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00:00 The National Aeronautics and Space Administration, NASA, is still the world's leading space
00:06 agency.
00:07 For decades it's been there, on the front line of space travel and cosmological research.
00:13 But now, with new studies being completed every single day and fresh discoveries being
00:19 made all the time, are we on the brink of something truly incredible?
00:24 This is Unveiled, and today we're taking a closer look at some of the most extraordinary
00:31 NASA breakthroughs, stories, and missions in modern times.
00:36 Do you need the big questions answered?
00:39 Are you constantly curious?
00:41 Then why not subscribe to Unveiled for more clips like this one, and ring the bell for
00:46 more thought-provoking content.
00:53 One of the main challenges when searching for alien life is that we still have very
00:57 little idea as to how they will communicate.
00:59 But, fortunately, searching for E.T. messages isn't our only option.
01:05 Researchers are increasingly saying that we should target alien planets first of all before
01:09 seeking out the aliens themselves.
01:11 And fueled by modern technology, we could be on the brink of a major breakthrough.
01:20 The search for alien life in the universe is an ever-more serious topic of astronomical
01:29 study.
01:30 The chief organization leading the charge is SETI, or the Search for Extraterrestrial
01:34 Intelligence.
01:35 SETI is the leading large-scale group in America that solely searches for alien life in the
01:40 universe, doing so with a variety of telescopes.
01:43 However, much of SETI's search still relies on radio telescope technology.
01:49 On attempting to recognize radio signals in space as either natural phenomenon or artificial,
01:55 alien-made broadcasts.
01:56 This though perhaps isn't a surefire way to find intelligent life.
02:01 There's always the chance that an alien force wouldn't send messages via radio, for starters,
02:06 or that we would be unable to recognize a message if we actually ever received one.
02:10 The best example is probably the famous "wow" signal.
02:14 Reveived back in 1977, it seemingly had all the signs of being created by an intelligent
02:20 species.
02:21 But, more than 45 years later, and we're still not sure if that's the case or not,
02:26 we only heard the "wow" signal once and have never managed to get another sample.
02:31 Was it alien life, or just a natural process in space?
02:35 No one knows, because radio messages remain so ambiguous to us.
02:39 Might it then be high time for a change of strategy?
02:42 Many scientists want to now find more definitive markers of alien power, and especially visible
02:48 signs.
02:49 Technosignatures are, exactly as they sound, characteristics or effects detectable on a
02:54 planet, moon or cosmological object that explicitly point to the presence of technology and, therefore,
03:01 intelligent life.
03:02 As such, some argue that radio signals shouldn't be included under this classification.
03:07 That they shouldn't be considered a true technosignature, because they leave so much
03:11 room for uncertainty.
03:14 Examples of firmer, much less debatable technosignatures are generally large-scale megastructures
03:20 that are big enough to be seen from across space; hypothetical concepts like Dyson Spheres
03:25 - a massive machine to harvest energy from a star - or Shkadov thrusters, which are giant
03:30 devices that can move stars and are known as stellar engines.
03:35 These would all be certain signs of civilization.
03:39 Scientists have an advantage over biosignatures, too - or signature effects created by biological
03:44 life - because technology can outlive biology.
03:48 Studies have suggested, then, that technosignatures could be more common in the universe.
03:52 And also that they should be easier to see, should last longer, and should be easier to
03:57 understand than possible biological traces.
04:00 This means that even were an alien group to go extinct, there's a chance that we could
04:05 still "discover" them by spotting one of their technostructures hundreds or thousands
04:10 of years later, long after their biological imprint has disappeared.
04:14 If we view the universe searching for machines, rather than straight-up life, then the chances
04:19 dramatically increase that we will find evidence that we really are not alone.
04:25 Published in the journal Acta Astronautica, a new study by lead author Jacob Huck Misra
04:30 and an international team of scientists was written as the result of a NASA workshop,
04:35 and it argues that we already have the tools to start studying technosignatures in-depth…
04:41 it's just that generally we don't seem to be using them.
04:44 One reason for this is cost.
04:46 Funding can be difficult to obtain for studying non-radio technosignatures, perhaps because
04:51 they're sometimes so far beyond human imagination.
04:54 However, Huck Misra and his team argue that grant funding isn't necessarily needed,
05:00 as most space missions that are already underway could be adapted to specifically look for
05:05 technosignatures at no extra cost.
