The Most Breathtaking Sights In Our Galaxy [4K] | Cosmic Vistas [Season 1 All Episodes] | Spark

for generations our world has challenged explorers to seek what lies beyond the horizon now the invention of space flight is leading us outward to explore a host of alien worlds with vast new territories today we see the sun moon and planets with penetrating clarity through the eyes of the intrepid machines blazing a trail for us across the solar system their cameras have become our windows onto a bold new adventure their discoveries have become our cosmic vistas [Music] [Music] since the dawn of humanity the night sky has been our window onto a larger reality [Music] for our ancient ancestors the heavens above were evidence that there is something out there [Music] out of reach yet somehow connected to life on earth as they gazed upward from night to night and year to year our ancestors noticed changes in the sky and wondered what those changes might foretell about their own destinies some of those changes were easy to spawn like the nightly drift of the constellations from east to west or the monthly spectacle of the moon marching through its phases [Music] and there were more fleeting changes like colorful displays of aurora borealis or the chance appearance of a bright comet slicing across the heavens [Music] but no change attracted as much attention from our ancestors as the complex dance of a few brilliant objects moving around among the constellations they looked like stars but by their motions it was clear these objects were somehow different they were called the wanderers or in greek the planets for centuries astronomers puzzled over the motions of these planets trying to decipher the clockwork nature of our universe but it would take the invention of the telescope to show us how special the planets really are when the telescope arrived it offered a new kind of window on the universe one that transformed the planets from lights moving in the sky into distant worlds orbiting around the sun in other words the telescope helped us understand that we are part of a solar system full of planets asteroids comets and more but there is also a limit to how much of the solar system any telescope can show us which is why what happened next was the most exciting development of all in the 1960s a new kind of technology appeared that was destined to show us the planets like never before [Music] [Music] thanks to space flight it was no longer going to be a matter of getting better windows on the distant planets [Music] now our windows were moving to the planets and giving scientists back on earth a taste of what it would be like to visit alien worlds [Music] the earliest space voyages to reach beyond earth were aimed at our nearest neighbor the moon and when a soviet space probe named luna 3 became the first to image the moon's hidden far side it was clear a new age of exploration had begun [Music] suddenly every planet was a potential destination before long space probes were crossing the great ocean of interplanetary space and sending back their close-up glimpses of mars venus and the sun-baked surface of mercury [Music] by the 1970s and 80s the u.s space agency nasa was ready to reach even farther to the distant outer planets [Music] the most celebrated mission of this time voyager 2 managed to visit four giant planets in a row including jupiter saturn and uranus before finally reaching neptune in 1989 more recently a second wave of missions has given us powerful new views of many of the planets and allowed us to see the solar system from a fresh perspective [Music] so in some cases that perspective means more detail and more complexity than we could ever have dreamed of like the detail in these cloudy swirls in jupiter's turbulent atmosphere or these broken and re-frozen icebergs on the surface of jupiter's moon europa [Music] in other cases spacecraft have revealed more history than we could ever have hoped for here in a crater punched into the barren martian desert we find ancient layers of rock jutting from the crater's rim [Music] geologists have read these layers like the pages of a novel and the story they tell speaks of long vanished water that once bathed an alien landscape [Applause] collectively the rich new views and precious data that are coming to us from so many planetary missions make it clear our solar system features astonishing diversity yet the evidence is also telling us these very different places in the solar system have a common origin according to the best available evidence some four and a half billion years ago our sun was born out of a vast cloud of interstellar gas and dust [Music] today the hubble space telescope can see the same process at work throughout our milky way galaxy [Music] what appears to us as a gorgeous nebula of glowing gas is really a star factory and our sun came into being in just such a place but the sun was not created in isolation as matter swirled together to form our newborn star a small fraction of that matter ended up in a disk of gas and debris spinning around the infant sun as material in the disk coalesced it formed planets moons asteroids and comets and like different children born to the same parents each member of our solar system family has its own distinct characteristics one of the big questions to come out of planetary science is how could all of these solar system objects have started from the same basic ingredients but followed such very different pathways as far as we know only one of those pathways led to earth a planet capable of supporting life and keeping that life well protected for the billions of years it took for us to finally show up and start wondering about the solar system [Music] the poet t.s eliot wrote we shall not cease from exploration and the end of our exploring will be to arrive where we started and know the place for the first time when it comes to exploring the solar system elliot's words are literally true every planet every moon every asteroid we visit has a different story to tell us and by putting together all those stories scientists hope to understand how we came to be here in our place in our time these are questions that touch us all and the journey to answer them has now begun [Music] ah [Applause] [Music] [Music] of all the destinations that await explorers in our solar system none could be more terrifying or more beautiful in its alien grandeur than this hellish domain of searing writhing and dancing fire this is the vast and volatile powerhouse whose explosive outbursts can reach across millions of kilometers of space to rattle our tiny planet but it is also the fountain of creation upon whose energy our entire living world and civilization critically depend it is our son even in ancient times our ancestors understood that without the sun's warmth and light life as they knew it would not exist [Music] for them the sun was nothing less than a god today we know the sun is a star just one among the hundreds of billions that populate our milky way galaxy [Music] but for us the sun is special in our solar system there are eight planets several dozen moons hundreds of thousands of asteroids and possibly trillions of comets but there's only one sun and it's one thousand times more massive than all the rest of the solar system combined the gravitational pull of all that mass is what keeps everything in its orbit