NOVA scans the universe with the infrared eye of IRAS—the Infrared Astronomical Satellite—and discovers never-before-seen comets, stars, galaxies and other celestial wonders and enigmas.
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00:00Tonight, on NOVA.
00:06We've now realized, or are beginning to realize, that the visible universe is only a fraction
00:13of what may be there.
00:15What I call the invisible universe may be as important as the part that we can see.
00:21A satellite called IRAS made the invisible visible.
00:25I kind of liken the excitement of the launch to perhaps the moment of Columbus setting
00:33forth to look at the new world.
00:35We knew that we were opening a new window on the universe and that this was likely to
00:40change man's entire outlook in ways that we could only guess at and conjecture about in
00:47some respects.
00:48Go behind the scenes of a triumphant adventure in space technology.
00:52Countdown to the invisible universe.
01:02Major funding for NOVA is provided by this station and other public television stations
01:06nationwide.
01:09Additional funding was provided by the Johnson & Johnson family of companies, supplying health
01:13care products worldwide.
01:18And by Allied Signal, a technology leader in aerospace, electronics, automotive products,
01:24and engineered materials.
01:25There is news from across the universe.
01:53In these strange new images, news of the birth and death of stars, of other solar systems,
02:00of turmoil in galaxies far beyond our own.
02:05Discovered by a satellite called IRAS that extended our range of seeing into a new world
02:10that had always before been invisible to us, the world of the infrared.
02:16These infrared images will forever change the way we think about the universe.
02:22We got an altogether new view of what our galaxy looks like at infrared wavelengths.
02:28And I think, I mean, it's just an enormous, stupendous new view of our universe, and our
02:35universe is absolutely spectacular.
02:38One of the exciting aspects of IRAS is that it was really looking at the sky in a totally
02:44new way.
02:45We can now study in a very deep way how the universe is put together, where stars come
02:49from, where planets come from, what the ultimate fate of the universe really is.
02:57The nighttime sky.
02:59When seen with the naked eye, it appears to be composed of pinpoints of light, a multitude
03:03of stars in a vast emptiness.
03:07But our eyes alone can deceive us.
03:15Three hundred years ago, people believed that everything there was to know of the universe
03:19was already understood.
03:22Until the scientist Galileo, using the newly invented ground glass telescope, made some
03:27unexpected discoveries about other objects contained within the sky.
03:32When he turned his telescope to the point of light that was Jupiter, much to his surprise,
03:36he found it to look like this, surrounded by moons.
03:41For the first time, it was possible to look into the heavens in a new way.
03:45With the increased sensitivity of his amplified vision, Galileo was able to perceive something
03:50which had until then been invisible.
03:53Thanks to a single new tool, the science of astronomy was born.
04:02For hundreds of years, astronomers continued to refine the technology of optical telescopes.
04:08Every time they looked through a more powerful instrument, they made new discoveries that
04:12tested their notions of the cosmos.
04:15But despite these advances, the skies still contained mysteries.
04:20There was only so much they could learn, no matter how powerful their telescopes.
04:26The optical astronomers were able to see these objects because they emitted energy in the
04:30form of visible light.
04:33But visible light is only one way that information comes to us from the heavens.
04:39Throughout the universe, matter emits energy in the form of waves, known as the electromagnetic
04:44spectrum.
04:45But if that energy doesn't happen to fall within the narrow band that we sense as visible
04:49light, then we can't see it.
04:53The other energy wavelengths are invisible to us.
04:57But invisible or not, space is filled with energy emitted at all wavelengths, and all
05:02of it carries important information about something that is happening or has happened
05:06somewhere in the cosmos.
05:09Yet much of this information remained hidden until astronomers created the tools that could
05:14make the invisible visible.
05:17Technological advances only possible in this century began to reveal the universe of the
05:22electromagnetic spectrum.
05:30In the 1940s, the huge receiving dishes of radio astronomy started to collect signals
05:35from space that found more surprises.
05:38The existence of strange new celestial features, such as quasars and pulsars.
05:44X-ray astronomy was not far behind, yielding even more secrets from the invisible spectrum.
05:52With each technological breakthrough and the unexpected information they found, scientists
05:57were able to build up a picture of the universe far richer than Galileo could have dreamed.
06:03Yet long after the sky had been thoroughly surveyed at visible and radio wavelengths,
06:08and even after ultraviolet, microwave, X-ray, and gamma ray surveys had been made, the picture
06:14was still not complete.
06:16A 200-year-old puzzle remained in the infrared portion of the spectrum, the energy we feel
06:22as ordinary heat.
06:26In 1800, in a classic experiment, astronomer Sir William Herschel used a prism to break
06:31up the sun's white light into the rainbow colors of the visible spectrum.
06:36Using crude thermometers, he found that each color was a different temperature.
06:40And even when he could see no color, Herschel measured an increase in temperature.
06:45The first to discover an invisible portion of the electromagnetic spectrum, Herschel
06:49named it infrared.
06:54If our eyes were sensitive to infrared, we might see a matchstick man this way, with
06:59different shadings that reflect different levels of heat intensity.
07:03The point of greatest heat, the head of the burning match.
07:09Everything in the universe, every dust mote warmed only a few degrees above absolute zero
07:14by distant starlight.
07:16Every planet, star, and even the universe itself emits some heat or infrared radiation.
07:23The information contained by this invisible infrared universe was a crucial link in the
07:27quest to understand the cosmos.
07:30But astronomers had no way to explore the vast infrared universe and reveal its secrets.