05:08 That "beyond human imagination" aspect, though, is another problem.
05:12 Even our brightest scientists don't really have a solid understanding of which signatures
05:16 could be artificial and which could be natural.
05:19 In both cases, we're largely guessing as to the machines or lifeforms that could be
05:23 making them.
05:24 So, there remains a big gap in our knowledge, creating a similar level of ambiguity as seen
05:29 with radio waves.
05:31 One solution to the current hesitancy would be for the astronomical community to come
05:35 together to catalogue and understand the various types of technosignatures that we might expect
05:40 an intelligent civilization to produce.
05:42 If we had a library of possible signatures, then we'd have a much surer base to work
05:47 from… and could apply that library to every single exoplanet we come across.
05:52 But, unfortunately, no such grand project exists.
05:55 There are private enterprises like Breakthrough Listen… and there's some interest from
06:00 within SETI, although radio waves remain most studied.
06:03 But, at present, we're at something of a dead end.
06:06 A valid technosignature could be our best bet to find alien life, but we're still
06:11 hedging our bets with radio and largely neglecting the search for technology.
06:15 Undeterred, however, Huck Misra's study provides specific examples of the technological
06:20 signatures we should be looking for.
06:22 Using different observational mediums such as ultraviolet, visible, and infrared radiation,
06:27 astronomers can search for a wide variety of markers like waste heat, energy-intensive
06:32 illumination, surface modifications, atmospheric pollution, stellar pollution, non-terrestrial
06:38 artifacts, and megastructures.
06:40 One sign of technology, for example, could be present in a planet's atmosphere.
06:44 The paper suggests that by examining the atmospheric content for artificial molecules like sulfur
06:50 hexafluoride or by looking for expected signs of life like oxygen or methane, we could clearly
06:56 identify the worlds that are the best candidates for life.
07:00 Of particular interest here is nitrogen dioxide, because while it can occur naturally on Earth,
07:06 human technology produces exponentially more of it through the burning of fuel.
07:11 Should NO2 turn up when we look at another world, then, there could be a good chance
07:15 of some similarly industrial, intelligent creatures living there.
07:19 As bizarre and seemingly straightforward as it sounds, there are also calls within the
07:24 study for astronomers to look more pointedly for cities just as optical light; for massive
07:30 city structures that could shine brightly enough on their home planet so as to be picked
07:34 up by simply watching for long enough.
07:37 It's thought that aliens more advanced than us might have built what's known as an "ecumenopolis".
07:43 This is a city so advanced and vast that it covers the entire surface of a planet.
07:49 And the immense light that such a structure would generate should clearly shine out across
07:54 the distances of space, not unlike stars do.
07:57 And then, against the potential backdrop of an ecumenopolis, researchers might also try
08:02 to pick out artificial satellites as the next greatest sign that life is present.
08:07 There are even some proposals that the movement of satellites could double up as a method
08:12 of cross-cosmological ET communication, too.
08:16 Again, for those pushing for a greater emphasis on technosignature hunting, the beauty is
08:21 that all of these examples can be searched for in the data we already have.
08:26 And current and future telescopes can add in technosignature searches at no extra cost,
08:31 as well.
08:32 According to those behind this latest study, current telescopes or current data banks that
08:37 are already fit for purpose include the Kepler Space Telescope, the Transmitting Exoplanet
08:43 Survey Satellite (TESS), the Gaia spacecraft, the James Webb Space Telescope, and more.
08:50 With Webb, we've already seen the incredible detail our telescopes can now produce with
08:54 the Atmosphere Composition Study of WASP-96b, an exoplanet that's 1,100 light-years away.
09:02 It's perhaps surprising, then, that there hasn't yet been a significant search made
09:06 for technosignatures.
09:08 More than 5,000 exoplanets have now been catalogued, but they've yet to be thoroughly scoured
09:13 for tech signals.
09:14 It's the hope of Jacob Hakmisra, his team, and a growing number of other scientists that
09:19 this will soon change.
09:21 And there is reason to think that it will.
09:23 The first-ever NASA grant, given specifically for the study of technosignatures, was awarded
09:28 in 2020 to the astronomer Adam Frank.
