6. Beyond Earth 00:00:23:12 00:00:25:09 The Hubble Space Telescope. 00:00:25:10 00:00:28:08 It is by far the most famous telescope in history. 00:00:28:09 00:00:29:19 And for good reason. 00:00:29:20 00:00:33:13 Hubble has revolutionised so many fields in astronomy. 00:00:33:14 00:00:37:00 By modern standards, Hubble's mirror is actually quite small. 00:00:37:01 00:00:40:00 It only measures about 2.4 metres across. 00:00:40:01 00:00:43:15 But its location is literally out of this world. 00:00:43:16 00:00:47:08 High above the blurring effects of the atmosphere, it has an exceptionally... 00:00:47:09 00:00:49:14 ...sharp view of the Universe. 00:00:49:15 00:00:54:08 And what's more, Hubble can see ultraviolet and near-infrared light. 00:00:54:09 00:00:57:11 This light just cannot be seen by ground-based telescopes because... 00:00:57:12 00:01:00:21 ...it is blocked by the atmosphere. 00:01:00:22 00:01:04:21 Cameras and spectrographs, some as big as a telephone booth... 00:01:04:22 00:01:09:14 ...dissect and register the light from distant cosmic shores. 00:01:09:15 00:01:14:07 Just like any ground-based telescope, Hubble is upgraded from time to time. 00:01:14:08 00:01:17:18 Spacewalking astronauts carry out servicing missions. 00:01:17:19 00:01:19:10 Broken parts get refurbished. 00:01:19:11 00:01:21:24 And older instruments get replaced with newer and... 00:01:22:00 00:01:24:19 ...state-of-the-art technology. 00:01:24:20 00:01:28:06 Hubble has become the powerhouse of observational astronomy. 00:01:28:07 00:01:32:05 And it has transformed our understanding of the cosmos. 00:01:35:13 00:01:40:13 With its keen eyesight, Hubble observed seasonal changes on Mars... 00:01:41:15 00:01:44:12 ...a cometary impact on Jupiter... 00:01:46:05 00:01:49:15 ...an edge-on view of Saturn's rings... 00:01:52:06 00:01:55:19 ...and even the surface of tiny Pluto. 00:01:55:20 00:02:01:08 It revealed the life cycle of stars, from their very birth and baby days... 00:02:01:14 00:02:07:14 ...in a nursery of dust-laden clouds of gas, all the way to their final farewell: 00:02:07:14 00:02:12:21 ...as delicate nebulae, slowly blown into space by dying stars... 00:02:12:22 00:02:20:00 ...or as titanic supernova explosions that almost outshine their home galaxy. 00:02:20:01 00:02:24:00 Deep in the Orion Nebula, Hubble even saw the breeding ground of new... 00:02:24:01 00:02:29:02 ...solar systems: dusty disks around newborn stars that may soon... 00:02:29:03 00:02:31:03 ...condense into planets. 00:02:31:04 00:02:35:09 The space telescope studied thousands of individual stars in giant globular... 00:02:35:10 00:02:41:00 ...clusters, the oldest stellar families in the Universe. 00:02:41:01 00:02:43:09 And galaxies, of course. 00:02:43:10 00:02:46:24 Never before had astronomers seen so much detail. 00:02:47:00 00:02:53:21 Majestic spirals, absorbing dust lanes, violent collisions. 00:02:56:01 00:03:00:12 Extremely long exposures of blank regions of sky even revealed... 00:03:00:13 00:03:05:02 ...thousands of faint galaxies billions of light-years away. 00:03:05:03 00:03:09:00 Photons that were emitted when the Universe was still young. 00:03:09:01 00:03:13:10 A window into the distant past, shedding new light on the... 00:03:13:11 00:03:16:15 ...ever-evolving cosmos. 00:03:17:04 00:03:19:22 Hubble is not the only telescope in space. 00:03:19:23 00:03:24:21 This is NASA's Spitzer Space Telescope, launched in August 2003. 00:03:24:22 00:03:28:18 In a way, it is Hubble's equivalent for the infrared. 00:03:28:19 00:03:32:24 Spitzer has mirror that is only 85 centimetres across. 00:03:33:00 00:03:36:03 But the telescope is hiding behind a heat shield that protects... 00:03:36:04 00:03:37:12 ...it from the Sun. 00:03:37:13 00:03:42:04 And its detectors are tucked away in a dewar filled with liquid helium. 00:03:42:05 00:03:45:03 Here the detectors are cooled down to just a few degrees... 00:03:45:04 00:03:46:21 ...above absolute zero. 00:03:46:22 00:03:50:15 Making them very very sensitive. 00:03:50:16 00:03:53:18 Spitzer has revealed a dusty Universe. 00:03:53:19 00:03:57:15 Dark, opaque clouds of dust glow in the infrared when heated... 00:03:57:16 00:03:59:14 ...from within. 00:03:59:15 00:04:03:18 Shock waves from galaxy collisions sweep up dust in telltale rings... 00:04:03:19 00:04:08:12 ...and tidal features, new sites for ubiquitous star formation. 00:04:10:12 00:04:14:03 Dust is also produced in the aftermath of a star's death. 00:04:14:04 00:04:18:03 Spitzer found that planetary nebulae and supernova remnants are laden... 00:04:18:04 00:04:23:09 ...with dust particles, the prerequisite building blocks of future planets. 00:04:23:10 00:04:27:03 At other infrared wavelengths, Spitzer can also see right through a dust... 00:04:27:04 00:04:32:19 ...cloud, revealing the stars inside, hidden in their dark cores. 