Reposted from The Fabius Maximus Blog
Larry Kummer, Editor Science & Nature 30 July 2019
Summary: We have had several near-misses – asteroids passing close by with little warning from our sensors. This reminds us that asteroid and comet impacts have changed the course of life on Earth, and will again unless we stop them. Which we will, eventually, either when we go deeper into space – or after we are hit. This post discusses this risk and what steps we can take now to better prepare. Perhaps it is humanity’s role to defend the planet.
“The dinosaurs became extinct because they didn’t have a space program. And if we become extinct because we don’t have a space program, it’ll serve us right!”
— Science fiction author Larry Niven, as quoted by Arthur C. Clarke.
We can’t say that we weren’t warned
WaPo: “‘It snuck up on us.’ Scientists stunned by ‘city-killer’ asteroid that just missed Earth.”
How much would an asteroid impact hurt?
Even a small asteroid could devastate a city. What would impacts of different sizes do to your community? See the stunning results at Purdue U’s Impact Earth website. A presentation by NASA’s David Kring gives examples and consequences of impacts.
How likely is an impact? One could hit tomorrow.
The U.S. Government’s sensors recorded at least 556 meteors entering the atmosphere (fireballs, technically bolides) from 1994-2013. The largest in this record was a 20 meter asteroid near Chelyabins in central Russia on 15 February 2013 (details here), an explosion equivalent to 440- 500 kilotons of TNT.
The size of the dots on this NASA map represents the meteor’s optical radiant energy. The smallest dot on the map is 1 billion Joules (1 GJ), the equivalent of roughly 5 tons of TNT. The dots for 100, 10,000 and 1,000,000 GJ convert to 300 tons, 18,000 tons and one million tons of TNT. The Hiroshima blast was equivalent to 15,000 tons.
Scientists have accumulated enough data to estimate the odds of impacts from space.
“Every day Earth is bombarded with more than 100 tons of dust and sand-sized particles from space. About once a year, an automobile-sized asteroid hits Earth’s atmosphere, creating a spectacular fireball (bolide) event as the friction of the Earth’s atmosphere causes them to disintegrate – sometimes explosively.
“Studies of Earth’s history indicate that about once every 5,000 years or so on average an object the size of a football field hits Earth and causes significant damage. Once every few million years on average an object large enough to cause regional or global disaster impacts Earth. Impact craters on Earth, the Moon and other planetary bodies are evidence of these occurrences.
“Meteor Crater near Winslow, Arizona, is evidence of the impact with Earth’s surface of a 50-meter asteroid about 50,000 years ago. Impact of the metal-rich object released energy equivalent to a 10 megaton explosion and formed a 1.2 kilometer-diameter crater.” {Source: NASA.}
The National Research Council published a typically magisterial analysis of this threat: “Defending Planet Earth: Near-Earth Object Surveys & Hazard Mitigation Strategies“ (2010). Here are the numbers, comforting or terrifying, depending on your perspective. Thirty-five million years ago, a 5-8 km impactor blasted out the Popigai crater – at the time of the Eocene–Oligocene extinction event. The dinosaurs were killed by an object 11-81 km in diameter.
Books and films about how this happens and how we respond
Stories about collisions with space objects go back to the 19thC. Perhaps the best story about doom from the sky is When Worlds Collide
An example of an optimistic science-fiction story in this genre is Rendezvous with Rama
Lucifer’s Hammer
Hollywood has given the inspiring stories about humanity defending the world against doom from space.
- When Worlds Collide
(1952). Trailer here. A faithful telling of the book.
- My favorite (for those who like big thinking): Gorath (1962)
. Trailer here. The object is too big to move. So they build giant fusion rockets in Antartica and move the Earth.
- Meteor (1979)
. Trailer here. Starring Sean Connery and Natalie Wood, it was inspired by the MIT report “Project Icarus” (1967). The Soviet Union and the US stop the Cold War and work together to save the world. It has a tragic scene in which the World Trade Center is destroyed.
- Armageddon 1998
. Trailer here. Bruce Willis leads roughnecks into space to save the world. I enjoyed it!
- Deep Impact (1998)
. Trailer here. More scientifically accurate, but still a gripping story.
What can we do to prepare?
“Find all asteroid threats to human populations and know what to do about them.”
— NASA’s Grand Challenge, 18 June 2013.
The Apollo program burned billions of dollars) but did little for America. Since then, the manned space program has done even less. The reason is simple: we lacked a good reason to put people in space. An asteroid or comet will eventually provide the motivation – either to prevent another impact or mitigate its effects. We have the technology and money to begin preparations.