09:30 There are calls to add machine learning processes into our study of the moons and planets that
09:35 we do know about, too, to increase speed and efficiency into the future.
09:39 And so, the push towards this new way of thinking is gathering pace.
09:44 Of course, all of this raises further interesting questions.
09:47 Could we have already spotted an alien world without realising it?
09:51 Might we have already viewed alien life just without understanding what we were seeing?
09:57 Our 5,000 confirmed planets is certainly only a small window relative to the rest of the
10:02 universe.
10:03 But could one of those worlds be home to something else?
10:07 Very, very possibly.
10:10 NASA, the National Aeronautics and Space Administration, has long led the line for space research,
10:18 delivering various iconic moments since its inception in 1958.
10:23 But today, partway through the 21st century, the landscape has dramatically changed.
10:28 Where once NASA was out on its own, with only the Soviet space program for company, now
10:33 there is a raft of major competitors in the field.
10:36 To stay ahead of the game, then, NASA will need to pull out all the stops.
10:48 First up, long-distance astronauts.
10:50 You might reasonably argue that any astronaut capable of reaching the moon is or already
10:55 has been suitably long-distance in themselves.
10:58 But again, times have changed, and getting to the moon is now relatively small fry in
11:03 the minds of today's future planners.
11:05 Instead, with all eyes on a proposed mission to Mars, around 140 million miles away, we
11:11 need a new breed of astronaut, capable of not only a few days cooped up inside a spaceship,
11:17 but a few months - and probably more than a year away from Earth for an entire return
11:21 mission.
11:22 NASA is on it, though, with its Crew Health and Performance Exploration Analog and Mars
11:28 Dune Alpha facility.
11:29 A simulated Martian habitat located at the Johnson Space Center in Texas, Mars Dune Alpha
11:35 is designed to mimic what life would be like on the Red Planet.
11:39 And in summer of 2023, it'll get its first proper use, when four volunteers start a year-long
11:45 experiment of living inside it.
11:48 For those four, life will become a daily test, as they'll take on tasks such as simulated
11:53 spacewalks and the growing of crops… all while discovering how easy (or not, it is)
11:59 to maintain the environment itself, plus their own personal hygiene and mental and physical
12:04 health.
12:05 Experiment runners will also trigger instances such as deliberate equipment failures, to
12:10 test how well problems like these can be solved.
12:13 Even if we never actually get to Mars, then, we should soon at least have a band of people
12:18 capable of surviving the trip.
12:20 Of course, and even if it is perhaps less remarkable than it once was, before Mars comes
12:25 the moon.
12:26 And here, NASA is increasingly confident of making major progress in just the next few
12:31 years.
12:32 The Artemis program is the agency's flagship project right now, promising to return astronauts
12:37 to the lunar surface, and this time to stay there.
12:41 While we haven't actually been to the moon in person since Apollo 17 in 1972, the plan
12:47 is for Artemis to kickstart a new era of the US having a constant presence on our lunar
12:52 neighbour, with perhaps months-long shifts for the astronauts up there, as we currently
12:56 do on the International Space Station.
12:58 What's arguably more exciting, however, is the Lunar Gateway, which NASA describes
13:03 as a "vital component" of the Artemis program.
13:07 When complete, it will cruise through the skies around the moon, orbiting at an optimum
13:12 distance to one, provide around-the-clock support to any moon-based astronauts at the
13:16 time, and two, to serve as a key outpost and potential launch location for other missions
13:22 into the solar system and deep space.
13:25 In some ways like the ISS, only circling the moon instead of Earth, building the Lunar
13:30 Gateway is set to start in 2024, with a proposed finish date of 2031… although many believe
13:36 it will be later.
13:37 Our moon isn't the only moon out there, though.
13:40 And in fact, it probably isn't even the most interesting moon in the eyes of most
13:44 at NASA.
13:45 One of the key challenges facing the next generation of NASA scientists is how to explore,
13:50 in detail, all of the other moons in the solar system… but most notably, Jupiter's Europa
13:55 and Saturn's Titan.
13:57 Of all the other worlds that are relatively nearby, in the grand scheme of the universe,
14:02 these are the ones that appear most habitable, to us and perhaps to alien life as well.
14:07 And over the coming years, you can well expect missions to them to be making the headlines.
14:12 For example, the Europa Clipper mission is one of the latest initiatives, reportedly
14:17 set to launch in 2024.
