Surviving the Next Doomsday Asteroid Impact

One day, as has happened many times before, a large asteroid thousands of metres in diameter will hit our planet.

The result of the impact will rain hot debris across the entire Earth, heating the atmosphere to an oven-like temperature and shrouding it in dust clouds. Fires will burn for years adding billions of tonnes of soot to the atmosphere, and then the global temperature will fall dramatically. Photosynthesis will grind to a halt. Almost all species of plants and animals will perish. The only survivors will be those lifeforms that are able to eat the remains of long dead life, such a cockroaches and deep sea creatures.

The collision of a large asteroid thousands of metres in diameter with our planet will almost certainly result in the extinction of most lifeforms. It is unlikely that humans would survive.

If such an impact happened now humans would not survive. The extinction of our species would be certain. Essentially, life on Earth would be reset to the point just after the last massive impact event 66 million years ago (the Cretaceous-Paleogene extinction event that caused of the extinction of the dinosaurs).

By the next century we are likely to have permanently inhabited colonies on the Moon, Mars and possibly even beyond, but there will be a few hundred inhabitants at best. And most crucially those colonies will not be self-sufficient. If Earth is rendered uninhabitable and our civilisation destroyed then those colonies will die soon after. It will be a couple of centuries until self-sufficient colonies with tens of thousands (preferably millions) of people exist away from our planet. Until then we will need sanctuaries on Earth where a significant human population can survive should a massive asteroid impact occur. And by 'significant' I mean several million people at least.

The cost of building such underground sanctuaries would be extreme, and it would take decades or longer before they were ready for habitation. Hundreds of billions of dollars would be needed each year, and a workforce of millions. But it is actually affordable and achievable, if only the world's governments could be less paranoid and divert some of their defence spending to the project. The total spending each year by NATO members (29 European and North American countries) is more than one trillion dollars. If just a quarter of that budget could be redirected then the underground sanctuaries for North America and Europe could begin construction. If the likes of Russia, China, Japan and their neighbours did the same then sanctuaries in their region of the world could begin construction, too.

After a century of construction and expansion, the main chamber of a vast underground sanctuary, deep beneath mountains in Europe, is home to a thriving city of a million people. Powered by geothermal energy, the sanctuary is a self-sufficient haven for humans, one of several spread around the Earth. Even the impact of a large asteroid, such as the one that resulted in the extinction of the dinosaurs and many other species, would not lead to human extinction if such facilities exist.

Each sanctuary would need to be hundreds of metres underground, with locations beneath mountains the most preferable. As well as hundreds of kilometres of tunnels and smaller chambers there would need to be huge areas for agriculture, and even larger caverns to create the feeling of space and distance we have evolved to need, if only to maintain the sanity of individuals. Power could be generated using geothermal technology.  Energy generation using geothermal power stations currently provides 30 percent of the electricity requirements of Iceland, with the Philippines not far behind that. It is a relatively clean and renewable source of energy and would be ideal for subterranean habitats. New power generation technology, such as nuclear fusion, will hopefully be perfected over the next decades, which could provide almost unlimited power capabilities.

One of the many farming chambers that surrounds the main city of each of the underground sanctuaries. Agricultural facilities such as this, powered by geothermal energy, or even fusion energy, provide food for millions for thousands of years in the event of a catastrophic incident up on the Earth's surface.

Once created the sanctuaries would need to be permanently occupied to a high capacity: at least 50 percent. This is necessary to ensure that the sanctuaries are fully functional and under constant maintenance. They should be regularly assessed to identify areas of improvement. They would need to be totally self-sufficient if the need for them arises. There would hopefully be many months, if not years, of notice before a large impact would occur, giving plenty of time for people to migrate into the sanctuaries.

There are ethical and moral issues with regards to who would be selected to migrate into the sanctuaries should an extinction level impact be confirmed. The choice of certain sections of the population is obvious: there needs to be specialists in all areas of science and technology (engineering, medical, computing, utilities, agriculture etc) and also educators; it will be essential that education levels are maintained for the generations that will live in the sanctuaries, so schools and universities would be required.  The majority of inhabitants, however, will be ordinary citizens with ordinary levels of education and skills. Whatever method is used to choose which of those individuals and families are chosen - a lottery, or genetics (to maintain the diversity of the gene pool) - there would be objections, protests and even wars fought no matter who is chosen (there would be nations of the world without any access to sanctuaries of their own). Great care would need to be taken to ensure that the security of the sanctuaries is maintained and the chance of sabotage is kept to a minimum.

The selection of who is to migrate to the sanctuaries, and how to prevent attacks on them as they travel there, will perhaps be a more troubled process than the construction of the actual sanctuaries themselves.

Of course, it would be best if a cataclysmic asteroid collision was prevented altogether. There are numerous proposals to deflect or destroy asteroids that are identified to be on an eventual collision course with Earth. None of them has yet been tried, and all of them required many years, or even decades, of warning. Research into such methods should be intensified and an effective asteroid defence system should be implemented as soon as possible. The underground sanctuaries would allow a small percentage of our human population to survive the aftermath, but they should be considered a last resort. The need for then should ideally never arise.