so no matter where you are in the solar system it's the sun that takes center stage [Music] four centuries ago the astronomer galileo was certain the sun not the earth was at the center of our solar system he would later be tried for heresy for defending this radical idea galileo was also one of the first to point a telescope at the sun which led him to another surprising discovery sunspots these are dark patches that appear on the sun from time to time and seem to drift across its blazing surface in time astronomers discovered that a subtle pattern governs the appearance of sunspots over a cycle lasting approximately 11 years they grow increasingly more numerous on both sides of the sun's equator spreading northward and southward until they cover all regions of the solar surface and then just as they reach their peak they diminish and the cycle begins anew sunspots offer a visible clue that the sun is not just our cosmic light bulb but a complex and dynamic system even before galileo's time there were clues that there is more to the sun than meets the eye the most obvious appears every time the moon passes directly in front of the sun causing a total eclipse this wispy white glow that stretches outward from the eclipsed sun is called the solar corona it is the sun's searingly hot outer atmosphere a region where ionized gas is energized to a temperature that is far higher than at the sun's surface and like sunspots the corona is always changing these clues suggest that the sun releases its energy in complicated ways but for generations scientists were stumped trying to understand where that energy comes from in the first place then came the atomic age with an unexpected side effect [Music] the discovery of nature's hidden nuclear forces gave scientists the insight they needed to understand what makes the sun shine like most stars in the universe the sun is mainly made of hydrogen gas at the sun's surface that gas is about 5600 degrees celsius hot enough to glow with a bright yellowish light but deep inside the sun's core the temperature rises to millions of degrees and under these extreme conditions hydrogen atoms can combine to form helium the energy released in this reaction gradually works its way outward from the sun's core through overlying layers until it is released into space only a tiny fraction of the sun's total energy falls onto our world but over the eons it has been remarkably steady and this has allowed life to evolve and flourish on earth yet there are also plenty of reminders that the sun is not always so benevolent scientists have long known about giant explosions on the sun called solar flares that can wreak havoc with power and communication systems while producing dazzling displays of aurora borealis to better understand the sun's changeable nature and its influence on earth scientists have learned that they must venture into space where the sun can be monitored around the clock and observed in ways that are not possible from the ground [Music] this has allowed astronomers to study the way features shift and change on the sun's rotating surface over a long period of time a less direct way of studying solar activity from space involves using a circular disk to block the sun's light this creates an artificial eclipse inside the spacecraft making it easier to follow dramatic changes in the sun's corona for years the soho spacecraft has made good use of this method here soho looks on as a comet swoops in near the sun and is greeted with a blast of high energy particles in some cases a vigilant spacecraft can even catch the occasional trespasser here we see the planet mercury transiting across the sun's fiery disk these views from space reveal an incredibly dynamic sun intimately connected from surface to corona by a powerful but invisible force the force of magnetism in fact the sun is the most powerfully magnetized object in the solar system the reason for this is that the sun is not a solid body but a turbulent electrically charged fluid it is the motions of that fluid that ultimately generate the sun's tangled and ever-changing magnetic field this field frequently pokes through the solar surface and forms long loops out into space the bases of these loops are where we find sunspots because that's where material that would normally be turning over and sinking back down into the sun's interior is temporarily held at the surface and allowed to cool and darken the loops and twists in the sun's magnetic field can store vast quantities of energy occasionally that energy is released with astonishing speed and violence the result is a solar flare on october 29 2003 soho captured these views of one of the most powerful solar flares in history it begins with a large magnetically active region rolling into view on the sun's left hand side as the sun rotates the region gradually moves to the center where it faces the spacecraft and us with a sudden flash the flare erupts followed by a burst of static as high-speed solar particles pummel soho's camera soho survived but a powerful solar flare like this can easily knock a satellite out of commission another hazard often associated with solar flares is a coronal mass ejection it begins as a huge release of magnetically energized particles from the sun's corona the particles shoot across space at high speed when they encounter earth the particles cascade down onto the atmosphere producing brilliant aurora around the north and south poles what the age of space exploration has taught us is that the sun is not an isolated and distant part of our solar system rather the sun is an environment that earth travels through and it's not just earth that experiences this the sun's magnetic fields and the flow of particles that stream off its surface travel well beyond our world and all the other planets of our solar system it ultimately creates a giant bubble that separates all of us from the flow of interstellar material that permeates the galaxy with the sun we not only live with a star we live within one billions of years ago each planet formed from the same primitive mix of atoms that went into creating the sun since then the planets have all gone their separate ways each with its own unique story to tell but there is also an underlying connection because in the end we are all children of the sun [Music] [Music] [Music] for generations our world has challenged explorers to seek what lies beyond the horizon now the invention of space flight is leading us outward to explore a host of alien worlds with vast new territories today we see the sun moon and planets with penetrating clarity through the eyes of the intrepid machines blazing a trail for us across the solar system their cameras have become our windows onto a bold new adventure their discoveries have become our cosmic vistas [Music] [Music] is [Music] to the human eye our universe is all about light it's the sign that matter is present in stars in galaxies and in great expanses of glowing gas but despite its beauty this colorful realm of gas and stars is not a place where life can exist life as we know it is too fragile to survive the searing temperatures that make atoms of gas glow in space what life needs is a very different kind of place one not simply made of swirls of gas but of something solid life needs a rocky planet without planets made of rock there would be no chance for life as we know