Intelligent Life on Earth 56 Million Years Ago

Almost 56 million years ago the Earth's climate suffered a fast and significant warming. It's quite possible that an ancient industrial civilisation was intensely active at that time.

The warming, known as the Paleocene-Eocene Thermal Maximum, was due primarily to a rapid rise in carbon dioxide levels in the atmosphere. The event may have happened over a very short period of time, possibly as short as 1,500 years, and the number of species that went extinct rose to several times that of normal levels.

During that period the average temperature was already several degrees higher than today, meaning there were no polar icecaps, but nevertheless sea levels rose due to thermal expansion. If a civilisation existed at that time it would have had to deal with relatively rapid changes to its coastal habitats and to weather patterns.

The parallels with what is happening to our climate right now are eerily obvious.

If the warming was due to the activities of an advanced civilisation it is likely that the rapid climate change was responsible for its demise. Finding out exactly what happened could give us valuable information that may help save our own civilisation.

A city on Earth, more than 56 million years ago. During that time the climate warmed rapidly. The civilisation that existed at that time would have found its existence increasingly threatened as a result of its unsustainable use of the planet's resources. We are facing the same threats. We must find a way to avoid making the same mistakes that that were made by previous advanced civilisations on our planet.

Finding the evidence of a civilisation that existed 56 million years ago is extremely difficult. Over such a timescale geological processes (plate tectonics, weathering and erosion) would wipe the Earth's surface clean of almost all traces of buildings, technology and transport infrastructure. For example, if our civilisation ended now, within a few million years there would be nothing left of any artefacts we created, or of our urbanisation which only covers about one percent of the surface of the planet. The only signs would be spikes of metals and possible traces of plastics, and certain radioactive isotopes in sedimentary deposits (if we destroy ourselves with a global nuclear war the evidence would be readily detectable millions of years in the future). Such chemical signatures would be the only evidence that we could reasonably hope to find, and even these would be very hard to find if the civilisation was only industrially active for a few hundred years.

If the civilisation had developed space flight capability then that would offer more hope. The best place to find evidence of its existence would be away from Earth. There may well be ancient space probes orbiting within our Solar-System, and on the surface of its airless worlds, that have been preserved quite well. Of course, the vastness of space would mean finding them will still be a challenge, but as we map the surfaces of many of the Solar-System's planets and moons in ever greater detail we may soon find something.

A previous industrial civilisation on Earth millions of years ago may have developed spaceflight capabilities. Evidence of their activities away from our planet would be the best way to prove their existence. Spaceships such as this one may have been built to enable the colonisation of our Solar-System and beyond as an attempt to survive the warming event that their activities on Earth inadvertently caused.

I discussed the possibility of finding evidence of ancient mining activity in the asteroid belt in my earlier article titled 'Pre-Human Technology in the Asteroid Belt'. If such evidence is found then it is possible that the civilisation felt the need to construct interstellar ships to colonise planets around other stars, probably as a way to preserve at least some of their knowledge and culture as the Earth rapidly became hostile to them. Right now there could be one or more Earth-like planets in nearby star systems that are thriving with the descendants of Earth life. The civilisation that populated those worlds may still exist, or another may have since risen to take its place. Perhaps they even returned millions of years later and influenced the rise of human civilisation on Earth.

Colonists from a pre-human Earth civilisation walk upon their new world. Their civilisation's activities on Earth millions of years ago damaged the climate to such an extent that their species faced extinction. Colonising an Earth-like planet orbiting another star seemed to be the only way for their species to survive. Perhaps one day, when we are able to visit other star-systems, we will discover life descended from Earth life.

The rapid climate change 56 million years ago is not the only time a possible industrial civilisation existed before our current one. There has been speculation that there could well have been a dinosaur civilisation, possibly created by a descendent of a Troodon, that would certainly have ended when the Cretaceous-Palegene extinction event occurred 66 million years ago. And extinction events such as the Toarcian turnover 183 million years ago could also be related to yet another industrial civilisation abusing the Earth's resources.

Discovering proof of the existence of pre-human industrial civilisations on Earth is quite an intoxicating prospect. Life has existed on our planet for at least 3.5 billion years, and life with very complex brains, and consciousness, has existed for hundreds of million of years. There has been ample time for multiple civilisations to rise and fall. The chances are that at least one of them would have developed to an industrial and even highly technological level.

With the right kind of research we will be able to find strong evidence of the existence of such a civilisation. Paleontological and geological expeditions with the sole purpose of uncovering that evidence should begin at the earliest opportunity, and all space missions, past and future, should have their data examined to see if evidence of an ancient technological civilisation is present in our Solar-System. It is exciting to think that there may well be evidence hidden within the vast amount of data already collected by NASA and other space agencies.

