The Mystery of the Late Heavy Bombardment

many kilometers beneath the moon's surface all is silent without liquid water or plate tectonics the quiet is broken only every so often by a tremulous rumble for the best part of 700 million years since formation in the fires of planetary collision little has changed this slice of the moon's crust has laying dormant until now with the power of more than 10 billion nuclear bombs its safe haven is atomized in seconds and it finds itself flung up into the maelstrom yet again the surface of its old home devastated in retreating from its vision is sloshing about in towering dusty breakers the moon has suffered a massive impact the new traveler arcs effortlessly across the sky accompanied by a tsunami of ejected material a diaspora beneath the surface of the moon scans past it is grey and cratered and dead the gale of displaced rock lands like a plague all at once and suffocating fusing together into one solid mass of stone on the monochrome plane from its new vantage point on the exposed surface the recent arrival watches its new neighbor it is also under siege disparate craters splash mata across the young earth's chaotic exterior it whips around with impatient futility immobile defenseless against the bruising circles appearing again and again on the surface as millennia pass earth changes color periodically reds turn to blacks blues sprout rushes of green ice comes and goes the circles of destruction still appearing on occasion mostly though it just shrinks it has been retreating for and so is very small now but recently something very odd has occurred it has blossomed only visible when the earth is black tiny lights have begun to pepper the planet spreading in white veins across its surface and this is when after four billion years of detached lonely observation our traveler is finally met by another forward coming down nicely 200 feet four and a half down five and a half [Music] back on earth the myriad lunar samples from the apollo missions were carefully studied for the first and to date only time scientists had access to mata harvested directly from another world with so many mysteries to unravel answers were now potentially within reach and to the delight of earth's scientific community this newfound data converged upon an insoluble truth gouged upon the lunar tissue rested the scars of a tremendous calamity inside the materials atoms providing substance form and identity had been shocked into a heightened alignment crushing pressures had coerced the rock into metamorphosis and armageddon was fossilized on the moon but of course evidence of stellar impacts had been expected galileo galilei first recognized the lunar craters back in 1609 and in preparation for their missions apollo astronauts were trained to spot the signs of impact looking at the moon through a telescope reveals gaping excavations hundreds of kilometers across and bands of wreckage slung even further explosions that punctured deep leaving pools of magma to burble in truth evidence of massive impacts surprised few what shocked the world was the age of that evidence locked inside metamorphosed minerals and inside the rocks liquefied by each kilometer strike lingered atoms edging towards disintegration by measuring and comparing these unstable elements and their offspring samples from the imbrium crater the highlands the sea of serenity samples collected a thousand kilometers apart or more we acquired an age the same age over and over 3.9 billion years old what catastrophe could have so traumatically reshaped the moon not a single impact but a throng a flood a bombardment each diving body dozens of kilometers across but if a swarm of celestial invaders assaulted the moon what then if it's more massive partner what happened to the earth modelling and the geological record show that for every collision suffered by the moon the earth endures 20 of its own such a disaster would have remade our planet momentously diverting it to a new evolution whatever traumatic effect this cataclysm had upon the earth 3.9 billion years ago its earthly evidence has long since been buried eroded melted and dissolved if we want to know what happened on our planet 3.9 billion years ago we must look towards the rest of the solar system for five decades experts have scoured their imaginations and scientific data for the origins of this catastrophe did a fifth terrestrial planet disintegrate spraying its minerals across the solar neighborhood did a clash near mars divert a string of projectiles in our direction many different causes were proposed but scientists settled upon one main hypothesis if jupiter's orbit was altered due to some catastrophe in the outer disk then a rabble of remnants from the early days of accretion could have been ousted from their homes and condemned to a brief and desperate exodus if this dissent did take place then evidence is just as likely to be found on our neighbors as on our earth the baked surface of mercury is pocked by a graveyard the same travelers that scarred the moon also dug great graves on mercury and mercury buried them in magma when the largest meteors crushed into the feeble surface they thrust and hurled enormous masses of stone away from their resting place leaving punctures in the crust hundreds of kilometers across into these gouges rushed the pressurized mantle superheated and relieved of its confinement the surging mantle melted and exuded through vast vents on the surface layer upon layer of hardened magma built until the cavities were filled with kilometres of basalt the most destructive meteors to strike mercury didn't just melt the crust but jump-started an era of regional volcanism that shaped the planet over hundreds of millions of years the moon too was likely provoked into volcanism by its bombardment thus producing its famous seas at the imbrium basin the elected landing site of apollos 14 and 15 a hardened ocean of basalt swamps the crater drowning a ring of islands denoting the crater's rim immense fields of basaltic flows would have dominated the earth's surface two seventy to one hundred percent of it smothered by this blanket of igneous rock beneath the crust the decompressing mantle surged and seethed swelling at the basin causing the weakened crust to bend buckle and slip beneath into the underlying turbulence the thin plate is dragged across the surface and into the depths and is replaced with new crust erupting from the vents these episodes of ephemeral subduction last no more than 10 million years but they may have instigated the modern phase of plate tectonics on the surface of mars too we see the results of destructive visitors across the southern hemisphere the highlands break suddenly into yawning cavities with distant rims in the north though are quiet endless plains devoid of landmarks the contrast between the north and south is stark and perplexing for many years scientists pondered this enigma until detailed topographic