps on the back of the duck, we'll see. 155 00:09:58,960 --> 00:10:01,960 Yes, OK, well, we can shoot for the back of the duck then! 156 00:10:01,960 --> 00:10:03,680 That's excellent. 157 00:10:05,400 --> 00:10:09,640 With Rosetta now in orbit, every day we see new critical 158 00:10:09,640 --> 00:10:12,800 and stunning surface detail on the comet 159 00:10:12,800 --> 00:10:15,400 and with the lander due to be released in November, 160 00:10:15,400 --> 00:10:18,480 we'll be keeping an eye on more pictures as they come in over the 161 00:10:18,480 --> 00:10:23,560 next few months and as the landing site is chosen and confirmed. 162 00:10:28,840 --> 00:10:32,560 Rosetta and the lander module carry more than 20 163 00:10:32,560 --> 00:10:36,720 scientific instruments between them, which will be sending back data. 164 00:10:38,400 --> 00:10:41,920 Here in the UK the Open University is home to the team 165 00:10:41,920 --> 00:10:44,840 in charge of a key instrument on the Rosetta lander, that will 166 00:10:44,840 --> 00:10:47,400 actually analyse the comet's samples. 167 00:10:47,400 --> 00:10:50,160 Comets are fascinating because they give us a snapshot 168 00:10:50,160 --> 00:10:53,320 into the ancient solar system and by looking at what they're made of 169 00:10:53,320 --> 00:10:57,440 we can understand how our world was formed and maybe even how life began. 170 00:11:01,680 --> 00:11:05,360 Dr Natalie Starkey is one of the comet research team here and 171 00:11:05,360 --> 00:11:09,320 has been studying particles of dust from the Earth's upper atmosphere. 172 00:11:09,320 --> 00:11:11,720 Amongst the normal dust and pollution 173 00:11:11,720 --> 00:11:14,960 she finds particles which form the tails of comets. 174 00:11:16,800 --> 00:11:19,160 So, this is one of the most interesting particles 175 00:11:19,160 --> 00:11:22,160 I've analysed actually because it contains all sorts of material. 176 00:11:22,160 --> 00:11:25,880 We've got amorphous material up in the top and also over to the right. 177 00:11:25,880 --> 00:11:28,560 - That looks quite gloopy. - Yes, exactly, it's kind of... 178 00:11:28,560 --> 00:11:30,640 It's more organic kind of material. 179 00:11:30,640 --> 00:11:32,440 Organic? That sounds interesting. 180 00:11:32,440 --> 00:11:35,800 Yes, it's not life, so people will think of organic material as life, 181 00:11:35,800 --> 00:11:39,240 but actually what we are talking about is carbon, hydrogen, nitrogen 182 00:11:39,240 --> 00:11:42,480 oxygen bonds and it's kind of organic precursor material. 183 00:11:42,480 --> 00:11:45,080 - Right. - The rest of the particle is quite rocky. 184 00:11:45,080 --> 00:11:47,640 So what sort of analysis do you do? 185 00:11:47,640 --> 00:11:49,360 Well, we try and do everything 186 00:11:49,360 --> 00:11:52,520 because this is a sample of space and we don't get many of them. 187 00:11:52,520 --> 00:11:54,880 So how many have you done in your career so far? 188 00:11:54,880 --> 00:11:58,040 I've measured about 50 so far, maybe five that are really, 189 00:11:58,040 --> 00:12:01,320 really interesting, that can tell us a lot about the kind of time 190 00:12:01,320 --> 00:12:03,760 we're looking into, this really early material. 191 00:12:03,760 --> 00:12:06,880 - 4.5 billion years ago. - Exactly, exactly. 