it but simply having a solid place to stand is no guarantee that life will gain a foothold we can see this in our own solar system where there are many different kinds of rocky worlds [Music] first in line is mercury a small and mysterious planet that is alternately baked then frozen as it slowly rotates in the sun's glare as the nearest planet to the sun mercury's daytime surface temperature can reach more than 420 degrees celsius yet on the planet's night side where heat is quickly radiated into space during long months of darkness the temperature can drop below -180 for decades mercury's one and only visitor was the mariner 10 spacecraft which flew past the planet three times starting in 1974. it gave us our first close-up look at mercury's baked and battered surface but mariner 10's view was incomplete capturing less than half of the planet during its few brief encounters [Music] so in 2004 nasa launched a new mission mercury messenger whose goal is to orbit mercury and provide the first comprehensive survey of its geological features and mineral composition at first glance messenger's images seem to be showing us a desolate and moonlike world the surface is rough and heavily pockmarked with craters from billions of years worth of meteorite impacts but first impressions can be deceiving although mercury is only slightly larger than our own moon its gravity is more than twice as strong which means mercury is much more massive in fact mercury is so heavy it may be almost entirely made of metal some scientists have speculated mercury began its existence as a much larger planet whose exterior was mostly shattered away in a giant collision leaving behind only a thin rocky mantle surrounding a large metallic core whatever happened it's clear mercury once bubbled and rumbled with the internal heat from a tumultuous formation numerous features suggest a world that was volcanically active in the distant past this view shows a landscape with multiple ripples underlying the more recent impact craters the ripples frozen in time reveal where vast pools of lava once flooded the planet's surface [Music] in this image false colors help to highlight mercury's complex history here the bluish areas represent an ancient terrain that was gradually buried by debris shown in orangey red the debris is made of material kicked up by large crater-forming impacts blasted into mercury's surface there are also giant cliffs and escarpments threading their way among the craters these cliffs are a common feature on mercury they may have formed when the planet's giant metal core cooled and contracted causing the overlying rock to wrinkle like a planet-wide version of shrink-wrap messenger's first views of mercury reveal the bare bones of a rocky world there is nothing here but a solid surface that hasn't changed very much over eons of geologic time while mercury may provide the beginnings of a stable platform it is far too hot and barren to be anything other than an empty stage to transform a dead planet into a living world more ingredients are needed first and foremost an atmosphere lack of atmosphere is not a problem for this planet enigmatic venus is the second rocky world from the sun permanently shrouded under a dense cloudy atmosphere venus was hidden from astronomers for centuries despite being the nearest planet to earth [Music] now we know that venus's atmosphere is a toxic brew composed of carbon dioxide with clouds rich in sulfuric acid the carbon dioxide is brutally effective at trapping the sun's energy heating up the planet to a staggering 460 degrees celsius that's even hotter than mercury although venus is twice as far from the sun and venus's atmosphere is incredibly dense the air pressure at the planet's surface is so high it would easily crush a human astronaut to death these conditions are so extreme that to date we have only fleeting glimpses of venus's surface taken by a handful of soviet landers none of which survived more than two hours with a planet so inhospitable to spacecraft scientists have had to come up with another way of exploring venus's hidden terrain from a safer distance radar can penetrate the planet's thick blanket of clouds and bounce off the rock below providing a detailed look at a bizarre and dramatic landscape what these images reveal is a world shaped by volcanoes and one that could still be volcanically active today the apparent lack of impact craters so different from what we see on mercury is a strong indication that venus's surface is young and may be continually evolving scientists now suspect that in the past venus may have been much more like our own planet but as its atmosphere heated up it lost something vital that makes earth special in our solar system it's water here on earth oceans have played a key role in keeping our planet suitable for life not only do oceans moderate the climate and help keep the atmosphere stable they lubricate earth's rocky surface so its internal heat is mainly channeled into moving the continents slowly around the planet without water heat would build up and burst out in vast and deadly lava flows as may have occurred on venus most of all oceans provide a liquid medium where complex molecules can interact the preconditions scientists now believe are necessary to turn mere chemistry into biology [Music] earth is our best example of the true potential of rocky worlds it seems that when a planet has all three ingredients a solid surface an atmosphere and oceans of liquid water it can foster something new the emergence and evolution of life [Music] but while life has come to dominate earth with its richness and complexity it has also buried its tracks making it difficult to understand how our planet came to be the way it is today that is one big reason why scientists are so keen to explore the rest of the solar system now that the technology is available to do so it is here where we may find the clues that will tell us what earth was like before life appeared and how it all happened it may be that only when we reach across the ocean of space to distant rocky shores can we truly understand our own identity [Music] [Music] [Music] in all of nature there is perhaps no view as haunting and beautiful as a full moon it is both familiar and mysterious a part of our world yet a world unto itself [Music] today we look across at our nearest neighbor and find not a mirror image but an alter ego [Music] while earth looks lush and colorful the moon is a study in black and white [Music] while earth's surface is shaped by water and air and abounds with the sounds of life the moon's is silent and still here no rivers run and no winds blow all that exists are memories of events long past memories of our solar system's violent beginnings and earth's own tumultuous history for billions of years the moon has been the ultimate silent partner keeping watch over earth from above and keeping its secrets to itself that's not very satisfying to humans which explains why every civilization in history has its own myth about how the moon came to exist but only after the invention of space flight did we finally get the real story to date over 50 spacecraft have now flown past orbited or landed on the moon with eye-opening results at long last our silent partner is beginning to reveal its fascinating story when viewed up close the moon's surface is inundated with impact craters