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The James Webb Space Telescope has uncovered how tiny galaxies played a key role in building the universe, while scientists also explore whether spacecraft can survive in space without power. These discoveries are pushing the boundaries of space science and our understanding of the cosmos.
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00:00Bang! Or should I say, Big Bang! The Big Bang! Ahem! So, after the Big Bang, the universe resembled all
00:08hot super protons, neutrons, and electrons.
00:11After it started to cool down, the protons and neutrons began to combine, first forming ionized atoms of hydrogen, and
00:19later, some helium.
00:21These ionized atoms of helium and hydrogen attracted electrons, turning them into neutral atoms.
00:27As a result, the light was able to travel freely for the first time ever, since it was no longer
00:33scattering off free electrons.
00:36What does it mean? The universe was no longer dark.
00:39At the same time, it was still about a few hundred million years after the Big Bang, before the very
00:45first sources of light started to appear.
00:47That's when the Cosmic Dark Ages came to an end.
00:51We don't know for sure what this universe's first light looked like or how the first stars formed.
00:57Luckily, we have the James Webb Space Telescope to help us find the answers.
01:01How come? All because this is an infrared telescope.
01:06Why is it important? Let's figure it out.
01:11Imagine a star. It's a very, very old star. Maybe the first star out there.
01:17Light leaves this star 13.6 billion years ago and settles off on an incredible journey through space and time.
01:24It needs to get to our telescopes.
01:27By the time this light reaches us, its color or wavelength shifts towards red.
01:32That's something we call a red shift.
01:36It happens because when we talk about very distant objects, Einstein's theory of general relativity comes into play.
01:43According to it, the expansion of the universe also means that the space between objects stretches, making them move away
01:52from one another.
01:53But that's not all. Light stretches too, which shifts it to longer wavelengths.
01:58Eventually, this light reaches us as infrared.
02:02In other words, red shift means that light that is originally emitted by the first stars or galaxies as ultraviolet
02:10or visible light gets shifted to redder wavelengths by the time we catch a glimpse of it here and now.
02:16For the farthest objects with very high red shift, that bare minimum of visible light is shifted into the near
02:23and mid-infrared part of the electromagnetic spectrum.
02:27That's why to see those space objects, we need a super powerful telescope.
02:33And if we talk about the Webb telescope, it can see back to about 100 million to 250 million years
02:40after the Big Bang, which is incredibly awesome.
02:45So, by observing the universe at infrared wavelength, James Webb lets us see things no other telescope has ever shown
02:52before.
02:53The primary goal of this incredible piece of equipment is to study the formation of galaxies and stars that formed
03:01in the early universe.
03:03To look that far back in time, we need to look deeper into space.
03:08All because it takes light time to travel back from there to us.
03:12So, the farther we look, the further we glimpse back in time.
03:17To find the first galaxies, James Webb is going to make an ultra-deep near-infrared survey of the universe.
03:24Then, it'll follow it up with a few other methods of research.
03:29Now, as you remember, the gas between stars and galaxies in the early universe was opaque, and energetic starlight couldn't
03:36penetrate it.
03:37But then, about 1 billion years after the Big Bang, it suddenly became completely transparent.
03:44Why?
03:45The James Webb telescope might have found the reason.
03:49At one point in the past, the first galaxy's stars emitted enough light to ionize and heat the gas around
03:56them.
03:56This helped clear the view over hundreds of millions of years.
04:00The newest insights scientists got were about a time period called the Era of Reionization.
04:06That's when the universe underwent some dramatic changes.
04:11After the Big Bang, gas in the universe was unbelievably hot and dense.
04:17Hundreds of millions of years passed, and it cooled down.
04:20But then, something baffling happened.
04:22It was as if the universe hit the repeat button, and the gas became ionized and hot once again.
04:28It could have happened because of the formation of early stars.
04:32After that, millions of years later, this concoction became transparent.
04:38For a long time, researchers have been hoping to find definite evidence that could explain these changes.
04:45And now, the telescope has finally shown that those transparent regions are located around galaxies.
04:52Astronomers have seen these galaxies re-ionize the gas surrounding them.
04:57Even better, they've managed to measure how large these transparent regions are.
05:03They're ginormous compared to the galaxies themselves.
05:07Imagine a hot air balloon.
05:09And now imagine a pea floating inside.
05:12You've got it, and guess what?
05:14These tiny galaxies drove the entire re-ionization process, clearing huge regions of space around them.
05:21These transparent bubbles kept growing until they merged and caused the entire universe to become transparent.
05:30The research team chose to target a period of time before the end of the era of re-ionization.
05:37At that time, the universe was not quite opaque, but not quite clear either.
05:41It was a patchwork of regions of gas in different states.
05:46To find out this cool fact, the astronomers aimed the James Webb Telescope in the direction of a quasar, an
05:53incredibly bright space object.
05:55It acted as a giant flashlight, traveling towards us through different regions of gas.
06:01It was either absorbed by the patches of near-opaque, or moved freely through the areas where the gas was
06:07transparent.