07:38For the mysteries of infrared, although tantalizing, represented a special challenge for astronomy.
07:44The Earth's atmosphere blocks out all but a very few infrared rays, and even those which
07:49can get through were poorly recorded because there was no suitable detector to pick them
07:54up.
07:57Until in the early 1960s, physicist Frank Lowe used the exciting new findings of solid
08:03state technology to invent one.
08:06The germanium bolometer, or heat meter, was the result.
08:09The instrument, a super sensitive thermometer, was able to detect the slightest heat radiations.
08:15A thousand times more sensitive than earlier detectors, it was certainly a good start.
08:20The next step would be to find a way to apply the heat meter to infrared work.
08:27I was aware that this large gap in astronomy existed, and I thought, well, now we've taken
08:34the first step, we've got the detector, what else do we need?
08:38And perhaps we can go and do some serious exploratory work.
08:46The detector had solved one of the key problems facing infrared scientists.
08:49A NASA jet solved another.
08:52It gave Lowe the height needed to get above much of the atmosphere, blocking out the infrared.
08:58But the detectors can only measure heat if they are colder than the objects being observed,
09:03so Lowe had to cool the sensors.
09:05He built a thermos containing liquid helium around them, lowering their temperature almost
09:10to absolute zero, minus 273 degrees Celsius.
09:15This made the detectors exquisitely sensitive to heat radiation.
09:20Other scientists had taken a different approach.
09:22They worked with balloons, which can fly to a hundred thousand feet, double the height
09:26of Lowe's jet.
09:28Both techniques met with some success.
09:31And this indeed did show that the center of our galaxy, many regions of star formation
09:38and so forth, were extremely bright sources of infrared radiation.
09:43The trouble with balloons, and airplanes, was that flight duration was only a few hours
09:48at most, and the balloons were difficult to control.
09:52And neither technique could completely eliminate interference from Earth's atmosphere.
09:56Still, their results were enticing.
09:59Very bright sources of infrared had been detected.
10:03But the astronomers knew that these findings only hinted at the vast infrared universe.
10:08There had to be more waiting to be discovered.
10:11The limits on their Earth-bound explorations caused the scientists great frustration.
10:16After all, this was the space age.
10:21Astronomers everywhere were eager to explore the infrared universe more effectively.
10:27In Holland, a country with a proud reputation in astronomy, a new idea was born.
10:32The year was 1973.
10:35Dutch scientists were convinced that a satellite could solve the problems of investigating
10:39in the infrared.
10:41It was here that the Infrared Astronomical Satellite, IRAS for short, became a real possibility.
10:51In the Amsterdam Planetarium, Dutch scientist Dr. Rijnder van Duinen describes the thinking
10:56behind the great experiment in infrared, which was about to begin.
11:01Building the telescope actually into the satellite and surrounding it by a vessel which contains
11:07liquid helium would allow us to do two things at the same time.
11:11We would get rid of the residual atmosphere, which always plagues us when we do balloon
11:17astronomy.
11:19And the second thing we could do is we would really cool the telescope down to very, very
11:24low temperatures, which we are unable to do in a balloon telescope.
11:29But in order to achieve this dream, many things would have to happen.
11:33Most of them had never been tried before.
11:36The technological challenges were staggering.
11:40Like Frank Lowe's airborne telescope, IRAS's sensors would have to be kept so cold that
11:45they could detect the faintest glow of heat energy from the sky.
11:49So liquid helium in a vast thermos would keep IRAS's eye close to absolute zero.
11:55But eventually it would evaporate.
11:57The mission would last only as long as the liquid helium lasted.
12:03Helium picked up by the telescope would be focused onto 62 infrared detectors designed
12:08to pick up different infrared wavelengths.
12:12Each detector would be paired so that a hit recorded by one could be confirmed by its
12:16partner within a second or two.
12:20It would be necessary to orbit IRAS clear of the Earth's atmosphere.
12:25But the satellite would also have to circle below the Van Allen belts formed by the Earth's
12:30magnetic field trapping particles from the sun.
12:33They start around 800 miles above us and they would swamp the sensitive detectors with
12:37false readings.
12:39So they decided to orbit IRAS about 540 miles up.
12:44There would be 14 orbits a day, each one taking 103 minutes, riding between atmosphere and
12:50radiation belts.
12:53Each orbit would overlap the previous one.
12:56This would allow confirmation of a previous sighting, another way of ruling out false
13:00detections.
13:06The IRAS project was too big for the Dutch to handle alone, and they approached NASA
13:11with the idea of international collaboration.
13:14Soon IRAS had become a joint Dutch and American project.
13:18The Dutch were to build the satellite, computer, flight control systems and power supply.
13:24The U.S. team would make the telescope and the enormously tricky cooling and detection
13:28system.
13:29Launch was set for February 1981.
13:32But the problem started right away.
13:36In the case of IRAS, we were taking a tremendous step forward in engineering and the technology
13:44that we were trying to accomplish.
13:46And this tension was, I would say, particularly great in this mission.
13:50We have had real difficulties.
13:54An example, the Dutch industry had to start rather too early in the program.
14:01The definition of what the American counterpart was going to provide to us was not that clear
14:08when we started.
14:09And as a result, we had initially, we had real difficulty of trying to adjust the interfaces
14:16that we both had to meet.
14:19Some of the IRAS problems were normal aspects of international collaboration.
14:24Others were due to the extraordinary demands of the scientific mission.
