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.

The Ice Billionaires

One day, when the human population away from Earth reaches a certain level, new economies will emerge, ones that are almost completely independent of our home planet. And not long after that the new economies' first Earth-independent billionaires will emerge. But what service or product will generate such wealth?

Providing construction material will be one way. Finding enough suitable material to construct human settlements, whether in space or on the surface of a moon or planet, is a difficult and awkward task. It would not be long before businesses are created that specialise in mining and distributing such material. The most successful will enjoy an ever-increasing demand for their materials as colonies expand and new colonies are started.

Another profitable service would be transportation. There will be a constant need to transport people and cargo of all kinds around the Solar-System. Businesses will be set up to provide reliable and regular transport services. Eventually huge spacecraft with the capability to move millions of tonnes of cargo, and hundreds of passengers, will be making journeys between the mining facilities and the colonies and outposts. Leaving Earth to work at one of the colonies for a few years, and then returning home or moving on to a different colony will become a relatively routine, if still lengthy, process. The large interplanetary ships will at least provide a high level of comfort and simulated gravity, which will be much healthier and safer than what we could provide travellers at the moment.

A typical mid-sized cargo ship. As well as cargo carrying ability, this ship has a large crew and passenger section which rotates to provide artificial gravity. Eventually there would be thousands of such spacecraft, some much larger, providing cargo and passenger transport between the colonies and mining facilities, and of course Earth.

But there is one product that will create the most riches for the people that set up businesses to mine and deliver it. That product is ice, and especially water ice.

There is a relative abundance of water ice in the Solar-System. Even Mercury, the closest planet to the sun, has water ice preserved in craters that are in permanent shadow.  There are many ice moons around Jupiter, Saturn, Uranus and Neptune, and Saturn's rings are 90 percent water ice. And then there are the Kuiper Belt objects beyond Neptune, which are mainly composed of ices, including water ice. And beyond that in the far reaches of the Solar-System, on the border with interstellar space, there is the Oort Cloud which is the source of many of the comets that periodically make their way into the inner Solar-System. It's likely to contain enough ice equivalent to several times the mass of Earth.

I expect the ice industry will be split into two: with one part specialising in ice mined on a planet or moon's surface and with it's customer base restricted to the body on which it was mined (due to the cost of transporting it out of the local gravity well), and the other part dealing with ice mined on asteroids, comets and other small bodies. Such ice will be easily transported to space-born colonies and orbital facilities, and to the small rocky worlds such as the inner Solar-System asteroids, and the moons of Mars: Phobos and Deimos. Those bodies will certainly have human activity on them as materials for construction are mined. Their demand for water ice will be high.

Surface-Bound Ice Mining

In the higher latitudes of Mars, close to the planet's north polar ice cap, lies the Korolev Crater: an almost 82 kilometre-wide impact crater filled with water ice. The base of the crater is more than two kilometres below the rim, creating a cold air trap that's allowed the crater to fill up with the ice to a depth of 1.8 kilometres.

Korolev Crater: An ideal location for a large human colony due to the vast amount of water ice contained within its rim. The first ice mining business is likely to be set up here. It will be the start of what will become a global corporation supplying essential ice to the entire planet.

The crater's location close to the polar ice cap, and just south of the expansive dune-filled region known as Olympia Undae, and it's abundance of water ice, makes it an ideal location for a large human colony, and the best example of a massive and conveniently located source of water. The area surrounding the crater will be relatively easy to traverse, making the construction of roads towards the north pole, and south towards the equatorial regions, straightforward. It is the most likely location for the first of the planet-bound ice mining businesses to be set up.

The person who will become the very first ice billionaire may well be living on the rim of the Korolev crater in several decades time just as material self-sufficiency from Earth is achieved. His or her vision and drive will enable the rapid expansion of the colonies on Mars, and become the inspiration for others elsewhere on the planet and far beyond.

