1 00:00:01,235 --> 00:00:08,200 Since its launch in 1990, the NASA/ESA Hubble Space Telescope has been exploring the Universe. 2 00:00:09,495 --> 00:00:14,600 To obtain crystal clear images of distant galaxies and faint nebulae, 3 00:00:14,695 --> 00:00:21,000 Hubble relies on sophisticated hardware to keep its gaze locked onto its target. 4 00:00:28,000 --> 00:00:31,000 How does Hubble orientate itself in space? 5 00:00:33,375 --> 00:00:40,000 From its vantage point above Earth’s atmosphere Hubble observes the Universe 24/7. 6 00:00:40,255 --> 00:00:48,100 Whirling around Earth at 28 000 kilometres an hour, Hubble has to rely on its finely tuned Pointing Control System 7 00:00:49,700 --> 00:00:54,200 to make sure its scientific instruments are looking directly at its remote targets. 8 00:00:57,875 --> 00:01:03,700 To ensure its gaze never falters, Hubble uses three Fine Guidance Sensors 9 00:01:03,915 --> 00:01:06,425 located around the circumference of the telescope. 10 00:01:07,015 --> 00:01:11,500 These sensors provide precise pointing information for Hubble. 11 00:01:11,545 --> 00:01:14,255 They look out for auxiliary guide stars 12 00:01:14,255 --> 00:01:20,900 which enable Hubble to determine its orientation in space and to stay focused on one point. 13 00:01:20,980 --> 00:01:26,400 When the telescope drifts by even a minuscule amount these sensors will detect it. 14 00:01:29,060 --> 00:01:35,800 To change its orientation and to correct for drifts Hubble does not use propellants. 15 00:01:35,865 --> 00:01:41,000 Their fumes could contaminate Hubble’s observations and limit its lifetime. 16 00:01:41,025 --> 00:01:48,000 Instead, Reaction Wheels steer the telescope, using the elegant principle of Newton’s third law: 17 00:01:48,000 --> 00:01:53,355 if one of the wheels turns clockwise, Hubble will turn counterclockwise. 18 00:01:56,205 --> 00:02:01,900 These four large, massive flywheels spin rapidly under the control of Hubble’s computer 19 00:02:01,960 --> 00:02:06,300 and move the telescope using the immense torque generated by their spinning. 20 00:02:09,620 --> 00:02:16,000 But even at its fastest, Hubble only rotates as quickly as the minute hand of a clock 21 00:02:16,080 --> 00:02:19,340 — just 90° in 15 minutes. 22 00:02:22,875 --> 00:02:29,900 Detecting such minute movements requires the best and most sensitive gyroscopes in the world; 23 00:02:30,845 --> 00:02:33,425 Hubble has six of them. 24 00:02:33,425 --> 00:02:38,300 They constantly measure if and at what speed the telescope is turning. 25 00:02:38,440 --> 00:02:45,000 In combination with the fine guidance sensors, they keep the telescope precisely pointed for long periods, 26 00:02:45,880 --> 00:02:50,120 enabling Hubble to produce its spectacular views of the Universe. 27 00:02:54,100 --> 00:03:00,000 To operate with optimal efficiency, Hubble needs three of its six gyroscopes — 28 00:03:00,280 --> 00:03:06,640 — but even if just one was available, its scientific capabilities would not be affected in the slightest. 29 00:03:11,140 --> 00:03:14,060 Together these three systems have allowed Hubble 30 00:03:14,065 --> 00:03:20,000 to perform its outstanding scientific mission over the last 28 years. 31 00:03:20,040 --> 00:03:26,000 And many more new discoveries can be expected in the years to come. 32 00:03:26,000 --> 00:03:30,960 Hubblecast is produced by ESA/Hubble at the European Southern Observatory in Germany 33 00:03:30,960 --> 00:03:35,900 The Hubble mission is a project of international cooperation between NASA and the European Space Agency. 34 00:03:36,640 --> 00:03:39,680 Sibtitles by ESA/Hubble. Translation by --- 35 00:03:59,280 --> 00:04:01,660 36 00:04:01,665 --> 00:04:04,405 37 00:04:04,405 --> 00:04:07,415 38 00:04:07,415 --> 00:04:10,135 39 00:04:10,135 --> 00:04:11,795 40 00:04:11,795 --> 00:04:13,875 41 00:04:13,875 --> 00:04:16,595