they form when small asteroids collide with the lunar surface at high speed the energy from a large impact is enough to liquefy and hollow out a crater many times the size of the original impactor while throwing debris thousands of kilometers in all directions [Music] over billions of years our planet has experienced just as severe a beating but on earth impact craters are eroded away or buried in sediment over time on the moon they simply accumulate leaving a vivid and detailed record of the hazardous nature of our solar system by carefully counting craters it's possible to tell which parts of the moon's surface formed first and which came later for example the dark patches on the moon we can see even from earth are clearly younger than the surrounding bright areas in the past astronomers named these dark patches maria latin for seas but when explored up close it's clear there's never been any water on these alien shores rather the maria are vast low-lying plains of volcanic rock long ago these planes were covered in hot lava that spilled out from the moon's interior and flooded over an older landscape because they are richer in iron than other parts of the moon they appear darker in contrast [Music] one of the big achievements of lunar exploration has been the complete mapping of both sides of the moon's surface the moon rotates in perfect time with its orbital period with one side constantly facing earth surprisingly the two sides of the moon turn out to be quite different from one another while the side that faces earth is covered with maria the moon's far side exhibits much less contrast it's an ancient rugged terrain interrupted only by a few larger impact sites this peculiar two-sidedness has to do with the moon's crust which is substantially thicker on the far side scientists now suspect that billions of years ago when the moon's internal heat forced lava upward it found a shorter route to the surface on the moon's near side but how and when did those circular planes form in the first place the surprising answer comes from the lunar samples that were brought back by apollo astronauts the samples show the lunar maria were once the sites of enormous impacts many of which date back roughly 3.9 billion years this is very early in the solar system's history when space was more crowded with debris than it is today nevertheless the evidence now suggests something exceptional happened 3.9 billion years ago as though a storm of asteroids suddenly swept through the inner solar system pummeling all of the planets as well as our own moon [Music] the devastating barrage left the moon plastered with giant circular scars on earth it was much worse the impacts would have vaporized oceans and liquefied large sections of our planet's crust though no animal or plant was living on earth at the time it is possible microbial life had already made its debut when the bombardment came perhaps only those microbes that were dwelling far down near deep sea vans survived to repopulate the ancient earth and become our distant ancestors the idea that the moon and earth were both heavily bombarded is one of the big results to come out of the samples that astronauts returned to earth an even bigger one is the astonishing revelation that the moon itself may have once been the product of a giant collision this theory is that early in our solar system's history an object as large as mars once collided with earth and dealt our planet a staggering blow the collision immediately spewed out vast amounts of debris much of this material found itself in orbit around earth where it eventually coalesced to form a single large moon as incredible as it seems this giant impact scenario offers the best explanation for some of the moon's more puzzling features including its apparent lack of an iron core ironically the moon's destructive birth may have also been crucial to maintaining earth as a cradle of life unique in our solar system the moon's presence helps to stabilize the tilt of earth's axis preventing climate swings that would be devastating to life and civilization because of the way it formed the moon's past is intimately linked with our own without it the evolution of life may have taken a very different course in fact if it weren't for the moon we might not even be here at all [Music] [Music] one exploring the moon has given us a remarkable window into the past but the moon may also be our gateway to a long-term future in space in the us china and elsewhere efforts are now underway to return humans to the lunar surface it is an ambitious goal but it's also a stepping stone along the road to more distant destinations exactly where the next human mission will land is still an open question but one thing is certain there is no shortage of interesting places on the moon where scientists would love to visit [Music] the lunar south pole would surely be at the top of their wish list here the sun never shines on the floors of some craters forever in shadow these dark craters should be cold enough to trap water vapor and maybe even form lunar ice although the moon is dry the water vapor could come from comets colliding with its surface scientists have now confirmed the presence of hydrogen in many south polar craters strong evidence for the presence of ice if there is enough ice it could provide lunar explorers with much needed water but finding and retrieving the ice will be a challenging task as it would involve venturing into perpetually dark places today the moon presents us with an intriguing and exciting destination in space and a staging ground for even more daring explorations on mars and beyond perhaps more than any other location in the solar system it is the moon that tells us we live on just one world among many and if we are determined enough we can one day visit them all [Music] [Music] for generations our world has challenged explorers to seek what lies beyond the horizon now the invention of space flight is leading us outward to explore a host of alien worlds with vast new territories today we see the sun moon and planets with penetrating clarity through the eyes of the intrepid machines blazing a trail for us across the solar system their cameras have become our windows onto a bold new adventure their discoveries have become our cosmic vistas [Music] [Music] uh when everything is exotic and strange the familiar beckons and when it comes to exploring the solar system the familiar calls us to mars [Music] although it is clearly an alien world mars is also a planet with landforms we immediately recognize it is a world with deserts and dunes cliffs and canyons a landscape we can imagine ourselves exploring first hand on two feet or on six wheels but familiarity doesn't make mars any easier to understand after scrutinizing its landforms from orbit and sampling its soil and rocks from the surface we have become better acquainted with mars than any other planet in the solar system apart from our own but our questions about its present state and complex history have only multiplied including the biggest question of all did life ever exist here mars is not like earth where life is abundant and obvious it's also not like the moon where there's really no chance for life at all mars is somewhere in between and so it can help us define where life can and cannot exist when we journey to mars we journey to the borderland mars