The crater could well become the site of several sizeable towns, even cities, whose inhabitants are specialised in mining water ice. The towns would be located on the rim of the crater. Access in to the crater will be easy as the slopes are gentle and natural routes for roads would be easy to find.

A close-up of part of the Korolev crater's rim, which is typical of where most of the human settlements will be located. Roads will be built down into the crater to provide easy access to the ice mining facilities. Roads will also be needed that head out of the crater to allow exploration of the areas beyond, and for transporting the ice south to the settlements in the equatorial regions.

The ice mining business's first contracts will be with Earth governments as they hand over the extraction of the ice to a private venture, but within decades, as the colonies themselves separate from direct Earth control and become truly independent, the contracts will be with Mars governments, and with other business sectors that have developed on the planet. By that time ice mining will have expanded to the north and south poles. It will be an efficient global industry that will allow millions of humans to live and thrive on the planet.

The same is likely to happen on other worlds that are suitable for human colonisation, with Saturn's moon Titan a prime example. There will be differences, of course. Mining anywhere on Titan, and the other ice moons will result in plenty of water ice being found. Many more smaller competing businesses are likely, which will ultimately merge to become a handful of large corporations.

Interplanetary Ice Mining

Space-bound colonies, either in orbit around planets, moons or the sun, will become a significant presence in the Solar-System once human colonisation away from Earth becomes established. They will be constructed from material mined from asteroids and most likely constructed in the asteroid belt (or from the Trojan asteroids that share Jupiter's orbit) and transported to their ultimate destination once complete. Such structures, each built to house thousands of people and to be as independent and self-sufficient as possible, will still need regular deliveries of water ice (and other volatiles). There will be no shortage of people ready to exploit that need, and the earning potential it represents.

Transporting water up from the surface of planets and the larger moons will be difficult and very expensive, due mainly to the effort and energy required to get millions of tonnes of ice out of such deep gravity wells. Such efforts would be foolish to attempt, and could never be considered as a viable business plan.

For such space-bound colonies the efficient solution is to mine the ice from small objects with a negligible gravity well, such as Kuiper Belt and Oort Cloud objects.

An artist's impression of the dwarf planet Eris, that resides in the Kuiper Belt. Eris is currently the most massive known Kuiper Belt object. Despite its size (over 2,300 kilometres in diameter) its low gravity of 0.083g would probably be low enough to make the export of ice volatiles viable. Eris could end up being one of the most active and profitable ice mining locations in the outer Solar-System. Image by S M Pritchard.

The objects in the Kuiper Belt, which lies just beyond the orbit of Neptune (and includes dwarf planets such as Pluto, Orcus and Eris), is the most conveniently located of the two. Once there is a human presence in that region mining operations with transport infrastructures will be set up to exploit the abundant ice riches that are available. There will be a regular fleet of cargo ships, largely crew-less, making their way inwards to the large space-bound colonies that are likely to exist around the major planets and moons. Their trajectories will be slow, but very efficient, and their regularity will ensure a constant supply of ice volatiles to a hungry and highly populated inner Solar-System.

A cargo ship prepares to dock with a massive space-bound colony in the inner Solar-System. Such a facility would need a regular supply of ice volatiles, including water ice. Supplies mined from objects in the Kuiper Belt or beyond would arrive at least annually to fulfil the needs of the thousands of colonists. Image by Bryan Versteeg.

Very large space-bound colonies have a distinct advantage over planet-bound colonies: those living there can live with Earth-level gravity, due to the ability to rotate the colony. With a large enough diameter any unpleasant coriolis effects can be eliminated (as the rotations per minute can be kept very low - less than one per minute if the colony's rotating section is 1,000 metres or more in diameter). It is likely that the ice billionaires would chose to live in such facilities due to the obvious space and luxury they could provide.

The interior of a space-bound habitat. With a diameter of hundreds of metres it would be able to rotate at a quite leisurely pace and still create enough artificial gravity to match that of Earth. The interior would be very spacious and would be the preferred home of the future ice billionaires. Image by Bryan Versteeg.