06:09The scientists then used Webb to examine galaxies in that region of space.
06:15They found out that these galaxies were usually surrounded by transparent regions with a radius of about 2 million light
06:23-years.
06:23For comparison, the area the galaxies cleared was almost the same distance as the space between our home Milky Way
06:31galaxy and our nearest neighbor, the Andromeda galaxy.
06:34And the telescope witnessed those galaxies in the process of clearing the space around them.
06:40It was the end of the era of re-ionization.
06:43Until then, no one had evidence of what caused re-ionization.
06:49The team is planning to dive into research about other galaxies in five additional fields.
06:55The Webb Telescope's results from the first field have been overwhelmingly clear.
07:01And even though the astronomers had expected to identify a few dozen galaxies existing during the era of re-ionization,
07:08they actually managed to spot 117.
07:13Now, let's talk a bit about the main hero of today's show, the James Webb Space Telescope.
07:19It's an absolutely stunning piece of equipment which is around 100 times more powerful than the Hubble Space Telescope.
07:26And the latter has observed places that are 13.4 billion light-years away.
07:32The James Webb Telescope is also on the pricey side, to put it mildly.
07:36Even though originally the cost of the telescope was estimated to be just $1 to $3.5 billion.
07:43The whole development process cost around $10 billion.
07:47For comparison, it cost NASA $4.7 billion to build and launch the Hubble Telescope.
07:54And it was another $1.1 billion to fix it in orbit.
08:00Even though the James Webb Telescope itself is three stories high and the size of a tennis court,
08:06its mirrors are the lightest large telescope mirrors of all time.
08:10During the manufacturing process, they underwent a 92% reduction in weight.
08:16When you look at them, the telescope's mirrors seem to be gold, but in reality, they're made of beryllium.
08:23This is a steel gray, lightweight, and brittle metal.
08:27A gold coating is applied to each mirror, that's true, but they can't be produced entirely out of gold,
08:32since this precious metal tends to expand and contract, even with small temperature changes.
08:39So, the total amount of gold in the James Webb Space Telescope is less than 2 ounces.
08:45That's a golf ball-sized piece of gold.
08:47And the gold plates covering the mirror are less than 1,000 atoms thick.
08:52As for the telescope's abilities, it would be able to clearly see a U.S. penny from 24 miles away
08:59and a football from 340 miles away.
09:03James Webb's telescope side is cooling itself down, and its temperature doesn't rise higher than minus 370 degrees Fahrenheit.
09:11That's cool enough to make liquid nitrogen.
09:15A truly enormous five-layered sunshield surrounds the telescope and reflects away as much sunlight as possible,
09:22letting the telescope stay cool.
09:25Let's say a spacecraft runs out of power far in deep space.
09:29It wouldn't fall in the traditional sense because there's no gravity.
09:34Newton once said that an object remains in motion unless acted upon by an external force.
09:40In our case, this external force is gravity.
09:43In other words, if there's nothing with gravity around, it would continue to move due to inertia.
09:49It would keep going the way it did, without us being able to change its trajectory or adjust it in
09:56any way.
09:57It would keep traveling through deep space almost forever.
10:01Well, at least until radiation and cosmic rays destroy it.
10:04And unless some celestial body like an asteroid doesn't destroy it either.
10:09And, of course, unless it encounters something with a gravitational pull, like a planet or a star.
10:16The likelihood of all this depends on the location and trajectory of the spacecraft.
10:22Voyager 1 was launched by NASA in 1977.
10:26It's been on its journey for almost 50 years now.
10:29Right now, it's the farthest human-made object from Earth, more than 50 billion miles away.
10:35It's already very far from all our planets.
10:39And it's the first spacecraft to enter interstellar space, the vast, empty space that exists between stars in a galaxy.
10:47It's the space outside our solar system, where there are no planets, moons, or other objects associated with our sun.
10:56However, it's still in our solar system.
10:59To leave it, Voyager 1 needs to bypass the Oort cloud, a big, icy collection of objects where all the
11:06comets in our solar system probably come from.
11:09It will take Voyager about 300 years to reach the inner edge of the cloud, and then about 30,000
11:15years to bypass it.
11:17Voyager 1 has a special plate on board, like a message in a bottle.
11:21This plate is called the Golden Record.
11:24It's not really golden, it's actually a shiny gold color.
11:28On this plate, there are things that tell a story about Earth.
11:32It was created in case Voyager ever encounters any extraterrestrial beings.
11:37The record has greetings in different languages, music from Earth, and even the sounds of nature, like birds chirping and
11:45the wind blowing.
11:46As the distance between us increases, the signal strength from Voyager 1 weakens over time.
11:53Eventually, it may become too weak to be detected by our communication equipment.
11:57The power output of Voyager 1's engine also declines over time.
12:02It's slowly running out of fuel.
12:04When all its systems shut down, we will lose contact with the spacecraft.
12:10Voyager 1 will work until 2025.
12:13After that, it will continue its journey on inertia.