14:28Ordinarily one would like to have perfect assurance that everything is under control.
14:32But in a pioneering mission like IRAS, that's just impossible.
14:35There were a lot of things that had never been tried before and we didn't know for certain
14:40that they were going to work.
14:41The satellite moves with great speed around the earth.
14:44It only, it takes about a hundred minutes for one complete circle.
14:49And while you're doing that, you have to keep pointing that telescope to the stars.
14:54And you have to avoid, and this is very important, that it points to the sun or to the, or to
15:02the earth.
15:03In both cases are dangerous.
15:04Because if the sunlight gets into that telescope while it's cooled with liquid helium, one
15:11would evaporate the liquid helium almost immediately and the mission would be lost.
15:16And the same holds for pointing it to the earth for any duration of time.
15:21So we had to be very careful to design the control system of the satellite such that
15:27it doesn't point to the sun and it doesn't point to the earth.
15:33So critical was this flight control system that Dutch researchers built a space simulator
15:38at their national aerospace laboratory.
15:41They represented the sun by the arc light of an old film projector.
15:45Here they confirmed the accuracy of the sun sensor and tested the onboard computer and
15:49other subsystems.
15:52The scientists cleverly reproduced the temperature difference between earth and space to get
15:56the best indication of how the real satellite would work.
16:00The Dutch were doing well.
16:01But just 18 months before the 1981 launch date, progress in the U.S. came to a sudden
16:06halt.
16:08Half of the critically important infrared detectors had burned out during testing.
16:13And the amplifiers to boost the faint signals back to earth wouldn't work.
16:17One of the problems was that the amplifiers, called JFETs, had to be placed close to the
16:22detectors, but at a very different temperature.
16:25NASA struggled to cope with the calamity.
16:27The detectors themselves had to operate within two degrees of the absolute zero, two degrees
16:33Kelvin, whereas these JFETs were happiest at about 60 or 70 degrees Kelvin.
16:41Still a very, very low temperature because room temperature is 300 Kelvin.
16:47So we had to come up with a way of operating the JFETs at the proper temperature, at very
16:52close proximity to the detectors themselves, which were much colder.
16:57We had to keep the infrared radiation from the JFETs away from the detectors completely
17:04and introduce no additional heat into this very cold environment.
17:10So a number of conflicting problems had to be solved.
17:17At NASA's Jet Propulsion Laboratory, a team of engineers and scientists came together
17:21to sort out the JFETs and a mountain of other emerging difficulties.
17:26In NASA terms, it was known as a Tiger team, and one of its teeth was Bill Iris.
17:31We were under a great deal of pressure because at that time we had already overspent our
17:35budget by a factor of two.
17:37We were a year late in our original launch schedule, and there was a good deal of pressure
17:44from all sides to make this thing work.
17:47In fact, being on the IRAS project at JPL, most people would look at you sympathetically
17:57as you walked back and forth across the halls because nobody was really sure we could make
18:02this work, including all the people that were working on the job.
18:06Meanwhile, the telescope and satellite body had been joined together in Holland.
18:13Then the whole unit was flown back to JPL, where the project's problems were still being
18:18tackled in an increasingly frenzied atmosphere.
18:21About the only thing cool was the telescope itself, kept secure in its thermos jacket
18:25month after month while the scientists labored on.
18:31Finally, the Tiger team had a breakthrough.
18:36They suspended the JFETs on Dacron fibers and placed them inside a gold-plated light-tight
18:41box.
18:42The detectors and amplifiers could now happily coexist in the focal plane.
18:52The focal plane itself, where an image would be in an optical telescope, was installed
18:56into the satellite, but their troubles weren't over yet.
19:00The focal plane was installed, all of the peripheral equipment was installed, and we
19:07had the big turning on party where we turned the telescope on and looked at the output
19:11of the data from the focal plane.
19:14We were all, we'd all hoped that we had solved our problems and we were home free.
19:19The fact is that the data from the focal plane was totally useless.
19:25All of the sensitivity that we expected to get out of the focal plane was swamped by
19:29enormous amounts of noise coming from we didn't know where.
19:35An eighth of the focal plane didn't work at all, and we didn't know why.
19:41So that really began phase two of the IRAS rebuild process, which was to understand what
19:48it is we had created and fixed the problems again.
19:54By now, nine years had passed, and the original launch date had come and gone.
19:58There were serious doubts that the mission would ever happen, yet the IRAS team continued
20:03their attempts to put the project back together.
20:08A committee of independent experts reviews each satellite program before launch.
20:13Unprecedentedly, the IRAS committee was undecided.
20:16Two members were against launch, and the project scientists all had their private worries.
20:21Well, I was one of the most notorious pessimists.
20:27I was aware of a half a dozen areas in which IRAS was on thin ice.
20:35One of the difficulties, of course, is that the telescope itself had essentially no moving
20:39parts.
20:40There was no way to adjust the focus.
20:41If it was out of focus when we saw the first star, it would be out of focus for the entire
20:45mission.
20:46It was also true for many, many other systems.
20:49There was no way to adjust anything once it had been launched.
20:52Another big question was, would the cover that went over the telescope and protected
20:56it all during the ground testing and the launch, would the cover actually come off?
21:01During one of the early ground tests, the cover didn't come off very well, and they
21:05had to do a whole redesign.
21:06Would it now work?
21:07The calculations said yes, but there's no substitute for actually going up and pressing
21:12the button.
21:14There comes a time when you just have to go with what you've got and accept the test
21:19results that you have and proceed with the mission.
