00:00Arguably the most significant scientific instrument in history has been the Hubble
00:10Space Telescope. It has changed our understanding of the universe, yet it has posed serious new
00:18questions about the nature of matter itself. Hubble has confirmed the widespread distribution
00:27of black holes and has viewed light from galaxies more distant than anything previously seen.
00:35As well as its scientific discoveries are the stunning images.
00:57In 1609, Galileo built an early telescope and soon turned it to the night sky. The telescope
01:17was a powerful tool that led to a complete re-evaluation of the Earth's place in the universe. In 1668,
01:25Newton invented the Reflecting Telescope to eliminate the problem of uneven refraction
01:32of the different wavelengths of light. The Reflecting Telescope became the design of choice for astronomers,
01:40and in 1781, William Herschel used an instrument he had built himself to discover the planet Uranus.
01:48The Newtonian Telescope was scaled up to immense proportions, and in 1924, it was with the 2.5-meter
01:58Hooker Telescope at the Mount Wilson Observatory that Edwin Hubble realized the Milky Way was not the universe,
02:05the universe, but just one of countless galaxies.
02:12But there was still a problem. No matter how mathematically perfect a telescope is, its images are distorted by the Earth's atmosphere,
02:21and some wavelengths cannot reach the ground. In 1946, astrophysicist Lyman Spitzer proposed a telescope in orbit above the Earth's atmosphere.
02:32The idea clearly outstripped the technology of the time, but by 1966, NASA began launching a series of orbiting astronomical observatories.
02:47Only two were successful, but the telescopes, in low Earth orbit, were the first to see the night skies in the ultraviolet part of the spectrum.
03:00In the 1970s, plans were drawn up for a large orbiting telescope. Part of its brief was for it to be visited regularly by maintenance crews,
03:08something that would become possible when the space shuttle went into service.
03:15The design called for a 2.4-meter primary mirror ground within very fine tolerances, because it was required to function well into the ultraviolet spectrum.
03:27Originally known as the Large Space Telescope, it was slated for launch in 1979, but delays in construction led to several postponements,
03:38and the Challenger disaster led to more delays.
03:42In 1983, the name Hubble Space Telescope was adopted in honor of the man who confirmed that the Universe was expanding.
03:57Finally, in April 1990, Hubble was ready for launch.
04:01Sound suppression water system has started.
04:06T-minus 13 seconds.
04:09T-minus 10, go for main engine start.
04:11We are go for main engine start.
04:13T-minus 6, 5, 4, 3, 2, 1, and liftoff of the Space Shuttle Discovery with the Hubble Space Telescope, our window on the Universe.
04:25Hubble has a unique relationship with the Space Shuttle, which would revisit the telescope on five different occasions.
04:33At this stage, nobody understood just how vital these missions would be.
04:40To deploy Hubble, the shuttle Discovery set a new altitude record of more than 600 kilometers.
04:46Release of the telescope was routine.
04:48It took several weeks methodically checking Hubble's control and communication systems,
04:57before astronomers working at the Space Telescope Science Institute in Baltimore could see Hubble's first images.
05:07Results were disappointing.
05:10Images were blurred.
05:12The telescope's mirror had been accurately ground, but to the wrong shape.
05:16An incorrectly assembled test instrument had been relied upon during manufacture, and nobody had double-checked.
05:25Soon, a fix was proposed.
05:28Because the error was understood, a corrective device could be fitted to the telescope.
05:34A series of small mirrors would compensate for the primary mirror's defect.
05:39It was called COSTAR, another of those cumbersome NASA acronyms.
05:43Training astronauts for the job of accurately installing COSTAR began.
05:48The high-speed photometer would be scrapped to make room for it.
05:53In addition to correcting the optics, a number of other modifications were set in train.
06:00A new, wide-field planetary camera would be installed.
06:03The original was obsolete.
06:06The telescope's solar panels would be replaced.
06:10There would be a new electronics processor, extra magnetometers, and two gyroscopes would be replaced.
