The Universe: Massive Asteroid Attack Threatens Earth (S5, E6) | Full Episode | History

in the beginning there was darkness and then back  giving birth to an endless expanding existence of   time space and matter every day new discoveries  are unlocking the mysterious the mind-blowing   the deadly secrets of a place we call the  universe they've already wiped out the dinosaurs   and many other species and there's no  doubt they will strike again it would   be a disaster far beyond biblical proportions  investigating asteroids isn't just about science   asteroids are going to be one of our biggest  problems for humanity it's about survival so the smarter we can get before  then the more we can figure out   can we do anything about it get ready for the  latest asteroid and daring discoveries plans   to go where no man has gone before it's the year 2029 and an asteroid that  scientists have been tracking for decades   is passing close to earth the asteroid  is about three football fields wide   its name is apophis after the  ancient egyptian god of destruction according to the latest predictions  apophis won't hit earth in 2029   but as it passes through a seemingly nondescript  area of space nearby the world scientific   community goes on high alert astronomers have  calculated a very small region of space which if   apophis happens to go through that region then it  will be set up for a collision with earth in 2036   in this very very tiny region which is less than  a mile across just a few thousand feet across   is called the keyhole an international  cooperative of space agencies   launches a rocket to take on apophis now you  don't want to blow it up with a nuclear weapon   first that would take a lot of energy  and it would just produce a huge number   of fragments all heading toward the earth what  you really want to do is give it a bit of a push   that slightly changes its trajectory  that way we don't get a collision but it's possible that the 30 million  ton space rock could simply be too   massive the collision hasn't knocked  the asteroid far enough off course the impact in 2036 is thousands of times stronger  than the atomic bomb dropped on hiroshima   the immediate crater is as wide as the island of  manhattan it would create a crater over two miles wide if apophis were to hit a city goodbye to that city and the  surrounding region for 100 miles   from the shock wave the blast the winds coming  out from the impact ejecta and from the massive   earthquake equivalent that would occur that  would reach out and be felt over huge areas when apophis was first discovered in 2004 the  initial odds of an impact were about 1 in 37.   but those odds have been dropping over the years   as scientists have obtained a better look  at its path you can make the analogy that   the orbit determination process is  similar to predicting hurricanes when a hurricane first starts out you  don't know exactly where it's going to go   and as you get more and more data in the next  week or two you can refine your predictions and   so it's very much like that with asteroids  and comets the more observations you get   over time the better you know where the object  will be in the future that's why today's odds of   an earth impact only 1 in 250 000 are so much  slimmer than the original 1 in 37 prediction but even if apophis doesn't hit earth there's  no doubt that something else eventually will   it's a disaster that space  agencies take very seriously   in july 2010 a nasa advisory panel recommended  the creation of a planetary defense office   to figure out how to detect and  deflect any asteroids heading our way we know for a fact that an asteroid is going  to impact the earth sometime in the next one   to 10 000 years a big one and it's a good  question as to when it's going to happen   and are we going to be ready for it when  it does a seaside amusement park is an   unlikely place to demonstrate how asteroids and  comets speed around our corner of the universe   but an arcade attraction here actually  reveals a lot about these deadly objects our solar system is kind  of like a shooting gallery   asteroids and comets can occasionally hit  planets and moons creating gigantic impact   craters now the bigger objects present a larger  cross-sectional area so they're easier to hit   in this case i actually have to hit these little  bull's eyes which are all about the same size but   imagine that the man over there is jupiter he's  big and the chipmunk might be the earth smaller   and these ants might be our moon even smaller so  jupiter is pretty easy to hit earth the chipmunk   is harder to hit it's a smaller cross-sectional  area ah there it goes earth was hit the ants   are small so they're even harder to hit most of  the asteroids miss only occasionally do they hit but unlike the shooting gallery where the  bullets or in this case flashes of light   always travel in straight lines asteroids and comets curve toward their targets  jupiter tends to draw in the asteroids and   comets through its gravity so it's kind of  like if i start with my aim way over there   jupiter pulls the barrel of the rifle  toward it giving me a direct hit since earth is much less massive than jupiter its  lower gravity doesn't draw in as many asteroids   and the moon with only a  fraction of earth's gravity   attracts even fewer but as the  moon's crater pot surface illustrates   infrequent asteroid impacts over a long period  of time