21:23The launch committee finally agreed and set the date, January 25, 1983.
21:30There was a feeling that we had been working for years, and now the testing and the building
21:35and the training were finally over.
21:39You really had the feeling that forces had come together that were necessary to get this
21:42thing done.
21:46Anticipation was really running high as the countdown ticked away those last few seconds.
21:53Night had fallen, everybody was quiet, and then suddenly this tremendous flash and the
22:01spectacle of IRIS leaving the Earth, rising up into the sky on a pillar of flame and thunder.
22:11It was really amazing.
22:18It had taken over a decade, but IRIS was finally aloft.
22:23The first command to open a valve worked.
22:26A faulty sensor was overridden too.
22:28The problems on the ground were forgotten.
22:30IRIS was alive and well.
22:34Once the cover, this large cryogenically cooled vacuum cover, was successfully ejected into
22:40space never to be seen again, then one's confidence could really rise.
22:46And of course, then we saw the first view of the sky.
22:50We knew that the detectors were working, the JFETs were working, the pointing system was
22:55working beautifully.
22:56All of the things that are necessary to make a successful mission started to fall into
23:01place.
23:02One of the things that I was tremendously worried about when we were doing IRIS is that
23:07it would be a technical success and we wouldn't find anything.
23:11And that would have been awful.
23:12IRIS was like our first infrared night.
23:17When that cover came off and when we got our first look at the sky with a cold telescope
23:22outside the Earth's atmosphere, we finally saw what the universe looked like at infrared
23:28radiations.
23:29We finally saw what our solar system looked like at these wavelengths.
23:33At last, the skies were open to infrared scientists.
23:37The controllers spoke to their satellite via a ground station set up by the third
23:41IRIS partner, England, at the Rutherford Appleton Laboratory in Chilton, Oxfordshire.
23:51IRIS passed over Chilton twice a day.
23:55The ground team had at most only 15 minutes to unload the gleanings of the previous 12
24:00hours, 700 million bits of information.
24:04Then they beamed up commands for the next 12 hours, around 1,000 orders for IRIS to
24:09obey on each orbit.
24:13Each sweep covered a prescribed slice of the sky.
24:16The ground operations team of 120 people would monitor the satellite 24 hours a day as long
24:22as the mission lasted.
24:27The resident astronomer appointed to run the scientific side of the mission, Dr. Peter
24:31Clegg, Queen Mary College, London, was among the first to see the IRIS signals.
24:37They were remarkable.
24:38They were extremely good, extremely strong, and indeed very much like some of the simulated
24:45signals we'd injected.
24:46In fact, some of us were a bit concerned that perhaps we were still looking at simulation
24:50data and not the real stuff from the sky.
24:53JPL, UK OCC voice check.
24:58We read you 5-Y also.
24:59We'd like to send you a tape.
25:01Can we have you off ready test online, please?
25:07A space link to jet propulsion laboratories in Pasadena relayed a rich stream of data
25:12that was almost overwhelming.
25:14Preparing for it and then cataloging it was the job of Dr. Tom Chester.
25:19There's been no astronomical project in the past that ever attempted to cope with this
25:23amount of data.
25:25As a way of comparison, the sky that you can see with your own eyes contains about 5,000
25:30sources.
25:31And that typically is what you see the first time you look in a new way of looking at the
25:36universe.
25:37You see about that many sources.
25:38For example, the X-ray surveys found a catalog of 100 sources.
25:41The radio surveys found catalogs of 1,000s of sources.
25:44So it's not too much different from what you see if you do a survey with your own eye.
25:49But we, on the other hand, were dealing with 100s of 1,000s of sources.
25:53That's a factor of 50 more than what your eye can see and a factor of 50 more than the
25:56usual survey.
25:58So we had all sorts of attendant difficulties with data size.
26:01We had to have a lot of data storage.
26:03We had to have a computer program that could deal with all of the different complexities
26:08that are in the data.
26:10This is the raw data.
26:12Volume on volume of figures which add up to what IRAS saw in the universe.
26:17Making something of it wasn't at first an exact science.
26:21The bedlam breaks out almost immediately.
26:23When we got the first data in, we were always running willy-nilly trying to process that
26:27first data because it turned out that there were, it came to us in a different form than
26:31we expected at the very beginning.
26:32So we had to adapt the very first program that we didn't think we were going to have
26:35to at the beginning just in order to read that data.
26:39That felt like being at the bottom of a waterfall, being inundated with water all the time, occasionally
26:43your head would poke out of the water, you'd see a drop of water coming by that you'd understand
26:47as a drop of water.
26:48But most of the time it was like looking up and not really being able to cope with the
26:52volume of information that's coming down.
26:57Dealing with the sheer quantity of information, the equivalent of an encyclopedia's worth
27:01of facts every day, was a monumental achievement in itself.
27:07In one form it became a 19 1⁄2-inch catalog, the infrared book of Genesis.
27:15This catalog is certainly one of the premier achievements of astronomy because we have
27:18more objects in this catalog observed with precise positions and with four different
27:24infrared colors, which represents a much bigger achievement than almost any other catalog.
27:29It increases the number of sources that astronomers have to play with, with good positions and
27:33with good colors, by about 50 percent.
27:36So we've multiplied by one and a half the number of sources that astronomers have to
27:41play with.
27:44Interpreting the raw data, making the invisible visible, was the next order of business.
27:49This was done by a technique known as image processing.