Here are the four kinds of space threats, with warning times ranging from decades to days. Buying warning time is the key to preventing impacts or minimizing their damage, but it will take time to build the necessary sensor systems. As a first step, in 2016 NASA created the Planetary Defense Coordination Office. Its staff supervises NASA’s programs to detect and track potentially hazardous objects, issues notices of close passes and warnings of any detected potential impacts, and coordinates the US government’s efforts to prepare for impact threats. See their website, which has a wealth of information.
Other nations have similar programs. NASA is a member of the International Asteroid Warning Network.
What happens after we detect an object on a collision course with Earth? A presentation by NASA’s Dan Mazanek describes deflection strategies. This NASA video shows what a mission to intercept a threatening space object might look like.
The longer the warning time and the better the preparations, the higher the odds of success. Here are some ways to defend Earth: a Gravity Tractor, a Kinectic Impactor, and a Blast Deflection. This graphic shows which works best for various combinations of warning time and asteroid size. For short warning times, we can use only what we have ready to launch.
From the NRC report (2010). Graphic by Tim Warchocki. Copyright © NAS.
A last note about these threats
“Estimates of the frequency of space-rock strikes are just estimates, and may not tell us anything about when the next impact will occur – it could be an eon, it could be tomorrow. Floods, earthquakes, volcanoes, and tsunamis are sure to happen more frequently, but humanity will survive these events; we might not survive an impact from space. Meanwhile, nothing can be done to prevent earthquakes, volcanoes, and tsunamis. But space strikes appear to be entirely avoidable, and not necessarily with “massive repositioning of government funding.” A fraction of the money NASA wants to waste on a moon base would likely be sufficient.”
— By Gregg Easterbrook in The Atlantic, September 2008.
For More Information
As a great starting point, see The Asteroid Day website. Especially this six-article series by Rusty Scheweickart (astronaut, aeronautical engineer, and fighter pilot). To learn about asteroids and the defense against objects from space, see their education page. If you prefer videos, see them here.
Ideas! For shopping ideas, see my recommended books and films at Amazon.
If you liked this post, like us on Facebook and follow us on Twitter. See all posts about shockwave events, about NASA, about shockwaves, and especially these…
- Why we have not gone into space, & why we will.
- Asteroid Day: reminding us of the threat, pushing us out into space.
- Three things to know about asteroids, certain death from the sky (eventually).
- Why we have not gone into space. Why we must.
Why do we keep getting hit by these things?
The solar system is not in equilibrium. To learn why I recommend the brief and clearly written Newton’s Clock: Chaos in the Solar System
“Peterson explains a mystery that has fascinated and tormented astronomers and mathematicians for centuries: are the orbits of planets and other bodies stable and predictable or are there elements affecting the dynamics of the solar system that defy calculation? It is one of the most perplexing, unsolved issues in astronomy, with each step toward its resolution-from Newton’s clocklike mathematical models to the astonishing work of super computers exposing additional uncertainties and deeper questions about the stability of the solar system.
“Newton’s Clock describes the development of celestial mechanics – from the star charts of ancient navigators to the great Renaissance scientists; from the crucial work of Poincare to the startling, sometimes controversial findings and theories made possible by modern mathematics and computer simulations. Equal parts science and history, the book shows how the exploration of the solar system has taken us from clocklike precision into chaos and complexity.”
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Off on a Comet — the Jules Verne classic in comic book form.
https://ia802908.us.archive.org/23/items/ClassicsIllustrated149OffOnAComet/Classics%20Illustrated%20-149-%20Off%20On%20a%20Comet.pdf
Don’t forget Comet in Moominland, Tove Jansson’s second novel. Published in 1946, it is rather more convincing than the current global warming predictions. And while the comet did arrive, preceded by significant global warming, the Professors at the Observatory on the Lonely Mountains turned out to have made a slightly incorrect prediction: The comet missed the Earth altogether and they lived happily ever after.
The Groke, who totally freezes everything she touches, first appears in the following novel.
This sounds like climate scientists that want money. How about…No.
I find it ridiculous to say the space program did little. I suspect the origins of this notion will be the left’s worldview which pollutes the internet “progressively” more each day. Newton’s work did ‘nothing’ by this measure. We weren’t technologically capable to make much use of it for several centuries.
The Wright Brothers made a stupid toy that only flew a 100ft. What possible contribution could this idiotic device make to mankind. The first steam locomotive was a pretty pathetic toy made by a mining engineer. He should have been fired for playing on company time.