14:18 It'll be beelining straight to Jupiter, following the collapse of a previously planned
14:23 NASA mission to the Jovian system, but will be targeting repeated flybys of Europa in
14:28 particular.
14:29 Meanwhile, and although Saturn missions have historically lagged behind Jupiter projects
14:34 with NASA, that could all change with the Dragonfly spacecraft, scheduled to launch
14:38 in 2027 - planned as it is to soft-land on Titan for an unprecedented up-close look at
14:45 this distant world.
14:47 Dragonfly could well become one of the most important bits of kit that NASA ever produces,
14:51 especially if it finds life where it's headed.
14:54 That's all well and good, you might say, but we're still confined to just our own
14:58 solar system, in a galaxy full of others like it - and a universe full of countless more
15:02 galaxies, too.
15:04 But while it is unlikely in anyone's lifetime that NASA will advance enough to begin sending
15:08 targeted probes to other cosmological structures entirely, there is hope in abundance that
15:14 the agency will break new ground with propulsion methods.
15:17 And there are multiple directions down which it could head.
15:20 For example, in January 2023, NASA announced that it and DARPA, the Defense Advanced Research
15:26 Projects Agency, will work together to test a nuclear thermal rocket engine in space.
15:32 According to NASA, this particular enterprise could be a key moment in its moon-to-Mars
15:37 push, as it should easily enable longer-period space travel.
15:41 NASA explains that, if the rocket works, inside it there will be a nuclear fission reactor,
15:47 which will heat a liquid propellant to incredible temperatures for a set-up that, quote, "can
15:52 be three or more times more efficient than conventional chemical propulsion".
15:57 It's an effort that falls under the wider Draco propulsion program at NASA.
16:01 And although it remains a way away from breaking out of the solar system proper just yet, it
16:06 appears to be a case of "watch this space".
16:09 And it looks a solid bet that we will see some major and fundamental propulsion upgrades
16:13 over the next generation.
16:15 We should remember, though, that not everything NASA does is space-bound.
16:19 And perhaps its greatest imminent impact in our own skies will be to do with supersonic
16:24 flights.
16:25 Anyone who remembers the Concorde knows that this actually isn't new technology.
16:29 Not exactly.
16:30 And particularly because we have many military jets today that are capable of breaking the
16:34 sound barrier.
16:35 However, NASA wants to make supersonic travel more practical than it's ever been before
16:40 by removing the sonic boom.
16:43 Most of the contemporary interest surrounds the Lockheed Martin X-59 Quest aircraft, with
16:49 Quest standing for "Quiet Supersonic Technology".
16:52 The characteristically deafening thunderclap that's usually generated is why, at present,
16:57 flight guidelines in the US prohibit supersonic travel over almost all land.
17:02 The noise associated with the shockwaves that are made is just too much.
17:06 However, the X-59 Quest is scheduled to begin test flights in 2023, with those behind it
17:13 hoping that it could be good to go by the end of the 2020s.
17:16 And with NASA partnering with Lockheed for this particular venture, there are already
17:20 hopes that the currently single-seater plane will one day be expanded into a larger, commercial
17:25 vehicle.
17:26 But, finally, and if there's one message to link almost all of these future NASA plans,
17:31 it's that there's beauty in the detail.
17:33 Over the years, the agency has pushed and pushed the boundaries of human knowledge,
17:37 so that now we have a very solid base understanding.
17:41 The next challenge, then, is to refine that understanding.
17:44 By returning to the places we've been before, but better prepared.
17:48 By obtaining clearer imagery and samples of even the most far-off worlds.
17:52 And by tweaking current technology to make it even better and properly fit for purpose.
17:58 This isn't one single breakthrough in itself, but more like a new era expectation, held
18:02 by those within NASA and by everyone else watching on.
18:06 Perhaps the James Webb Space Telescope is the greatest current example.
18:10 It is now producing an endless stream of incredible visuals.
18:14 So much so that for the casual onlooker, it might feel as though one intricately captured
18:18 supernova is the same as the next, as the next, as the next.
18:22 But that will never truly be the case.
18:24 And in a universe crammed with infinite possibilities, NASA is leading the charge to make it as accessible
18:30 as possible.
18:31 If there's one thing that seems certain to unfold over the next generation or two,
18:35 it's that the unknowability of space will finally be lifted.