Developing the ability to deflect or destroy asteroids on a collision course with Earth is essential to prevent the extinction of our species. A joint NASA and ESA mission in 2020-2021 will perform the first test of such technology.

If we construct several underground sanctuaries around the world, and deploy a system capable of destroying or deflecting asteroids, we stand an excellent chance of surviving as a species even if an object many tens of kilometres wide collides with our planet, and of eventually repopulating the surface once its ecosystem has recovered.

But, before the creation of the underground sanctuaries can happen we need to cultivate a will to change our thinking and work together for the greater good and the very preservation of our species and the wider ecosystem on which we depend. If we fail to do so we will fail all of humanity, and our extinction will be assured.

Living Inside Asteroids

For humans to live long-term in space we would need a healthy environment. This would mean somewhere spacious, with plenty of the comforts we find on Earth. And most importantly, we would need gravity, or at least a simulation of it.

Large space stations could be built with all of the above. With a large enough diameter they could be spun at less than two revolutions per minute, which would eliminate the uncomfortable symptoms of the Coriolis effect that would be experienced at the higher revolutions of a small rotating space station. Due to the huge amounts of material needed for construction of such stations, and the immense cost of launching it from Earth, the materials to construct the space stations would realistically have to be mined from asteroids.

A large diameter space station under construction in the Asteroid Belt. A single large asteroid will provide more than enough material for the construction of the station. Concept by Deep Space Industries.

Asteroid mining will not only provide the huge amount of construction material necessary for space habitats. If the asteroids are mined in a certain way, making large cylindrical chambers through the asteroid's centre of rotation, we could then convert the chambers into living spaces. Once mining is concluded the rotation of the asteroid could be altered until a high-enough centrifugal force provides enough artificial gravity comfortable for humans on the chambers' outer walls.

Such chambers, several kilometres in diameter, could well provide what may become the safest and most comfortable human living spaces away from the Earth.

Of course, the idea of hollowing out space inside an asteroid is not a new one.

This image was created in the 1960s by Roy Scarfo when the exploration and colonisation of the asteroid belt was being researched by Dandridge M Cole.

In the 1960s Dandridge M Cole, an aerospace engineer and futurist, was one of the first to propose hollowing out an asteroid and spinning it on its long axis to simulate gravity. Illustrated above, he envisaged a large single void within the asteroid with fields, lakes and villages. Sunlight would be reflected into the interior using mirrors. It would be a spacious and comfortable environment.

It's an impressive concept, but there are numerous problems with it, and not least the idea of a single huge chamber and relatively thin wall. It would make the asteroid habitat vulnerable to complete decompression if the wall was compromised in some way. If the rotation provided one gee of gravity the forces on the wall, especially at the asteroid's equator, would cause it to fly apart as soon as any cracks or flaws developed.

The very green and pleasant interior of Dandridge's asteroid habitat concept

It would be far better to cut several cylindrical voids, and have the outer walls very thick - several kilometres at least, depending on the overall size of the asteroid. Each chamber would be connected to the next, but with the ability to quickly seal off a particular chamber if it was compromised and at risk of decompression, or indeed some other dangerous event. Those living in the effected chamber could easily be evacuated to another chamber, making such asteroid habitats safe and with plenty of redundancy.

Once the chambers have been excavated the asteroid's speed of rotation can be increased slowly, until the right level of simulated gravity is reached. To generate an equivalent of one gee (the same as what we experience on Earth) the rotation speed would be quite substantial, and it would mean that, at the very least, loose boulders and dust would be thrown off the surface of the asteroid. It would also put considerable stress on the outer surface, which would rule out low density asteroids due to the high risk of instability.

A natural habitat for Earth life, many kilometres in diameter, created inside a hollowed out cylindrical chamber within an asteroid. Typically there would be a few such chambers. All would be linked but each could be sealed off should a disaster occur, which would protect the other chambers.

A supporting series of collars around the equatorial region of of the asteroid would negate many of the issues that such a high centripetal force would cause. It would be a huge construction task to build such collars, but no more than the excavation of the chambers themselves. Of course, the excavated material would provide everything required to build the collars, each of which could be many kilometres in width. They would be held in place by deep supports.

Visiting spacecraft would using large docking areas at the poles of the asteroid, situated at each end of the axis of rotation. People and cargo would then be transported through the asteroid along the axis of rotation. Essentially there would be zero gravity in this area. When the destination chamber is reached the visitors and cargo would be delivered to the surface using elevators. People descending in these would experience a steadily increasing sensation of weight as they approached the surface.

A diagram showing how the interior of a rotating asteroid colony could be divided up into separate chambers. This would provide higher levels of safety (colonists could be evacuated to another chamber if their own is compromised), and more structural integrity than a single large chamber.

It's likely that people arriving at the asteroid will have spent many months travelling in zero gravity so acclimatisation areas at the regular points down to the surface should be built to allow people to adapt gently to the full gravity of the facility.