Okay, so you want a space program. Do you jerrybuild a rocket full of alcohol and fire it off to take a man to Mars? No we better work on a vehicle until we have something that can do the job and hopefully land safely, first. Maybe its a good idea to send something to orbit earth if we can and test it and refine it. Maybe we should then put a man in it and try it out -hey that’s radical! So if we want to travel in space, let’s think of a place not to far away and see ….
I was born before WWII and went into engineering because of Sputnik! You have no idea what the space program did to boost academic and private research and development. You have no idea what it did for creating a can do spirit.
You can probably guess what it did to the social sciences that took the opposite tack bewailing the forgone better good that might have been achieved in distributing wealth to the poor, blah, blah … (we already had a track record of distributing countless billions to thieving despots who bought palaces in France and New York York realestate – Mobutu was a past master).
Now, in the golden age of Fake News having links to click on the subject isn’t reassuring. The oceans indeed.
My thoughts exactly, Gary. Well said!
Gary,
As an engineer, apply that rigor of thought to your own comment. There have been many studies about the benefits of the manned space program. None agree with you. NASA doesn’t even make such big claims anymore.
Also note the lack of specifics in your comment.
” so you want a space program.”
Rigor, Gary. We’re talking about the manned space program. Putting instruments into space has proven value. This distinction was clear from the start, and the two commissions examining prospects for space clearly said that instruments had great value.
“You have no idea what the space program did to boost academic and private research and development.”
It drained funds from projects of far higher potential, as was predicted at the beginning.
“You have no idea what it did for creating a can do spirit.”
And your evidence of that is….? Be an engineer and show us rigorous reasoning.
“in the golden age of Fake News having links to click on the subject isn’t reassuring. ”
So you think you know more than NASA about this (ie, NASA debunks many of the specific claims made), and that your unsupported big claims should be taken as fact? Fake News is people doing as you are doing – talking without given a shred of evidence.
Larry, Gary was expressing an opinion based on his experience living through that period as I did. He was not creating a scientific paper or a legal brief. Your comments are your opinion. That is one of the purposes of the comment section of this wonderful blog.
Gary, I can completely agree with everything you have said above.
While I always had been a “tech geek” and wanted to be an engineer before Sputnik, that event motivated our high school Math and Science teachers at my high school in Ohio (class of 1955 ) to decide to ratchet up the level of their classes for those of us planning to go to college. Their preparation helped me survive a tough electrical engineering program, graduate with a BSEE and go work for a large computer company that, among other things, developed the computers for the Apollo spacecraft.
The space program motivated all of us involved in technology development during this period to up our game and believe in the work we were doing, whether it be in the space program, research or commercial development. This was very important in the generally negative period following the Korean War.
Such a program could do the same today.
Amen!
Dollar for dollar, getting and reading a used copy of Lucifer’s Hammer has more value than another governmentental/scientific boondoggle.
These rocks have been flying past Earth for more years than there has been people. Because we just now notice shouldn’t stampede us into another wasteful spending spree. Too close to “Climate Science” for me.
How can anyone argue against such religious beliefs?
GP Hammer,
What “religious beliefs”?
Fires, famines, floods, wars, earthquakes, rivers turning to blood, oceans turning to blood, locus and the like are far greater concerns. Falling rocks don’t rate a vote.
You are failing to make the distinction between sheer fantasy, and low probability events with severe consequences.
@Tom Halla
I don’t know which is more fanciful, believing we men can caught a falling star or accepting the fact water turned to blood and that water was turned to wine.
Some put faith in the mortal man.
I am never surprised at the rejection of God, the Creator. Let me know if you change your mind when you stand in his presence. We all will.
I too am ‘never surprised at the rejection of God’. You believe I will be surprised when I’m looking at St Peter. This is a science blog ( I hope). Maybe I’ll stop there.
The left actually WANT a mass culling of humans. The term “sustainable development” is code for a stable population of humans of 500 million. Thus, 94% of us are surplus to requirements. At my age, being white, straight, male, climate skeptic, educated, love ridiculing the left, activist etc, I am on the chopping block.