192 00:12:06,880 --> 00:12:09,600 So we want to throw every single instrument at them that we have, 193 00:12:09,600 --> 00:12:11,920 you know, all these really advanced techniques 194 00:12:11,920 --> 00:12:13,520 because they're precious samples 195 00:12:13,520 --> 00:12:16,280 and as we are analysing it, we are destroying it as we go... 196 00:12:16,280 --> 00:12:18,560 - Taking bits off the top. - Exactly. - Yes. 197 00:12:18,560 --> 00:12:20,800 But we are getting some numbers at the same time. 198 00:12:20,800 --> 00:12:23,680 And the next images you have here show some of the beautiful 199 00:12:23,680 --> 00:12:25,440 isotopic images we get. 200 00:12:25,440 --> 00:12:27,600 So when you say isotope, what do you mean? 201 00:12:27,600 --> 00:12:30,480 Well, an isotope is just a special type of an element really, 202 00:12:30,480 --> 00:12:32,960 it just contains a different number of neutrons in it 203 00:12:32,960 --> 00:12:35,720 so we're just looking at these very little variations. 204 00:12:35,720 --> 00:12:38,520 So those isotope distributions, what do they tell us? 205 00:12:38,520 --> 00:12:41,120 Well, what we can see from this particle is that actually 206 00:12:41,120 --> 00:12:44,680 there's quite a lot of variation in this single piece of dust. 207 00:12:44,680 --> 00:12:48,080 Actually, this allows us to trace not only time - 208 00:12:48,080 --> 00:12:50,600 so when that comet might have formed, a little bit, 209 00:12:50,600 --> 00:12:53,480 it doesn't give us a date but we can kind of relative times - 210 00:12:53,480 --> 00:12:57,240 but also processes, kind of what happened to those isotope ratios 211 00:12:57,240 --> 00:13:00,480 because they change depending on the temperature 212 00:13:00,480 --> 00:13:03,200 - and the conditions that that comet formed under. - I see. 213 00:13:03,200 --> 00:13:07,360 - So isotopes are actually giving you a location and timescale. - Exactly. 214 00:13:07,360 --> 00:13:10,680 So we start to be able to place things relatively to each other 215 00:13:10,680 --> 00:13:13,800 and what we find with particles like this really interesting one 216 00:13:13,800 --> 00:13:17,440 is that it contains pieces that are a bit mixed so it's not just 217 00:13:17,440 --> 00:13:20,080 all one composition, it didn't all form in one place, 218 00:13:20,080 --> 00:13:22,920 this piece of comet actually contains other pieces of comet 219 00:13:22,920 --> 00:13:25,640 that formed in different places all over the solar system. 220 00:13:25,640 --> 00:13:27,120 And somehow it all came together. 221 00:13:27,120 --> 00:13:29,920 It somehow came together at a later date so our understanding 222 00:13:29,920 --> 00:13:32,480 of comet formation is really led by research like this. 223 00:13:32,480 --> 00:13:35,400 When we use these particles from the stratosphere we don't know 224 00:13:35,400 --> 00:13:38,480 from which particular comet they've come from, but one time 225 00:13:38,480 --> 00:13:41,040 we've actually been into space and we've sampled a comet 226 00:13:41,040 --> 00:13:44,480 and it was the Stardust mission which landed back on Earth in 2006, 227 00:13:44,480 --> 00:13:47,560 it was a NASA mission and what they did was actually just fly through 228 00:13:47,560 --> 00:13:50,040 the tail of the comet, so all the material coming off 229 00:13:50,040 --> 00:13:52,400 they just collected this as impacting particles 230 00:13:52,400 --> 00:13:55,560 into the collectors and this mission was really groundbreaking. 231 00:13:55,560 --> 00:13:58,960 So, our very simple comet model is that they formed 232 00:13:58,960 --> 00:14:01,600 far from the sun and they only contain material that formed 233 00:14:01,600 --> 00:14:04,280 far from the sun, in the cold outer reaches of the solar system. 234 00:14:04,280 --> 00:14:07,240 Which would make sense, if they formed there, that's the material. 