If evidence of an ancient pre-human industrial civilisation on Earth is discovered it would have profound implications. It would mean that intelligence, at least to our own level, is a natural and relatively common evolutionary occurrence. And it would mean that industrial civilisations on other life-bearing planets should be common, too.

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.

The Next Mass Extinction Has Begun

There have been five major mass extinction events in Earth's past. During each one more than 70 percent of all species were wiped out.  One of them, the Permian-Triassic event 252 million tears ago, actually killed off about 96 percent of all species.

Most of the events were caused by a significant climate change brought on by a combination of volcanic activity, asteroid impacts, sea level changes and drops in oxygen levels. The most recent mass extinction - the Cretaceous-Paleogene event 66 million years ago - is thought to have been almost entirely due to a massive asteroid strike known as the Chicxulub Impact, on Mexico's Yucatan Peninsula. It has become the most well-known of all extinction events, primarily because it caused the extinction of the non-avian dinosaurs. The dust cloud created by the impact reduced global temperatures by several degrees for decades. After that there was a period of rapid warming due the huge increase in carbon-dioxide in the atmosphere. For up to 100,000 years the global temperature was an average of five degrees higher. There was little time for most species to adapt.

An artist's impression of the Chucxulub impact crater a few hundred years after the asteroid hit. The crater is about 150 kilometres in diameter, and up to 20 kilometres deep.

There will be another mass extinction event - a sixth massive reduction in the number of species living on this planet. That extinction event, known as the Holocene extinction, is already under way, and its cause seems to be exclusively linked to human activity.

Humans have been responsible for extinctions for many thousands of years. The mammoth, which had been in decline as a species since the end of the last ice age more than 11,000 years ago, is one of the first examples. It was finally hunted to extinction 5,000 years ago. This was the start of our destruction of our planet's ecosystem.

Over the last century our rapid advance into a global technological civilisation, and our massive population growth, has lead to extremes of habitat destruction, over hunting, pollution and subsequent climate change. Without a drastic change to our activities most species will be extinct within a few centuries. Humans will have caused the fastest and most extreme mass extinction ever known on this planet. And it is more than possible that our own species will be one of those driven to extinction as the ecosystem we rely on collapses.

To survive as a species we need to do two things. And we need to do them now.

1. Halt our Destruction of Earth's Ecosystem

An extreme level of cooperation between the governments of the world's nations is required if we are to stop, or even just slow down, the climate change caused by our activities. And that cooperation needs to start this year. Unfortunately, as always, governments seem preoccupied with political, economic and territorial disputes. Climate change, and its effect on our very survival as a species, seem to be far down the list of priorities.

Radical policies are needed, with developed countries pushing for the complete replacement of fossil fuels with clean energy generation within a decade. Nuclear energy, despite its controversial nature, is very clean compared to coal and gas burning. In fact, nuclear energy generation produces zero emissions, and very little waste due to the density of nuclear fuel. The land required for a 1,000 megawatt nuclear energy generator is only about one square mile, compared to 75 square miles for the equivalent solar power plant. As well as building many more nuclear power stations, solar and wind power generators should, of course, be expanded rapidly, too. This will accelerate the closure of coal and gas power stations.

The massive and ever increasing human population on Earth needs to be ethically controlled. Developing countries in particular need immediate help to remove the need for people to have more than two children. If population growth is not controlled it is predicted that there will be almost ten billion people living on this planet by 2050 (up from 7.6 billion now). The demand on resources is already unsustainable. With such an increase we are condemning billions to starvation.

2. Build Self-Sufficient Colonies Away From Earth

The creation of self-sustaining colonies away from Earth should have started decades ago, but at least there seems to have been some recent minor progress towards such colonies. NASA have brought forward plans to get humans back to the Moon. It will create a sustainable human presence on the Moon by the middle of the next decade, and the Gateway, a space station in orbit around the Moon, will be a staging post for crewed missions to Mars.

NASA's space station orbiting the Moon. Construction is expected to start as early as 2022. It will be used as a staging post for Moon landings, and as a stepping stone to Mars.

While NASA does not seem to have much of a timeline beyond for the crewed missions to Mars (other than 'sometime in the 2030s') the plans for the Moon seem to be quite well defined, and impressively ambitious. The resources of the Moon can and will be used to manufacture the fuel for future missions to Mars.

This relatively sudden new momentum is encouraging, and must continue.