12:16Luckily, it was designed to last, and the chance that it will encounter anything on its way is very small.
12:23Considering this, it might even keep going for billions of years.
12:27One day, it might even reach other star systems, and maybe even outlast our Sun.
12:34The same goes for Voyager 2.
12:36It will keep traveling until it reaches interstellar space, joining its twin brother.
12:41Voyager 2 will continue to send us scientific and systematic data for a while, even in interstellar space.
12:49However, it will also cease to function eventually, becoming a silent artifact drifting through the Milky Way.
12:55When there's something with gravity near the spacecraft, the inevitable happens.
13:01It falls onto that object.
13:03This is why out of the vast South Pacific Ocean beyond New Zealand lies a unique and intriguing place known
13:11as the Spacecraft Cemetery.
13:13Officially, it's called the South Pacific Ocean Uninhabited Area.
13:17It's located near Point Nemo, the most remote spot from any island.
13:22It serves as the final resting place for spacecraft that have completed their missions and reached their lifetime limit due
13:29to wear and tear.
13:30Sometimes, these larger spacecraft are too hefty to burn up during re-entry into Earth's atmosphere.
13:36In that case, they're directed to crash or splash down in this remote ocean location.
13:42This helps protect us from any potential harm during re-entry and impact.
13:47There are, however, some big problems with this place.
13:52Scientists are worried about the impact this spacecraft cemetery has on the ocean.
13:57When spaceships come back to Earth, they often spill chemicals.
14:01One of these chemicals is hydrazine, a dangerous rocket substance.
14:06Unfortunately, it might not completely burn up during re-entry, so it leaks out into the ocean.
14:12Posing a threat not only to marine life, but to us as well.
14:16We made up some rules, both within countries and internationally, to stop this.
14:21However, it's not easy to figure out how risky it is for certain spacecraft to enter the cemetery.
14:27We can't say for sure how much of a substance is left after it enters the air.
14:33As for spacecraft that don't fall, they're often left in space as debris.
14:38This is what we call any man-made object orbiting Earth that's no longer useful.
14:43It's also very dangerous.
14:45There are over 27,000 pieces of space debris orbiting Earth at high speeds.
14:51All this puts human and robot missions at risk and harms spacecraft.
14:57As we mentioned, usually we get rid of space debris by trying to bring the crafts back to Earth.
15:04This makes them burn up when they re-enter due to high speeds and air pressure.
15:08This usually works with smaller objects.
15:11There are also riskier methods, like letting spacecraft break down themselves or crash into other things or blow up.
15:19These methods aren't great because they just make up even more debris, even if it's smaller.
15:25So now, scientists are trying to find new ways to get rid of retired spacecraft.
15:31For example, nets and magnetic arms.
15:35There's also a thing called reusable spacecraft.
15:38It's a space vehicle that's built to be used more than once.
15:41For example, space planes such as the Space Shuttle and the Dream Chaser or capsules like the SpaceX Dragon.
15:49They're designed to launch, orbit, come back to Earth and do it all over again.
15:54But it's important to make sure these spacecraft and their passengers or cargo stay safe during the return, which is
16:01quite hard to do.
16:03Reusable spacecraft have special systems to guide them back to Earth safely.
16:08The Space Shuttle, for example, had OMS pods, sort of special backpacks that help the spacecraft move and control its
16:15position in space.
16:17The SpaceX Dragon had its own engines to slow down and enter the atmosphere in a controlled way.
16:24They also have a heat shield to protect it during re-entry.
16:28The heat shield can be made of different materials, but they need to be tough and able to withstand multiple
16:34trips.
16:35Coming up with a heat shield that's both strong and lightweight is a bit of a challenge.
16:41Finally, if a spacecraft lands on a runway, it needs wings and landing gear.
16:46They also add weight.
16:48Some designs like lifting bodies or the delta wing of the Space Shuttle try to reduce the mass of these
16:53parts.
16:55After landing, the spacecraft might need some fixing up before it can go on its next adventure.
17:00This process can take a while, up to a year, and it might not always be possible to use the
17:05spacecraft again if it's been fixed up.
17:08There's also a limit to how many times a spacecraft can be fixed and used again before it has to
17:15retire.
17:16Different spacecraft have different abilities to be reused.
17:20Finally, sometimes we can rescue a spacecraft, or even remake and repurpose it.
17:27Voyager 2 is one of the examples.
17:29It had a little trouble with its radio in 1978.
17:33Engineers fixed it by using a backup system.
17:36Since then, it's been exploring our solar system for over 40 years.
17:40The Hubble Space Telescope is the most famous telescope we have, the grandfather of them all.
17:47However, it had a blurry start in 1990.
17:50The work wasn't done at all as expected.
17:53The pictures were of low resolution.
17:55Luckily, astronauts fixed it right in space in 1993.
18:00To do that, they used some corrective mirrors.
18:03Now it gives us fantastic views of the universe.
18:07As you can see, even in bad scenarios, there are many possible options to solve spacecraft-related problems.
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