06:15Ten, nine, and we have a go for main engine start.
06:25Five, four, three, two, one.
06:30Two, zero.
06:31We have liftoff.
06:32Liftoff of the space shuttle Endeavour on an ambitious mission to service the Hubble Space Telescope.
06:38Finally, in December 1993, the mission to repair Hubble began.
06:43Roger all, Endeavour.
06:45It took the Endeavour three days to catch up with Hubble, and it was clear from the beginning that one solar panel was damaged.
06:56The work on the telescope was considerable, and there were five spacewalks scheduled.
07:01Firstly, the shuttle's robotic arm grabbed the Hubble so it would remain stable while the work was carried out.
07:07The work would be shared between two teams of two astronauts.
07:14Over five days, the allocated tasks were carried out, with the Space Telescope Operations Control Centre monitoring the Hubble's performance as each new component came online.
07:28Most of the parts replaced were stowed in the cargo bay for return to Earth,
07:33the one exception being the damaged solar panel which was set adrift in space.
07:41All five spacewalks went according to plan, with the only major problem being the difficulty involved in closing the telescope's doors.
07:52On the ninth day of the mission, Hubble was released.
07:56It would take controllers on the ground another month to fully check the telescope's new systems.
08:03Hubble had been repaired in December 1993, yet it would take close to two months for technicians on the ground to run through a complex series of optical alignments before they could be certain that the telescope was performing correctly.
08:21When astronomers finally saw results, they were stunned at the quality it was delivering.
08:30The repair mission had been successful.
08:36With the services of a powerful new tool finally at their disposal, astronomers at the Space Telescope Science Institute began addressing a pressing list of demands for time on Hubble.
08:49In March 1993, a comet had been discovered orbiting Jupiter.
08:58Its path suggested that it had only recently been captured by Jupiter's gravitation and that it would soon crash into the planet.
09:05No one had ever seen a collision between bodies within the solar system, and opinions differed about how visible the impact would be.
09:18Soon, Hubble captured this image of a chain of fragments.
09:23Comet Shoemaker-Levy 9 had been shattered by Jupiter's gravitation.
09:28The fragments ranged in size from several hundred meters to several kilometers across.
09:34Over six days in July 1994, Hubble observed the pieces crash into Jupiter's unlit face.
09:43As the planet revolved, the impact region showed a series of black swirls.
09:47Some of the dark shadows were as large as the Earth, and they persisted in Jupiter's atmosphere for months.
09:58Spectral analysis from Hubble revealed diatomic sulfur and carbon disulfide.
10:03These had never been seen at Jupiter, yet the amounts detected were too great to have come in with the comet.
10:11They had been stirred up from the planet's interior.
10:14Scientists learnt so much from observing these impacts, yet the observations almost didn't happen.
10:21Just days before the first impact was due, Hubble began acting unpredictably, and then went into safe mode.
10:30It would not execute any of its instructions.
10:35Technicians suspected a memory problem, and took measures to switch across to new memory installed on the recent service mission.
10:42Things started to improve until the spacecraft reported it had entered zero gyro some point.
10:51It appeared that two gyroscopes had failed, and the situation had dramatically deteriorated.
10:57The problem was traced to a counter that had run out of numbers with which to count.
11:03The issue was understood and quickly resolved.
11:06The incident underlined just how complex the operations of the Hubble would be,
11:14and that the ground engineers still had to learn how to operate the new hardware.
11:20Though Hubble functions as a telescope, it is also a spacecraft that must be controlled with exquisite accuracy.
11:28Unlike other spacecraft, it has no thrusters.
11:31Chemical residue from rocket engines would quickly contaminate the precision optics.
11:40To enable it to move, Hubble has four reaction control wheels.
11:45As they spin, the telescope will rotate in the opposite direction.
11:50Each one has a mass of 45 kilograms, and they are controlled by the telescope's computer.
11:55Combinations of spin in any three wheels will allow the telescope to point accurately in any direction.