As soon as a permanent settlement is established on the Moon the missions to build one on Mars must begin immediately. No time can be wasted. And as the Mars colony grows in the 2030s there must then be a push to establish colonies further afield, such as on Jupiter's moon, Callisto (which orbits outside of Jupiter's harsh radiation belt - see 'Humans on Callisto within 15 Years'), and on Saturn's moon, Titan. Despite the extreme cold Titan is particularly suitable for a very large human colony - see my article, 'Human Colony on Titan' for more on that subject. In fact, it seems to be one of the best places to create a very long term human presence.

There must also be space-born colonies: vast habitats that do not rely on a planetary body and that can exist in their own independent orbits around stars and in interstellar space. They would obtain all the resources they need from small asteroids and comets, found abundantly for example in the Kuiper belt and the Oort cloud.

Will this century be the last time we'll be able to look down on Earth from space? Is the damage to the environment and climate caused by human activity already beyond recovery? If so, our technological civilisation will soon end.

If we do nothing to limit the effects of the current extinction event then we certainly deserve our fate. If our species becomes extinct then at least our destructive activities will cease. Earth will begin a slow recovery and a new climate equilibrium will allow a host of new species to flourish. Over many millions of years the Earth will become a thriving and lush haven for life, at least until another highly intelligent species starts to dominate and abuse its environment.

Is it possible that some of the many smaller spikes of extinction and climate change in Earth's past were caused by a dominant intelligent species that brought about their own demise? We could simply be continuing a natural cycle of events that has already played out on this world and millions of others. That cycle needs to be broken right now, before we doom yet another of Earth's civilisations to oblivion.

Nuclear War - Our Biggest Immediate Threat

Climate change is considered the main threat to our civilisation. Over the life time of the human generation being born right now our planet will almost certainly experience a significant detrimental effect from the amount of greenhouse gases that have been pumped into the atmosphere by our  activities. The increase in the number of forest fires in North America, flooding in Asia, and longer and more intense heatwaves in Europe is just the beginning.

It is not impossible to slow down or even halt such effects, but the huge political, economic and social changes necessary make it very unlikely that the nations of the world can come to any sustainable agreement on what to do.

As the effects of climate change intensify over the next few decades there will be severe pressure on the countries worst effected. Ultimately wars will break out as failing harvests, flooding and desertification force desperate nations to fight for the resources that other less effected nations are holding.

An artist's impression of how Miami would look with the relatively small sea level rise expected with a 1.5 - 2.0 Celcius temperature increase. It is now expected that a 3 Celcius increase is likely by the end of the century without drastic action. Such a sea level rise will displace hundreds of millions of people from coastal areas and leave major cities abandoned. Wars are inevitable.

The recent report by an Australian think-tank that civilisation is likely to end by 2050 is not at all far-fetched, but civilisation is likely to end much sooner if the political situation in many leading countries continues to radicalise. There will be little attention given to climate change by the leaders of such countries, which will be disastrous as some of them are the very ones with the ability to actually do the things necessary to limit the effects of such change. There is an ever-increasing chance of a major war between those nations. And such a war is likely to quickly escalate out of control. There could well be an exchange of nuclear weapons, which will have an immediate and devastating effect on our climate, far and above that of the climate change expected from our normal activities. Even the use of just a few low yield nuclear weapons would have a worldwide effect.

One likely scenario is between India and Pakistan: both nuclear powers. Pakistan, one of the most 'water stressed' nations on Earth, relies on water flowing from India. If India diverts that water (which it has already threatened to do in part, in response to a terrorist attack in Kashmir) and Pakistan suffers droughts then it may become desperate enough to destroy India's dams. India would retaliate. And then Pakistan, desperate and pushed to the brink as its citizens protest and riot, may feel it has no choice but to launch a nuclear attack. India will certainly respond in kind.

A long range nuclear missile launching

As well as destroying large parts of both countries and killing hundreds of thousands almost immediately, the effects of such a regional nuclear conflict would be felt across the world. Even conservative estimates predict that five million tonnes of smoke would be released into the atmosphere and trigger a nuclear winter of two to three decades, reducing global temperatures by two to four degrees and decimating the protective ozone layer (removing most of our natural protection from UV radiation). There would be widespread famine as food production is significantly reduced. Skin cancer would become common place.

Of course, the threat of a major nuclear war has been present since the 1950s, but since the end of the cold war the strict controls and mutual understanding and respect of the nations with nuclear weapons seems to have eroded. The threat of such a war breaking out is increasing day by day, and the rhetoric and threats of the major nuclear powers recently does nothing but exacerbate the situation. Russia has recently exited the INF (Intermediate Nuclear Forces) treaty following the exit of the USA a few months earlier. Nuclear arsenals are being modernised and upgraded., and a new type of missile that can travel at hypersonic speeds (greater than Mach 5) is in rapid development by Russia, China and the USA (and France recently became the first European country to announce a desire for such a weapon).