The motivation of the ice billionaires (and those in other industries) to expand their businesses further to increase their own wealth will be an important factor in the speed at which human colonisation spreads further and further away from Earth. Such activity needs to be encouraged. It is one of the ways to ensure that our species will endure if a catastrophe - either natural or of our own making - occurs on our home planet.

This kind of insurance against our extinction is essential. Governments on Earth are too slow, fickle and bureaucratic to provide that insurance any time soon. We need to embrace the commercialisation of space colonisation.

The future entrepreneurs that can exploit the business opportunities in the Solar-System are quite possibly alive as children today. They will one day leave Earth and create the most far-reaching corporations in human history. They will be motivated by profit, but inspired by the innate desire in all of us to survive as individuals and as a species.

A Single Origin of Life

Is all life in the universe related, and from the same single point of origin?

Life is likely to have formed in the universe as soon as the right conditions arose. And that will have been soon after the first supernovae, when the violent deaths of those stars spread out the heavy and complex elements that are considered essential for life to form.

The oldest supernovas studied occurred 10.5 billion years ago, just two billion years after the formation of the universe itself. The planetary systems that formed soon after are likely to be the ones to evolve the first ever life in our universe.

The first supernovae more than 10 billion years ago created the elements essential for life to begin

For life as we know it to survive there needs to be a certain temperature range, plenty of liquid water, and the right mix of gasses. And this state needs to be maintained for hundreds of millions of years or more for anything other than the simplest types of life to form.

How often life begins (abiogenesis) once the conditions are right is unknown. It is possible that as soon as the conditions are right then life emerges. If this is the case then life will have arisen quite often, and is probably flourishing on billions of planets right now. But despite a huge amount of research and experimentation this has not yet been shown to be the case.

It's quite possible that something else is required, something we are yet to identify, that makes the process extremely rare. So rare, in fact, that it has only ever happened once.

If that is the case then the only way life could become widespread is via panspermia: the distribution of life via dust and meteoroids as collision debris is ejected into space, carrying primitive but hardy life with it. Life on Earth could well have arrived this way. It could have been travelling through interstellar space in a dormant state for many millions of years. And the world where it came from could itself have been seeded in such a way.

A procaryote: a simple but hardy life form that can survive in some very extreme conditions. Could such simple archaeal/bacterial life have spread throughout the universe from a single point of origin?

Life on our planet could be descended from life that originated on a planet millions of light-years away, and it could have evolved billions of years before even our sun was born.

Ultimately there could be just one source of life in the universe, formed soon after those first supernovae. All life in the universe, at least all life of the kind that is found on our planet, could be related to that single abiogenetic event.

The only life we know of and have studied is on our planet. The biochemistry of all of life on Earth is carbon-based with water as a solvent and DNA or RNA to define growth, structure and function. But life is theoretically possible with other forms of biochemistry, which would increase quite significantly the number of planets and locations where life could survive. Silicon, like carbon, can create molecules large enough to support biological information, and ammonia or methane are suitable alternative solvents to water.

There is one place in our Solar-System where an alternative kind of life could be present right now: Saturn's moon, Titan.

Saturn's moon, Titan, is the most likely place in the Solar-System where we might find non-Earth-like life, based on methane/ammonia rather than water

This possibility is something that needs investigating (see my previous article 'Human Colony on Titan' where I mention the indigenous life that we could encounter there). It is so cold on Titan that the lakes consist largely of methane rather than water, and the thick atmosphere (thicker than Earth's) provides great protection from cosmic rays and small meteorites. Saturn's magnetosphere also provides some shielding. It is the most likely place for us to find non-Earth-like life in the Solar-System.