27:52Each wavelength IRS scanned was assigned a color, and each infrared source was programmed
27:57into a computer.
27:59By this method, numbers were transformed into the views we might be able to see if our eyes
28:04were infrared sensitive.
28:08One of the most important products of the IRS mission is an actual picture of the sky
28:14in the four wavelength bands of IRS.
28:16The spectacular IRS images are the results of taking the electronic signals in the four
28:22different wavelength bands and combining them into images that the brain and the eye can
28:27work with.
28:28We've taken radiation that's invisible to the human eye and color-coded it in such a
28:33way that the eye can actually look at it and understand the physical processes going
28:39on in a given region of sky.
28:42The resulting pictures are essential for the scientists in expanding their understanding
28:46of the cosmos.
28:48For the first time, they can map and explore the invisible infrared world.
28:52Armed with both the IRS catalog and the bank of computerized images, astronomers can now
28:57attack unsolved problems of the universe with new power and insight.
29:02They can stretch the colors to bring out very low contrast details, they can make the
29:08images very high contrast, and they can do numerical work on the pictures.
29:12They can ask the computer to give the position and brightness of a star or a nebula that
29:17they see on the screen and the computer will print out numbers corresponding to that.
29:22Those numbers can then be compared to theories and used to derive the mass, the brightness,
29:27the power output of a given star or galaxy or star formation region.
29:32Months before the work of compilation and computing was finished, the IRS satellite
29:36began to make its scientific contribution.
29:40In the very early stages of the mission, two American astronomers first spotted something
29:44very odd in the raw data coming back from the transmissions.
29:49To check the accuracy of IRS's detectors, the scientists had lined the satellite up
29:54on some of the familiar stars in the sky.
29:57One of these, Vega, in the constellation Lyra, had no special claim to distinction.
30:02They chose it for their calibrations because it's bright, easily seen with the naked eye,
30:07only 26 light years away, and they thought well understood.
30:12Yet IRS discovered something quite extraordinary about Vega.
30:17In the centuries before IRS, astronomers have tried and failed to detect any other solar
30:22system in the universe.
30:24We've known of only one planetary system, our own, the nine planets that revolve around
30:29the sun.
30:30And the first time we looked at Vega, we saw that there was something very strange going
30:36on with the star.
30:37We could compare it with some of the other stars we had been looking at as standard stars
30:42and we could see that it was just much too bright at the longer wavelengths, much brighter
30:46than we would have expected it to be.
30:50Vega was emitting more energy at the long infrared wavelengths than was characteristic
30:54of a normal star.
30:55Its infrared signature was unusual, perplexing, and difficult to decipher.
31:01At first the team doubted their results.
31:04We had not been observing with the IRS satellite for very long and we really didn't understand
31:10whether it was a flaky instrument, whether it was a very stable instrument.
31:17We just didn't know what to think of this observation.
31:22The readings came out the same every time the satellite surveyed Vega.
31:27It was clear that there was something going on with that star that we didn't understand.
31:33After months of measurement and analysis, the team decided they must be seeing radiation
31:38from solid material, dust grains, orbiting Vega.
31:43Space is full of tiny particles of dust, but the emissions suggested that these were larger
31:47grains about the size of pebbles that had been put into place around Vega while it was
31:52being formed, the same process that led to our own solar system.
31:58They had found the first evidence for another planetary system in its first stages of growth.
32:03This was something that we hadn't been looking for at all, but by eliminating all the possibilities,
32:09we concluded that we were looking at the same process going on around another star and that
32:15just kind of knocked us off our chairs.
32:19Recently there is more evidence of planetary systems forming around other stars.
32:23This is Beta Pictoris, a star in southern skies, in an optical telescope follow-up of
32:28an IRAS finding.
32:31The Beta Pictoris example is a very good one.
32:33It's very astounding that there's this large disk around that.
32:37It's very large in the optical.
32:39It's most amazing that somebody hasn't seen something like that, but of course nobody
32:43ever thought which objects to look at to try to image to find such things.
32:47So we have a long list of interesting and peculiar sources that people will be following
32:50up for decades probably to come.
32:54Although the follow-up studies with optical and radio telescopes are only just beginning
32:58to get underway, Vega's irregular infrared signature is now accepted as the first clue
33:04to the existence of other planetary systems being born.
33:07To date, 12 have been found.
33:12The whole process of birth in space, especially of stars, is one area where IRAS material
33:17was rich and informative.
33:20This is because stars form out of what astronomers call cold matter, invisible to human eyes
33:26but not to the eye of IRAS.
33:32Where are stars forming?
33:34Why?
33:35What sort of numbers do they form in?
33:38Do we get, for instance, low mass and high mass stars forming in the same sort of regions?
33:43These are the questions that in star formation we need to know the answers to, and for the
33:48first time we're going to get those answers.
33:50The whole question of where stars come from is a topic that really belongs to the infrared.
33:56In the beginning phases, a star forms out of the interstellar matter that floats between
34:00the stars, these clouds of gas and dust, and as clouds collapse and contract, a star is
34:05formed still inside the gas and dust, and it glows brightly in the infrared, but nothing
34:10is obvious to either the naked eye or even the most powerful optical telescopes.
34:17This is a dense cloud in space, Barnard 5.
34:21Astronomers have long believed that new stars, called protostars, are being born here.
34:26As with Vega, IRAS has given us another first, a view of the birth of a star, like our sun.
34:33It's been known for a long time that our galaxy contains clouds of very dense cold matter.