A hypersonic missile seconds after launch. It would only take it a few minutes to travel hundreds of kilometres, and it would be unstoppable with current defences. It is in development by the major world powers and is a highly destabilising weapon. 

Hypersonic missiles, against which there is currently no effective defence, can hit a target in minutes at an incredible speed. They are designed primarily to carry conventional weapons (but could carry small nuclear warheads if required), and one White House official has even dubbed them 'instant leader-killers'. This suggests one use for them: a means to assassinate the leader of a nation virtually without warning and with almost no risk of the missile being intercepted. Such an ability is incredibly destabilising.

The amount of money spent on military defence around the world is staggering. In 2018 the world's governments spent more than $1.8 trillion. The USA alone accounted for just over a third of that. We are spending about 28 times more on military hardware and development that we are on tackling climate change. To put it simply: we seem to be more concerned with securing our self-inflicted annihilation than securing our survival. Imagine what could be achieved if we could divert even just ten percent of that spending from defence to renewable energy production, for example?

One of the most chilling explanations of the Fermi Paradox (which refers to the contradiction of the lack of evidence for intelligent extra-terrestrial life when observations suggest it should be quite common) is that civilisations destroy themselves soon after developing radio or spaceflight technology (and with it the technology to wreak mass destruction). We now have that capability. It is quite likely that a nuclear war will end our technological civilisation, and the subsequent immediate climate change will almost certainly result in our near or actual extinction. And if we manage to avoid such a war, it seems that we may well be too late in trying to tackle the climate change that is happening now.

As I've discussed before, our survival instinct, which has served us well up until now, continues to ensure that we will develop more and more powerful weapons to defend ourselves, and allow us to forcefully take what we need to survive. Ironically this instinct now seems to be taking us closer to extinction. Our natural instinct to be suspicious of others seems almost impossible to overcome. We are unlikely as nations, and even as individuals, to cooperate enough, and to put aside our differences, to work together and sacrifice some of our comforts in order to stop climate change or the risk of a nuclear war.

If we can survive the next few decades, and work together instead of feeling the need to build ever more destructive weapons with which to destroy each other, our civilisation will be well on the way to expanding beyond Earth and creating colonies on and around other planets. Pictured here is the impressively conceived Venus cloud colony.

If it's true that almost all the intelligent civilisations in our galaxy destroyed themselves soon after they developed the ability to do so, then it is likely that we will too if there is not a radical change in our behaviour. We must strive to be one of the exceptions. We need to grow beyond our blind sprint towards our own destruction. It is the only way we can avoid an eventual nuclear war. And it is the only way we can tackle climate change and save our planet. If, against all odds, we manage that then we will be well on the way to expanding our civilisation beyond the Earth. Our long term survival as a species will then be assured, and we will take our place among the select few civilisations that overcame their self-destructive tendencies.

There is still time. There is still hope. But both are dwindling fast.

Tiny Moons - The Perfect Hiding Places

The Solar-System's smallest moons, many of which are only just being discovered, may hold vital clues as to the nature of the activities of extra-terrestrial civilisations in our region of the galaxy.

I've mentioned before the possibility that there are abandoned extra-terrestrial facilities in the Solar-System. In 2014 in my article 'Atlas and Pan - Saturn's Generation Ships' (and in a recent follow-up 'Saturn's Unnatural History') I discussed the prospect that Saturn's unusual moons, Atlas, Pan, and Daphnis, could well be huge star ships that arrived in our star system millions of years ago.

Saturn and its moons seems to have been a system of great interest to extra-terrestrial visitors many millions of years ago.

Atlas, Daphnis and Pan: Saturn's unusual moons that may well be abandoned star ships. The amount of dust covering their surfaces suggests that they were abandoned many millions of years ago.

This has had me thinking more and more about the smallest moons in the Solar-System. They are very hard to find, even when a space probe is in orbit around the host planet for many years. Very recently 12 new moons were discovered orbiting Jupiter. They are all very small, the largest no more than five kilometres across, and many are in a retrograde orbit. It's surprising that the Galileo spacecraft, which was in Jovian system for 8 years from 1995 to 2003, did not see those moons at all, but it's not surprising that they exist. Some of them may well have been placed there intentionally. Such moons would be ideal locations for clandestine colonies to hide, and for passive surveillance equipment to be placed to monitor our civilisation's development.

Calypso, one of the trojan moons that shares the orbit of Tethys, one of Saturn's moons. Calypso is just under 11 kilometres in length. It would make an ideal observational outpost.