Panspermia could also be responsible for life on Titan. If methane-based life is abundant then it too could have arisen around the same time as water-based life and been spread aboard collision debris in the same way. If there is indeed something special and extremely rare that needs to occur for life to form then methane-based life could have a single point of origin in just the same way as water-based life. All life, no matter what biochemical base it has, could be related to a single distant ancestor for that biochemical type, perhaps even in the same star-system that the other forms of life arose. Something very unique could well have occurred there: the event that kick-started life - the spontaneous occurrence of something profound that enabled non-living matter to become life.

Whether or not that is the case could have profound ramifications for our species as we embark on interstellar colonisation. We could find that life is present in most of the star-systems we visit. If so, will it be beneficial, a hindrance, or a danger that's lethal to our species? Or we could find that each and every planet that we visit is barren of life, no matter how Earth-like it appears to be. That could be a good thing, allowing us to colonise suitable planets without having to deal with strange and potentially harmful lifeforms. But it would also mean that we are truly alone.

Earth could end up being that single source of life in the universe.

That is quite a profound thought...

Machines Meeting Machines

Most science fiction stories that feature alien encounters or visitations show biological creatures that have traveled vast distances. The more I think about it, and the more I read about it, the more I am convinced that this is unlikely to be the way we will eventually meet an extra-terrestrial intelligence.

Our first encounter with such an intelligence will almost certainly be with a machine.

Most people expect that the first encounter with an extra-terrestrial intelligence will be with a biological being, but this is highly unlikely

But why will that be?

Interstellar travel by biological creatures such as ourselves is difficult, costly, and fraught with danger. The food, water and air that's needed for such a journey has to be provided by the star-ship itself. This requires an incredibly complex and almost perfectly tuned biosphere which will need to function for at least a few centuries, and probably far longer. And the ship will need to be huge if it's to accommodate a large enough population to maintain genetic health and diversity.

Building such a star-ship is not impossible. The technical challenges are in no way insurmountable. But the political, emotional, and even ethical obstacles probably are. The world's governments would have to come together and cooperate to get such a project even started. All the military and economic conflicts would need to be resolved, and all the hate and suspicion of our cultural and religious differences transmuted into something positive, respectful and cooperative. And, of course, the general population (whose taxes would fund the venture) would need a lot of convincing as they and their descendants would not see any personal benefit from it.

It does not take much thought to realise that such cooperation goes against the most basic but intensely powerful instinct of any biological life-form: that of self-preservation. Such an instinct is generally beneficial,  but for an advanced civilisation such as ours it could, on a national scale, easily result in an endless series of territorial and ideological conflicts that consume our time and energy. One day the result of such squabbling is likely to result in another global war that could wipe out our species. It's ironic that the survival instinct that has served us well throughout our primitive history, allowing us to evolve into a creature of such high intelligence, could well end up destroying us completely.

Large interstellar spacecraft capable of supporting humans for generations are unlikely to be built until our territorial, political and religious differences on Earth are resolved

That survival instinct is not going to change. Cooperation between governments is not going to reach anywhere near the levels required to build human-crewed star-ships. But the development of crewless interstellar spacecraft requires no such cooperation. And neither does the development of the advanced artificial intelligence to run it. Individual nations, and even individual corporations, can certainly do that.

Because of this our interstellar exploration will almost certainly be conducted by machines. And those machines will contain within them a sophisticated artificial intelligence; one that is able to function autonomously for centuries. And it will be designed to be our ambassador should an advanced alien civilisation be encountered .

Our first encounter with extra-terrestrial intelligence will be with something artificial , rather than a biological life-form. 

And that will be the same for all intelligent extra-terrestrial civilisations. Highly intelligent machines will do the exploration. And due to the communication problems across the vast distances between star-systems those machines will be designed to deal with first contact situations. They will also be able to utilise the resources in the star-systems they visit, replacing and repairing themselves, and even improving their own design. My earlier article, 'Intelligent Machines Are Watching Earth', discusses the possibility that such machines are observing our planet right now.