34:40We've known about these since the days of optical astronomy because they block out all
34:44the optical light.
34:46Now back in 1926, James Jeans predicted that under sufficiently cold, dense conditions,
34:54a mass of matter would collapse under its own gravity, and that that collapse would
35:00continue as the mass became more dense, so that it's a sort of self-perpetuating process.
35:05And this process will continue, the fragmentation and the contraction, until it gets to the
35:11stage where the matter is so dense that the heat generated by the collapse can no longer
35:17escape, and we then no longer have this coldness condition that's required.
35:22The collapse will cease to continue, and at that stage we have what we call a protostar.
35:29The analogy you could use is you've got a furnace with a bright flame going on on the
35:34inside, there's a bright star in there, but the walls of the furnace prevent you from
35:38seeing it optically, yet if you look with an infrared sensor, you can see and feel the
35:44warm walls of that furnace.
35:45So there's a star in the center that you can see only in the infrared.
35:51As stars come to the end of their lives, they start really burning in a very sooty sort
35:55of manner.
35:57As lots of solid particles of dust start forming around the star, the star can actually disappear
36:02from sight visually, yet be still a very bright infrared source.
36:08Then eventually a star, depending on its brightness, may explode in a spectacular way, that again
36:13optical and radio astronomers can study as well, but the IRS catalog is full of objects
36:18that are stars surrounded by gas and dust, and that are almost invisible, or certainly
36:24not prominent to optical astronomers.
36:27So we can study this whole phase of the cycle of the birth, life, and death of stars using
36:32the infrared.
36:37The study of the life cycle of stars could be essential in deciphering another of astronomy's
36:42ongoing puzzles, the question of missing mass.
36:47At the moment there isn't enough detected material in space to add up to what physicists
36:51think it should contain.
36:54The thing that's so terribly exciting about astronomy today is that we've now realized,
36:59or are beginning to realize, that the visible universe is only a fraction of what may be
37:06there.
37:07What I call the invisible universe may be as important as the part that we can see.
37:15The so-called hidden matter or invisible universe may be in the form of very cold matter, much
37:24of it very nearby the Earth, just outside the solar system, as it were, in the form
37:30of brown dwarfs.
37:33Brown dwarf is a star, it's a failed star.
37:35It's something like Jupiter, one of our planets, only a little bit larger, that just didn't
37:39get to be big enough when it was formed to ignite nuclear fuel, so it's not burning like
37:45the normal stars.
37:47But one of the interesting questions in astronomy is this question of missing mass.
37:51We're always finding, at all different scales in astronomy, that there's much more mass
37:56around different objects than we can see.
37:59And you can lock up a lot of mass in brown dwarfs without seeing them because they're
38:02very, very faint.
38:03They don't have the nuclear fuel, therefore they're not emitting a lot of light.
38:07But one of the things that IRIS can do very well is see things that are emitting very
38:10feebly in optical light if they happen to be fairly strong infrared emitters.
38:15And that's what a brown dwarf would do, it would emit almost all of its radiation in
38:18the infrared, so we would expect to find objects that we can see that cannot be seen
38:22on optical photographs.
38:24There are the interesting cases in which we take a chart, we plunk it down, and we don't
38:28see anything.
38:29It's what we call a blank field.
38:31That has the potential of being any one of a number of interesting objects.
38:35We're hoping it may be a brown dwarf or so, but what we have to do is then follow it up,
38:39go to the telescope, observe at that position with a more sensitive detector, and see what
38:43we can see there.
38:45And that will enable us to categorize what kind of an object it might be.
38:48The search is somewhat like the proverbial needle in a haystack, in that the catalogue
38:54is 246,000 objects, only a handful of those could conceivably be brown dwarfs.
39:02But that search is underway, both here and in California, and I think in other places
39:07as well, and fairly soon we should know the answer.
39:13Whether or not the missing mass will be found in the infrared awaits further analysis.
39:18But past generations of stars did provide the IRAS survey with a major new finding.
39:26The discovery came directly from the images on their computer screens.
39:30It's called infrared cirrus, named after the wispy cloud in our atmosphere.
39:36Cirrus is interstellar dust, veil upon veil of it.
39:39It pervades the space between the stars, and IRAS saw it everywhere in our galaxy.
39:46I personally find the cirrus fascinating from two different points of view.
39:53From one point of view, it's just the size of it.
39:57It goes throughout the entire galaxy.
40:01That means that it has structure which in many cases is on the size of a thousand light
40:08years.
40:09It's really big, and there's some coherence to the whole thing, and that, I think, is
40:17an intrinsic interest in the cirrus itself.
40:20And that, by the way, I think is something that was really not expected.
40:26The second aspect which excites me about the cirrus is its effects on us looking outside
40:33of our galaxy, because the cirrus is blocking our view.
40:39And so that means that, in fact, our whole view of the outside world, we now know there's
40:47more obscuration than we thought there was initially.
40:52The cirrus is so bright in the IRAS images because of its temperature.
40:57It's much hotter material than the astronomers expected to find.
41:01Perhaps one explanation is that the tiny dust grains of cirrus, only about the size
41:05of a molecule, can absorb starlight, but are too small to radiate energy themselves, and
41:11so store up heat.
41:14Astronomers do know that these clouds are composed of all the raw material for making
41:18the next generation of stars, and tell us that many have already passed.
41:24Until IRAS, the scientists hadn't seen the shadowy cirrus, not only because they lacked
41:29the tools, but because they didn't know what to look for.
