In movies and TV shows, asteroids the size of cities are often referred to as `planet killers'. Scientists have developed cutting-edge technology that can prevent such asteroids from destroying Earth.
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LearningTranscript
00:00we've seen the film a huge asteroid heads towards earth it plunges through the atmosphere and slams
00:12into our planet's surface sending up a huge fireball and a deadly shockwave humanity dies
00:22screaming but this is not one of those films this is how we and the earth can fight back
00:34putting the apocalypse on hold
00:39planet earth
01:01a cradle of life floating peacefully through space
01:06or is it our planet can be one of the most hostile places in the universe
01:14think about what natural disasters befall humanity you know earthquakes hurricanes tornadoes all of
01:24these sorts of things we can't do anything about those but an asteroid hey this is a huge natural
01:31disaster that we can actually prevent when people hear the word asteroid the first thing that comes
01:37to mind are these sci-fi movies of these very dangerous asteroids coming to hit us the story
01:42of how the dinosaurs became extinct yes there are some asteroids out there that are dangerous
01:48when it comes to finding asteroids and defending the earth scientists are very solidly the heroes
01:53across the world teams of planetary protectors are working out ways to halt an apocalypse
02:04they're scanning the skies
02:08doing the calculations
02:11designing the technology
02:12and making the plans that could ensure planetary extinctions from space
02:20are nothing more than science fiction
02:22if you're facing an opponent you need to know a lot about them in order to defeat them their size
02:31their strength what they're made of how they move well we need to know the same things about these
02:36asteroids because we want to knock them out
02:39they're going to knock them out
02:45Kathy Plesko from los alamos national laboratory is in arizona
02:52around 50 000 years ago this was the site of an impact that left a crater over 170 meters deep
03:00this is meteor crater
03:11this is awe-inspiring to stand on the rim of a crater like this and see the the scale of something this
03:21large and feeling this small understanding just how much energy it must have taken to
03:30excavate this much rock
03:37the meteor that carved out the crater landed with the power of a hydrogen bomb
03:48yet it was just 40 meters across
03:53meteor crater is helping us understand how speed can turn a small projectile
04:00into a killer
04:03asteroid came in at about 27 000 miles an hour that is 10 times faster than the muzzle velocity of a
04:11bullet coming out of a rifle
04:15it comes slamming into the surface and just explodes
04:18and that explosion then opens up the crater
04:28the force of the impact turned the surrounding solid rock to dust
04:32and sent an immense shock wave barreling outwards
04:38it's pretty windy here today but that's nothing like it would have been in the shock wave from an impact
04:43anywhere nearby here would have seen winds of thousands of miles an hour as the shock wave came out
04:49scientists calculate there's a 20 percent chance of a similar strike on earth every century
05:01if an asteroid like this struck today
05:04it could destroy a city
05:05but kathy's research is helping build up our defenses
05:13so we think that there's a variety of ways that we might prevent an asteroid from hitting the earth
05:17the earth
05:19my colleagues and i at los alamos and at livermore and at other places can use computer models on
05:24supercomputers to do very careful high fidelity simulations to tell us what's a good idea
05:31maybe what's not a good idea and then be able to present to policy makers
05:35okay here's what we can do in comparison to what bruce willis could do
05:44the most potent weapon that planetary protectors can currently utilize
05:49is a nuclear bomb
05:54however using one to blow up an asteroid has its drawbacks
05:59it risks showering the earth with hundreds of smaller meteors
06:02but kathy's team is working on plans that would avoid this risk
06:09they'd use a nuclear weapon to deflect an asteroid instead
06:15so one of the things i do study is nuclear deflection
06:18in some cases and in the near-term future there could be a scenario where we might need to
06:26shove something fairly large out of the way and those sorts of things
06:30um if they're large enough we might need to use a nuclear device to do that
06:36we might launch a nuclear device detonate it above the surface of the object changing its velocity a little bit
06:46detonating a nuclear device near an asteroid vaporizes part of its surface
06:50pushing the asteroid off course
06:57but firing nuclear weapons into space is no one's first option of choice
07:04so there are some pros and cons to using nuclear deflection there are some situations where it is
07:08definitely an appropriate technology where it may be the only option at the time but we hope in the future
07:15that we'll have other methods at our disposal that are not as challenging diplomatically or politically
07:27and scientists are currently on the hunt to find a way to deflect an asteroid without using nuclear weapons
07:33we're discovering more and more about the asteroids we're understanding them and we're realizing that