borderland status is nothing new astronomers have been musing about the potential for life on the red planet for more than a century [Music] when the first grainy close-ups of mars were radioed back in 1965 scientists were surprised and a little disappointed the images showed a barren and cratered surface much more like the moon than any place on earth apparently the red planet was the dead planet and any notion of spotting life on the surface even primitive life all but vaporized but first impressions can be deceiving as follow-up missions arrived in the late 60s and 70s with increasingly better cameras it became clear mars is a far more interesting and diverse planet than anyone had realized yes there were impact craters but there were also signs of a colossal geologic history giant volcanoes larger than any on earth were found towering over the martian plains the largest of all olympus mons rises to a height of 24 kilometers from its base three times higher than mount everest making this not just the tallest peak on mars but the tallest in the solar system such an impressive structure must have arisen through widespread eruptions of lava that poured out across the surface again and again possibly over billions of years olympus mons sits atop a giant bulge known as tharsis that protrudes from mars and makes it a distinctly lopsided planet ultimately it led to a spectacular splitting of the planet's crust and the creation of this giant canyon valles marineris the proportions of valles marineris stagger the imagination it is more than ten times longer than earth's grand canyon and four times as deep today the best images of mars come from the mars reconnaissance orbiter an orbiting spacecraft that carries the most powerful telescope ever sent to another world [Music] [Music] capable of resolving details on the surface as small as a dinner plate it has given us an unprecedented look at mars in all its splendor from exquisite sand dunes to tracks left behind by martian dust devils but perhaps the most interesting views are the ones that suggest water once float on mars deep inside valles marineris it appears as if there were layers of sediment deposited in shallow martian lakes long before the giant canyon formed [Music] even the shape and orientation of the terrain suggests water once float on mars these hints of a watery past grow much stronger as we cast our view beyond valles marineris to a series of large but empty channels leading away from the tharsis bulge toward the low-lying regions further north although they dried up long ago these valleys must have been created by vast outflows of moving water that cut across the martian landscape spilling out into the northern plains in some cases these channels measure 100 kilometers across and carve their way through thousands of kilometers of terrain their discovery drastically changed scientists view of mars today mars is far too cold and its atmosphere far too thin for a liquid water to persist on the surface yet these channels which bear all the marks of catastrophic flooding suggest that mars once had water in abundance if so what caused the release of this water and where did it go the answer to the first question probably lies with the tharsis bulge it now seems likely the intense heat that led to the formation of mars's giant volcanoes also forced the release of vast quantities of water stored in the martian crust at first the water flowed underground but then it broke out onto the surface creating the features visible today across mars there are other signs that water may have flowed billions of years ago strong evidence from orbiting spacecraft now suggest much of this water lies frozen underground in the form of permafrost near the martian poles certainly the marsh and polar regions are different from the rest of the planet [Music] not only do both the north and south poles of mars have visible caps of frozen carbon dioxide that grow and shrink with the changing seasons both possess a smaller underlying cap of water ice that is never warm enough to melt away the surface at the poles also looks different a substantial quantity of ice mixed in with the rock in these locations means cliffs and crater walls tend to slump giving them a smooth rounded look [Music] one of the most exciting recent developments has been the discovery of small gullies running down the sides of craters and canyons all across mars they look suspiciously as though they were carved by groundwater seeping from the cliff faces and running downhill yet these features are so small they must be recent otherwise the steady deposit of wind-blown dust would have obscured them could there really be liquid water periodically bubbling to the surface on mars if so the implications for a life are enormous after more than four decades of concentrated exploration there's no doubt that mars has a rich history which certainly included liquid water and may have once included life furthermore there are hints that mars continues to be an active planet today it is not yet a dead world at least in the geologic sense it is still a borderland [Music] all of this is impetus to explore mars further but there are limits to what can be seen and sensed from space to answer the question of whether mars is a living world we must touch taste and smell it these goals can only be achieved by taking our explorations down to the very surface of mars [Music] five four three two one like the great voyages of discovery centuries ago the journey to another world is fraught with danger atmospheric entry on my mark and when it comes to landing on mars five four three two one mark it is always the final moments phoenix now two minutes and 25 seconds past the entry point when the peril is great 80 meters 50 meters come on lock face detected i'll just 40 meters 30 meters 27 meters 20 meters 50 meters standing back for touchdown touchdown signal detected [Applause] initiated it is hard enough to design a machine that can land itself on earth but to do it on another planet where humans have never set foot where knowledge of changing conditions is scarce at best to have no margin for error between a safe landing and total catastrophe and to do it in a place that is so distant even a simple call for help would take several minutes to reach earth that is a challenge indeed but that is precisely what must be done to touch another world so far six landers have sat down safely on martian soil and they have transformed our understanding of the planet as only first-hand experience can scientifically these missions were designed to discover the geologic history of mars but they also carry a powerful implication about the future it's not just the ancient past we seek when we land our probes on mars but a new dawn in space exploration a red dawn in 1976 two nasa spacecraft named viking one and two became the first to establish a beachhead on mars and the view was electrifying geologists were immediately reminded of deserts they had visited on earth once the viking landers set to work the similarities began to fade while the results did not completely rule out life on mars they suggested that any life that managed to survive here would need to be sheltered underground or in some other impossible to reach location it would be more than 20 years before another successful attempt was made to land on mars in 1997 nasa's mars pathfinder