18:39 Space will be painted not as an abyss, as it may have felt in past decades, but as an
18:44 opportunity.
18:45 As a blank canvas.
18:47 As an inspiration for hope.
18:49 And while it remains true that NASA is no longer out on its own, it is still a very
18:53 major player in making that happen.
19:00 When humans first began exploring Earth and migrating to new locations, a complete map
19:06 of the world, the like of which we have now, was still a far-off dream.
19:12 Let alone an instant, detailed picture of almost any place on the Earth, as we also
19:17 have thanks to satellite technology.
19:32 Naturally, NASA is trying its best anyway.
19:44 For most of our history, humans have only been aware of one planet in the universe,
19:50 Earth.
19:51 It feels strange to modern minds, but knowing that there are other worlds out there is still
19:57 a relatively new sensation for us.
20:00 It's only been over the last few thousand years that we've really gotten to grips
20:05 with it, identifying the likes of Mercury, Venus, Mars, Jupiter, and Saturn some four
20:12 millennia ago, before a long gap in which our astronomical technology and know-how improved,
20:18 until our telescopes could finally pick out Uranus for the first time in 1781, Neptune
20:25 in 1846, and the dwarf planet Pluto in 1930.
20:30 But of course, today, we know that all those planets, dwarf planets, and their surrounding
20:36 moons and other objects are all quite close to us since they're in our own solar system.
20:43 So exoplanet discovery, revealing planets in other star systems, is an even more recent
20:51 phenomenon.
20:52 In 1992, the first two confirmed exoplanets, nicknamed Poltergeist and Phobetor, were found
20:58 revolving around a pulsar, and ever since then, exoplanet discovery has grown and grown.
21:06 It's not as simple as just pointing your telescope in the right region of the sky and then spotting
21:11 one, however.
21:12 Most of the time, astronomers don't even see the planet they identify at first.
21:17 Instead, a variety of methods are used to predict the presence of a massive body nearby.
21:23 For example, most exoplanets are discovered via something called a "transit method".
21:29 This is the technique of watching a usually much larger star to see if its intensity dims
21:36 at all due to its light being obscured by an object in orbit around it.
21:42 Based on how much light is covered, scientists can then calculate how massive that orbiting
21:47 object is, and thereby determine whether it is or isn't a planet.
21:54 Another technique used is called the "radial velocity method", where astronomers again
22:00 watch stars first and foremost to see if their light becomes red or blue-shifted, presenting
22:06 a kind of wobble which could be the result of a nearby planet's gravitational influence.
22:13 Other methods for exoplanet detection include direct imaging and gravitational microlensing,
22:19 which we saw in a recent video, was also used to detect perhaps the most distant star ever
22:26 found.
22:27 But back to planets, and although some are used more than others, all methods have their
22:32 own advantages and can be used to verify the findings of another.
22:36 Nowadays, then, we have plenty of bases covered, and although all these techniques require
22:43 super-advanced telescopes, we have an ever-growing fleet of cutting-edge, specifically designed
22:49 facilities both on the ground and in space itself.
22:54 Using all these instruments and methods, NASA reached a milestone in exoplanet discovery
23:00 midway through 2022, when it officially added the 5,000th discovered world to its archive.
23:08 To break it down, many of those 5,000 were found by the Kepler Space Telescope, an iconic
23:14 design launched in 2009 for the express purpose of discovering planets that revolve around
23:20 distant stars.
23:21 Kepler spent an eventful nine and a half years in space, and uncovered thousands of planets
23:28 and thousands of more potential planets before it finally ran out of fuel in 2018.
23:34 In many ways, its mission is a model for how the search for exoplanets has unfolded in
23:39 general, because although 5,000 have now been confirmed by NASA, there are still many more
23:46 suspected discoveries that haven't been verified yet.
23:50 The verification process is long and intensive, with any one potential planet having to be
23:57 shown by at least two methods of observation.
24:00 The findings must then be published in a peer-reviewed journal, which can often take years.
24:07 The Transit Exoplanet Survey Satellite, or TESS for example, has so far confirmed the
24:13 discovery of more than 200 planets, but it's discovered more than 20 times as many planet
24:19 candidates that are currently under review.