235 00:14:07,240 --> 00:14:10,200 Yes, but actually what Stardust showed us is that this comet called 236 00:14:10,200 --> 00:14:13,120 Wild 2 contained material that was formed in the inner solar system 237 00:14:13,120 --> 00:14:16,280 so it contained material that is very similar to what we see 238 00:14:16,280 --> 00:14:19,360 in asteroids, so it's a little bit complicated. 239 00:14:19,360 --> 00:14:22,600 We probably have asteroids at one end, comets at the other, 240 00:14:22,600 --> 00:14:25,280 but now we think there's a bit of a continuum in between 241 00:14:25,280 --> 00:14:28,520 and so we need to go and measure more comets to really find out 242 00:14:28,520 --> 00:14:31,640 what this continuum is and what's going on really. 243 00:14:31,640 --> 00:14:34,760 - So I guess that is where Rosetta comes in? - Exactly. 244 00:14:34,760 --> 00:14:37,520 In your ideal scenario, the dream wish now, 245 00:14:37,520 --> 00:14:39,480 what would you like to get out of Rosetta? 246 00:14:39,480 --> 00:14:42,240 For me it's all about the landing because I want to drill into that 247 00:14:42,240 --> 00:14:45,000 comet and get some of the samples and find out what it's made of. 248 00:14:45,000 --> 00:14:48,560 It will hopefully tell us how far from the sun potentially this comet 249 00:14:48,560 --> 00:14:52,320 formed and what kind of processes it's undergone in its lifetime 250 00:14:52,320 --> 00:14:54,720 so where all those little pieces that form that comet 251 00:14:54,720 --> 00:14:56,360 actually formed themselves. 252 00:14:56,360 --> 00:14:58,600 Whether it was in the inner solar system which will be 253 00:14:58,600 --> 00:15:01,560 a bit of a surprise or whether it was way away from the sun, 254 00:15:01,560 --> 00:15:04,240 so this is one of the things will help us 255 00:15:04,240 --> 00:15:07,880 build up that picture of the comet and its life history, basically. 256 00:15:07,880 --> 00:15:10,760 Well, very good luck for it all and I am really looking forward 257 00:15:10,760 --> 00:15:13,120 - to seeing some of this data coming out. - Thank you. 258 00:15:25,040 --> 00:15:29,200 Every decade or so we get a spectacular comet passing close by 259 00:15:29,200 --> 00:15:33,120 the sun and giving us a display that dominates the night sky. 260 00:15:34,720 --> 00:15:37,720 But there are actually comets visible much more frequently 261 00:15:37,720 --> 00:15:40,480 than that and Pete's here to show you how to see one 262 00:15:40,480 --> 00:15:42,520 that's in the night sky right now. 263 00:15:43,960 --> 00:15:48,000 Typically there are lots of faint comets visible in the night sky 264 00:15:48,000 --> 00:15:51,480 but occasionally one will get bright enough so that they can be seen 265 00:15:51,480 --> 00:15:54,880 with a small telescope, or even a pair of binoculars. 266 00:15:54,880 --> 00:15:58,200 Now, there's one of those visible this month. 267 00:15:58,200 --> 00:16:01,280 This particular comet is relatively easy to see 268 00:16:01,280 --> 00:16:03,600 as long as you know where to look. 269 00:16:03,600 --> 00:16:08,760 This newly discovered comet, called C/2014 E2 (Jacques), 270 00:16:08,760 --> 00:16:11,920 can be found by locating the bright star Capella. 271 00:16:11,920 --> 00:16:14,640 At this time of year it's the brightest star 272 00:16:14,640 --> 00:16:16,960 in the north-eastern part of the sky. 273 00:16:18,120 --> 00:16:21,480 At the start of the month the comet lies in a patch of sky 274 00:16:21,480 --> 00:16:25,920 approximately one fist width at arm's length to the right of Capella. 