41:34It now turns out that if you look very well at optical photographs, carefully taken optical
41:40photographs, for example, one of the best telescopes is a survey telescope from the
41:46UK, which is in Australia.
41:50And if you look, inspect good photographs of that telescope, then you see weak emission
41:54on the sky.
41:55In the optical picture you see, the plate has some emission everywhere, and that emission
42:03corresponds exactly to what we see in the infrared.
42:07But it's so faint that people haven't seen it, and on the older photographs you can't
42:11see it.
42:12It needs some expertise to make them.
42:14But it has been seen now, and the correspondence is beautiful.
42:22But knowing what to look for, even with an instrument as sensitive as IRAS, did not always
42:26guarantee results, even when it looked closer to home.
42:31Little is known about the origin of our planets, except that they coalesced from dust particles
42:36and hydrogen and helium gas.
42:38There are nine planets, including Earth.
42:40But astronomers feel there ought to be a tenth, because the orbit of Neptune wobbles in a
42:45way that suggests interaction with a body beyond Pluto, the outermost planet known.
42:50The tenth planet has been both the bane and the boon of IRAS's existence.
42:55Ever since the beginning, people have realized that if there was a tenth planet, then it
42:58would be a very cool object, because it would be so far away from the sun that it can't
43:02be warmed up very much by the sun's radiation.
43:04Therefore, it would be most visible in the infrared, and be very, very faint in the visual
43:08light.
43:09So IRAS's data will contain a tenth planet, if such one exists, because it's very sensitive
43:14to the infrared wavelengths.
43:16The problem has been is that everybody who's come to our facility, and everybody connected
43:20with the facility, has been on a mad search for the tenth planet, of course.
43:23And everybody who comes has done every search in every conceivable way of looking for an
43:27object, looking for objects that have moved over a period of six months, that have the
43:31expected temperature, and so on.
43:33But no one has yet found out any evidence of a tenth planet in the data.
43:37So it's a very interesting search.
43:38It may well be there, but it's very difficult to say at the moment.
43:45Originally, the astronomers had planned to set aside all the data from our solar system
43:49during the mission, because they doubted they'd see anything other than the man-made junkyard
43:54in orbit around us, or planets already well known.
43:57But one astronomer, Professor Jack Meadows, had other ideas.
44:04The world, you might say, is divided, as far as astronomy is concerned, into the lords
44:09of creation, who gaze at the universe, and the grubbers after facts, who look at the
44:15solar system.
44:16And most satellites are designed by the lords of creation, you understand.
44:21The original intention was to reject anything that moved.
44:26In other words, if it moved, don't shoot it.
44:30This seemed to me, I have a parsimonious soul, you understand, seemed to me a pity.
44:35But I discussed with the British team members, who were extremely helpful, and then over
44:40with the Americans and the Dutch, the possibility of not rejecting this data, but of siphoning
44:46it off as it came in, and examining it in real time.
44:51The team trying to pull out these data went through just about the depths and the heights
44:59during the course of this, because it was not at all clear at the beginning we were
45:04going to detect anything.
45:05It was clear that the sensitivity was not what we'd expected, and therefore we didn't
45:09know whether we were going to pick up over a nine-month period anything at all, or just
45:13sit twiddling our fingers.
45:16So at the beginning, as a month passed, and then another month, we had to spend most of
45:21the time banging each other's backs and saying, well, we're getting paid for it, and so forth.
45:26And then the first discovery, you see, and that first discovery was this incredibly bright
45:31comet that made the headlines and everything else.
45:34And suddenly you shot up to the peak, and you were saying, we're in the middle of things,
45:38things are happening.
45:39It was really a remarkable oscillation.
45:44They had sighted a previously unknown comet.
45:47It shed much more dust than comets had been thought to do, making it unexpectedly bright
45:52in the infrared.
45:54Named for the satellite and scientists that discovered it, IRAS Iraqi Alcock burst its
45:59way into the news in 1983.
46:04Bigger than Halley's Comet, it passed within three million miles of Earth, the closest
46:07known approach of any comet within the last 200 years.
46:12After that, every month except August, until the end of the satellite's lifetime, we picked
46:16up something of interest.
46:20Within our solar system, IRAS went on to discover another five comets, each with a long, dusty
46:25tail.
46:29Our solar system is part of a larger galaxy.
46:32We see it at night as the faint serpentine band of stars called the Milky Way.
46:37It holds all the stars in our neighborhood of the universe.
46:40Here, IRAS turned up a revelation about the physical nature of the galaxy, a concentration
46:46of stars at the end of their lives.
46:48One of the most striking differences in the optical results versus the IRAS results are
46:53that we can see much deeper into our own galaxy than optical results, visual results.
46:59In fact, if you look at this photograph or this map of the stars, which have been picked
47:03out visually, this is looking along the edge of our galaxy, so looking into the galaxy.
47:08You can see that the stars that have been picked out visually actually seem to avoid
47:12the plane of the galaxy.
47:14The reason for these blank spaces in here is because optical light, visual light, doesn't
47:18travel very far through the galaxy.
47:20It gets scattered or absorbed, so that previous observers have only been able to identify
47:25these stars around the edge of the galaxy.
47:28With IRAS, we have this picture, a much different picture.
47:32You can see a heavy concentration of these forces to the plane of our galaxy, looking
47:37along the edge of the galaxy.
47:39You can see a concentration to the galactic bulge, which was only briefly hinted at in
47:43some of these studies.
47:44And the other thing is, we have vastly more stars.