07:41there really are ways we can mitigate the destructive effects of an impact on earth
07:47this could be the most important scientific endeavor humanity has ever undertaken
07:53and the best way to cancel the asteroid apocalypse could be to destroy them before they even become a threat
08:03and the best way to destroy them before they even become a threat
08:17our solar system is a dangerous place
08:22fast-moving asteroids hurtle through space
08:28and many of these rocks are headed our way
08:33to counter the asteroid threat scientists are drawing up battle plans
08:45the very first step in understanding this hazard and in preventing this hazard is to find them
08:51not just the big ones that can end our civilization but even the small ones that can devastate your city
08:56however just finding these asteroids won't be enough
09:04we need to find them early in order to have time to deflect them
09:09the problem is that asteroids are smaller and darker than things such as planets
09:15and in the vast darkness of space that makes them much harder to find
09:20asteroids are pretty good at playing hide and seek in their own way imagine you're flying over the sahara
09:28and you're looking for a pebble that's the same color as the desert that's what looking for asteroids is
09:33like in the solar system astronomers believe there are more than a million asteroids a kilometer wide
09:40within our solar system and that there could be millions or even billions more that are smaller
09:47there's an uncountably large amount of asteroids in our solar system
09:53we're constantly looking and it's hard to find them all because they're tiny dots in a very dark background of space
10:08high in the mountains of the catalina sky survey in arizona
10:12asteroid hunter greg leonard is leading the search we are the eyes for the world on this night
10:21at this telescope on the summit of this mountain
10:26by comparing four images of the same patch of sky taken over a 20-minute period
10:31greg can hunt for elusive asteroids hidden among the stars
10:35that's because in these images the stars don't move but the asteroids do
10:45if it's a really bright asteroid we will see some bright points of light tracking across the four images
10:52you have to kiss a lot of frogs before you get a prince or a princess and this is the case
11:03tonight as it is almost every night
11:07ah here we go
11:10this is a real object
11:12you can see it's moving across the sky here from the lower right to the upper left
11:17we are very very excited to have discovered one tonight because this is an object that's approaching
11:23nearer space likely in the neighborhood of earth
11:30greg's research revealed this 30 meter asteroid could get as close as 1.01 million kilometers to earth
11:38that's less than three times the distance to the moon
11:40yet in the future this asteroid's orbit could move closer to earth and even onto a collision course
11:51if that happens we need to be prepared
11:56and the earlier we spot it the better our chance of altering its course
12:03space is so big and the earth is so small and the asteroid would be starting from so far away
12:08that if you just deflected it a little bit gave it a little nudge a tiny course correction
12:13by the time it got to where the earth's region is it would miss us completely
12:19to do that we need to move asteroids off their trajectory
12:26think of a golf swing hook or fade the ball by just one degree off the tee
12:32and you'll miss the green completely
12:38now scale that up to asteroids
12:42over time these space rocks can leave their home in the asteroid belt
12:47becoming threatening near earth objects 50 million kilometers away that could one day hit our planet
12:54but if planetary protectors can change the course of a dangerous object by just a
12:5910th of a degree it would miss the earth completely
13:05and scientists have developed a very direct way to do it
13:12in a football game if somebody on the defense is seeing the quarterback running into the end zone what
13:17do they do boom hit them knock them out of bounds knock them down do something like that
13:22that's what we want to do with asteroids
13:23so if we send something moving towards an asteroid very quickly to hit it we call that a kinetic
13:30impactor slams into it really hard changes not just the velocity of the asteroid but also its trajectory
13:36scientists have already intercepted asteroid-like objects in space
13:50in 2005 the deep impact spacecraft arrived at temple one a 14 by 4 kilometer comet
13:58this spacecraft shot a little probe at the comet
14:08which slammed into temple one kicking up material from the surface
14:18research is continuing into kinetic impactors
14:20in 2022 a spacecraft called dart will slam into an asteroid at over 21 000 kilometers per hour
14:33that transfer of momentum would change the velocity of the asteroid
14:38just a little bit maybe a fraction of a mile per hour but over maybe a decade
14:45that change in velocity even though it's very tiny would add up to a change in position big enough to
14:52completely miss the earth
14:59knocking a giant space rock off course might sound unusual
15:06but astronomers have discovered that in space it's occurred a lot
15:11when you have a lot of traffic driving down the highway and a lot of lane changing going on