24:22 So, although 5,000 is the official total number only just passed, we know that thousands more
24:30 have likely already been found, we're just waiting for them to be rubber-stamped.
24:35 If there's one thing that astronomers have learned from cataloging all these other worlds,
24:41 it's that there's a huge amount of diversity in the types of planets that form.
24:46 NASA has a categorization system that tries to break exoplanets up into four distinct
24:53 types; gas giants, Neptunians, super-Earths, and terrestrials.
24:59 Which category a planet ends up in is mostly according to its size and mass, but other
25:06 factors are taken into consideration as well.
25:10 Gas giants, in general, are massive, unsurprisingly gaseous giants about the size of Jupiter or
25:17 larger, but there are various more distinct sub-categories too.
25:22 Hot Jupiters, for instance, are particular types of gas giants found so close to their
25:28 home star that, according to NASA, their temperatures soar into the thousands of degrees.
25:35 Neptunian planets are of varying composition, but are usually around the size of Neptune.
25:42 They have solid cores and atmospheres that consist of only the most basic elements, but
25:47 again, there are variations.
25:51 Many Neptunes are much like other Neptunian planets, except that they're much smaller.
25:57 Next, super-Earths are planets found to be very like our own, but they're much more
26:03 massive.
26:04 And lastly, terrestrials are those smaller, rocky worlds, like Earth, where it's thought
26:10 that there might be water, and therefore, a greater potential for life.
26:16 There have been some even more distinct planets identified as well.
26:20 The Unified Astronomy Thesaurus, an open-source database for exoplanet information, has further
26:26 categories including pulsar planets, extrasolar ice giants, free-floating planets, and thonium
26:33 planets, which are gas giants stripped of their atmosphere and outermost layers.
26:38 Some of the strangest exoplanets ever discovered have included unique features like glass rain,
26:45 sideways rain, coal-black surfaces, 100% lava surfaces, and even diamond cores.
26:53 But there are patterns to be found, too.
26:57 For one, planets seem to have a preference when it comes to their overall size.
27:02 There are very few that exist in the range of between 1.5 to 2 times the size of Earth.
27:09 This apparent gap is called the Radius Valley, or the Photon Gap, and researchers think that
27:15 it could exist because there's a critical size that determines how a planet evolves.
27:22 If it grows large enough, then it quickly moves beyond the gap, gathers an atmosphere,
27:28 and becomes a gas giant.
27:30 But if it doesn't grow large enough, it never pushes through that gap at all, and
27:36 remains on the other side of it.
27:39 And what of the search for life?
27:42 The number of confirmed exoplanets that are located within the habitable zone around their
27:47 home star, with potentially perfect temperatures and Earth-like conditions, has mounted up
27:53 and up.
27:54 Using information gathered from these worlds, scientists can today better estimate the likelihood
28:00 of alien life in the universe.
28:02 An important measure on the Drake Equation, for example, is how many habitable planets
28:08 there are out there, and now, according to projections made following confirmed observations,
28:15 it's thought that there could be as many as 300 million habitable planets at least,
28:22 and in just the Milky Way.
28:25 We're a long way from officially registering all of them, but the first steps, it seems,
28:31 have been made.
28:33 Moving forwards, the technology is always changing.
28:37 The Kepler is no longer in service, but more planets are continually being discovered by
28:43 still-operational telescopes like the TESS, and researchers are also looking to new technology
28:50 to help in the search, including the recently launched James Webb Space Telescope, which
28:55 is capable of studying even the precise atmospheric conditions of these faraway worlds.
29:03 For now, 5,000 officially discovered exoplanets and counting is certainly something to celebrate,
29:10 but compared to the number that are estimated to be out there, with suggested hundreds of
29:16 billions, perhaps trillions in the universe as a whole, the work has really only just
29:22 begun.
29:23 We still have many, many more to find, especially as most of what we've spotted so far have
29:29 also been the planets that are closest to us in space, and often just a few hundred
29:35 light-years away.
29:37 Each new planet registered, however, is another subject to study and to learn from, another
29:43 new world to explore.
29:45 It's been a long and exciting road to this point, but there's plenty more to come.
29:55 All the time, NASA is developing new technologies that will help us unravel the mysteries of
30:00 the universe.
30:01 Despite its uniformity, the cosmos remains an explosive and wildly unpredictable place,
30:06 full of things we can't yet understand.