275 00:16:25,920 --> 00:16:28,480 By the 15th it'll have moved up the sky 276 00:16:28,480 --> 00:16:31,480 to sit left of the star Mirphak in Perseus. 277 00:16:31,480 --> 00:16:36,040 Look up from Mirphak and you'll eventually arrive at the W shape 278 00:16:36,040 --> 00:16:40,880 constellation of Cassiopeia. During August the W appears on its side. 279 00:16:42,240 --> 00:16:45,480 After the 15th the comet tracks up towards Segin, 280 00:16:45,480 --> 00:16:48,320 the star that marks the left hand end of the W. 281 00:16:49,800 --> 00:16:53,680 It's so close to it on the nights of the 22nd and 23rd of August 282 00:16:53,680 --> 00:16:56,200 that a pair of binoculars pointed at the star 283 00:16:56,200 --> 00:16:59,120 should include the comet in the same field of view. 284 00:17:00,320 --> 00:17:04,080 At the end of August E2 (Jaques) moves into the constellation of 285 00:17:04,080 --> 00:17:06,480 Cepheus and, although it should be fading, 286 00:17:06,480 --> 00:17:09,200 will hopefully remain a binocular target. 287 00:17:15,480 --> 00:17:18,320 OK, you should be able to see this comet quite easily 288 00:17:18,320 --> 00:17:22,040 with just a pair of binoculars, but if you've got a digital SLR camera, 289 00:17:22,040 --> 00:17:26,880 a decent lens, and a tripod, you can try taking a photograph of it 290 00:17:26,880 --> 00:17:28,680 to get an even better view. 291 00:17:30,040 --> 00:17:32,800 Put the ISO or sensitivity of your camera high 292 00:17:32,800 --> 00:17:36,320 and use an exposure of 30 or more seconds, 293 00:17:36,320 --> 00:17:39,400 open the lens wide and set your focus to infinity 294 00:17:39,400 --> 00:17:42,800 and take a photo of what you think is the right area of sky. 295 00:17:42,800 --> 00:17:45,880 Use a remote trigger if you can to avoid camera shake. 296 00:17:47,080 --> 00:17:50,520 Now, hopefully, if you're in the right area of sky, 297 00:17:50,520 --> 00:17:53,760 you should be able to pick out a little fuzzy blob. 298 00:17:53,760 --> 00:17:55,320 Let's have a look. 299 00:17:58,040 --> 00:17:59,880 Just like that. 300 00:17:59,880 --> 00:18:01,520 And that should be the comet. 301 00:18:02,760 --> 00:18:06,160 The comet nucleus itself is, of course, not only tiny 302 00:18:06,160 --> 00:18:09,560 but incredibly black so all we're looking at is the sun's light 303 00:18:09,560 --> 00:18:13,360 reflecting off the dust it's emitting and from glowing gases. 304 00:18:13,360 --> 00:18:17,480 The fuzzy, diffuse nature of a comet does make it quite 305 00:18:17,480 --> 00:18:20,520 difficult to find first of all because it looks much fainter 306 00:18:20,520 --> 00:18:24,080 than a star, but once you have identified it in your photograph 307 00:18:24,080 --> 00:18:26,880 the thing to do then is to centre up the frame 308 00:18:26,880 --> 00:18:28,920 so you're pointing directly at the comet 309 00:18:28,920 --> 00:18:32,400 and then use a lens with a longer focal length to get closer in. 310 00:18:32,400 --> 00:18:35,200 I'm going to use a telescope for this one. 311 00:18:37,000 --> 00:18:39,920 Now, as most comets move relative to the stars, 312 00:18:39,920 --> 00:18:43,440 if you take a long exposure shot on a tracking mount, 313 00:18:43,440 --> 00:18:47,240 which keeps up with the stars, the comet will appear blurred. 314 00:18:47,240 --> 00:18:51,120 One way around this is to take shorter exposures and, 315 00:18:51,120 --> 00:18:54,160 using image processing software, combine the images, 316 00:18:54,160 --> 00:18:56,680 using the comet's head as the reference. 