15:17sooner or later there's going to be a fender bender and that happens in our solar system as well
15:22it's a busy place out there in the asteroid belt asteroids will run into each other
15:26at many miles per second relative speeds and when that happens the sparks fly
15:32if you started with two asteroids uh and they collided suddenly you'd have 10 asteroids those 10
15:42asteroids are now going to collide again and now you have 100 asteroids those asteroids will collide
15:48and now you have a thousand a million a billion possible impactors for the earth
15:53but this isn't just a numbers game
15:55even though any one of the millions of asteroids could result in a major impact
16:04they're not identical
16:07this means each one presents a different type of threat
16:12its speed size and distance from the earth help dictate the degree of danger
16:20the more we can really understand about an asteroid the better prepared we are to be able to
16:24defend against it this is definitely a case of know thy enemy you know we need to know something
16:30about the about the properties of these objects if we have any hope of of moving a threatening one
16:35out of our path one day
16:39but scientists are realizing that an asteroid's composition could be the deadliest factor
16:45knowing what asteroids are made of can help us find chinks in their armor
16:57to do so marina brozovic from the center for near-earth object studies
17:02uses a technology developed during world war ii radar
17:07planetary radar is really like a big cousin of airport radar and so the same way like the airport
17:17radar is tracking the airplanes we are tracking asteroids that are you know hundreds of thousands
17:22sometimes even millions of kilometers away another thing that radars do is they tell us about how
17:28this asteroid looks like you want to know what's their size what's their shape what's their chemical
17:35composition considering the detail that we see on the surface short of sending a spacecraft
17:40you cannot achieve that so radar is in a way its own little space mission
17:47radar shows that asteroids can be made of rock metal and a combination of the two
17:57and this is crucial information for calculating how to deal with them
18:00so metallic asteroids are far more dense than a normal rocky asteroid and so an impact from a
18:10big iron asteroid could have much more energy for the same size asteroid that was just rocky
18:18just as a metal cannonball would do more damage than a similar sized rock
18:23metallic asteroids could be far more deadly than rocky asteroids
18:26but scientists have now discovered that most asteroids are less like cannonballs
18:34and more like vast cosmic shotgun shells
18:40most of the asteroids they're not single object they're not monolithic but instead they're rubble piles
18:45so they consist of many smaller rocks and pebbles and grains and and pieces of sand and all this is held
18:52very loosely with gravity rubble pile asteroids such as the peanut shaped itokawa probably formed from
19:01violent collisions between asteroids
19:06initially the rocky debris from these collisions scattered like shrapnel
19:13then gravity pulled some of the rocks loosely back together again
19:17this loose pile of rocks can actually reshape shed mass build satellites and form these interesting shapes that we see among a lot of these asteroids
19:31they may sound odd but these loosely bound space rocks form a crucial part of our research
19:37so what we've learned about the asteroid population is that once you move in size to asteroids that are maybe 10 miles across
19:49we think that almost all of those asteroids are actually
19:53re-accumulated debris from huge collisions early in the history of the asteroid belt
20:00the structure of rubble pile asteroids presents a major challenge to our planetary protectors
20:08how can they safeguard us from a pile of rubble
20:12if the object is a solid mass of metal it's going to respond to an impact or an explosion in a far
20:18different way than if it's just a loosely bound rubble pile barely held together by its own gravity
20:25they're very very delicate objects and so those objects need some special consideration we can't just go
20:32slamming into them necessarily
20:36smashing into a rubble pile asteroid would be like kicking a pile of sand
20:42thousands of smaller rocks would go hurtling out in every direction
20:47they'd be undetectable unpredictable and could continue to head our way
20:53but we have a plan instead of using violent force we could use the gentle tug of gravity
21:05so instead of this ham-fisted approach of whacking it and then just walking away we need something
21:13we need something more careful something more precise and that's where the gravity tractor comes in
21:22rubble piles of rock may be small but it has gravity and if we send up a probe that has the mass of say a ton
21:30it has gravity too now not much but it's there and if you put it near the asteroid you can actually
21:37use the mutual gravity the attraction between them to tug the asteroid into a safe orbit
21:45all you have to do is park a spacecraft next to the asteroid hover it there don't let the gravity of
21:50the asteroid and the spacecraft pull each other together and let the gravity of the spacecraft act as
21:56a tow line to pull the asteroid out of the way this sounds like science fiction but it turns out the