12:04They are mounted in angled pairs around Hubble's center of gravity.
12:09In 1997, on the space telescope's second servicing mission, one of the reaction control wheels was replaced.
12:19It had developed an electrical fault.
12:20So that Hubble can remain pointed accurately, three fine guidance sensors positioned toward the back of the telescope will lock onto any of a series of bright guide stars.
12:35Hubble only needs two guidance sensors to point with accuracy.
12:41They are so sensitive, they can detect wobble in the motion of closer stars.
12:49The third vital aspect of the telescope's pointing system is its ability to detect the rate and direction of its movement.
12:57Hubble is equipped with six gyroscopes that register its orientation.
13:02These are essential when pointing the telescope in a new direction.
13:05The gyros spin at 19,200 RPM and they do wear out.
13:13This is why there are six units, even though when designed, Hubble only needed three to function properly.
13:19With new algorithms, Hubble can now point with only two gyros, though less accurately.
13:25Work has been done to enable it to work at reduced capacity with only one gyroscope.
13:34Hubble can point with an accuracy better than two millionths of one degree.
13:40This ability to stay fixed on one narrow region of the sky for a very long time led astronomers to perform a unique observation.
13:49For ten days, in 1995, they pointed Hubble at a small, empty region of the sky near the constellation Ursa Major.
14:03To some, this was folly, a waste of valuable observation time.
14:10The results astounded everyone.
14:12This empty part of the sky was packed with irregular-shaped galaxies.
14:21Some were as old as 13 billion years.
14:25Hubble had looked back in time at the formation of new galaxies in a range of shapes not seen closer to our own Milky Way.
14:35It became known as the Deep Field Survey.
14:38It was the first of a series of similar explorations of areas of the sky in which nothing had previously been seen.
14:48Animators have added depth to these images by using spectral information, known as redshift, which indicates a body's distance from Earth.
14:59This was a completely new area of astronomy, and it was one reason why Hubble had been built.
15:03But the space telescope was already running into design constraints.
15:10Engineers began work on equipment that would upgrade the telescope's performance in the near-infrared part of the spectrum.
15:18This would be fitted during the next servicing mission, along with updated support equipment, such as a solid-state recorder,
15:24which would replace the original reel-to-reel recorder.
15:29Yet even at this early stage of Hubble's life, astronomers were realizing its limitations.
15:37The distant galaxies it had seen were approaching the extent of its view in the infrared end of the spectrum.
15:42Even with enhancements, the telescope could not be kept cold enough to observe the large redshift wavelengths revealing very old, very distant objects.
15:56Plans were drawn up for a new, larger telescope, known as the Next Generation Space Telescope, that could explore the most distant parts of the Universe.
16:07But there was still plenty that Hubble could do better than any other telescope, and there appeared no reason that it wouldn't continue being refitted with the latest technology as it became available.
16:20Early in 1997, the space shuttle Discovery visited Hubble for a second servicing mission.
16:31Astronauts fitted new instruments to improve its reach into the infrared.
16:38In 1999, Discovery again visited Hubble.
16:41This mission had been brought forward, as four of the gyroscopes had failed and the telescope had gone into safe mode.
16:47Four, three, two, one, and liftoff of space shuttle Columbia to broaden our view of the Universe through the Hubble Space Telescope.
17:00In 2002, Columbia lifted off with a new instrument, the Advanced Camera for Surveys.
17:07It would replace the faint object camera, the last of Hubble's original instruments.
17:12When it departed, Hubble was again in peak condition.
17:21Less than a year later, at the close of its next mission, Columbia burnt up during re-entry.
17:27Foam insulation had come loose during launch, damaging thermal protection tiles.
17:31After an exhaustive search for debris and a thorough inquiry, it was decided that the shuttle system was aging.
17:41It would be retired upon completion of the International Space Station.
17:45All other missions were ruled out.
17:53For the Hubble Space Telescope, this was a death sentence.