landed at the mouth of the ars valley a vast channel that looks like it was carved by running water the landing site was surrounded by broken and tumbled rock boulders were slanted in a downstream direction all signs of an ancient and violent flood the star attraction of the mission was a small rover that rolled off the lander and trundled up to nearby rocks to analyze their compositions it was a vivid demonstration of what was needed to really begin tackling the mystery of mars a set of wheels [Applause] in early 2004 two rovers named spirit and opportunity landed safely on opposite sides of mars [Music] each embarked on its own motorized track across the red planet's surface [Music] from the start it was obvious that the two rovers had landed in very different settings spirit had been sent to gusev crater evidence from orbit suggested it was an ancient lake where standing water may have left its mark in the soil chemistry [Music] but when spirit opened its electronic eyes it found a barren plane littered with volcanic rock [Music] meanwhile opportunity scored an early triumph it was sent to meridiani planum where remote sensing had spotted hematite an iron-rich mineral that on earth is often associated with water meridiani turned out to be a flat nearly featureless plane but miraculously opportunity landed in a small crater with an exposed rock outcrop for the first time scientists would be able to sample rock on mars in the place where it formed what opportunity found after wheeling up to the outcrop exceeded everyone's wildest expectations the rock was layered and contained ample evidence that it formed in a watery environment it also contained hematite in the form of tiny spheres nicknamed blueberries which grew by precipitating out of water and were later exposed as the rock weathered away but the best was yet to come [Music] back on gusev crater after investigating the terrain near the landing site scientists sent spirit rolling towards a set of distant hills nearly four kilometers away it would take three months to reach the hills and many more to climb them but eventually spirit reached the top and radioed back a sweeping panorama in the years that followed spirit descended to the other side of the hills surviving three martian winters and eventually discovering home plate the remains of a volcanic vent where hot rock once made explosive contact with water things were also going well at meridiani once opportunity set out across the plains it discovered an even larger rock outcrop whose layers read like a geologic history book the story it told was of a place that once had been wet but with highly acidic water while at other times there was no water there at all after nearly two years more of roving opportunity arrived at the edge of victoria crater and recorded one of the most spectacular vistas in the history of mars exploration [Music] high overhead the newly arrived mars reconnaissance orbiter was there to record the moment from space spying the tiny rover perched at the crater's rim [Applause] [Music] the journey of the mars rovers has been a scientific adventure unlike any so far in our exploration of the red planet [Music] rather than showing us mars in an isolated spot for a brief window of time they have shown us mars over many years and many kilometers including places where water once flowed [Music] next scientists wanted to know about the state of water on mars today compared to the mars rovers the phoenix lander was a modest mission but with an ambitious goal to become the first spacecraft to touch water on mars scientists expected to find that water locked in a frozen state just below the surface of mars polar regions here the landscape is dominated by low mounds with trough-like boundaries these mounds are caused by the expansion of ground ice forcing the soil upward after a bit of digging with its robot arm phoenix exposed something white just centimeters below the surface [Applause] it was ice the first direct link to a watery past on mars phoenix landed in the low-lying northern plains of mars an area that may once have been a martian ocean although phoenix could not confirm this it found the soil here is alkaline similar to what might be found in seawater on earth what we've learned from all these missions is that mars was a water world and still is today although that water is hidden from view as for what that means for life on mars that's a question for future missions but in a sense all of these missions are already paving the way for life on mars human life the landers and rovers we build could be the leading edge of a new wave of exploration that might one day take astronauts to the red planet if so the human story on mars has already dawned [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] children [Music] [Music] [Music] [Music] so [Music] in the outer reaches of the solar system it was always cold enough for gas molecules to stick together and form ice billions of years ago that ice gathered into bigger and bigger chunks until gravity took over pulling in vast quantities of material and setting the stage for planet-making on a giant scale [Music] [Music] so [Music] [Music] [Music] [Music] [Music] [Music] so [Music] [Music] [Music] [Music] [Music] [Music] so [Music] my [Music] cassini has revealed saturn so beautifully that it is now one of the best imaged planets in our solar system despite its great distance from earth yet with each new image saturn continues to surprise and amaze us [Music] [Music] [Music] [Music] [Music] [Music] once the telescope was invented we discovered there was a lot more to our solar system than meets the eye there's uranus neptune and the weird case of a planet that's not really a planet pluto but even through the most powerful telescopes these worlds remained remote and mysterious to probe the solar system's real outer limits you need a spacecraft [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] my [Music] so so when new horizons finally shows us pluto it will mark the end of an era pluto is no longer officially called a planet but it represents the last type of solar system object that we have yet to see up close [Music] thank you [Music] [Music] [Music] for generations our world has challenged explorers to seek what lies beyond the horizon now the invention of space flight is leading us outward to explore a host of alien worlds with vast new territories today we see the sun moon and planets with penetrating clarity through the eyes of the intrepid machines blazing a trail for us across the solar system their cameras have become our windows onto a bold new adventure their discoveries have become our cosmic vistas [Music] [Music] there are more than 100 moons in our solar system the vast majority of them orbit the two largest planets jupiter and saturn collectively they run the gamut from small to large cold to hot and quiet too active could it be that somewhere in that range of possibilities we will find a hidden haven for alien life [Music] most of the moons that orbit jupiter and saturn are quite small but a few are so large and complex they could easily be considered planets for more than 300 years there was almost nothing astronomers could say about these intriguing places thanks to space flight that's no longer the case in 1979 voyager 1 and voyager 2 sailed past jupiter's four largest moons with their cameras