1 00:00:07,639 --> 00:00:08,940 The Allgäu public observatory 2 00:00:08,940 --> 00:00:12,400 lies amidst the picturesque landscape of southern Germany. 3 00:00:16,347 --> 00:00:17,322 As night falls, 4 00:00:17,322 --> 00:00:19,017 a team of scientists and engineers 5 00:00:19,017 --> 00:00:22,848 prepares to field test a very cool piece of technology: 6 00:00:22,848 --> 00:00:25,031 a laser guide star unit, 7 00:00:25,031 --> 00:00:28,886 which will soon be on its way to ESO’s Paranal Observatory. 8 00:00:34,500 --> 00:00:37,152 This is the ESOcast! 9 00:00:37,152 --> 00:00:39,962 Cutting-edge science and life behind the scenes at ESO, 10 00:00:39,962 --> 00:00:42,330 the European Southern Observatory. 11 00:00:42,330 --> 00:00:48,855 Exploring the ultimate frontier with our host Dr J, a.k.a. Dr Joe Liske. 12 00:00:52,106 --> 00:00:53,935 Hello and welcome to the ESOcast. 13 00:00:54,335 --> 00:00:58,445 Today we’re at the Allgäu public observatory in southern Germany 14 00:00:58,445 --> 00:01:01,881 because this is where a team of scientists and engineers from ESO 15 00:01:01,881 --> 00:01:05,712 is testing a brand new laser guide star unit. 16 00:01:05,712 --> 00:01:07,152 ‘What’s that?’ you ask. 17 00:01:07,152 --> 00:01:08,360 Let me explain. 18 00:01:09,033 --> 00:01:12,562 Now, we have all looked at the sky at night and seen the stars twinkling. 19 00:01:13,166 --> 00:01:15,674 Now, the stars themselves, of course, don’t do any twinkling. 20 00:01:15,674 --> 00:01:19,157 The twinkling is caused by turbulence in the Earth’s atmosphere. 21 00:01:19,600 --> 00:01:21,618 As the starlight crosses the atmosphere 22 00:01:21,618 --> 00:01:23,708 it encounters different pockets of air 23 00:01:23,708 --> 00:01:25,658 with different temperature and pressure 24 00:01:25,658 --> 00:01:27,841 which bend the light in different ways, 25 00:01:27,841 --> 00:01:29,513 thus causing distortions. 26 00:01:29,792 --> 00:01:32,880 In fact you can see this effect often in broad daylight, 27 00:01:32,880 --> 00:01:35,689 whenever you look towards a distant object on the horizon 28 00:01:35,689 --> 00:01:37,036 on a hot day. 29 00:01:39,149 --> 00:01:42,168 Now the twinkling is all very pretty and even romantic, 30 00:01:42,168 --> 00:01:45,279 but for us astronomers it’s actually a real problem 31 00:01:45,279 --> 00:01:47,532 because it means that our images are blurred 32 00:01:47,532 --> 00:01:49,645 and less sharp than they could be 33 00:01:49,645 --> 00:01:51,827 if it wasn’t for the atmosphere. 34 00:01:52,083 --> 00:01:53,755 So, what do we do about it? 35 00:01:54,000 --> 00:01:57,330 Essentially we need a method to cancel out the distortions, 36 00:01:57,330 --> 00:01:59,838 in effect, to “un-twinkle” the stars. 37 00:02:00,326 --> 00:02:03,135 The way to do it is to bounce the starlight off a mirror 38 00:02:03,135 --> 00:02:06,711 that is slightly deformed in exactly the right manner 39 00:02:06,711 --> 00:02:08,848 to cancel out the distortions. 40 00:02:09,544 --> 00:02:12,470 But how do you know how to deform your mirror? 41 00:02:18,623 --> 00:02:21,363 As ESO’s Very Large Telescope observes the sky, 42 00:02:21,363 --> 00:02:24,382 a specialised computer can pick a bright star 43 00:02:24,382 --> 00:02:26,843 and constantly monitor how it twinkles 44 00:02:26,843 --> 00:02:29,931 — deducing the atmospheric conditions above the telescope 45 00:02:29,931 --> 00:02:31,928 many hundreds of times a second. 46 00:02:32,276 --> 00:02:34,088 The computer then sends commands 47 00:02:34,088 --> 00:02:37,338 to a series of devices attached to a mirror in the telescope, 48 00:02:38,000 --> 00:02:42,100 bending and flexing it precisely in time with the atmospheric turbulence, 49 00:02:42,700 --> 00:02:45,558 cancelling out the distortion in the images. 50 00:02:48,043 --> 00:02:50,133 So, for this correction process to work 51 00:02:50,133 --> 00:02:52,199 you need a really bright star 52 00:02:52,199 --> 00:02:54,312 in the field of view of your telescope. 