1 00:00:03,000 --> 00:00:06,000 How did the Solar System form? 2 00:00:08,000 --> 00:00:11,000 What was the Universe like when it was very young? 3 00:00:15,000 --> 00:00:18,000 What are planets around other stars like? 4 00:00:21,000 --> 00:00:28,000 Over the last 25 years, Hubble has provided answers for these and many other questions. 5 00:00:29,000 --> 00:00:34,000 However, even the best of telescopes needs a colleague... 6 00:00:34,000 --> 00:00:37,000 … and that’s where the James Webb Space Telescope comes in. 7 00:00:57,000 --> 00:00:59,000 Episode 83: A cosmic double act: Hubble meets James Webb 8 00:01:03,000 --> 00:01:06,000 Presented by Dr J, aka Dr Joe Liske 9 00:01:09,000 --> 00:01:21,000 Launched in 1990, the NASA/ESA Hubble Space Telescope has been incredibly successful, and has not only reached, but exceeded all of its targets. 10 00:01:24,000 --> 00:01:29,000 The telescope is perhaps best known for beaming back stunning pictures of the Universe 11 00:01:29,000 --> 00:01:33,000 — but it does much more. 12 00:01:36,000 --> 00:01:43,000 Over the past 25 years, Hubble has proved to be on the most successful scientific instruments ever devised. 13 00:01:44,000 --> 00:01:49,000 From its vantage point, high above the Earth’s atmosphere, it has made many discoveries. 14 00:01:49,000 --> 00:01:53,000 Among its achievements, is an accurate measurement of the age of the Universe. 15 00:01:54,000 --> 00:02:00,000 It has also played a key role in the discovery that the expansion of the universe is accelerating. 16 00:02:00,000 --> 00:02:08,000 It has analysed exoplanets, discovered supermassive black holes, and watched galaxies grow, collide, and merge. 17 00:02:08,000 --> 00:02:10,000 And that’s just to name a few. 18 00:02:12,000 --> 00:02:19,000 Well, Hubble was really the first telescope we put in space that could do optical and near-infrared imaging, 19 00:02:19,000 --> 00:02:27,000 so Hubble really kind of set the stage and made a number of game-changing discoveries in different fields of astrophysical science. 20 00:02:27,000 --> 00:02:37,000 But it’s also raised a lot of questions as we’ve discovered new things, like the accelerating Universe, and how the distant Universe looks. 21 00:02:39,000 --> 00:02:45,000 Hubble has been undeniably brilliant, but there are some parts of the Universe that it just cannot see. 22 00:02:50,000 --> 00:02:55,000 Enter Hubble's future colleague, the James Webb Space Telescope! 23 00:02:55,000 --> 00:03:04,000 This magnificent telescope is a joint venture between NASA, the European Space Agency and the Canadian Space Agency. 24 00:03:06,000 --> 00:03:17,000 James Webb’s infrared view of the Universe will peer through obscuring dust to reveal the delicate structures of the star-forming regions beneath, 25 00:03:17,000 --> 00:03:24,000 probe light from the first galaxies and stars, born when the Universe was still in its youth, and much, much more. 26 00:03:32,000 --> 00:03:39,000 We’ll be able to see structure evolving with cosmic time in a much more profound way. 27 00:03:39,000 --> 00:03:54,000 We’ll be able to map, to see for example, this effect of gravitational lensing, these tiny arcs around clusters, which tell us how massive clusters are, in fantastic level of detail. 28 00:03:54,000 --> 00:03:58,000 And actually also hopefully to constrain the nature of the dark matter. 29 00:03:59,000 --> 00:04:02,000 It’s almost hard to conceive, it’s going to be a complete game-changer. 30 00:04:04,000 --> 00:04:06,000 It’ll totally change the landscape of what we can do and what we can measure. 31 00:04:08,000 --> 00:04:11,000 So, what are some of the differences between Hubble and James Webb? 32 00:04:11,000 --> 00:04:17,000 Well, first of all, James Webb is incredibly big for a space telescope. 33 00:04:17,000 --> 00:04:26,000 While Hubble’s 2.4-metre mirror is already quite large, it is simply dwarfed by James Webb’s 6.5-metre mirror. 34 00:04:26,000 --> 00:04:33,000 James Webb stand a much better chance of detecting the faint light from the first galaxies.. 35 00:04:33,000 --> 00:04:39,000 Another difference is that Hubble was designed to be visited by astronauts for a service once in a while, 36 00:04:39,000 --> 00:04:41,000 swapping out instruments and faulty components. 