30:08 But one day we will, and that's thanks to humanity's constant ingenuity.
30:20 In December 2021, NASA launched the Imaging X-ray Polarimetry Explorer, a space observatory
30:27 with a huge mandate - to study some of the weirdest, most complex and dangerous celestial
30:32 bodies in the universe.
30:34 Called the IXPE for short, the craft is one satellite of many that NASA has designed to
30:39 study astrophysical phenomenon in the wider universe.
30:42 In its sights, IXPE has everything from black holes to quasars to magnetars - truly the
30:47 biggest, most powerful and most dramatic objects that exist in outer space.
30:52 IXPE can study them because it's able to image the X-rays that these objects produce,
30:56 which other kinds of telescopes are incapable of seeing.
31:00 Not only are X-rays invisible to other telescopes, they're invisible to humans, as well.
31:04 Our eyes can't see X-rays, because they're beyond the visible light spectrum.
31:09 IXPE is necessary over other, more famous telescopes like James Webb, launched the same
31:14 month, because it's an infrared telescope looking at the other end of the electromagnetic
31:18 spectrum.
31:19 The Hubble Space Telescope doesn't look at the X-ray region of the spectrum, either.
31:24 IXPE is, however, not the only X-ray telescope NASA has.
31:28 It also has the Chandra X-ray Observatory, which has been in operation since 1999.
31:34 But Chandra and IXPE aren't quite looking at the same things.
31:37 Chandra is looking at the X-rays emitted by stellar-mass black holes, among other things,
31:42 while IXPE wants to examine active galactic nuclei, quasars, pulsars, supernova remnants,
31:49 and more.
31:50 By looking at the X-rays these objects produce, we're going to learn far more about them
31:54 - potentially even about the centre of our own galaxy, which remains mysterious.
31:59 When it comes to the galactic centre, we still have a lot to learn.
32:03 We do know that there's a powerful radio source in the middle of the Milky Way, just
32:07 like there is in the centre of every other galaxy.
32:09 In 2020, scientists finally proved that this radio source is a black hole.
32:14 Called Sagittarius A*, it's estimated to be around four million times more massive
32:19 than the sun.
32:20 And there are some theories that there could be multiple black holes hiding there, rather
32:24 than just the one.
32:26 In recent years, other X-ray telescopes - specifically Chandra - have made phenomenal discoveries
32:31 about this region.
32:32 The problem with studying the centre is that there's so much gas and dust swirling around
32:36 there that it completely obstructs our view.
32:39 Chandra, however, can cut through the white noise, and map powerful X-ray sources that
32:44 would otherwise be totally hidden.
32:46 IXPE is going to be able to do very similar things.
32:49 Looking through gas clouds to pinpoint large radio sources and massive objects.
32:54 It could finally show us exactly what's lurking in the centre of the galaxy.
32:57 And if we can study our own galactic centre, this paves the way for studying other galactic
33:01 centres that we can observe.
33:03 Specifically, IXPE also wants to look at AGNs, or Active Galactic Nuclei.
33:09 An AGN is an exceptionally bright and compact region in the centre of a galaxy - something
33:15 that the Milky Way, which has an inactive galactic nucleus, lacks.
33:19 The brightest AGNs of all are quasars, another dramatic object that IXPE has its eyes on.
33:25 A quasar is a supermassive black hole with a gaseous accretion disk swirling around it.
33:30 As this disk spirals down into the black hole, friction causes it to heat up and it releases
33:35 electromagnetic radiation.
33:37 This energy is then emitted in the form of an astrophysical jet.
33:41 A quasar with a jet pointing directly towards Earth is called a blazar.
33:45 IXPE specifically wants to see exactly how these jets are produced in quasars and blazars.
33:51 It's not just black holes that interest IXPE, either.
33:55 Already in early 2022, IXPE has sent back an image of a supernova that happened hundreds
34:00 of years ago.
34:01 This particular supernova remnant exploded in the seventeenth century and is called Cassiopeia
34:07 A. And with the IXPE, we can finally see the residue that it left behind.
34:12 The latest image of Cassiopeia mirrors one taken by Chandra in the nineties, but the
34:17 new picture is even more striking.
34:19 The massive explosion of a supernova is certainly one of the most dramatic and chaotic events
34:24 to happen in the universe.