You could just bet that when some 2km wide asteroid is detected, infighting on how to deal with it will delay mitigation until it is too late. I can see the bleeding hearts saying breaking it up before it hits the atmosphere will mean multiple destructive impacts. What the bleeding hearts are too daft to recognize is that when a single large impact breaches the crust and gets to the mantle, it will create a massive rupture on the opposite side of the planet, with sulphur emissions and volcanism that will create the sort of post nuclear winter that would drive humans to extinction. The Siberian traps were almost certainly created this way. Better to have a thousand potentially city destroying impacts than a single one that stuffs the planet for any life form larger than a cockroach. Besides, the additional surface area of a pre fractured bolide has a larger percentage ablated away.
“Meteor Crater near Winslow, Arizona, is evidence of the impact with Earth’s surface of a 50-meter asteroid about 50,000 years ago. Impact of the metal-rich object released energy equivalent to a 10 megaton explosion and formed a 1.2 kilometer-diameter crater.” {Source: NASA.}
I clicked on that NASA link:
https://www.nasa.gov/feature/asteroid-day-and-impact-craters
The first sentence is confirmed by that webpage, and that it is 1.2 km diameter.
The second sentence is not. The words “megaton” and “metal” do not appear in that web page.
That huge crater was just 10 megaton? Really? What are we up to now, 100? 200 megaton nukes?
One megaton is equivalent to 4.18 x 10^15 joules. (source atomicarchive.com)
10^6 GJ = 10^15 J
The biggest ever detonated on earth would probably be the Tsar Bomba, which topped the scales at 50MT. It was apparently designed to be capable of 100MT.
The US’s current largest nuke is 1.2 Mt. I think that is the B83 dial-a-yield. It was scheduled to be dismantled by 2010 or so. But that never happened. Almost all of our other nukes are 1Kt-175Kt dial-a-yield.
The last nuclear weapon built in the US was in 1989.
“an object the size of a football field ”
What sort of football? Rugby? FIFA? Australian Rules? They have different sizes of pitch. And the AR one is oval.
Actually, most of proposed approaches to planetary defense are neither effective nor scalable even to asteroids capable of country-wide destruction. For example, it is unlikely that the kinetic impact will work because of the internal structure of near-Earth asteroids is crumbly: “We think they’re very loose aggregates. They’re not solid through and through” said Melissa Morris, OSIRIS-REx deputy program scientist at NASA Headquarters in Washington, D.C. The detailed photos and probe impacting of Bennu and Ryugu reveal rubble-pile natural properties of the NEOs, which will prevent shock wave propagation and proper impulse transfer.
The nuclear blast method is risky and can pose danger both on the ground and in the atmosphere. This type of explosion could potentially create a stream containing hundreds of “city-killing” radioactive pieces, e.g., in the case of disintegrating a sub-km asteroid. Moreover, as follows from computer simulations, shortly after explosion all of the pieces will tend to settle towards the center of mass, which would still be headed on a collision with the Earth.
The asteroid laser ablation method is not viable because of cooling concerns for powerful (over 100 W) lasers. In space, the laser source will not have a means to radiate heat quickly enough to avoid damage to itself.
As of now, it appears that asteroid ablation using highly concentrated sunlight is the only method that meets all of the following criteria: scalability up to global-threat sizes and any type of hazardous bodies owing to maximum thrusting power without huge volume of propellant, as well as low cost and environmental friendliness. This method creates thrust similar to the laser ablation method, creating a natural rocket out of the asteroid, without the power and heating concerns.
An improved concept for such solar-based deflection using an innovative solar collector was proposed and substantiated in 2013 – see https://link.springer.com/article/10.1007%2Fs11038-012-9410-2
and also a short demo-video
You apparently don’t know how a nuclear deflection would work. It is not a matter of blasting the asteroid apart. Instead the nuclear charge(s) are set off some distance from the asteroid. In space the fission/fusion energy will go almost completely into radiation and high-speed ions which ablate one side of the asteroid and the reaction from the ablated material will change the orbit of the object.
Surprisingly this is a much less violent method than kinetic impact and as it will affect one whole “hemisphere” of the object is unlikely to break it up.
The optimal method is gravity tugs, but this is very slow and will require a very long warning time.
For comets the warning time will always be short and nuclear deflection the only pracical alternative.
Regarding the inefficiency of the impact method – see:
Deflecting by kinetic impact: sensitivity to asteroid properties
Bruck Syal, Megan; Michael Owen, J.; Miller, Paul L.
Icarus, Volume 269, p. 50-61, 2016.
(In this model, asteroid Golevka (approximately 500 meters across) is impacted by a 10,000 kilogram mass roving during 10 kilometers per second along a principal pivot of a asteroid. The final change in asteroid quickness for this instance is approximately 1 millimeter (!!!) per second).