rolling the pictures they radioed back reveal that each moon has its own distinct character and a range of features unlike anything seen before the biggest surprise of all was io the innermost of the four moons its rocky surface is a mottled and sulfurous mess unlike our moon there are no craters on io it's as though they are being erased by some mysterious agent the explanation came when voyager 1 spied something unusual protruding 300 kilometers from one side of io it was a fountain of ash spewing from a large volcano since that discovery it's now become clear io is the most geologically active world in the solar system io's surface is one vast lava flow with more than a dozen active volcanoes towering over the sulfur-rich landscape the gravitational pull of jupiter and some of its other large moons creates a tug of war inside io which generates vast amounts of heat [Music] while this makes for a dynamic surface it is not particularly hospitable to life jupiter's outermost large moon callisto couldn't be more different callisto's battered face is saturated with ancient impact craters suggesting not much has happened here since callisto formed but looks can be deceiving the most recent data suggest there could be a zone of salty water somewhere deep below callisto's surface of ice and rock whether life could survive in such a hidden environment remains an open question meanwhile on ganymede we find more obvious signs of a geologically active past ganymede is the largest moon in our solar system and one of the strangest looking part of its surface is as old as callisto's dark and heavily cratered but the dark areas are fractured by a more recent terrain made up of parallel grooves and ridges exactly how these grooves and ridges formed is still a big mystery it is clear ganymede has a warmer interior than callisto in the past that warmth may have risen up through ganymede's interior and forced sections of its surface to drift apart just like the continents on earth because of its heat ganymede's interior has likely separated into layers starting with an iron-rich core at the center a surrounding mantle of rock and a thick layer of ice on top of that as with callisto there is evidence on ganymede for an ocean of salt water somewhere below the surface this is exciting news because the right combination of heat and water may provide the conditions necessary for life on ganymede such life forms would be cut off from the sun and the surface environment but like the creatures that live around deep sea vents in earth's oceans it might survive on chemical energy this tantalizing possibility won't be tested anytime soon if ganymede has an ocean it's at least 200 kilometers below its frozen surface a better opportunity for exploring the ocean of another world may exist on europa at first glance europa seems like the least interesting of jupiter's moons because its surface is so flat and smooth its lack of dramatic relief like mountains or large craters might be an indication that water isn't far below europa is crisscrossed with a network of cracks that suggest its icy crust has opened up from time to time letting a watery slush spill out onto the surface [Music] in one area scientists have found what appeared to be icebergs that cracked and floated apart like rafts before the surface re-froze some of the cracks on europa have a darker and more reddish hue than the rest of the surface ice this could mean that the underlying ocean is rich in sulfur compounds and perhaps organic molecules indications are that in some places this ocean may be less than 10 kilometers from the surface possibly within reach of a future attempt to drill down and explore the marine environment of another world today europa's ocean is high on the list of locations where scientists are eager to search for alien life the surfaces of jupiter's moons may conceal many mysteries but on saturn's giant moon titan even the surface is hidden from view titan is the only moon in our solar system with a substantial atmosphere and it shows when voyager 1 arrived at saturn in 1980 it found titan shrouded by a thick orange haze this haze is like a photochemical smog produced when sunlight reacts with methane in titan's atmosphere it would be a full generation before scientists had their next chance at titan when the cassini mission arrived at saturn in 2004 it used a high-powered camera equipped with an infrared filter to penetrate the veil of titan's thick haze what cassini found was even stranger than expected a surface divided into mysterious light and dark regions resembling ancient coastlines cassini also bounced radar signals off of titan confirming that the moon's surface is solid with unusual landforms like ice volcanoes and wind blown dunes after several more passes of titan cassini's radar made an even more exciting discovery a series of dark patches that were perfectly flat resembling the surfaces of small lakes scientists were eager for more direct evidence of potential fluid flow on titan they found it in dramatic fashion when cassini dropped a probe into titan's cloudy atmosphere after the probe deployed its parachute and slowly descended it radioed pictures back to cassini [Music] as soon as the probe emerged from the clouds it began to see exciting details that looked suspiciously like they had been carved by a flowing liquid [Music] then to everyone's surprise the probe survived its impact and sent back one final spectacular image [Music] it showed chunks of ice clearly rounded by fluid flow like rocks in a stream bed on earth on titan it's so cold that water is like rock but methane which is a gas here on earth can rain down from titan's atmosphere and flow as a liquid over the surface methane is a building block for the kinds of complex molecules that led to the emergence of life on earth and that means if titan has an internal heat source like some of jupiter's moons it could also be harboring its own ecosystem deep below the surface [Music] one thing is clear titan and jupiter's moons are no longer sideshows to the planets they orbit together they have become the main motivators in our exploration of the outer solar system [Music] [Music] [Applause] [Music] [Music] here on planet earth it's easy to take water for granted water covers 70 percent of earth's surface and its presence is essential for life as we know it [Music] farther away in the dim reaches of the outer solar system water plays a different role around saturn water is everywhere with temperatures near minus 180 degrees celsius it's far too cold for water to exist in a liquid state here water remains frozen solid so solid that it doesn't just cover worlds it makes worlds when we get to saturn we discover ice is the main ingredient in building moons in fact saturn is surrounded by an entire family of icy moons that the cassini mission has now revealed in spectacular detail by exploring these frozen worlds scientists hope to reveal an ancient story not just about saturn but about the entire outer solar system this is certainly the case with phoebe the first of saturn's moons that cassini encountered up close just 200 kilometers across phoebe is too small and it's gravity too weak to pull itself into a sphere when cassini sailed past phoebe it found a surface rich in carbon with deep craters exposing layers of bright white ice lying just below overall phoebe is darker