22:04physics of this is relatively simple and we can do it but gravity tractors will only work if we can
22:15accurately track the movements of these asteroids the problem is there's a massive complicating factor
22:24at the center of our solar system the sun
22:49planetary protectors want to stop an apocalypse
22:54their mission is to protect the earth from these seemingly inevitable asteroid impacts
23:05but to do that they need to predict their every move
23:10and in a constantly changing solar system
23:13that's not easy we measure their orbits and we can draw maps of of all their orbits as we see them today
23:21but we know that it's not a static population that it's dynamic things are constantly evolving in the
23:27asteroid belt
23:30it's not just about size with asteroids you have to understand the density the orbit the speed in order
23:36to really tackle it
23:40collisions can set asteroid debris off on new orbits
23:44the gravity of the gas giant jupiter
23:53jupiter jupiter is the most massive planet in the solar system and it's sitting outside the asteroid belt
23:59its gravity can tweak and tug these asteroids and make their orbits more elliptical sending them in
24:05towards the sun crossing earth's orbit
24:10modeling jupiter's effect on millions of asteroids is hard enough
24:16then add the influence of some of the asteroid belt's largest objects
24:21530 kilometer wide rocks such as vesta and palace
24:26a tricky task becomes near impossible
24:38but gravity isn't the only force creating orbital chaos
24:45this is the asteroid Bennu
24:48there's one chance in 2700 it'll hit the earth
24:52the moon's orbit keeps changing
24:58in the last 18 years it shifted over 160 kilometers off course
25:04and the culprit could be the sun
25:08so what can change the orbit of an asteroid it's easy to think of these large rocks passing by each
25:14other tugging on each other gravitationally but could the most dramatic changes be due to something as
25:18gentle as sunlight it might feel very subtle but the sunlight on our bodies exerts a subtle pressure
25:26the fact that you're hotter on one side than on the other side actually exerts a kind of a thrust that
25:33can move you around
25:36sunlight is made up of tiny packets of energy called photons
25:41when photons hit an asteroid they pass on a tiny amount of momentum and a tiny amount of heat
25:49let's actually you know let's imagine this this situation here's our asteroid uh you know in
25:53reality this might be you know 10 miles across or a mile across something like that here's our
25:58asteroid here's the sun uh this asteroid is orbiting the sun this way this face of the asteroid is
26:04being warmed by the heat from the sun out here on the back side facing the cold vacuum of space it's
26:10it's a lot colder in fact i can even feel it already with my hands
26:13the warm side that's being illuminated by sunshine actually re-radiates that that heat in the infrared
26:21portion of the spectrum all of that infrared radiation off the side of the asteroid acts like a little
26:26rocket motor in a in a way it actually pushes on the asteroid this is known as the jakovsky effect
26:36it's a slow process the asteroid is pushed by a force equal to the weight of a few grapes on earth
26:43but as benu circles the sun it heats up on one side which moves it into a different orbit
26:57the arkowski effect is actually a bit of a problem if there were just gravity acting on these asteroids
27:03then we could predict where all the asteroids and planets will be and we'd be able to figure out the
27:07trajectory of these asteroids many years in the future but with the jakovsky effect that actually
27:13changes it in ways that are difficult to predict because it depends on how dark the asteroid is
27:17whether it's spinning what shape it is and so it makes the orbit of the asteroid much much more
27:23difficult to predict a long time into the future the jakovsky effect makes predicting the movement of
27:31asteroids such as benu even harder but our planetary protectors are ingenious and they're attempting to
27:40use the jakovsky effect to create a new weapon for their armory so the jakovsky effect we know can can
27:48change asteroids orbits pretty dramatically it's an effect that we could use to move asteroids ourselves
27:56if we could change the way the asteroid is heated by the sun by changing its color or changing its shape
28:03so that it gets heated in a very specific way that we could change its orbit that way
28:10if scientists could send a satellite to an asteroid it could use black or white paint to increase or
28:17decrease the heating effect
28:21but at the university of southern california a team of scientists are working on a higher
28:25tech solution
28:28they're trying to better the jakovsky effect using a space-based laser called d star
28:36let's say we see an asteroid that's on its way towards the earth
28:40we can use space lasers to zap the asteroid
28:43you vaporize the surface material that turns it into a gas which expands very quickly
28:48and that acts like a rocket and so you can use that to push the asteroid into a safer path as well
28:55you can use that to push the asteroid into a space-based laser
28:58space lasers are another powerful weapon for our planetary protectors fight against asteroids
29:05they join gravity tractors kinetic impactors
29:11and nuclear weapons in the armory