still means plenty of destruction jupiter's ability to pull in comets and  asteroids has been on display a lot recently   in 1994 the shoemaker levy nine comet  fragments pounded jupiter scientists   thought this kind of large impact was a rare event  something to be seen once every few hundred years but then another comet or asteroid hit in july  2009 it created a large dark spot and a fireball   as large as the earth seeing two different sets  of impactors hitting jupiter only 15 years apart   gives some indication that the solar system  might even be busier than we thought then   in june 2010 a third object hit jupiter with an  amateur astronomer capturing the moment of impact   would this force scientists to change  their estimates and acknowledge the   jupiter is hit by large objects much  more often than every few hundred years   i think that there's not necessarily  many more than we thought before that's   because the object that hit in 2009 was  smaller than comet shoemaker levy 9.   and there are many many more small objects  flying around there than there are large objects but information about any  type of impact large or small   is always helpful to understand the impact  hazard on earth we need to understand   the asteroid population their orbits so every  piece of information even if it's understanding   how often they hit jupiter or out in the jupiter  region contributes to our understanding of the   overall population of objects in the solar system  and how concerned we need to be about earth impact the major source of that population is the  main asteroid belt between mars and jupiter   that's where the strong gravitational pull  of jupiter has kept millions of smaller rocks   from becoming another planet but that's not the  whole story so we think of asteroids as those   things that just live in the belt between mars  and jupiter because that's historically where   most of them were found at first but in fact  there are asteroids that travel way out past   jupiter there are asteroids that come close  to the sun asteroids that come close to earth the largest asteroid is 600 mile wide ceres  which would stretch from washington dc to chicago   it's so large that it makes up about a  third of the total mass in the asteroid belt   an impact from something like that would be  very bad news for every living creature on earth   it's about a hundred times bigger than the  impactor that caused the chick's loop impact which resulted in the extinction of  70 of species on earth and dinosaurs   so right off the bat it seems like a bad  thing but it's a really really bad thing   it would be a disaster far beyond biblical  proportions it would create a crater nearly   as big as the united states but while it  was doing that it would spew out molten   material around the globe create supersonic  winds around the globe it would be ugly luckily ceres is in a stable orbit around the sun  and large asteroids are easy to spot and track   we probably have decades of warning  if an asteroid larger than a mile wide   had a chance of hitting earth but the  smaller ones present a tougher challenge   as the latest information shows there's  far more small ones than large ones so   if you say the objects that are one kilometer  or two thirds of a mile in diameter or larger   we think there's about 940 of those and  we've discovered 86 percent of the population   if you move to smaller objects say 100 meters and  larger we think there's about 50 000 of those and   we discovered 10 percent if you move to smaller  still objects 30 meter and larger sized objects we   think there's about two million of those objects  and we've discovered much less than one percent better telescopes coming  online over the next decade   will allow astronomers to identify  many more asteroids of all sizes but a 30 meter or 100 foot wide asteroid on  a collision course with earth might not be   discovered until just before it hits something  that size could still pack a devastating punch the earth is covered with evidence  of past collisions with asteroids   and today's scientists are working  feverishly to figure out what's coming next they know that enormous space rocks have  wiped out most life on the planet in the past the good news is that they don't hit very often  it's measured in many millions or tens millions   of years and they're big enough that through our  observations we know where those objects are so   we'd have long long lead time and warning it's  actually the smaller ones that are the bigger risk   because they happen more often  and they're harder to find   imagine that one of these smaller  asteroids is streaking toward a city   it may not be spotted until just a few hours  before impact leaving little time for evacuation   and no chance to try and deflect it in space  if it's about a hundred feet wide on impact   then it will hit with the energy of a five  megaton nuclear blast 400 times more powerful   than the atomic bomb dropped on hiroshima when  it hits the earth it can cause a lot of damage   because the crater that's produced is typically  10 or 20 times the width of the incoming object   so that would be a thousand or a few thousand  feet and many miles surrounding the impact region   are affected by all the debris that gets ejected  you'd have all this stuff raining down upon you   but even if the asteroid hit  hundreds of miles from the city it could still create chaos for the millions of  people living