Its not hard to imagine them setting up machine colonies and constructing more of their kind that will head off in new directions, greatly speeding up their exploration. New machine civilisations will be created. Entire planets could be engineered to be the new home worlds for such artificial creatures.

The home planet for an intelligent artificial species. Over millennia the entire planet has been engineered to accomodate such a species. It will be a highly efficient and sustainable machine civilisation.

It does seem to me that due to the relative ease of manufacturing and distributing intelligent machines across interstellar space, the most abundant form of intelligent life in the universe (if it can be called life) is artificial.

There will, of course, be some biological beings exploring interstellar space, probably on 'world ships': huge vessels, tens or even hundreds of kilometres in length. But they will be exceptionally rare. Due to basic and irrepressible instincts, almost all advanced biological civilisations will render themselves extinct within a few centuries of developing high technology. But many will have survived long enough to initiate interstellar exploration using intelligent machines. Some of those machines - those that are designed to manufacture copies of themselves and make improvements - will go on to establish themselves in other star-systems. Eons after the biological civilisations that first created them have died out, the machine civilisations will continue to thrive and explore.

One day one of our machines will meet one of those machines.

I hope our biological civilisation is still around to appreciate that moment.

Climate Change - The Point of No Return

We are on the verge of rendering our planet uninhabitable, unless drastic action is taken.

Scientists have recently announced, quite alarmingly, that climate change on our planet could soon reach its tipping point. We are only decades away from that moment. It will happen within a generation.

Lowering our carbon dioxide emissions is no longer enough. Carbon dioxide needs to be extracted from the atmosphere. And we need to start doing that now on a large scale. Otherwise, global warming will enter an unstoppable feedback stage, where warming triggers more warming, which triggers even more warming. Such feedbacks include the release of methane due to the thawing of permafrost, loss of snow cover, the melting of Arctic ice, warming seas, and the loss of forests. All of those will reduce our planet's ability to reflect heat and absorb carbon. The number and intensity of forest fires will increase dramatically, releasing huge amounts of greenhouse gases into the atmosphere. This will only magnify the feedback effect even more.

Global warming will result in an increase in the frequency and ferocity of forest fires. Such fires add vast amounts of greenhouse gases to the atmosphere.

The end result of such warming is not clear, but at best it will significantly limit the areas of the Earth where humans can comfortably survive. At worst it will render the whole planet uninhabitable, water will boil away, and the Earth will suffer the same fate as Venus,

Even the 'best case' scenario will cause massive migrations, and subsequently major wars over dwindling food, water and energy resources. Such wars will only add to the warming feedback. As the desperation of governments increases those with nuclear weapons at their dosposal will eventually use them. Countries such as Israel, India, Pakistan and Iran - all nuclear powers and all located in what will become some of the worst affected regions - will feel compelled to use such weapons as countries to their north attempt to stop the migration of their populations. This will cause tremendous damage to the environment, and render even more areas uninhabitable. And there would be a very high chance that a limited nuclear war would escalate rapidly into a global nuclear conflict.

At that point our current technological civilisation will end, and with it humanity's chances of spreading beyond the Earth to become an interplanetary, and then an interstellar, civilisation. Our ability to preserve our species will have slipped away.

If he climate change wars turn into nuclear conficts they will bring to an end our current technological civilisation. Humans may have a change to develop another advanced civilisation one day, but it is likely to take centuries or even millenia to get back to anything like that which we have achieved today. Without forewarning such a civisation is almost certainly doomed to suffer the same fate as the one before it.

Such a dramatic warming of the atmosphere will cause a rapid rise in sea level, raising it to well over a hundred metres higher than it is at present. In addition to the billions who had already perished in the wars of the previous decades, hundreds of millions more will die. Survivors, who will eventually number just a few tens of million at best, will struggle to live in the few remaining higher altitude lands. Their existence will be basic and medieval. It will be a return to the dark ages. Thousands of years of progress and knowledge will have been lost.