317 00:18:56,680 --> 00:18:59,920 This will make the stars appear like dotted lines 318 00:18:59,920 --> 00:19:02,200 but the comet will really shine through 319 00:19:02,200 --> 00:19:05,880 and hopefully show its true colour, an astonishing green glow. 320 00:19:05,880 --> 00:19:10,560 And that's a very characteristic colour, seen in a lot of comets. 321 00:19:10,560 --> 00:19:14,560 That's due to the gases which surround the central core 322 00:19:14,560 --> 00:19:16,520 of the comet, the nucleus, 323 00:19:16,520 --> 00:19:20,560 and they're giving off this amazing green coloured light. 324 00:19:20,560 --> 00:19:23,720 It's the sun's ultraviolet light that causes the gases, 325 00:19:23,720 --> 00:19:27,880 mainly cyanogen and diatomic carbon, to fluoresce and it's one 326 00:19:27,880 --> 00:19:31,960 of the features of comets only really picked up by photography. 327 00:19:31,960 --> 00:19:35,320 Comets make fantastic photographic subjects 328 00:19:35,320 --> 00:19:39,360 and if you do manage to get a long exposure shot of it, that'll pick out 329 00:19:39,360 --> 00:19:43,440 some good detail and give you a great image to show off as well. 330 00:19:43,440 --> 00:19:46,600 If you do get a nice photo, share it via our website... 331 00:19:50,720 --> 00:19:53,960 ..where you'll also find my guide on how to find E2 (Jaques). 332 00:20:01,760 --> 00:20:06,200 Dix, neuf, huit, sept, six... 333 00:20:06,200 --> 00:20:09,480 It's been more than ten years since Rosetta was blasted into space 334 00:20:09,480 --> 00:20:11,560 at the start of an epic mission. 335 00:20:11,560 --> 00:20:13,960 Decollage. 336 00:20:15,160 --> 00:20:17,680 It's taken more than £1 billion of investment 337 00:20:17,680 --> 00:20:19,840 and decades of scientific work. 338 00:20:21,600 --> 00:20:25,240 So why does visiting a comet warrant so much investment? 339 00:20:25,240 --> 00:20:28,800 And how on earth are we going to achieve the mission's objectives? 340 00:20:28,800 --> 00:20:31,080 Chris has been finding out. 341 00:20:33,360 --> 00:20:36,280 One of the questions this mission sets out to answer 342 00:20:36,280 --> 00:20:37,800 is a surprising one. 343 00:20:39,280 --> 00:20:41,440 Could this water, this precious liquid 344 00:20:41,440 --> 00:20:43,600 that makes all life on Earth possible, 345 00:20:43,600 --> 00:20:47,800 have been carried here from space on the icy asteroids and comets 346 00:20:47,800 --> 00:20:50,680 which have bombarded the Earth over millennia? 347 00:20:52,960 --> 00:20:55,680 We think of ourselves as the blue planet, 348 00:20:55,680 --> 00:20:58,400 with vast amounts of liquid water, 349 00:20:58,400 --> 00:21:01,840 but if all of our water were gathered into one place, 350 00:21:01,840 --> 00:21:05,680 well, this image shows how little there really is on Earth. 351 00:21:05,680 --> 00:21:09,160 Nevertheless, it would take perhaps 100 million comets 352 00:21:09,160 --> 00:21:11,560 to bring us all this. 353 00:21:11,560 --> 00:21:15,200 It seems ridiculous that all of Earth's water could have been 354 00:21:15,200 --> 00:21:18,600 delivered from space and yet, in the early days, Earth would have been 355 00:21:18,600 --> 00:21:22,840 a hot world - any water would have boiled off almost immediately. 356 00:21:22,840 --> 00:21:26,440 And so water must have arrived on Earth and the other rocky planets 357 00:21:26,440 --> 00:21:30,480 later and one of the leading theories is that it was delivered 358 00:21:30,480 --> 00:21:34,440 during a period of heavy bombardment nearly four billion years ago, 359 00:21:34,440 --> 00:21:37,840 as icy comets and asteroids slammed into the Earth. 