there the food supply for the city   residents could be drastically altered if the  asteroid hit a major agricultural area nearby not only would all of the humans  there be fearing likely dead   but it would sear hundreds of square miles  of the growing lands it would destroy all   the current crops and it would render the  area pretty unusable for quite a period of time smaller asteroids don't even need to impact  the ground to cause widespread destruction   in 1908 an air burst from an asteroid that  broke apart in the atmosphere leveled an   estimated 80 million trees over hundreds of  square miles near the tunguska river in siberia when an asteroid or a comet is coming toward  the earth it first encounters the atmosphere   and it squeezes it it compresses it and that  pressure causes the asteroid or comet to explode   that explosion then spreads the energy over  a vast region of the ground below it so   these atmospheric air bursts  are very dangerous as well but the rock that caused all of that destruction  may have been even smaller than first thought   when it hit the atmosphere the tunguska object  may have been only a few dozens of yards across   instead of hundreds of yards  as originally estimated at first it may seem like a good thing tunguska  smaller than we thought but it's actually a   bad thing for our future predictions because  there are more smaller objects than larger ones   so if a small object can cause that much damage  then that means it's going to happen more often   than if it were a big object we may have  that impact here every few hundred years   instead of every few thousand years at the really  small end of the scale below about 100 feet   space rocks are often known as meteoroids  instead of asteroids shooting stars are   caused by meteoroids burning up in the atmosphere  they're sometimes captured by amateur cameras   with some small chunks hitting the ground or  even cars or buildings in fact the earth's   atmosphere is pelted with objects from outer  space far more often than most people realize i'm here at this active rock quarry next to  this big pile of crushed rock because this is   about the amount of stuff the amount of dust and  sand and pebbles that hit the earth's atmosphere   every day about a hundred tons that's  enough to fill about six or seven   of these dump trucks now down here we've got  a basketball sized rock on average about two   of these slam into the earth's atmosphere every  single day next is the small car sized object imagine this pile of rocks as one object  slamming into the earth's atmosphere about   the size of a small car this happens  about once every two weeks but even   something this big is probably going to burn up  completely before reaching the earth's surface for a typical object hitting the earth's  atmosphere needs to be at least 100 feet   in diameter to actually do serious damage to the  surface now 100 feet is a really big rock that's   like going from the front of the dump truck over  there all the way to that orange cone over there   at the other end of the spectrum is  earth's largest confirmed impact crater   located in vrida fort south africa it  stretches more than 180 miles across   and drastically changed the ancient earth  when it hit about two billion years ago it would have sent a sheet of material  into space which would then have come   back and impacted on the earth ignited  fires if there was anything to burn   and the climactic effects from that  impact would have lasted for decades   the oceans would have been completely acidified  there would have been tons and tons of soot up   in the atmosphere and so that is something  that we really would not want to see happen for the primitive life on earth at the  time it was a major extinction event   with a crater more than one and a half times  larger than the one that wiped out the dinosaurs the south african crater wasn't discovered  until the 1990s since most of its features   had eroded in the last two billion years  but photos from space revealed its existence a hilly region in the center of the deep crater  initially had scientists thinking that there   had been volcanic activity in the area but it's  actually what's known as a central rebound peak   a distinctive feature for craters  about 100 miles wide or larger as you get to larger sizes  the energy of the impactor   is so high that when it comes in the rock  essentially acts like it has no strength   then what you get is something very much like  when you drop a pebble in water and you see   that rebound peak as the water fills in comes  back up but since it is rock it then solidifies   we see lots of these central peaks on the  moon and elsewhere in the solar system but there are other large asteroids  that have hit much more recently   even more recently than the dinosaur  killing asteroid from 65 million years ago 30 million years later another massive  asteroid pummeled the east coast of america   and helped form what is now chesapeake bay   we see evidence of debris from that impact  all the way up and down the eastern seaboard   all the way up to new jersey new york  and comparable on the south end of it the 55 mile wide crater was hidden from view  underwater until oil exploration confirmed its   existence in the 1990s and since the asteroid  hit just offshore it created a massive tsunami   some say that the waves could have  been 10 20 maybe even 30 miles high   that's a big wave the appalachian