53 00:02:54,869 --> 00:02:57,609 But bright stars are very few and far between, 54 00:02:57,609 --> 00:03:00,257 and remember that the VLT was designed 55 00:03:00,257 --> 00:03:04,320 to image only a very small part of the sky at any given time. 56 00:03:04,692 --> 00:03:06,224 So for most observations 57 00:03:06,224 --> 00:03:10,589 there just won’t be a bright star in the field of view of the VLT. 58 00:03:10,705 --> 00:03:12,099 So what do we do now? 59 00:03:12,377 --> 00:03:13,213 Well, 60 00:03:13,213 --> 00:03:14,653 we make our own. 61 00:03:16,116 --> 00:03:17,973 90 kilometres above our heads, 62 00:03:17,973 --> 00:03:19,413 in the upper atmosphere, 63 00:03:19,413 --> 00:03:22,176 is a relatively thin layer of sodium. 64 00:03:22,455 --> 00:03:25,613 If you fire a powerful laser beam into the sky 65 00:03:25,613 --> 00:03:28,400 you can make these sodium atoms glow, 66 00:03:28,400 --> 00:03:31,557 thereby effectively creating an artificial star 67 00:03:31,557 --> 00:03:33,577 for the computer to lock on to. 68 00:03:37,850 --> 00:03:39,057 In 2006, 69 00:03:39,057 --> 00:03:43,747 ESO installed the Southern Hemisphere’s first laser guide star on the VLT. 70 00:03:44,212 --> 00:03:46,905 This system greatly improves the telescope’s power, 71 00:03:46,905 --> 00:03:50,713 meaning the VLT can even make sharper images than Hubble 72 00:03:50,713 --> 00:03:53,175 for certain types of observation. 73 00:03:55,241 --> 00:03:57,749 But this existing system has limitations. 74 00:03:58,190 --> 00:04:01,162 It can only create one artificial star at once 75 00:04:01,162 --> 00:04:03,647 meaning it can only correct the telescope’s vision 76 00:04:03,647 --> 00:04:06,666 for a small part of the sky at any one time. 77 00:04:08,268 --> 00:04:09,684 It’s also very bulky 78 00:04:09,684 --> 00:04:12,331 – the equipment has to be kept in a separate laboratory 79 00:04:12,331 --> 00:04:16,464 and the laser beam fed along an optical fibre to the telescope. 80 00:04:21,084 --> 00:04:24,290 Based on the experience obtained with its first system, 81 00:04:24,290 --> 00:04:27,540 ESO engineers have been working to build a much improved, 82 00:04:27,540 --> 00:04:30,002 new laser guide star unit. 83 00:04:33,400 --> 00:04:35,249 So, Domenicos, this is it — this is the laser. 84 00:04:35,249 --> 00:04:36,550 It’s incredibly small, 85 00:04:36,550 --> 00:04:38,918 it fits on the back of this small telescope, 86 00:04:38,918 --> 00:04:39,754 that’s amazing. 87 00:04:40,404 --> 00:04:44,305 Yes. So this is what we’ve been working on for the past five years, 88 00:04:44,305 --> 00:04:46,790 to make a 20-watt laser, very compact 89 00:04:46,790 --> 00:04:47,672 and lightweight 90 00:04:47,672 --> 00:04:50,667 so that it can be mounted directly on the back of the telescope. 91 00:04:50,667 --> 00:04:52,664 So we had to develop fibre lasers first 92 00:04:52,664 --> 00:04:56,054 and then developed these kinds of laser heads. 93 00:04:56,054 --> 00:04:58,540 So, you’ve just said it, it’s a 20-watt laser. 94 00:04:58,540 --> 00:05:00,350 That’s quite a bit of power isn’t it? 95 00:05:00,350 --> 00:05:02,858 Yes. This is the power we’ll need, actually, for 96 00:05:02,858 --> 00:05:05,319 the next generation of laser guide star systems. 97 00:05:05,319 --> 00:05:07,293 And right now, for example, at Paranal 98 00:05:07,293 --> 00:05:09,359 we have about 5-watt in the sky, 99 00:05:09,359 --> 00:05:11,914 so this is quite a jump in power. 100 00:05:11,914 --> 00:05:15,629 Is the laser beam that comes out of the end of this telescope dangerous? 101 00:05:15,629 --> 00:05:17,626 What happens if I put my hand into it? 102 00:05:18,160 --> 00:05:20,389 If you put your hand in, you’ll feel warmth. 103 00:05:20,389 --> 00:05:23,389 But don’t have to look into the beam. 104 00:05:23,500 --> 00:05:24,847 OK, so it won’t burn my hand. 105 00:05:24,847 --> 00:05:26,147 But what about aeroplanes, 106 00:05:26,147 --> 00:05:27,308 is it dangerous for them? 107 00:05:27,889 --> 00:05:30,165 It’s not dangerous for the equipment or for the aeroplane, 108 00:05:30,165 --> 00:05:32,533 it’s dangerous for the eyes of the passengers. 