360 00:21:41,800 --> 00:21:44,840 We think there might have been enough comets hitting the Earth 361 00:21:44,840 --> 00:21:48,120 to supply all of our water, but one of Rosetta's tasks 362 00:21:48,120 --> 00:21:51,520 is to look for hard evidence that they really did. 363 00:21:52,760 --> 00:21:56,760 Water can contain different kinds of hydrogen, different isotopes. 364 00:21:58,080 --> 00:22:02,200 And the ratio of these isotopes gives Earth's water a distinct signature. 365 00:22:03,520 --> 00:22:06,720 Rosetta will analyse the water on the comet to see 366 00:22:06,720 --> 00:22:09,640 whether it shares that same distinctive signature, 367 00:22:09,640 --> 00:22:13,480 real evidence that our water could have come from comets. 368 00:22:13,480 --> 00:22:15,560 But that's not all, 369 00:22:15,560 --> 00:22:20,000 Rosetta will also be looking for complex chemicals like amino acids 370 00:22:20,000 --> 00:22:23,800 which form the basis of life, to find out whether these, too, 371 00:22:23,800 --> 00:22:25,760 could have come from comets. 372 00:22:25,760 --> 00:22:30,240 These are some of the most profound questions in science today and 373 00:22:30,240 --> 00:22:34,680 that's why this particular mission is so exciting, and so ambitious. 374 00:22:36,840 --> 00:22:39,960 To answer these big questions Rosetta has to do something 375 00:22:39,960 --> 00:22:43,440 really new, land on the surface and drill down to analyse what 376 00:22:43,440 --> 00:22:47,640 lies beneath, and before you can do that you have to catch the comet. 377 00:22:51,320 --> 00:22:53,480 It's an incredible undertaking, 378 00:22:53,480 --> 00:22:56,120 challenging in just about every respect 379 00:22:56,120 --> 00:23:00,280 and it's made Rosetta a huge engineering project. 380 00:23:01,360 --> 00:23:04,840 Now the most crucial moments are finally upon the team. 381 00:23:06,000 --> 00:23:09,080 Andrea Accomazzo's been working on Rosetta 382 00:23:09,080 --> 00:23:12,520 since the earliest design stages and is the flight director. 383 00:23:13,920 --> 00:23:17,400 It is one of the most challenging space missions ever. 384 00:23:17,400 --> 00:23:20,320 Nobody has ever gone to such an irregular body, 385 00:23:20,320 --> 00:23:24,400 such an active body with the need of such a high accuracy of flying 386 00:23:24,400 --> 00:23:27,920 the spacecraft around the body so it's definitely something new, 387 00:23:27,920 --> 00:23:32,520 it's unique in the history of space flight and it's fantastic. 388 00:23:32,520 --> 00:23:35,240 How do you go about rendezvousing with the comet? 389 00:23:35,240 --> 00:23:38,600 What we wanted to do, we wanted to reach the comet and stop there 390 00:23:38,600 --> 00:23:40,320 and start orbiting the comet 391 00:23:40,320 --> 00:23:43,880 so we had to slow down the spacecraft compared to the comet and slowly 392 00:23:43,880 --> 00:23:47,520 approach it and once we were close to it then we could start our mission. 393 00:23:47,520 --> 00:23:51,040 At the end of our ten-years journey we now start exploring 394 00:23:51,040 --> 00:23:54,440 a new world and we have to characterise it completely. 395 00:23:54,440 --> 00:23:56,360 We don't know anything of this new world. 396 00:23:56,360 --> 00:23:58,480 We have to characterise the gravity field first, 397 00:23:58,480 --> 00:24:00,960 we have to characterise how it's rotating, 398 00:24:00,960 --> 00:24:03,800 we know the shape, we have taken a couple of images but we have to 399 00:24:03,800 --> 00:24:07,120 characterise it to a level such that we can then orbit and land. 400 00:24:07,120 --> 00:24:09,600 And, of course, this is a changing body as well, 401 00:24:09,600 --> 00:24:12,840 we expect the comet to become more active as it gets near the sun. 402 00:24:12,840 --> 00:24:15,440 We have already seen some activity from the comet. 