mountains are  only a few thousand feet high so even though   a lot of the wave was diminished as it went  inland that's a lot of water and it could well   have flooded over the appalachians and into  what we now think was the ohio river valley and if that same impact happened today the  east coast would never be the same again an asteroid attack has the power to  instantly kill millions of people the largest impacts can also  cause global catastrophes   threatening the very existence of mankind that's why the study of asteroids is  one of science's highest priorities 35 million years ago an enormous asteroid  slammed into america's east coast the 55 mile wide crater was hidden until recently   under chesapeake bay its effects were devastating  but what if that same impact happened today it would wipe out the east coast essentially  through a combination of tsunamis   blast waves thermal effects and it would  also throw out huge amounts of ejecting   that would spread to great distances  igniting additional forest fires   it would be millions of people instantaneously  killed or shortly after the impact but   it would have farther reaching consequences too  because of the overriding disruption throughout   the entire region farming communication certainly  our center of our government is on the east coast but according to recently uncovered fossil records   the one-mile wide chesapeake bay asteroid  didn't seem to have the same global effects   as the massive extinctions triggered by the  six mile asteroid that killed the dinosaurs the impact that created the  chesapeake bay structure   more than 30 million years ago was enormous  but it was still only a small fraction   of the energy that was released during the  impact in the yucatan 65 million years ago the impact was right on the threshold  of providing truly global effects right on the threshold of what's  required to make a mass extinction occur because of that destructive power it's crucial  to know exactly what we're dealing with   and that means getting up close and personal in 2001 the nasa mission named nir was  supposed to just orbit the asteroid eros   but once it got there and it  completed its mission objectives   the decision was made let's try to land  this thing which is really really fun it's   kind of old-fashioned exploration hey  go ahead and give it a try so they did the images from the approach and landing gave  scientists a much more detailed look at the   surface of an asteroid than they'd ever  had before with some unexpected results   one of the surprises looking at these  small bodies is that they have geology   it had tectonic features and looks like it had  landslides and erosion happening on its surface   and impact craters all over it and boulders  everywhere and one imagines the scenario where   a little asteroid comes along and hits a bigger  asteroid crashes into it digs up a whole bunch   of debris and that slowly settles down and these  boulders just spread across the entire surface the near spacecraft even transmitted  information back to earth for about two weeks   while on the surface but it has lost its  radio link with the earth and so now it's   simply sitting there mute for billions of years the asteroid explorer hayabusa of the  japan aerospace exploration agency   recently one-upped near it's the first spacecraft to ever land on an  asteroid and then return to earth it arrived   in june 2010 after a 4 billion mile round trip as  planned most of the spacecraft burned up in the   earth's atmosphere but the sample return capsule  successfully landed in the outback of australia even today it's still unclear  if minute samples are present   the careful examination of  the capsule is continuing   it's a long process but people are optimistic that  we're going to get great data out of the first   asteroid samples returned to earth to a geochemist  a couple of micrograms of material is plenty to   do some detailed chemistry and mineralogy and  compositional work even before hayabusa returned   another asteroid mission was already underway after a 2007 launch the nasa dawn spacecraft is on its way   to two of the largest asteroids in the  asteroid belt between mars and jupiter dawn will arrive at 320 mile wide  vesta in 2011 orbit for a year   then reach 600 mile wide series in 2015. you couldn't find two asteroids more different  from one another ceres is thought to be relatively   wet perhaps subsurface ices the other one  vesta is thought to be the opposite it's   completely lacking in hydrated minerals or water  ice it's been heated over its lifetime to such an   extent that is thought to be layered a surface  layer a mantle and a core much like the earth all of these missions are revealing that asteroids  are made from a much wider assortment of materials   than we first realized there's a huge variety in asteroids some of them  are iron rich or nickel rich very much like this   iron dumbbell others are very similar to this  earthbound rock they're stony they're rocky still   others are a combination between the iron type and  the stony type we've also got exotic things like   rubble piles which are like having this handful  of gravel but if it all were gravitationally bound   in a big asteroid kind of a form we also have  x comets and x comets have gotten rid of all   their isis and we're left with this fine grain  material held in a very porous type fluff ball but asteroids are surprising us in  other