29:16but there is one very big problem
29:18all of the methods of defending against asteroids that we've mentioned are technologically possible
29:24the thing that's a little bit nerve-wracking is that none of them are actually ready to go right now
29:31so it's not time to cancel the apocalypse yet
29:34we've made a lot of progress especially in the last few years but we're not really there yet
29:39but we could get to that point within the next maybe 10 or 15 years
29:46but don't panic just yet
29:50it transpires that the earth has its own defense system
29:54that can burn up asteroids before they ever hit the ground
29:58arizona june the 2nd 2016. a one and a half meter wide rock hurtled towards the earth
30:14it was moving at over 60 000 kilometers per hour
30:17and as it streaked overhead it lit up the sky
30:27in the very early morning hours an asteroid came screaming into the earth's atmosphere
30:32far faster than a rifle bullet there was a fireball that lit up the red rocks all around us at night
30:38it was bright enough to burn out cameras on the ground from nasa that were watching for fireballs
30:43the asteroid was just seconds away from impact and major damage seemed inevitable
30:52dude did you see that but the asteroid never hit the ground why
31:01we do have a natural barrier against at least small asteroid impacts and let me give you a hint about what
31:07that is the air around us seems too tenuous to actually defend against a threat from space
31:18but in fact the atmosphere is sort of the last line of defense against asteroids
31:25one day our planetary protectors will be ready to save us from asteroid strikes
31:31until then we have to rely on the earth's built-in defense system
31:37the atmosphere we know for a fact that our atmosphere acts like a shield because space rocks come to
31:45earth every day some of them are tiny some of them are a bit larger but what's happening is that as
31:51they enter the atmosphere at high speed the friction burns them up even though the top layers of the
31:58atmosphere are very thin compared to the vacuum of space they're extremely dense
32:07as rocky asteroids hurtle through the atmosphere friction and air pressure can heat them to over
32:131 600 degrees celsius
32:18the larger the asteroid the longer it takes to burn up
32:22and for these larger rocks the effects can be dramatic
32:27if there's a rock that's big enough that it doesn't burn up very quickly we call that a bolide
32:31and as the bolide falls through the atmosphere it creates a spectacular show called a fireball
32:40in february 2013 the town of chelyabinsk in russia had its own fireball
32:47when an 18 meter wide space rock barreled through the sky
32:50this asteroid was bigger than a bus and it traveled at 18 kilometers per second
33:02it got super hot broke up into small pieces those pieces then ran through the atmosphere
33:08when all of that vast energy of motion of this rock was converted into light and heat it exploded
33:15the chelyabinsk meteor is the largest natural object seen entering the atmosphere in over a hundred years
33:29it exploded 19 kilometers above the earth's surface with the power of 30 nuclear bombs
33:35the blast caused over 1500 injuries and damaged 7 000 buildings
33:46but if it wasn't for the protective shielding of our atmosphere the results would have been far worse
33:56the problem is the atmosphere can only protect us from rocky and rubble pile asteroids up to about 50 meters wide
34:06and there is also something much more dangerous to consider the metallic asteroids if you had a rocky
34:14asteroid hitting or a rubbly rocky asteroid hitting it wouldn't make it to the ground an asteroid that's
34:20around 100 feet across would actually blow up in the sky but if a hundred foot metallic asteroid were
34:28to hit first of all you wouldn't have much warning it would hit the top of the atmosphere and then it
34:32would hit the ground about a second later causing an enormous explosion that would open up a crater
34:39that would be about a mile across you'd have a flattened ruin of remnants of buildings uh millions
34:47uh dead from the shock wave that would be radiating out and a layer of dust falling back down over the next
34:57minutes and hours a metallic asteroid would punch through the atmosphere because it's too hard for
35:04friction and air pressure to break it up completely so it would slam into the ground in a catastrophic explosion
35:15metallic asteroids could be our planetary protectors greatest foe
35:19but it transpires that the earth could have another built-in defense
35:31we know an asteroid punched through the atmosphere and killed off the dinosaurs
35:36but research is showing our planet could have saved them
35:40the dinosaurs were incredibly unlucky even if the object does make it past our atmosphere we still
35:47have another line of defense it's not always what an asteroid is made of that makes the difference
35:54the difference sometimes it's all about where it hits
36:09our planetary protectors are creating technologies to divert a potentially catastrophic asteroid
36:31but until their armory is complete the earth has its own defensive strategy
36:39one of the things that is sure is that we will be hit by an asteroid or comet again it may not
36:46happen for millions of years but it will happen and on that day the thing that will differentiate