Non-destructive explosion (insufficiently powerful) will have a similar (weak) result, and powerful one is only an increase in danger …
The gravity tug is really very slow (it is obvious), therefore I emphasize again: «most of proposed approaches to planetary defense are neither effective nor scalable even to asteroids capable of country-wide destruction». So it appears that the solar approach is the best. Is not it?
In addition to my previous reply.
Well-known estimates show that in order to sufficiently divert the sub-kilometer asteroid with a warning time of less than a year, it is necessary to vaporize up to several hundred thousand tons of its material, which should fly off in approximately one direction (jet-type ejection). Such mass corresponds to a layer thickness around ten centimeters on the half surface of the asteroid. This is possible with prolonged local ablation using highly concentrated sunlight, which is able to burn out a “hole” or “trench” on a rotating asteroid about a meter deep in just one hour. However, this is not possible even with a series of distant and impulse fission/fusion explosions that vaporize (due to both particles and electromagnetic radiation) a thin layer of the surface with subsequent chaotic ejection of material in all directions from the convex and too uneven surface of the target.
Viktor wrote: “The asteroid laser ablation method is not viable because of cooling concerns for powerful (over 100 W) lasers. In space, the laser source will not have a means to radiate heat quickly enough to avoid damage to itself.”
The scientists quoted below didn’t mention any cooling problems that would prevent them from operating a large, space-based laser for use in deflecting killer asteriods. Do you know something they don’t?
https://phys.org/news/2016-03-laser-weapon-earth-killer-asteroids.html
“Generally speaking, the technology is available today. The main challenge with building a full DE-STAR is the necessary scale to be effective,” Qicheng Zhang of the University of California, Santa Barbara, one of the authors of the project, told Astrowatch.net.
Zhang and his colleagues claim that if DE-STAR had a 330-feet-wide phased laser array, it could divert volatile-laden asteroids 330 feet in diameter by initiating engagement at about two million miles.”
end excerpt
I am interested in your sunlight-powered alternative although I know nothing about it. I assume it has to match orbits with the target asteriod, and you say it has to be *very* large in order to handle large asteriods, so I’m wondering how that’s going to work.
It would seem to be much easier to target the killer asteriod from an orbit in the Earth/Moon system where we can build the power supply as large as is necessary (the Solar Power Satellite) and we don’t have to match orbits with anything. Some of the mirrors you are talking about building are as big as the asteriod they are supposed to move, and all this material has to be put into a matching orbit with the killer asteriod. Or do I have something wrong?
Using a laser in close proximity to the killer asteriod will cause material to ablate from the asteriod and this material could interfere with the laser’s operation, although there are those who claim this can be overcome.
Actually, I don’t know why the authors of DE-STAR “forget” to mention that there are no materials in nature whose thermal conductivity is sufficient to remove heat from the core of a quasi-continuous kilowatt-class diode laser. It is possible that this is a consequence of “publication only for publication” … I am a Ph.D. in physics and astronomy and have participated in the use of relatively powerful lasers of this type. Even air convection, which is ten times more efficient than radiant cooling, will not be enough. But convection in open space “is absent”, therefore, such a fundamental limitation exists regardless of the size or type of the passive heat spreader and heat sink for the entirely cooling. The only way to cool of powerful continuously or quasi-continuously operating lasers is to use active fluid systems (“water loops”) with open-type refrigerators, the use of which in open space is impossible.
Regarding the method in which use highly concentrated sunlight for local ablation of an asteroid, which has been used for several decades in huge solar furnaces for the evaporation of solid materials. The details of this approach (dimensions of the collector-concentrator, degree of concentration, exposure time, relative positions, etc.) are described in my publication and partially shown in the video – see my first post. In particular, a concentrator with a diameter of about 200-300 meters is sufficient to deflect a sub-kilometer asteroid within a warning time of less than a year. The location of the concentrator at a great distance from the asteroid will lead to an increase in the size of the focal spot and, consequently, to a dramatic decrease in illumination and heating of the target – this is dictated by insurmountable factors: the laws of optics and the divergence of sunrays. By the way, at “about two million miles” distances, the laser beam will also be significantly expanded, which will lead to its inefficiency.
You are absolutely right that “using a laser in close proximity to the killer asteroid will cause material to ablate from the asteroid and this material could interfere with the laser’s operation.” A similar (technological, but not fundamental!) problem should also be solved for solar concentrators, among which the type I proposed is least affected by the possible polluting effect of the ablated material.
Thanks for that reply, Viktor. It looks like more study on my part is required.