As well as fairly static colonies inside asteroids in the Asteroid Belt, or in the Trojans, asteroids that are on highly elliptical orbits - that head in to the inner Solar-System and then out beyond the orbits of Neptune and Uranus - would make very useful passenger ships. As the asteroid gets close to Earth (and the probable large colonies on the Moon and Mars) passengers who need to travel to the outer Solar-System could rendezvous with it. They could then spend the next couple of years living in comfort in relatively Earth-like conditions as the asteroid's orbit takes them closer to their destination.

Ultimately, such asteroids could become our first interstellar star ships. They would make voyages lasting thousands of years, with a hundred generations or more of humans living out their lives in comfort until the asteroid is captured by the target star system. With the right energy generation technology such as nuclear fusion that could provide light and warmth during the interstellar period of the voyage, humans would have a relatively good chance of reaching their destination.

Converting asteroids into large human habitats, and then into interplanetary and interstellar spacecraft, seems to be a logical and necessary step as humans embark on colonisation beyond Earth, and it is likely to be an essential step towards securing the future of our species.

The vast resources and protection that such objects can provide must be utilised at the earliest opportunity.

Pre-Human Technology in the Asteroid Belt

I've discussed before the possibility of an advanced prehistoric technological civilisation existing on Earth. But due to geological activity any evidence of such a civilisation is likely to have been lost due to continental plate subduction and other processes. Evidence of a pre-human civilisation from hundreds of millions of years ago will be buried many kilometres deep, and even destroyed completely by the immense pressure and high temperature found at such a depth.

We need to look elsewhere.

An ancient advanced civilisation in Antarctica. Perhaps one of the few benefits of global warming will be to reveal evidence of such lost civilisations. Studying such civlisations could reveal the secrets as to how they left the Earth, and where they went.

If a civilisation had developed to a level high enough for space travel then the moon would be an obvious place to look for signs of its existence, but even there geological processes may have destroyed any evidence. Volcanic activity may well have been occurring on the moon as little as a hundred million years ago.

Fortunately there is another region in the Solar-System where such evidence, even from a billion years ago, could be preserved. Geological activity is almost completely absent there. That region is the asteroid belt.

Of course, asteroids are not completely free of erosionary forces. Impacts would destroy surface artifacts over time, but unlike on Earth the results of activities beneath the surface, such as mining or habitat construction, would be preserved almost indefinitely.

This makes objects in the asteroid belt the prime target for research into pre-human civilisations.

And already, the first purpose built asteroid mission has found what could well be evidence of extensive mining activity.

Ceres

NASA's Dawn mission to the two largest asteroids, Vesta and Ceres, is the only significant asteroid belt mission so far. The probe is still in orbit around Ceres and will remain there indefinitely. The intriguing bright spots seen on Ceres could indeed be evidence of mining activity.

Evidence of extensive mining activity in the Occator crater on Ceres

There is also an unusual mountain, named Ahuna Mons, in another region of Ceres that could be a huge mound of excavated waste material, much like the slag heaps found near mines on Earth.

A mountain of excavated material on Ceres

Such discoveries on Ceres show that it must be explored in much more detail from the surface. A lander, rover, or even a manned mission is needed.

If one of the first asteroids to be orbited by a dedicated probe throws up such compelling evidence of a pre-human civilisation, it's highly likely that others will, too.

16 Psyche

Another very interesting body in the asteroid belt is 16 Psyche. The asteroid is unique in its composition - almost pure iron and nickel. Nothing else like it has been discovered in the Solar-System. It's possible that it once had an exterior of rock and ice, and that it was once a planet, and that that exterior was blasted away completely by an unfortunate set of collisions with other massive objects. But the likelihood of that is very small.

16-Psyche - possibly the most heavily mined object in the Solar-System

Another explanation must be found. It could well be that the rocky outer shell was intentionally removed, and if that's true it would probably be the most incredible evidence of mining that we could ever find. It's no surprise that NASA has recently announced it will be sending a probe to 16 Psyche, which will arrive in 2030.

If such a huge amount of material was mined it would be enough to construct thousand of starships and habitats, certainly enough to provide a refuge for millions for a civilisation that needs to evacuate its home world. 16 Psyche could be hiding the evidence of the ancient technological civilisation that lived on Earth hundreds of millions of years ago.

Humans explore one of the last surviving tunnels on 16 Psyche

The evidence of a civilisation that we may find in the asteroid belt may not have originated on Earth, of course. It could have been from Mars or even Venus, both of which seem to have suffered catastrophic climate changes. Such changes would have prompted any advanced civilisation on those worlds to do everything possible to preserve its species. It could have set up home on Earth (it could have formed one of the long extinct Earth-based civilisations), but at that time the Earth's atmosphere would probably have been unsuitable. What's more likely is that the species utilised the vast resources of the asteroid belt to construct interstellar starships (see my earlier article on the evacuation of Mars).

It's thrilling to think that when we do identify life-bearing planets around other stars (which I'm confident we'll do within the next few decades) the life we're observing may well have originated in our Solar-System.