ways besides their composition the galileo mission on its way to jupiter went  past an asteroid called ida and discovered that   it had a little tiny moon called dactyl this was  a big surprise and now we see that that's not   so rare an incident asteroids do come with  their own moons sometimes several moons   we're also learning that a lot of asteroids  are traveling in pairs as binaries or even   with three of them and that's a very new set  of observations and new thing to understand knowing how asteroids are grouped and what  they're made of is more than a matter of   scientific interest imagine in the future that an  enormous deadly asteroid is speeding towards earth   it needs to be deflected if mankind is going  to survive but if we don't know exactly what   the asteroid is made of then the effort  to save the planet could go horribly wrong   an asteroid impact can unleash more destruction  than just about any other kind of natural disaster but it's also one of the few types of  nature's fury that we may be able to prevent imagine in the future that a huge asteroid is  racing towards earth at 70 000 miles per hour   international space agencies have banded together  and launched a rocket in an effort to save mankind the trick is to understand the enemy is it made of  solid iron is it made of shattered rock is it made   of rubble pile an ex-cometary fluff ball because  if you hit a slab of solid iron with a spacecraft   it's going to react far differently  than an object that is a fluff ball the asteroid turns out to be a  rubble pile it's soft enough to   mostly absorb the impact of the rocket and  to stay on course to collide with earth it's also large enough that it  doesn't burn up in the atmosphere it hits and forever changes life on our planet  this is the price we could pay if we   don't learn as much as possible about the  variety of asteroids in our solar system   but at least with large asteroids we should have  years or decades of warning about their approach with comets even enormous ones the  warning time will be measured in months   why that's what clayton l in atlanta georgia  wanted to ask the universe so he emailed us why   would there be so much less warning time before an  earth impact for a comet compared to an asteroid   good question clayton we'd love to  know when something might hit us   it turns out that asteroids are so nearby  that we can track their orbits precisely   that means we can make accurate predictions  of where they will be tens or even hundreds   of years in advance that means we might be able to  deflect them before they hit the earth now a comet   comes in from the outer depths of the solar  system and doesn't become bright enough to   see until it's maybe six months or a year away  from hitting us so we have very little warning   fortunately most of the things that  potentially could hit the earth   are asteroids not comets and we can  track the asteroids pretty accurately the fact that asteroids have a much greater chance  of destroying life on earth sometime in the future   is one of the main reasons why studying  them with unmanned missions is so important but in april 2010 u.s president barack  obama announced an even bigger challenge   by 2025 we expect new spacecraft designed  for long journeys to allow us to begin the   first ever crude missions beyond the  moon into deep space so we'll start we'll start by sending astronauts to an  asteroid for the first time in history   in my experience as a college teacher the  younger generations they want to go beyond   yeah my grandparents went to the moon you know  let's go beyond and so that was an inspiring part   of the president's message that we need to  get nasa back into the business of deep space a manned mission to an asteroid will be very  different from moon missions of the past   in some ways it will be easier  and in other ways much harder whichever asteroid the astronauts visit  will likely be a lot farther from earth   than the moon so the journey will probably last  for months instead of the eight days it takes to   get to the moon but the round trip will actually  use less fuel than a lunar landing mission   when you go to the moon you're dealing with a  body with significant gravity of its own you're   having to use more fuel to safely slow yourself  down and descend all the way to the surface when   you head to an asteroid with very low gravity  even though you're going farther to get there   you aren't having to expend nearly as much  fuel for things like getting to the surface   it also takes less propulsion ability when  you leave the asteroid to head back to earth but landing on an asteroid surface will be much  more challenging than setting down on the moon it's more like docking than it is landing but  you do have some gravity so you have to deal   with having a little bit of gravity but you have  to deal with actually anchoring yourself holding   on you don't have to hold on when you're  in the one-sixth earth gravity of the moon   exploring a small rotating asteroid will also be  much harder for astronauts than hopping around on   the moon it'll be more similar to a space walk  your sense of up and down is sort of screwed up   and you have to be very careful when you walk  around on an asteroid because the gravity of   the asteroid is so weak a good jump can send  you into an orbit around the asteroid or even   send you out at escape velocity and  escape from the asteroid