Only then, with the destructive output of our current civilisation at an end, can the climate of Earth have a chance to stabilise. The ice caps will reform and the sea level will reduce. After many centuries flora and fauna will start to recover. Only at that point, humans, if they are not extinct, will have another chance at building a technologically advanced civilisation.

It's unlikely that we can prevent a climate change disaster on our planet, but we can improve on the 'best case' scenario if we start doing three things right now:

1. Preserve Knowledge of our Discoveries and Inventions

We must help survivors in the post-climate change world avoid repeating our calamitous mistakes, and allow them to 'fast-track' through what has taken our current civilisation thousands of years to learn, discover and invent.

A comprehensive record of our achievements (and of our destructive actions, so that mistakes are not repeated), must be preserved in a way that they can understand, and in a way that will last for thousands, even millions, of years. We must investigate how we can provide such knowledge to our distant descendants, and then store it in multiple safe yet easily accessible locations, including locations elsewhere in the Solar-System.

DNA could be the ideal solution to extremely long term information storage

Using paper or digital media to preserve knowledge will only be suitable for a few hundred years or so, but such means should be used initially, as our descendants will be able to understand and use these forms of storage.

But a more radical solution is needed for complex and advanced knowledge that will be useful once any new civilisation progresses to a certain level. Storing information in DNA is one such solution. It's been shown that if the DNA can be kept at sub-zero temperatures the information will maintain its integrity almost indefinitely. DNA information stores would be best located away from Earth, perhaps on the Moon in the permanent darkness of one of the polar craters, and deep within some of the planetary bodies of the outer Solar-System.

2. Work to Avoid or Delay the Climate Change Tipping Point

Even to just delay the tipping point we need to start work now.  The small steps some of us are currently taking are utterly inadequate.

Our civilisation needs to fast track the very widespread use of electric vehicles by banning petrol and diesel engines within a decade. All developed countries need to push this idea hard, and give incentives to developing countries to do the same. And governments need to increase vastly the funding for research into clean energy, and get nuclear fusion working. The generation of electricity by burning coal and oil has to stop on a worldwide scale without delay. Countries like China appear to be increasing the use of fossil fuels for energy generation, which is going to be catastrophic if it is not prevented.

But that alone will not be enough. We need to start undoing the damage we've already done.

Various climate engineering projects should be started immediately. These are possible with current technology. To help reduce global warming solar radiation management needs to be implemented to reduce the sunlight absorbed by the atmosphere. Relatively simple things can be done such as seeding clouds with sea water to brighten them (and therefore reflect more sunlight), and using pale roof colourings and promoting the expansion of polar ice.

Removing carbon dioxide from the atmosphere using facilities such as this is possible. It can be stored in hard pellets which can be buried deep underground.

We need to start removing some of the excess greenhouse gases that our activities have pumped into the atmosphere. This can be done directly using machinery that would then store the extracted carbon dioxide deep underground, and indirectly by promoting natural processes, such as extensive tree planting to reverse deforestation, and ocean fertilisation to add nutrients to the upper oceans to increase carbon dioxide absorption.

And the growth of our human population needs to be controlled, especially in developing countries. We can no longer support such large increases, which are generally located in regions that can least support it. It should be stabilised as soon as possible, and allowed to reduce naturally to a more sustainable level.

Doing all of the above is the best chance the Earth has of remaining a viable place for humans to live. But it is likely to only buy us some time - nothing more. We need to establish our civilisation elsewhere to properly secure our future.

3. Secure the Survival of Our Civilisation Independent of Earth

There's a significant possibility that the feedback warming will not stop, and if that is the case the Earth could indeed end up in a state similar to that of Venus.

The only way to ensure the continuation of our species beyond that event is to make sure that there are self-sustaining human colonies beyond Earth, on planetary bodies such as the Moon, Mars, and especially on what is looking like the best location: Titan, the largest moon of Saturn.