Four of Jupiter's other small moons that are also of interest are Telesto and Calypso (above), which are trojan bodies in the same orbit as that of the large moon Tethys, and Helene (below) and Polydeuces, both trojan bodies of the large moon Dione. It would be very easy for an advanced civilisation to conceal passive monitoring technology on such moons, and keep it hidden even after a technologically capable civilisation such as ours had made very close observations.

Helene, one of Dione's trojan companion moons

Another example is Neptune's 14th moon, which was discovered in 2013 and recently named Hippocamp. It was found hidden in some of the Hubble Space Telescope's old data. At just under 35 kilometres in diameter, and dark in colour, it's no surprise that it was missed when Voyager 2 passed through Neptune's system in 1989. This small moon is another ideal example of an object large enough to sustain a colony, but small enough to be largely ignored.

An artist's impression of Hippocamp, the recently discovered moon of Neptune. At just under 35 kilometres in diameter it would be large enough to sustain a colony, or host a wealth of clandestine observational equipment, but it is small enough to go unnoticed, and to be largely ignored when eventually found.

To understand why extra-terrestrial explorers would make use of such small moons, we only need to consider why we would use such moons in a similar situation. If humans found a star system with a life-bearing planet and we were able to visit that system we would want to learn as much about that life as possible. How advanced that life is would determine how we would monitor it without affecting its development.

If the life was primitive and consisted of nothing more than simple plant and animal life, such as during Earth's Ordovician period almost half a billion years ago, then probes in close orbit of the planet, and even airborne craft in its atmosphere, could be used. Surface missions could also be permitted (under very strictly adhered to planetary protection protocols) to gather samples. A permanent surface base would be possible.

If intelligent life was detected, but it was still in the early stages of building a civilisation such as bronze age societies, then close orbital probes would still be possible. Missions to the ground would be unwise anywhere but the most remote and underpopulated areas, but high altitude airborne flights could be done over populated areas. Such early civilisation would have little understanding of things beyond their immediate environment, but they would be curious, so great care would have to be taken not to be noticed.

Monitoring the development of a civilisation capable of producing art such as this from the bronze age in China more than 5,000 years ago would need to be done very carefully to avoid influencing their development

If there was a more advanced civilisation at the level of a pre-industrial society where it is likely that scientific research into what lies beyond the atmosphere is being done, close orbital probes should be avoided as they could be seen. Monitoring should be done from high geostationary orbit. Research bases on the planet's moon(s) or nearby bodies should be used.

If there is a technologically advanced civilisation that is able to launch space missions, then it should be monitored well away from the planet. The small moons around that system's other planets would be ideal, as they will remain undetected for much longer, and are unlikely to come under close scrutiny even when discovered.

We are such a civilisation.

It's quite possible that we have been under surveillance by an extra-terrestrial civilisation for quite some time. And now, as we are sending spacecraft out to explore the Solar-System, that surveillance has retreated to distant small moons where we are unlikely to pay much attention. For that reason we should be paying extra attention to those moons. Many 'small moons' missions should be launched. And perhaps we should also launch probes to the outer Solar-System to an orbit beyond Neptune, where we can detect the possible transmissions that are being sent back to the home system of those that are monitoring us. Some of those probes should also orbit the sun well out of the normal planetary plane to ensure full coverage.

If we do all that we should have a good chance of discovering evidence that we are being watched.

And if we do make such a discovery, those watching will know about it. They may well decide that it's time to make direct contact.

Saving Planet Earth - Forever

Human-induced climate change is the biggest short term threat to our planet and our species. Neutralising that threat should be our top priority. But ultimately, the natural warming of our sun will change our climate to such a degree that one day the Earth will uninhabitable for even the hardiest and most basic life.

The warming of the sun is something that we can have no control over.

No matter how we balance our ecology with sustainable energy generation, recycling, pollution and population control, in a few hundred million years our world will warm up to a point that will render our species and all other higher life forms extinct. And a billion years after that the Earth will be nothing but a hot and sterile planet - wiped clean of billions of years of evolution, experience, culture and history. It will be a hellish world not unlike how Venus is at the moment.

This image of Venus, taken by Japan's Akatsuki probe, is how Earth could look in a few hundred million years time. The natural warming of the sun has caused the oceans to boil away, and the uncontrollable greenhouse effect that followed has rendered the planet uninhabitable. 

Earth, the cradle of our species and civilisation, will become a dead world. No matter how far humans have spread throughout the Solar-System and beyond, it would be a sad and poignant day when our planet of origin is finally abandoned by humanity to face its natural fate.