37 00:04:41,000 --> 00:04:48,000 This will not be possible for James Webb. Once it’s launched, it will have to fend for itself. 38 00:04:57,000 --> 00:05:00,000 The amazing thing about the Hubble Space Telescope is it was designed to be serviced, 39 00:05:03,000 --> 00:05:09,000 and so over 5 space shuttle missions we’ve upgraded the telescope, the last time in 2009 — I was lucky enough to be on that mission — 40 00:05:09,000 --> 00:05:20,000 and we’ve put new instruments on Hubble, new solar arrays, new computers, new memory sticks, everything you need to have a long life left in the telescope left. 41 00:05:20,000 --> 00:05:26,000 So I think Hubble has a lot left in it because the Universe provides us plenty of mysteries to solve. 42 00:05:26,000 --> 00:05:30,000 I’m convinced that maybe even the greatest discovery of Hubble is still to come. 43 00:05:32,000 --> 00:05:38,000 The reason for the different design is that James Webb will look at a different kind of light compared to Hubble. 44 00:05:39,000 --> 00:05:46,000 While Hubble can see ultraviolet, visible, and some infrared light, James Webb is specialised for the infrared, 45 00:05:47,000 --> 00:05:53,000 and that means it has to be a cold telescope — a very cold telescope. 46 00:05:54,000 --> 00:06:03,000 In fact, James Webb will have to operate at something like minus 230 degrees celsius — just about 40 degrees above absolute zero. 47 00:06:04,000 --> 00:06:09,000 The reason is that warm objects emit infrared heat radiation. 48 00:06:09,000 --> 00:06:17,000 So, if you want you your infrared telescope to be exceptionally sensitive, you have to cool it down to very low temperatures. 49 00:06:17,000 --> 00:06:21,000 Otherwise, it will simply blind itself with its own heat radiation. 50 00:06:25,000 --> 00:06:32,000 Because it has to operate at incredibly cold temperatures, James Webb can’t be built in the same way as Hubble. 51 00:06:34,000 --> 00:06:40,000 In particular, it has to carry its own huge sunshield to keep the telescope cool. 52 00:06:41,000 --> 00:06:48,000 The telescope and the sunshield are so big that James Webb will have to unpack itself once launched. 53 00:06:58,000 --> 00:07:04,000 It is a great feat of engineering, as everything for the telescope has to be built at room temperature, 54 00:07:05,000 --> 00:07:13,000 but still needs to be aligned and working properly when it is cooled down — which changes the size of the components inside. 55 00:07:24,000 --> 00:07:29,000 Just the act of having to get something to 40 K is non-trivial. 56 00:07:29,000 --> 00:07:33,000 With JWST, we have a big sunshade, so everything’s in the shadow, 57 00:07:33,000 --> 00:07:43,000 but we still have a lot of hardware that has to be covered in multiple layers of blankets, and they’re cryogenic blankets which means they have to be specially designed, specially tailored, 58 00:07:43,000 --> 00:07:53,000 and it’s very hard to install them, so it really moves you away from the serviceability or modularity idea that Hubble was built with. 59 00:07:54,000 --> 00:08:00,000 Keeping James Webb cold is the reason behind another big difference between it and Hubble. 60 00:08:04,000 --> 00:08:08,000 Whilst Hubble orbits the Earth at around five hundred kilometres, 61 00:08:08,000 --> 00:08:17,000 James Webb has a very different path — not in orbit of the Earth — that will keep it one and a half million kilometres from Earth. 62 00:08:20,000 --> 00:08:22,000 And astronomers have an additional bonus to look forward to — 63 00:08:23,000 --> 00:08:26,000 when James Webb is launched, Hubble will still be active. 64 00:08:26,000 --> 00:08:33,000 So, for some period of time, astronomers will be able to use both telescopes to explore the cosmos. 65 00:08:33,000 --> 00:08:35,000 Who knows what they will find? 66 00:08:36,000 --> 00:08:43,000 This is Dr. J, signing off for the Hubblecast. This time, engineering surprised us beyond our wildest imagination. 67 00:08:45,000 --> 00:08:49,000 Hubblecast is produced by ESA/Hubble at the European Southern Observatory in Germany. 68 00:08:50,000 --> 00:08:55,000 The Hubble mission is a project of international collaboration between NASA and the European Space Agency.