and contains more rock than saturn's other icy moons this suggests it did not form near saturn but in the kuiper belt beyond neptune the objects inhabiting this zone are ancient the original building blocks of the outer solar system it now appears phoebe is an escapee from that region and only later captured by saturn and turned into a moon this moon is giving us a sneak preview of what we'll find at much further distances from the sun four times closer to saturn and four times larger than phoebe e apotus is a very different kind of moon it is 80 percent ice but its most distinctive feature is its strange two-tone shading while one side of the apotus is extremely dark the other is whitish gray this color difference also corresponds to a significant temperature difference on average the dark side is 15 degrees warmer than the light side [Music] scientists now suspect that dark material possibly blasted from the surface of phoebe may have fallen down onto a apotus long ago the side that received the dust absorbed more of the sun's energy and the ice there began to sublimate leaving behind grains of dust and rock that would darken the surface even further meanwhile the vaporized ice resettled on to the other side of the apetus and around its poles creating the look it has today even stranger is a long ridge cassini discovered running along the equator of iapetus giving it the appearance of a walnut in places the ridge is 13 kilometers high the forces that created this bizarre feature are not well understood but it likely happened when iapetus was spinning more rapidly than it is now and had more internal heat shaping its surface moving even closer towards saturn we find hyperion a misshapen object with a strange honeycombed surface hyperion is so irregular in shape and appearance it is probably just a fragment from a larger moon that was destroyed in a collision it may not even be solid but a loosely packed pile of rubble measurements by cassini reveal hyperion is more than 40 percent empty space signs of ancient collisions are visible everywhere on saturn's moons including ria deoni and tethys at first glance this trio of round moons could be mistaken for identical triplets each one is more than one thousand kilometers across and carpeted with impact craters from billions of years ago [Music] but they are also variations on a theme each of the three has its own distinct features suggesting a more complex and diverse history for example this giant canyon called ithaca chasma wraps around tethys like a waistband it may have formed long ago when the icy interior of tethys froze and expanded forcing its crust to stretch apart at the seams looking at dione from afar scientists long wondered about a series of wispy white lines running across its surface [Applause] now cassini has revealed the lines are the bright faces of steep cliffs formed when dione was repeatedly fractured by internal forces [Music] but the biggest surprise came from rhea cassini found indirect evidence this moon is surrounded by a dark dusty ring making rhea the only moon anywhere in the solar system with a ring of its own while most of saturn's icy moons were likely once geologically active worlds which later cooled and grew dormant at least one seems to have forgotten to fall asleep and the implications are enormous enceladus is only 500 kilometers across under ordinary circumstances an object of this size should be too small to retain heat for billions of years but enceladus is nowhere near ordinary here cassini spotted vast geysers of water vapor shooting outward from a region near its south pole the vapor carries fine grains of dust which escape into space and form a diffuse ring along enceladus orbital path around saturn looking down at the surface for clues cassini has revealed a strange and puzzling sight enceladus is scored with long deep gouges nicknamed tiger stripes from which the geysers are thought to emanate the stripes are surrounded by fresh ice which suggests that somewhere below the surface temperatures are high enough to melt ice and hold liquid water under pressure before venting it into space like a tea kettle no one yet knows exactly how enceladus does this one important clue from cassini is that enceladus has more rock and metal than many other of saturn's moons and so perhaps it is being warmed by a combination of radioactive heating from within and strong tides produced by saturn and its other moons even more exciting is the presence of organic molecules near the tiger stripes when this is combined with the likelihood of liquid water it appears enceladus may have all the ingredients necessary for life for a tiny moon at the leading edge of the icy solar system this is an astonishing revelation to call the icy moons of saturn strange is an understatement these odd little worlds are utterly unlike earth but understanding how they formed and evolved is an important goal for scientists why because if there are so many icy moons in our solar system there must be countless others out there among the stars [Music] whenever one of those moons is warmed up enough to melt the ice into water there exists at least the potential for life and perhaps our best chance to answer the age-old question are we alone [Music] [Music] [Music] [Music] um [Music] foreign [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] [Music] so [Music] for centuries astronomers thought of the solar system as an orderly place where the planets including earth quietly went about their business today we realize the solar system is really more of a cosmic shooting gallery full of asteroids and comets that could threaten life on earth that's why exploring these objects is not just a quest for science but a question of survival [Music] [Music] so four three two one [Music] [Music] [Music] [Applause] [Applause] [Music] [Music] [Music] [Music] [Music] [Music] quite a trail [Music] near spec has a great view dave on the ground [Music] so [Music] [Music] so [Music] there is an irony in these results our interest in comets and asteroids is motivated partly by the danger they pose to life on earth but it's quite possible that without comets and asteroids and the organic materials they bring life might not have even started here in the first place [Music] [Music] [Music] [Music] once astronomers realized the sun is just one star among billions and the earth just one planet it was natural to assume other worlds existed beyond our solar system but finding those worlds is a technical challenge of the highest order and it has taken nearly four centuries since the invention of the telescope to do it [Music] [Music] [Music] [Music] [Music] [Music] so [Music] [Music] [Music] [Music] [Music] rocket with kepler on a search for planetside [Music] [Music] [Music] [Music] [Music] the last 15 years have seen a revolution in our ability to find and study planets beyond our solar system the next 15 could be even more exciting as kepler and its successors try to zero in on planets like earth and then hunt for signs of life on those worlds children

Channel: Spark

Views: 8,290,073

Keywords: Spark, Science, Technology, Engineering, Learning, How To, education, documentary, factual, mind blown, construction, building, full documentary, space documentary, bbc documentary, Science documentary

Id: 8vkqH3r1-f4

Length: 155min 25sec (9325 seconds)

Published: Sun Dec 19 2021