completely   so you have to make sure that you're  tethered down when you're exploring but since rovers have already proved to be so  successful at exploring other worlds is there a   strong reason to send astronauts to an asteroid  astronauts explorers the public interested in   space yearn to see what it's like in person  through real human eyes and that day is coming robots can do a lot and have done a lot in  space exploration but there is no better   geologist than a human being to be a geologist  exploring an asteroid and being able to recognize   the history of a particular region looking at  familiar types of geological formations you know   just what you want to do you want to go sample  that rock you don't want to go sample that rock   asteroids are also important because  of the resources they might contain the year is 2050 and a crew of astronauts has  just landed their spacecraft on an asteroid   they're not here to explore  this is merely a pit stop   but what types of precious resources could  this small rocky world possibly contain an asteroid attack can wipe out entire species including humans but instead of accepting that  fate scientists are trying to   learn enough about them to prevent disaster and asteroids that aren't headed towards  earth may even turn out to be helpful   one of the reasons to visit asteroids and  to study them is that they may have some   resources that could be useful to future human  explorers and among the most important of those   would be ice water people are going to need ice  to live and drink and use in a practical sense the year is 2050 and a crew on its way to mars   has just stopped at an asteroid  for water and other supplies the oxygen in the water can be separated  to refill the crew's breathing tanks   but there's even more that this rocky  supply station has to offer it's conceivable   that with advanced technology  we could go to those asteroids   break down the water and use the hydrogen and  oxygen as fuel to take spacecraft even farther and there may even be priceless  materials to bring back to earth   elements so rare and critical to high-tech  success but they could be the cause of future wars some asteroids have platinum and titanium  and rare earth elements that are important   in many aspects of electronics which are  called rare earth elements for a reason   because they're rare on the earth they might  not be so rare in certain kinds of asteroids but the most important reason to investigate   asteroids remains their ability to  instantly kill millions of people or wipe out the human race altogether to counter this threat nasa launched  the wise mission in december 2009 the wide field infrared survey explorer has  already found 25 000 asteroids and more than   a dozen comets that were too dark to find using  visible light it's actually looking all around   our solar system hopefully to look at 99 of the  sky and try and map uh more of these near-earth   objects these asteroids that we haven't found  in the past and hopefully that'll help us   in understanding if there are any that are in  the near-term collision courses with the earth   and even though it doesn't usually make front-page  news there are already plenty of asteroids that   pass close to earth in april 2010 a 70-foot wide  asteroid passed within 220 000 miles of earth   which is closer than the distance  from the earth to the moon and a few months before that a 23-foot wide  asteroid came much closer in the winter of 2009   in november there was an asteroid that passed  so close to the earth it was only eight to nine   thousand miles away at its closest approach and we  didn't know about that until it got fairly close   that's about the same distance as  flying from los angeles to mumbai india and back in 1972 a tourist camera   near the grand tetons in wyoming captured a  much closer pass by a similar sized object the 1972 event was about as close as you can  get to a collision without actually colliding   on its way in it was going to collide with  the earth but it skipped off of the atmosphere   due to the pressure of the air like a pebble  being skipped off of the surface of the lake   that was a really close call then in  october 2008 a small and seemingly   uneventful impact occurred in a remote  part of the african country of sudan but it actually represented a giant step forward  in the science of predicting asteroid impacts   a small asteroid was discovered and it was  predicted to land in sudan the next day and it did   now this is the first case we have of an object  that was discovered and then predicted to land at   a particular time and place and in fact fragments  of this object were later found over the desert   but that was only a small impact  with a single day's notice today the jury is still out on whether  we'll be able to identify and deflect   something that could inflict  catastrophic damage on earth   believe there are still millions of unidentified  asteroids out there capable of destroying a city or worse will we be able to figure out  which ones will cross our path   and will we be able to prevent  them from slamming into earth the stakes couldn't possibly be any higher  each new discovery in the world of asteroids   isn't just a scientific advance but an  opportunity to increase the survival chances of mankind you

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Id: R0J6lUH4dsw

Length: 44min 21sec (2661 seconds)

Published: Mon Jan 25 2021