18:01In the corridors of power, Hubble had friends.
18:03The sheer beauty of images from the telescope gave it a public profile, and key senators began campaigning for one last servicing mission.
18:14After a new administrator took charge at NASA, a final shuttle flight to Hubble was reinstated.
18:20Work began on what would amount to a rebuild of Hubble's operational systems, as well as another update of scientific instruments.
18:29New, fine guidance sensors would be fitted.
18:34All gyroscopes would be replaced, and a new set of batteries would replace the originals that Hubble was still using.
18:42Within the imaging spectrograph, a power supply had failed, and training began to open up the unit and replace an electronics board.
18:52The advanced camera for surveys had also malfunctioned, and its repair work was seen as even more detailed.
18:59As the shuttle now had to operate with a backup, and because Atlantis could not reach the International Space Station from Hubble's orbit,
19:10the shuttle Endeavour was prepared for a rescue mission.
19:13On 11 May 2009, Atlantis sat on NASA's Pad 39A ready for Hubble's final servicing mission.
19:24This was to be the most complex servicing mission.
19:27This was to be the most complex servicing mission. It had to deliver the longest possible life for the orbiting telescope.
19:37The 14-day operation went according to plan. When problems arose, they were solved, and Hubble was eventually released as the best telescope it had ever been.
19:50On the ground, astronomers from the Space Telescope Science Institute waited for the first pictures from Hubble's new, more sensitive instruments.
20:04This means the telescope can operate more efficiently, needing less observing time than earlier incarnations.
20:22The team was quick to release examples of the new generation images.
20:31In the Eagle Nebula, the pillars of creation, thousands of light years from Earth,
20:36immense clouds of hydrogen and dust are giving birth to new stars.
20:43The five galaxies of Stefan's Quintet in the Pegasus constellation. Four of these are colliding.
20:5316,000 light years from Earth. Omega Centauri in the constellation Centaurus is a globular cluster.
21:00Stars here are so densely packed that, on average, there is just one tenth of a light year between them.
21:12While Hubble has been adding to its list of discoveries, everyone understands that, without further servicing, the telescope will eventually die.
21:23That slow death has already started, and it's the gyroscopes that are failing.
21:27Engineers have been careful, operating just three gyros, keeping the other three as spares.
21:36By mid-2018, three of the units had ceased functioning.
21:40As the last of the three gyroscopes held in reserve was brought online, it misbehaved,
21:46and all science operations of the telescope were suspended.
21:49By recycling power to the unit, a measure akin to switching it off and back on, normal function resumed.
21:58As further gyros fail, the telescope will use its star trackers to help it point accurately.
22:07Hubble is expected to function well into the 2020s, by which time a new space telescope should be in orbit.
22:13The next generation space telescope is now called the James Webb Space Telescope, named after NASA's Apollo-era administrator.
22:26The telescope has been completed, and is undergoing exhaustive checks before it is launched.
22:35It has a giant mirror of 18 hexagonal segments that is folded before deployment.
22:41Compared with Hubble, it is huge, yet the complete spacecraft weighs considerably less than Hubble.
22:46NASA built the Webb Telescope in collaboration with the European and Canadian space agencies,
22:55and it will launch on an Ariane 5 from the European spaceport in Kourou, French Guiana.
23:00It will orbit at the second Sun-Earth Lagrangian point, a place 1.5 million kilometers from the night side of the Earth,
23:12where the telescope can maintain a stable position.
23:14A large, very thin sunshield will protect the James Webb, allowing the optical components of the telescope to cool to around 50 degrees Kelvin.
23:28Its operational temperature must be very low to allow it to see deep into the infrared end of the spectrum.
23:38The mid-infrared instrument needs to be colder still.
23:41A cooler, using helium as its refrigerant, will enable the sensor to function at just 7 degrees Kelvin.
23:51The Webb Space Telescope is designed to build on the work of Hubble by seeing further back,
23:55to the earliest emergence of galaxies, stars and exoplanets.
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