There are, however, things we could do to preserve our home world's habitability for much longer, and possibly forever:

1. Block Some of the Sunlight

There is a point between the Earth and the Sun known as a Lagrangian point (specifically L1 - there are four others). It is a stable point where the gravitational pull of the Earth cancels out that of the Sun. In other words, any small object positioned there will stay there, directly between the Earth and the Sun.

It is the ideal position to place a filter - something that can reduce the amount of light and energy from the Sun. Unfortunately L1 is 1.5 million kilometres away, which means the filter would need to cover tens of millions of square kilometres. This would be unfeasible for a single object which would need to be many thousand of kilometres in diameter, but a formation of very small spacecraft, each just a metre or so across, would be quite possible.

A swarm of hundreds of millions of smart probes positioned at the stable L1 point between the Earth and Sun would be able to filter out a few percent of the Sun's energy. This would stop global warming, allowing the reversal efforts on the Earth to have time to work. In the longer term this would allow the climate on Earth, and life, to be less affected by the gradual warming of the Sun.

The objects would need to be very light - just a couple of grams - and would consist of a very thin stretched panel to deflect sunlight. Each spacecraft would be intelligent enough to maintain its position within the formation, and use its panel as a solar-sail to move away from the Sun, and ion engines to move in other directions.

Such a swarm of spacecraft would need regular renewal as a certain number of them fail each day. Ideally a permanent production facility away from Earth would be needed, perhaps on the Moon, to enable a constant supply of replacements.

The swarm would only need to reduce the amount of energy reaching Earth by two or three percent to halt global warming. And it could even be used to cool certain areas of the Earth at crucial times, such as over the oceans to lower the intensity of hurricanes and typhoons, and even prevent them altogether.

2. Move Earth to a Higher Orbit

As the Sun slowly warms up the effectiveness of the filter at L1 would reduce. The next step is to alter the Earth's orbit, increasing its distance from the Sun. The most efficient way of doing this is to cause a relatively massive object, such as an asteroid, to repeatedly pass very close to our planet, pulling it into a slightly higher orbit each time.

The larger asteroids in the asteroid belt, such as Vesta or Pallas, would be ideal candidates, although changing their orbits, and directing them into the inner Solar-System on the correct course is a mammoth undertaking. It would take many millennia to get those objects on the right trajectory so that they pass by Earth at just the right distance to have the desired effect.

Vesta, one of the largest asteroids in the asteroid belt between Mars and Jupiter. Such an asteroid would be able to 'pull' Earth into a higher orbit around the Sun if it were sent on the correct trajectory to pass very close to Earth.

There is, of course, an immense risk to such a strategy. Any miscalculation could send the asteroid on a collision course with the Earth, or the Moon, which would be truly catastrophic. Fortunately the Sun's warming is a very slow and steady process, so as long as the L1 filter is in place we would have plenty of time to overcome the technical challenges and design in all the necessary safeguards.

Once the process has begun the asteroid would be directed to pass the Earth regularly, possibly every couple of centuries, to carefully nudge our planet's orbit away from the Sun. Our climate and the life it supports would remain stable and comfortable.

There is a limit to how far the Earth's orbit could be altered. We could only move our planet so far before we get too close to the orbit of Mars. We could, of course, start moving Mars as well, but then eventually the asteroid belt would become a hazard to both worlds (and Mars will be far too important to the humans living there to be placed in such danger). We would end up having to alter the orbits of all the significant bodies in the asteroid belt as well, which would then put at risk the colonies we will have set up on Jupiter's moons, or in the inner Solar-System. It would be an impossible task to manage.

3. Build a Shell Around Earth

As the Sun's relentless warming continues there is something else that we could do to further protect our climate: build a shell around the Earth. Just like altering Earth's orbit, this will be a massive undertaking, and one that could take millennia to build. But it is possible, and there will be plenty of time to complete it.

A huge amount of material will be needed, which would make mining it all from the Earth almost impossible. The Moon and the asteroid belt would be able to provide all the resources necessary. The supports would be built first, evenly placed around the whole planet. These would ideally rise up to the Karman line, the officially recognised edge of the atmosphere at an altitude of 100 kilometres.

The view from the Karman line, a hundred kilometres above the Earth's surface. The planet's protective shell would be built at this altitude.

Next the shell would be built, spreading out from each support until it joined together with other shell segments. On the inside surface of the shell there would be artificial lighting, powered initially by the Sun beyond. Once completed the shell would ensure that the intensity of light and energy reaching the Earth's surface is fully under our control. Excess heat would be radiated up the supports and out into space from the shell's outer surface. It's interesting, and even sad, to think that life on Earth would never again see the Sun, Moon or stars in the sky, but as the construction of the shell could take a hundred human generations or more, those alive to see the shell completed would not really have seen them and so would not miss the experience.