109 00:05:32,997 --> 00:05:36,109 And, this laser is above the maximum permitted exposure so 110 00:05:36,109 --> 00:05:39,267 we have to avoid planes crossing the beam. 111 00:05:39,267 --> 00:05:40,405 In fact, here where we are now 112 00:05:40,405 --> 00:05:43,725 we have obtained a no-fly zone above us, 113 00:05:43,725 --> 00:05:46,100 so we don’t risk hitting a plane. 114 00:05:46,906 --> 00:05:48,578 The new device is more reliable, 115 00:05:48,578 --> 00:05:52,061 easier to maintain, and much smaller. 116 00:05:52,061 --> 00:05:53,686 In fact, as we’ve just seen, 117 00:05:53,686 --> 00:05:56,612 the whole unit fits into one small package 118 00:05:56,612 --> 00:05:59,491 which is easy to mount on the launch telescope. 119 00:06:03,833 --> 00:06:05,134 Because it’s so much smaller, 120 00:06:05,134 --> 00:06:08,895 up to four of these lasers can be installed on a single telescope, 121 00:06:08,895 --> 00:06:13,075 correcting the VLT’s image over a much wider field of view. 122 00:06:15,954 --> 00:06:17,115 So what’s happening here in Germany 123 00:06:17,115 --> 00:06:19,762 is that our team is testing the new prototype 124 00:06:19,762 --> 00:06:24,453 to make sure that it works perfectly before it gets shipped to Paranal. 125 00:06:24,801 --> 00:06:27,495 The facilities here at the Allgäu public observatory 126 00:06:27,495 --> 00:06:28,609 are perfect for this 127 00:06:28,609 --> 00:06:29,677 — and, what’s more, 128 00:06:29,677 --> 00:06:32,371 they’re only a short drive from ESO Headquarters. 129 00:06:35,691 --> 00:06:38,060 Laser guide stars like this will be crucial 130 00:06:38,060 --> 00:06:41,032 for the forthcoming European Extremely Large Telescope, 131 00:06:41,032 --> 00:06:43,586 which will use adaptive optics routinely. 132 00:06:44,399 --> 00:06:48,067 The telescope will be many times the size of today’s biggest telescopes, 133 00:06:48,067 --> 00:06:50,854 which should mean much sharper image quality. 134 00:06:51,597 --> 00:06:55,219 But this great image quality will depend on how well the adaptive optics 135 00:06:55,219 --> 00:06:57,773 and the laser guide stars work. 136 00:06:59,817 --> 00:07:02,046 Pioneering new technologies like these 137 00:07:02,046 --> 00:07:07,154 will make a big difference to the world’s most advanced observatories of the future, 138 00:07:07,154 --> 00:07:09,198 especially the E-ELT. 139 00:07:10,173 --> 00:07:12,681 This is Dr J signing off for the ESOcast. 140 00:07:12,681 --> 00:07:16,396 Join me again next time for another cosmic adventure. 141 00:07:30,862 --> 00:07:32,441 While we were filming this episode, 142 00:07:32,441 --> 00:07:35,227 we got a stark reminder of why ESO’s telescopes 143 00:07:35,227 --> 00:07:38,292 are located on mountaintops of Northern Chile, 144 00:07:38,292 --> 00:07:40,846 and not here in the hills of Southern Germany. 145 00:07:44,956 --> 00:07:49,090 Thankfully, storms like this are not something you ever see at Paranal. 146 00:07:50,901 --> 00:07:54,546 ESOcast is produced by ESO, the European Southern Observatory. 147 00:07:54,918 --> 00:07:58,900 ESO, the European Southern Observatory, is the pre-eminent intergovernmental science and technology organisation in astronomy, 148 00:07:58,900 --> 00:08:01,900 designing, constructing and operating the world’s most advanced ground-based telescopes. 149 00:08:03,000 --> 00:08:08,000 Transcription by ESO ; translation by — 150 00:08:19,926 --> 00:08:23,037 Now that you've caught up with ESO, 151 00:08:24,964 --> 00:08:28,494 head 'out of this world' with Hubble. 152 00:08:30,839 --> 00:08:37,666 The Hubblecast highlights the latest discoveries of the world´s most recognized and prized space observatory, 153 00:08:39,708 --> 00:08:43,900 the NASA/ESA Hubble Space Telescope