403 00:24:15,440 --> 00:24:17,840 How do you have to take that into account? 404 00:24:17,840 --> 00:24:20,440 It sounds like a scary place for a spacecraft to be. 405 00:24:20,440 --> 00:24:23,600 Indeed, indeed, it is also a scary place to be with a spacecraft 406 00:24:23,600 --> 00:24:25,760 which has huge solar arrays. 407 00:24:25,760 --> 00:24:29,600 Fundamentally the comet is releasing material and gases 408 00:24:29,600 --> 00:24:32,400 so we are going to a windy place with huge sails 409 00:24:32,400 --> 00:24:34,600 and it's not easy to navigate around a body like this 410 00:24:34,600 --> 00:24:36,960 but this is the mission we have and we will do it. 411 00:24:36,960 --> 00:24:39,480 A lot of science will come from the main spacecraft 412 00:24:39,480 --> 00:24:42,320 but the lander is very, very exciting. Tell us about that, 413 00:24:42,320 --> 00:24:45,440 how is the lander going to touch down on the comet? 414 00:24:45,440 --> 00:24:49,200 The lander, for sure, is the most fascinating part of this mission. 415 00:24:49,200 --> 00:24:52,400 You can imagine we are landing on a body that is far away from the 416 00:24:52,400 --> 00:24:55,520 Earth, a body that is so irregular so it definitely is the most 417 00:24:55,520 --> 00:24:59,800 fascinating, and also technically it is the most challenging for us. 418 00:24:59,800 --> 00:25:01,880 We have to release the lander when we are flying 419 00:25:01,880 --> 00:25:04,800 in front of the comet which is a very bad region for the wind. 420 00:25:04,800 --> 00:25:06,640 The wind is expected to be very high. 421 00:25:06,640 --> 00:25:09,280 - Because that is where the sun's energy comes in. - Right, right. 422 00:25:09,280 --> 00:25:11,440 The sun is heating the surface of the comet 423 00:25:11,440 --> 00:25:13,400 and it's blowing out a lot of gases. 424 00:25:13,400 --> 00:25:16,880 We have to fly very fast in front of the comet, release the lander, 425 00:25:16,880 --> 00:25:19,720 the lander will slowly fall onto the surface of the comet... 426 00:25:19,720 --> 00:25:21,960 - Just pulled by the comet's gravity? - Right. 427 00:25:21,960 --> 00:25:24,280 It is pulled by the gravity of the comet. 428 00:25:24,280 --> 00:25:27,200 There is no active system to slow down on the lander 429 00:25:27,200 --> 00:25:31,280 and when it lands, it anchors itself, it has two harpoons underneath 430 00:25:31,280 --> 00:25:35,080 and they will be fired onto the surface, hoping to hook it there. 431 00:25:35,080 --> 00:25:38,120 And so the lander will do its thing, it will send back information, 432 00:25:38,120 --> 00:25:41,320 but the mission goes on even after the landing. 433 00:25:41,320 --> 00:25:42,680 What happens next? 434 00:25:42,680 --> 00:25:47,040 The mission itself is spending 18 months at least around the comet. 435 00:25:47,040 --> 00:25:51,400 There's much more we have to discover through the science instruments on board Rosetta. 436 00:25:51,400 --> 00:25:53,880 So taking it together, it's 18 years of work for you, 437 00:25:53,880 --> 00:25:57,240 what does it feel like to be this close to starting to get data back? 438 00:25:57,240 --> 00:26:01,200 Well, when I started working on Rosetta in 1996 it looks so far away 439 00:26:01,200 --> 00:26:05,080 the whole thing but my life has gone through, in my professional life 440 00:26:05,080 --> 00:26:08,560 and my private life, has gone through this 18 years and now we are there 441 00:26:08,560 --> 00:26:12,440 and it can't be anything better than what we are living right now. 442 00:26:12,440 --> 00:26:15,400 Well, I hope it all goes well, we look forward to seeing the results. 