Having such a shell around the Earth would have other benefits besides climate control. It would provide another surface on which to construct manufacturing, accommodation and space launch facilities. It would be the idea place for astronomical research. Additional outer shells are likely to be constructed, with the spaces between the shells used for any number of functions. Such spaces could be hundreds of metres high in some cases, which could be pressurised and provide vast areas for agricultural activities that would cultivate and breed enough food to feed billions of people on Earth, and for export to colonies around the Solar-System.

After thousands of years of construction, millions, even billions, of humans and animals could end up living on the plains and cities constructed in those vast spaces between shells way above Earth's natural surface.

Eventually the very outer shell, one of hundreds, could have a diameter many thousands of kilometres greater than that of the Earth that is hidden and protected far below.

4. Move Earth to Another Star System

There will come a time, more than a billion years from now, when the Sun starts to swell. Slowly but surely it will expand and engulf the inner planets Mercury and Venus, and then, no more than five billion years from now, it will engulf the Earth, and possibly Mars, too. The magnificent multi-layered shell that we will have constructed around the Earth will no longer be enough protection. It will be vaporised along with our planet.

The inner Solar-System will have become a hellish place long before that. Without a protective shell, the Earth would become uninhabitable for humans in a couple of hundred million years. Within six hundred million years plant life would most likely die off completely bringing the food chain to a halt. And a hundred million years after that the oceans will have boiled away.

Within 200 million years we will need to be preparing for the next stage of Earth's survival. It will involve much more than just moving to a higher orbit in the outer Solar-System (although that could be an interim stage). We will need to move the Earth to another star system.

This would be a truly momentous task, but we would have millions of years to get the Earth and its all encompassing shells ready. A means of propulsion will need to be developed. It would have to be gentle, with a barely noticeable gee force, but able to be sustained for years due to the incredible mass it would need to move. Over many centuries the Earth's orbit would need to be changed to a more and more elliptical one, taking it far out to the orbits of the outer planets, and then back in to the inner Solar-System. Eventually, when the destination star has been chosen, the Earth can be directed on a course that would take it very close to the Sun.  With its propulsion system pushing as hard as it safely can, the Earth would head in to the inner Solar-System and sling-shot past the Sun, picking up enough extra velocity to escape from our planetary system and head out into interstellar space. At this point the Earth and its shell would be travelling at many hundreds of kilometres per second, and this would be maintained by the propulsion system until the planet left the influence of the Sun's gravity. The Earth and its shell would now essentially be a massive generation star ship: one with a huge amount of comfortable and well-protected living space for billions of people.

There would be many options with regard to the destination star, and the obvious choice would be a star very similar to the Sun, but younger. The disadvantage of that would be the need to move to another star system in a few billion years time. A better choice would be a different kind of star: a smaller and cooler star type that just happens to be the most common type of all - a red dwarf. Red dwarf stars are very stable and very long lived. At a minimum they can live ten times longer than the Sun, and many will exist in a stable condition for a trillion years or more - hundreds of times longer.

As red dwarf stars are much smaller and cooler than the Sun, the Earth would need to be in an orbit much closer to it to receive the same amount of energy that we do at the moment: so close that a year would last just a few days. Of course, Earth's extensive system of shells and energy generation would allow it to have a much more varied choice of orbits. If a red dwarf is chosen as the destination star there would be no need to move the Earth to another star system again, at least in any timescale that we could comprehend.

Earth, safe beneath its worn but still intact outer protective shell, arrives on in the region of a younger star after a voyage of many millennia across interstellar space

Once the Earth is settled and secure in its new star system humans would once again begin exploiting the local resources to enhance their home. More and more layers would be added to the shell, and over many thousands of years there would be tens of billions more people thriving up there. It's not inconceivable that one day the Earth would be no more than just a small part of a vast structure that has grown to something a hundred thousand kilometres in diameter - almost ten times that of the planet within. There's no reason why it could not keep growing and growing.

By this time, hundreds of millions of years from now, there will be other planets that have been terra-formed and had their own shells built to protect them. The Earth will be one of many highly protected planets hosting billions upon billions of humans. Some of those planets will be mobile and able to traverse the vast distances between stars, and some will even be capable of travelling the intergalactic voids between galaxies. Perhaps the Earth, with its ever deepening structure of shells, will become a legend amongst those intergalactic travellers: the unreachable source of all humanity where hundreds of billions still live out their lives.