36:50between it just being a very bad day and it being a global catastrophe is location location location
37:00some regions of the earth could actually reduce the damage caused by a killer asteroid
37:05how do we know
37:10dinosaurs
37:1265 million years ago the dinosaurs had a very bad day they had the bad luck to be wiped out by an asteroid impact
37:24we thought we knew the full story but researchers have revealed something astonishing
37:30if the asteroid had hit the earth just minutes later
37:38dinosaurs may still be roaming the planet today
37:43but how this object hit right at the yucatan peninsula it caused an incredible tsunami that flooded north
37:50america but it also threw a lot of sulfates into the air
37:54the nine kilometer wide asteroid landed in shallow seas in what is now the gulf of mexico
38:08it vaporized rocks in the sea floor of the continental shelf
38:12the impact blasted out trillions of tons of gases into the atmosphere
38:17triggering catastrophic climate change
38:19the impact of all life on earth became extinct including the dinosaurs
38:30the thing that's kind of tragic is that if the earth had rotated just a little bit more when that
38:35impact hit it would have been in deeper ocean and there wouldn't have been all of that vaporized rock and sulfur
38:40our planet spins at 1 600 kilometers per hour
38:5070 percent of the earth's surface is covered by ocean
38:56with a little luck the dinosaur destroyer could have struck in deeper water there's no good place on
39:03the earth to take a five mile wide asteroid strike there's just no good place some places are worse than
39:09others and the yucatan peninsula with that much sulfur was one of the worst possible so it's just not going to be a good day
39:21the asteroid that killed the dinosaurs allowed us mammals to take over the earth
39:28fortunately these giant asteroids only strike once every few million years
39:32but every two thousand years or so a rock about the size of a football field hits earth
39:45what would happen if one of these smaller more common asteroids was to hit the ocean
39:52if you think of something like the pacific ocean there's a lot of coastline there
39:55and so you have many many people that are at risk most of the earth's surface is ocean so it's a much
40:01more likely scenario for an asteroid to hit the ocean and so the question is how much of a tsunami risk is there
40:12scientists have modeled what would happen if an asteroid strikes different points in the ocean
40:17it was studied in three dimensions with different types of compositions different ocean depths different
40:26entry angles and found out that the continental shelf actually saves us
40:35the continental shelf is an underwater landmass that extends around 80 kilometers beyond the coast
40:40so if an asteroid hundreds of meters across slammed into the deep ocean the shallow sea created by the
40:51continental shelf could force a tsunami to collapse before it hit land it seems the ocean could be a
40:59natural protector for the deep ocean we think that asteroids smaller than 400 feet across which is quite large
41:08are not a tsunami risk and so we don't need to worry as much as we thought we did about it
41:15that shallow part of the water actually buffers any tsunami wave that might be coming in
41:26nina lanza demonstrates
41:29let's imagine that this rock here is our asteroid it's heading for earth it's probably going to hit the ocean
41:38when it hits it's going to make a huge big wave
41:47but as the wave travels outward it's going to get smaller and smaller and so by the time that
41:51wave hit the shore it was no bigger than these smaller waves lapping at my feet
41:58if an asteroid were to strike the ocean it's going to wreak some havoc
42:02but the tsunami from this type of event is probably not as bad as you might imagine
42:16so our planet has defense mechanisms
42:19and our scientists are devising plans aiming to combat the dangerous asteroids
42:24however what they need is time astronomy very well can save the world because we're on the lookout
42:37for all the asteroids that may someday collide with earth and if we find them we can avoid
42:42a civilization ending event if we have warning time we then have the advantage of being able to
42:49think about the problem plan for it and actually build up the technologies practice the techniques
42:54it's going to take to push that asteroid out of the way time is definitely an ally for us
43:00we're not ready to cancel the apocalypse just yet
43:02but with the planetary protection team on the case soon we'll have a fighting chance
43:13if you want to know what like an astronomer's sweatiest nightmare is
43:17it's an asteroid impact it's kind of personal right this is happening right here on earth
43:24it's a challenge to us and that's why we want to prevent them
43:28the good news is we actually are on the cusp of being able to deflect them we're almost there we
43:36just have to push it through
43:40the planet is incredibly resilient even if one specific species or one specific individual is
43:46very fragile as a whole the earth is actually quite tough it really comes back to as human beings
43:54what is our will to discover to explore and understand the solar system it becomes very
43:59important when you think about asteroids we need to keep scanning the skies we need to keep being
44:05scientists to defend the earth