47:47We have more stars in our survey than all star catalogs have seen in the past.
47:52So we're going to gain a lot of information about these stars with the IRAS results.
47:59Because IRAS could look so deeply into our galaxy, it was able to confirm its classic
48:04shape, something that had been suspected, but until the mission had never actually been
48:08seen.
48:14As the satellite swept across the sky, it investigated other galaxies, and it discovered
48:19many new ones, millions of light-years beyond our own.
48:24Before launch, we were hopeful of seeing perhaps 1,000 galaxies beyond our own Milky Way.
48:31The first source that we recognized for sure beyond the initial calibrator was in fact
48:35a galaxy.
48:36It was clear at that point we'd seen many, many galaxies, and indeed in the entire mission
48:40we've seen probably 20,000 galaxies or more.
48:45The presence of these galaxies, and the clues infrared can give about their behavior, are
48:49critical pieces of evidence in the quest to understand the universe.
48:56We discovered that there were galaxies which were far brighter than infrared wavelengths
49:00we'd ever expected before launch, and far brighter than one would expect from their
49:05optical appearance in the sky.
49:07And one explanation of this is that these galaxies are undergoing vast quantities of
49:13star formation at very rapid rates.
49:17We don't really understand the reason for this.
49:20It may be that some of the galaxies are interacting with others, and it's this interaction which
49:25is triggering such events.
49:27When one galaxy sweeps past another, their intense gravitational embrace stirs up the
49:32stars and gas in each of them.
49:35Their infrared activity suggests levels of star formation on a scale never before imagined.
49:41These galaxies appear close together, and in many cases we think they actually are close
49:45together in space.
49:47As one galaxy goes past another, there is a tidal interaction, just as the moon causes
49:52tides on the Earth, and in some models of this interaction, at any rate, gas is stripped
49:58off one galaxy and plummets into the center of the other galaxy, and because it's moving
50:03at high speed and rushing into the center, it's in turmoil and in the process creates
50:09a very large burst of star formation.
50:12It would be very nice to find out, in the case of many of the IRS galaxies, just where
50:16this radiation, the intense infrared radiation, is coming from, because if it is in the center,
50:23it would help to confirm some of these theories.
50:27We'd always thought there would be galaxies with much starburst, what we call going on,
50:32and so in a way that was expected, but it certainly wasn't predicted by analytic means
50:37and the only way that you can find out about them is to just look at every spot and see
50:42what is it really.
50:45As the scientists ponder the secrets that IRS has revealed, the closer they will be
50:50to understanding the origin and the fate of the universe itself.
50:59On November 23, 1983, the liquid helium keeping IRS cool finally evaporated.
51:06The satellite quickly warmed up and the mission was over.
51:09Or was it?
51:11We have thought up the instrument, we've designed and built the instrument, and we've
51:15made the observations, and now we're in the fun part.
51:18Now we're trying to understand what the observations are trying to tell us about our universe,
51:25about our solar system.
51:27The analysis of IRS continues today.
51:30Its huge catalog must contain many more exotic objects.
51:34For the scientists, the wealth of data collected allows them, in a sense, to fly the satellite
51:39over and over again.
51:44Just as the optical telescope revealed the visible universe to Galileo three centuries
51:49ago, IRS has brought us the invisible universe.
51:53Stars and solar systems forming, new comets, cirrus, and starburst galaxies.
52:03Around the world, astronomers are swinging their great telescopes to look more closely
52:08at what IRS found.
52:11What we want to do now in the future is plan missions that let us zoom in and study in
52:15great detail what's going on within a particular galaxy, what's going on in a particular star
52:21forming region.
52:22It's now the time for the very detailed studies of the objects that IRS has revealed to us.
52:28The next step beyond IRS will be some sort of infrared observatory.
52:35And of course, the European Space Agency have already started to plan ISO, the Infrared
52:43Space Observatory.
52:45In this country, NASA is working on a somewhat similar concept of a Space Infrared Telescope
52:52Facility.
52:53We call it SIRTF.
52:56Using the same technology, improved detectors, which we're all working on these days, one
53:02would be able to fly a mission similar to IRS, but with a thousand times more sensitivity.
53:10I think the important thing about IRS is that since we didn't go with a preconceived idea,
53:20what we are doing is seeing the entire universe.
53:24And I was reading in the paper today the comparison between the stars and grains of sand on a
53:31beach.
53:33And I think that we're now seeing all the grains of sand on the beach, and that's about
53:37how many we see.
53:38I mean, we're seeing that same number.
53:40And now the exciting thing for us to do is to pick out which of the grains which are
53:44interesting and which tell us something about how the universe was formed.
53:49That's going to be the challenge now.
53:51I kind of liken the excitement of the launch to perhaps the moment of Columbus setting
53:59forth to look at the new world.
54:01We knew that we were opening a new window on the universe and that this was likely to
54:06change man's entire outlook in ways that we could only guess at and conjecture about in
54:13some respects.
54:14IRS has uncovered the answers, or at least solved some questions and raised more questions
54:22about the nature of planet formation, about distant galaxies, distant quasars, the whole
54:27problem of star formation.
54:29All these are questions that can only really be answered by studies at infrared wavelengths.
54:37IRS was a scientific and technological adventure of the highest order.
54:42It brought us a universe never before seen, images painted not with light but with heat.
54:49In its 300 days in space, IRS suddenly illuminated a new spectrum of the universe.
54:56And it seems likely that the biggest surprises and insights are yet to come.
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