mapping revealed a titanic ellipse the relic of a colossal crater covering 42 percent of the planet so large as to be almost invisible the borealis basin this could mean only one thing in the deep past a planetoid nearly the size of pluto hurtled into the north pole atomizing itself along with much of the planet as thea struck earth so this giant hit mars the explosion exhumed half of the martian crust ploughing it southward in a rolling deluge that entombed the rest of the planet in drifts of rubble possibly kilometers deep it is likely that the earth was struck by several borealis level impacts of its own it was inundated with meteors at least one hundred 000 of which left a crater 20 kilometers across or larger some much larger around 3000 the thought would struck the surface obliterating 25 times their surface area atomizing and liquefying awful chasms into the crust hundreds of meters of ejected material would have swamped the planet co-mingling with the sheets of basalt the earth churning beneath the chaos under this deluge earth's primordial atmosphere would have been asphyxiated by vaporized rock condensing into blazing droplets of molten rain a global storm of cinders the heat of which boiled away ancient seas the planet would have baked in unendurable heat sterilizing the surface if the first saplings of life survived this apocalypse it would have done so hidden within hydrothermal systems veins of superheated mineralized fluids jetting between fractures deep inside the hellish world but the borealis basin formed 4.47 billion years ago long before the era of lunar bombardment mercury the moon and mars all pockmarked and pitted by the passage of those unfortunate bodies that collapsed onto the earth however mercury the moon and mars are unlike earth in many ways they are small bodies with little atmosphere and limited geologic activity they are breathless and still but venus is akin to earth a living planet comparable in size and closest in its orbit to ours and like the earth venus is still evolving but also like the earth its past experiences are shrouded deep within layers of elemental cloud and as yet we can glean no answers testament from the asteroid belt further muddies the chronology a bevy of inter-asteroid impacts between 4.1 and 3.5 billion years ago could this disruption in the belt reflect the origin of the bombardment or its passing through how can we square this 600 million year period with the history of lunar bombardment a sixth as long what evidence the earth can provide tells a similarly confusing story beds of beads stone raindrops birthed from the asphyxiated atmosphere after a major impact are common as late as 3.5 billion years ago it's clear that the terrestrial planets were brutally pounded the question though that is now being asked is when attempts to date the other titanic impact basins of mars and mercury output ages that corroborate the lunar record around 3.8 to 4.1 billion years but these dates are based on models tied to the same apollo samples that first revealed the late heavy bombardment the theory therefore balances precariously on the reliability of a handful of lunar samples collected half a century ago [Music] so far we have sent six apollo missions to the moon just 12 travellers making steps on the surface of another world three of those missions apollos 14 16 and 17 returned samples that record evidence of late heavy bombardment the furthest distance between these three landing sites indeed the furthest distance between any two apollo missions is only one thousand six hundred and seven kilometers barely further than the distance between the apollo astronauts training facilities in houston texas and where they landed at kennedy space center in florida though limited by practicalities scientists had selected these sites for the differences in their cratering apollo 14 at imbrium basin apollo 17 at serenitatus basin and apollo 16 at a heavily cratered highland region in the 50 years since we have trained our eyes mechanical and organic upon these assumptions crispr imaging of the outcrops sampled by apollo 16 shows that rather than originating from local craters the stones in question flew a thousand kilometers from the imbrium impact a diaspora worse chemical evidence of the apollo 17 samples suggests they too emigrated from the same imbrium basin indeed one way to create an unexpected anomaly is to accidentally date the same event three times the eager scientists of the 1970s failed to imagine just how far the influence of a catastrophic collision could spread in recent years these time-stretching revelations have destabilized the theory of the late heavy bombardment the end of the bombardment is clearest evidence shows that it tapered off between 3.8 and 3.5 billion years ago by the earth's billionth anniversary the bombardment had abated the solar system was finally modified the beginning of the bombardment however retains its mystery though there is little doubt among scientists that jupiter was the cause the date of this event still eludes them some suggest a chilling explanation one that has been lurking on the peripheries of the scientific discussions since the seventies what if the glimpse we have of this catastrophe is too scant what if we have only spied its shadow the tortured minerals scattered across the solar system tell us their most recent trauma but they have forgotten their deep past their crystalline memories wiped impacts devour digest remake is it possible that buried beneath the lunar surface is a brutal history clawing all the way back to there to genesis not a brief apocalypse no calm before the storm simply storm all the way down so deeply buried we cannot yet peer through to it scrambling for reliable physical evidence scientists are coming to the conclusion that this bombardment may well not have been late or indeed heavy but a constant battering lasting eons in 2024 for the first time in 50 years nasa intends to land astronauts once more on the moon this time at the lunar south pole will they find evidence to corroborate the late heavy bombardment or to disprove it rocks showing the same timestamp as those first examined 50 years ago or a new brutal billion-year time span what earth-shattering revelations will be revealed this time around next time we dive deep into the first oceans of our world we investigate the tremendous tectonic forces that reshaped and made the earth and finally still billions of years in the primordial past the very first saplings of life you've been watching the entire history of the earth don't forget to like subscribe and share and let us know in the comments what you'd like to see covered in the future thanks for watching and we'll see you next time

Channel: History of the Earth

Views: 574,867

Keywords: Asteroids, space, deep space, meteors, nasa, science, geology, astronomy, moon, Mars, earth, hadean

Id: _x2GlgyF8yE

Length: 20min 4sec (1204 seconds)

Published: Sun Jun 07 2020