00:04:32:20 00:04:35:24 Finally, the space telescope's spectrographs have studied... 00:04:36:00 00:04:39:22 ...the atmospheres of extrasolar planets - gas giants like Jupiter... 00:04:39:23 00:04:43:23 ...that race around their parent stars in just a few days. 00:04:45:17 00:04:47:22 So what about X-rays and gamma rays? 00:04:47:23 00:04:50:15 Well, they are completely blocked by the Earth's atmosphere. 00:04:50:16 00:04:54:04 And so without space telescopes, astronomers would be totally blind... 00:04:54:05 00:04:57:02 ...to these energetic forms of radiation. 00:04:57:03 00:05:00:13 X-ray and gamma ray space telescopes reveal the hot... 00:05:00:14 00:05:05:06 ...energetic and violent Universe of galaxy clusters, black holes... 00:05:05:07 00:05:09:13 ...supernova explosions, and galaxy collisions. 00:05:13:16 00:05:15:19 They are very hard to build, though. 00:05:15:20 00:05:19:09 Energetic radiation passes right through a conventional mirror. 00:05:19:10 00:05:24:15 X-rays can only be focused with nested mirror shells made of pure gold. 00:05:24:16 00:05:28:01 And gamma rays are studied with sophisticated pinhole cameras... 00:05:28:02 00:05:31:12 ...or stacked scintillators that give off brief flashes of normal light... 00:05:31:13 00:05:34:15 ...when struck by a gamma ray photon. 00:05:35:22 00:05:40:01 In the 1990s, NASA operated the Compton Gamma Ray Observatory. 00:05:40:02 00:05:43:05 At the time, it was the largest and most massive scientific... 00:05:43:06 00:05:44:20 ...satellite ever launched. 00:05:44:21 00:05:48:01 A fully fledged physics lab in space. 00:05:48:02 00:05:51:10 In 2008, Compton was succeeded by GLAST: 00:05:51:11 00:05:55:17 the Gamma Ray Large Area Space Telescope. 00:05:56:16 00:06:00:05 It will study everything in the high-energy Universe from dark... 00:06:00:06 00:06:02:15 ...matter to pulsars. 00:06:04:23 00:06:08:22 Meanwhile, astronomers have two X-ray telescopes in space. 00:06:08:23 00:06:13:23 NASA's Chandra X-ray Observatory and ESA's XMM-Newton Observatory... 00:06:13:24 00:06:18:00 ...are both studying the hottest places in the Universe. 00:06:18:20 00:06:22:12 This is what the sky looks like with X-ray vision. 00:06:22:13 00:06:26:24 Extended features are clouds of gas, heated to millions of degrees by... 00:06:27:00 00:06:30:12 ...shock waves in supernova remnants. 00:06:30:13 00:06:34:19 The bright point sources are X-ray binaries: neutron stars or... 00:06:34:20 00:06:38:11 ...black holes that suck in matter from a companion star. 00:06:38:12 00:06:42:02 This hot, infalling gas emits X-rays. 00:06:42:03 00:06:46:09 Likewise, X-ray telescopes reveal supermassive black holes in... 00:06:46:10 00:06:48:14 ...the cores of distant galaxies. 00:06:48:15 00:06:52:15 Matter that spirals inward gets hot enough to glow in X-rays... 00:06:52:16 00:06:56:24 ...just before it plunges into the black hole and out of sight. 00:06:57:00 00:07:01:16 Hot but tenuous gas also fills the space between individual galaxies... 00:07:01:17 00:07:03:03 ...in a cluster. 00:07:03:04 00:07:07:01 Sometimes, this intracluster gas is shocked and heated even more... 00:07:07:02 00:07:11:07 ...by colliding and merging galaxy clusters. 00:07:11:08 00:07:15:14 Even more exciting are gamma ray bursts, the most energetic... 00:07:15:15 00:07:17:10 ...events in the Universe. 00:07:17:11 00:07:21:18 These are catastrophic terminal explosions of very massive, rapidly... 00:07:21:19 00:07:23:14 ...spinning stars. 00:07:23:15 00:07:27:14 In less than a second, they release more energy than the Sun does in... 00:07:27:15 00:07:30:14 ...10 billion years. 00:07:33:06 00:07:37:06 Hubble, Spitzer, Chandra, XMM-Newton and GLAST... 00:07:37:07 00:07:39:17 ...are all versatile giants. 00:07:39:18 00:07:42:18 But some space telescopes are much smaller and have much more... 00:07:42:19 00:07:44:08 ...focused missions. 00:07:44:09 00:07:46:09 Take COROT, for example. 00:07:46:10 00:07:49:24 This French satellite is devoted to stellar seismology and the study... 00:07:50:00 00:07:51:24 ...of extrasolar planets. 00:07:52:00 00:07:56:08 Or NASA's Swift satellite, a combined X-ray and gamma ray observatory... 00:07:56:09 00:08:00:20 ...designed to unravel the mystery of gamma ray bursts. 00:07:20:21 00:08:05:06 And then there's WMAP, the Wilkinson Microwave Anisotropy Probe. 00:08:05:07 00:08:08:23 In just over two years in space, it had already mapped the cosmic... 00:08:08:24 00:08:12:09 ...background radiation to unprecedented detail. 00:08:12:10 00:08:16:07 WMAP gave cosmologists the best view yet of one of the earliest... 00:08:16:08 00:08:21:19 ...phases of the Universe, more than 13 billion years ago. 00:08:21:20 00:08:24:18 Opening up the space frontier has been one of the most exciting... 00:08:24:19 00:08:27:08 ...developments in the history of the telescope. 00:08:27:09 00:08:29:21 So what's next?