443 00:26:15,400 --> 00:26:17,280 - Thank you very much. - Thanks. 444 00:26:21,080 --> 00:26:24,920 The Rosetta probe is an astonishing piece of craftsmanship. 445 00:26:24,920 --> 00:26:29,280 Here at the control centre they have what's called an engineering replica 446 00:26:29,280 --> 00:26:32,680 of it, kept in pristine, space-like cleanliness 447 00:26:32,680 --> 00:26:36,160 and used to test all of the software on board. 448 00:26:40,560 --> 00:26:45,240 This engineering replica is obviously missing its solar panel wings, 449 00:26:45,240 --> 00:26:47,960 but other than that it's the perfect way to admire 450 00:26:47,960 --> 00:26:49,880 all of Rosetta's features. 451 00:26:56,720 --> 00:27:00,720 The whole thing weighed 2.9 tonnes on launch. 452 00:27:02,640 --> 00:27:05,560 But 1.6 tonnes of that was fuel. 453 00:27:12,360 --> 00:27:16,680 24 tiny thrusters give precision control. 454 00:27:19,560 --> 00:27:23,520 Rosetta itself carries 11 on-board instruments, 455 00:27:23,520 --> 00:27:26,560 which all have to share the same power supply. 456 00:27:28,840 --> 00:27:32,680 There are 12,000 separate electrical connections. 457 00:27:32,680 --> 00:27:37,320 They alone took three years to build and all of them have to work. 458 00:27:39,000 --> 00:27:40,880 Over the next three and a half months, 459 00:27:40,880 --> 00:27:43,440 Rosetta will be working its way closer to the comet, 460 00:27:43,440 --> 00:27:46,880 taking images and measurements with these instruments all the time, 461 00:27:46,880 --> 00:27:49,040 helping us to understand what's going on 462 00:27:49,040 --> 00:27:52,440 and trying to select a site for the all-important landing. 463 00:27:52,440 --> 00:27:56,120 After nearly 20 years of work, I can't imagine what the team 464 00:27:56,120 --> 00:27:59,880 here must be thinking as they get close to these historic moments. 465 00:27:59,880 --> 00:28:02,240 We're going to explore a brave new world, 466 00:28:02,240 --> 00:28:05,160 we're going to learn so much not just about this comet, 467 00:28:05,160 --> 00:28:07,560 not just about the origins of the solar system, 468 00:28:07,560 --> 00:28:10,720 but also about what happened a long time ago here on Earth. 469 00:28:10,720 --> 00:28:13,160 It's a really, really exciting time. 470 00:28:16,840 --> 00:28:19,600 Of course, we'll be following Rosetta's progress over the next 471 00:28:19,600 --> 00:28:22,600 nail-biting couple of months as it spirals down towards the comet, 472 00:28:22,600 --> 00:28:25,840 releasing the lander with its grappling hooks, ready for drilling. 473 00:28:25,840 --> 00:28:28,120 And next month we'll be looking at new worlds 474 00:28:28,120 --> 00:28:31,040 discovered on planets outside our solar system. 475 00:28:31,040 --> 00:28:35,600 In the meanwhile, get outside and get looking for comets. Good night. 476 00:28:37,360 --> 00:28:41,360 # Let's hitch a rocket to the moon 477 00:28:41,360 --> 00:28:44,640 # Open out the throttle 478 00:28:44,640 --> 00:28:48,280 # Steer towards the sun 479 00:28:48,280 --> 00:28:52,000 # Rosetta's in her stride 480 00:28:53,520 --> 00:28:56,880 # Surf the comet's tail on an astronomic trail 481 00:28:56,880 --> 00:29:00,440 # Take the world along just for the ride 482 00:29:00,440 --> 00:29:02,800 # Comet chaser! #