Hundreds of million years from now there could be trillions of people spread throughout our galaxy, with billions more on their way to other galaxies, safely cocooned within planetary shells.

It's an incredible prospect, and an awe-inspiring concept. But it's not impossible. If this happens then the survival of our species will be secured for trillions of years.

Alien Technology Could Seal Our Fate

It's possible that the technology of an advanced extra-terrestrial civilisation is in the possession of some governments. If so, reverse engineering efforts will certainly be in progress, and the fruits of such efforts are likely to have already been incorporated into various, and still secret, machines and devices.

While the initial use of such technology will almost certainly be for military purposes, it will ultimately benefit our species as a whole. We could be on the verge of a surge in development of advanced and super-efficient energy generation and space propulsion. If alien technology is secretly being studied then it couldn't be more timely. Understanding and utilising it could literally rescue the human race and our planet from the devastating effects of climate change. It may even prevent our extinction.

Small and incredibly efficient nuclear fusion technology could soon provide all of us with clean and almost unlimited power, thanks to the reverse engineering of extra-terrestrial technology that's centuries ahead of our own

The 21st century will be a make or break period for us. We'll either start on our path to interstellar colonisation, or condemn ourselves to oblivion. Those are the two very clear paths that our species can take. Even without the advantage of advanced alien technology those paths are open to us (such technology would simply help us to take either path much sooner). We can either resolve our destructive differences and work together to heal and protect our planet, and take our human civilisation to the stars, or we can remain conflicted, arrogant and selfish, and continue on our ever accelerating plunge to extinction.

Unfortunately, any government that has access to advanced alien technology will keep it a secret for as long as possible, and any benefits gained from its use will be closely guarded. The reasons are understandable when you consider human nature. If the technology were made public its use for criminal or military action would be swift. No nation possessing it would want to put itself at risk of such action. Because of this the reasons for any government keeping the technology secret would be justified. And so would its reasons for developing military uses for the technology first.

The governments that have access to alien technology will almost certainly use it to gain a military advantage. That's understandable, when the world's political and economic problems are considered, but it could actually accelerate our civilisation's fall.

The depressing conclusion we can draw from that fact is that, even with such technology, we would still go down the route of self destruction. Innate selfishness, fear and even paranoia would ensure that. Human nature and our primary survival instinct may well be too powerful to suppress. Such an instinct becomes ironically suicidal when weapons of mass destruction are available (I also cover this point briefly in my 'Machines Meeting Machines' article earlier this year). This supports one of the popular theories as to why there are no detectable technological civilisations in our galaxy (the Fermi Paradox). Any such civilisations have destroyed themselves: all of them. Their once useful survival instincts sealed their doom.

There is the possibility that a more socially conscious government will obtain the technology. If so then it may well use it to develop the means to save our species. That chance is still available.

But, the countries that are most likely to have alien technology are the ones perhaps least likely to use it for the good of us all. Those countries are, of course, the USA and Russia. Those countries, especially Russia, have large amounts of underpopulated land and are best equipped to carry out such research. They have the resources to be able to do the work, and the means to keep the work secret.

The USA's most famous 'secret' area for supposed reverse engineering is Area 51 in the Nevada desert, and it's been the focus of attention for many decades. It is almost certainly involved in secret military development, but any research involving alien technology will have ceased there decades ago. The scrutiny is just too intense. The US government is no doubt happy to keep feeding those interested in the area just enough to keep them distracted from wherever the real research is going on, perhaps in the mountains of Alaska.

A remote and inhospitable valley in Alaska. Such locations would be ideal for a government to hide underground facilities for the reverse-engineering of alien technology.

Russia, too, is likely to doing its development in deep mountain areas, and in the wilderness of Siberia. Those inhospitable areas, with very insignificant local populations are ideal, if harsh, locations that are not easily accessible. And in the much more authoritarian states of Russia it would be easier keep things under wraps, and to keep those with knowledge of what's going on silent.

Whoever possesses alien technology, human nature combined with the current political and economic situation of the world will ensure that it is kept secret and used only for clandestine purposes. It is quite possible that there are even secret human colonies working away from Earth, on the far side of the Moon, and even on other bodies in the Solar-System. In a way that would be quite comforting: it would demonstrate that we have the ability to survive for long periods away from the Earth. But the secret nature of such activities means that it is all in the aid of military and intelligence operations: the result of paranoia and the fear of other humans, rather than the enlightened reason of the continuation of our species.

Humans really need to start working with each other, instead of against each other. We need to sort ourselves out, and fast. We are on the highway to oblivion, but there is still an exit we can take just up ahead. It leads to a road that may well be endless.