34:26 And with every day that the IXPE mission continues, we're learning more and more about them,
34:30 especially where X-rays are concerned.
34:32 But what about other, far stranger types of stars?
34:36 Magnetars are magnetically powerful neutron stars, themselves some of the brightest and
34:41 densest objects in space.
34:43 And IXPE wants to study them, as well.
34:46 Because magnetars have a strong magnetic field, they produce significantly more X-rays than
34:51 other astronomical objects, which is why IXPE is perfectly suited to study them.
34:57 Neutron stars alone are pretty weird, and in need of further investigation, since they're
35:02 the dead cores of giant stars that went supernova.
35:04 They're also denser than even white dwarf stars.
35:08 The decay of the magnetic field of a magnetar is what produces these huge bursts of ionising
35:13 radiation, all of which are totally invisible to the human eye and to non-specialised equipment.
35:20 Magnetars do all kinds of other strange things, as well, including the emission of fast radio
35:24 bursts - another cosmic phenomenon we're still studying.
35:28 Similar to a magnetar is a pulsar, another type of very magnetic neutron star.
35:34 It's unique because it creates huge beams of radiation, and to us here on Earth, it
35:38 seems like it's pulsing.
35:40 They're actually not pulsing, and are generally continually emitting these beams.
35:45 But we can only see the beams when they're coming towards us from tens of thousands of
35:49 light years away.
35:50 Pulsars are so weird that when they were first discovered in the late 1960s, some people
35:55 believed that they were an alien radio source, thanks to the power and regularity of the
35:59 signal.
36:00 That regularity was just the rotation of the pulsar, and eventually we discovered so many
36:05 that it became clear that they're not alien in origin at all.
36:08 They really are just bizarre neutron stars, and we still know very little about them.
36:13 One thing NASA hopes that IXPE will accomplish is discovering how, exactly, pulsars emit
36:19 these concentrated bursts of X-ray energy.
36:22 The more we can learn about pulsars, the better, because they could someday be used as interstellar
36:27 lighthouses - provided we ever come up with a way to travel between stars.
36:32 Pulsars also create something called pulsar wind nebulae.
36:36 As we mentioned, neutron stars are the leftover cores of massive stars that went supernova.
36:41 A pulsar is a neutron star that emits beams of electromagnetic radiation.
36:46 A pulsar nebula emerges when the energy from a pulsar charges the remnants of the supernova
36:52 that formed it.
36:53 The nebula spread out far beyond the pulsar, and continually emit radiation from across
36:58 the electromagnetic spectrum.
37:01 These nebulae don't just produce X-rays, but also infrared rays and gamma rays, becoming
37:06 yet more potent energy sources in the universe.
37:09 We know very little about pulsar winds beyond this, though older studies have tried to map
37:14 the winds in 3D.
37:16 Yet again, it was the Chandra X-ray Observatory leading these efforts, and the IXPE is going
37:22 to continue them.
37:23 One final mystery that the IXPE could unravel is that of X-ray binaries.
37:29 These are binary star systems where the two stellar mass objects are innately intertwined.
37:35 You could even describe it as a parasitic relationship.
37:38 There's always a living star, but the other object could be another neutron star or a
37:43 black hole.
37:44 They generate a lot of energy, often in the form of X-rays.
37:49 Sometimes the black hole pulls material from the star, creating a large accretion disk
37:54 around itself, much like the disk that collects around a quasar.
37:57 Some would even define these objects as microquasars.
38:01 There are so many complicated and powerful objects existing out there, in our own galaxy
38:06 and beyond, and the Imaging X-ray Polarimetry Explorer is just the latest attempt of many
38:12 to understand them.
38:14 So what do you think?
38:16 Given all the work that's being put in, could NASA now be on the brink of a momentous
38:21 discovery of a history-defining announcement?
38:25 It could be an alien city on a distant planet, or a breakthrough in our hopes for Mars.
38:32 Is NASA about to find something really good in its search of deep space?
38:38 Or perhaps something will crop up on one of the thousands of exoplanets that have been
38:43 officially logged, or on the thousands more that are sure to be found in the future.
38:50 Or do you predict something else will happen with NASA in the near future?
38:55 What there's no doubt about is that now is an extremely interesting and exciting time.
39:25 Interesting and potentially pivotal moment in time.
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