Well, a 300-meter mirror seems to be very doable. Perhaps some type of inflatable design would be worth exploring. That would reduce the mass. I had trouble viewing your video. I’ll try again later.
I’m also interested in your device as a possible means of illuminating the interior of a large space-based Oneill-type Habitat (Gerard K. O’Neill). Of course, we would want to dial down the intenisty of the sunlight somewhat. 🙂
One of the approaching problems — a real problem, not AGW style — is the huge government debt in a large part of the developed world. I had a very interesting discussion with an economist who pointed out the solution was either massive inflation or war. My solution is for a world programme of space defence as spelled out in a short story, Hittile , in one of my collections on Amazon.
It might even unite humanity…. nah, sorry.
JF
All of this illustrating Vilfredo Pareto’s Power Rule distribution; of impactors and effects, and of commentators and their affect.
Space is huge, sure the rocks come flying by, but they miss by huge numbers.
It was within the Moon’s orbit, 200,000 mile radius sphere is huge, the Earth is just a dot.
Inside a geosynchronous orbiting satellite, still a lot of margin. think a marble inside a basketball.
so it hits the planet, its a city killer, the Earth is 70% water, and Urban areas are only 3% of land area.
I like our odds, as long as it isn’t a big one.
“… Perhaps it is humanity’s role to defend the planet.”
No. The planet is an inanimate object. It doesn’t give a rat’s u-know-what whether it is completely destroyed or not.
… Perhaps it is humanity’s role to defend themselves…
🇺🇸⭐️⭐️🇺🇸 The folks had better start paying attention to the Ancient Hebrew Scriptures.
Revelation 8:8 And the second angel sounded, and as it were a great mountain burning with fire was cast into the sea: and the third part of the sea became blood; KJV
“Elenin, Planet X, Nibiru, is Wormwood: The logic is Undeniable” Prophecy page Video.
Click my name to watch the video.
Actually that “great mountain burning with fire” seems to be the Cumbre Vieja volcano on the Canary Islands. But the next trumpet judgment of “a great star falling from the sky, blazing like a torch” would seem to be the Apophis asteroid, scheduled to hit on Friday the 13th of April, 2029.
Notify me of follow-up comments.
Only slightly OT I was wandering around Wikipedia and came across this:
‘On 29 August 2006, a 90% iron meteorite weighing 6.8 kilograms fell in Kanvarpura village, near the power station [Rajasthan Atomic Power Station]. The Deputy Director-General (western region) of the Geological Survey of India, R.S. Goyal, said that devastation on an “unimaginable scale” would have ensued had the object struck the station.’
What does the panel think? Would a piece of stuff I could easily lift with one hand bounce off doing no damage at all? Or would the kinetic energy involved be enough to cause Mr Goyal’s “devastation on an unimaginable scale”?
The probability of a CME is much greater than an asteroid. There has been 2 events(that we know of) in the last 1000 years which would send us back to the stone age. We just missed another major CME by 9 days in 2012. Worrying about asteroids when you are not hardened against a CME or EMP is foolish. You need to prioritize your risk and plan accordingly.
Tell that to poor lil Greta, and she will have a nervous breakdown thinking everything thing that go wrong, just not the climate! If the asteroid don’t get you, the CME and EMP will. True, but all have fairly long odds and when something does go wrong significantly with one of the above, it will not be a good day. We pays our monies and takes our chances…every day. Odds are higher we will get run over by a bus or die from an infection.
Articles like this are a form of hypochondria accompanied by a fear of the known. The idea that we should spend massive amounts of money and effort on a quixotic quest because of a vague theory, and then to push this with hysteria (with absurd solutions) is scientifically unsound.
The actual science has shown that space is far more dangerous to humans than anything on earth. Further, all the actual scientific evidence right now is that humans aren’t going to be leaving earth any time soon in self-sustaining colonies that would persist. We can’t even maintain McMurdo station without a constant stream of supplies! The arrogance to believe we can successfully colonize other planets is scientifically irresponsible at this point.
This is very similar to the global warming scam; frighten everyone to give an elite power and money.
(One sign of this is quoting Arthur C Clarke, a fantasist, as though he had scientific legitimacy. The truth is, we aren’t sure meteors have caused any mass extinction events. Opposing views are being continually shouted down by the same time of nonsense that has held up science to many times in the past. Frankly, we do have pretty good evidence that super volcanoes, and plate tectonics in general, and the sun itself are far bigger threats to the survival of humanity that errant asteroids.)