As well as colonies on planetary bodies there should be very large space habitats constructed throughout the Solar-System that would house tens of thousands. The resources to build such massive facilities can be found in the asteroid belt between Mars and Jupiter.

We will have to mine asteroids on a large scale to construct the off-world facilities humans will need to live independently from Earth

Extracting those resources would be relatively easy due to the very low gravity wells of the asteroids. The establishment of mining operations there must be an immediate priority. The space habitats could be constructed in the asteroid belt and then maneuvered into their final positions, either into planetary orbits, or into their own independent orbits around the sun.

In parallel to the development of colonies around the Solar-System there needs to be development of interstellar missions with the goal of establishing human colonies around other stars. More and more exo-planets with the potential for colonisation are being discovered all the time, with one, Proxima Centauri B, only 4.3 light years away.

The planet Proxima B, which orbits Proxima Centauri 4.3 light-years from Earth. It's the closest known Earth-like exo-planet, and has huge potential as a suitable destination for our first interstellar colonisation mission.

It would be a mammoth undertaking, and there are incredible engineering challenges to overcome, but investment in the rapid development of the methods and technology required is essential to build such habitats in time. As well as providing immediate funding, it should be the priority of governments to ensure that education systems are geared to maintain a constant supply of highly capable scientists and engineers to make it a success. The long term survival of our species depends on it.

If all three of the above steps - preservation of our knowledge, delaying or avoiding the tipping point, and establishing large self-sustaining human colonies elsewhere in the Solar-System and beyond - are pursued with the resilience, determination and creativity that our species has in abundance, then we will survive.

But we must start now.

Right now.

Uranus Mission: Essential and Urgent

Of the larger planets in the Solar-System, Jupiter and Saturn, and their moons, seem to get almost all of the attention when it comes to orbiter and lander missions. That's understandable, of course. There's a huge amount of fascinating bodies in those systems, and many mysteries to solve and theories to prove. And the fact that those systems are relatively easy to get to helps.

But a mission dedicated to Uranus and its system of moons is long overdue.

The planet Uranus: the coldest planet in the Solar-System

Since 2010 there have been five proposed missions to Uranus. These have been by the United Kingdom (Uranus Pathfinder), ESA (MUSE and ODINUS) and NASA (Oceanus and NASA Uranus Orbiter and Probe). It’s disappointing that none of them has yet been given the go-ahead, and none of them are likely to be given it due to budget constraints and the priority given to other missions, particularly those to the Jovian system.  Even if one or more of the Uranus missions was given the go-ahead, the earliest any of them would arrive at Uranus would be the mid to late 2030s (with ODINUS not even launching until 2034).

A Uranus orbiter and atmospheric probe

There is clearly the need for much more urgency and ambition. And there is a need to use a means of getting to Uranus that does not require a cruise time of up to 15 years (due the requirement for coventional rocket propulsion to make use of multiple gravitational slingshot maneuvers using Venus, Earth, Jupiter and Saturn). A more advanced method of propulsion is required: one that is much more powerful and sustained than current rocket technology. Nuclear thermal rockets, which have been developed and tested for decades, but never used, would allow for an orbiter mission to be launched on a direct trajectory to Uranus. The journey time would be reduced to just a few years.

But why would there be such an urgency to get an orbiter mission all the way out to Uranus so quickly? It's simply because there are many mysteries about the planet that need answers. And the sooner we know those answers the better.

One of the major mysteries about Uranus is that, unlike the other planets in the Solar-System, it seems to generate almost no heat at all. There seem to be no reasonable explanations as to why. It's quite possible that the heat energy could have been extracted from the planet by some extreme geo-thermal power generator. Indeed, the planet's unusual axial tilt, which makes the planet appear as if it's laying on its side compared to the Solar-System's other planets, and its magnetic field, which is at an extreme tilt in relation to the planet's rotation and is also off-centre by quite a margin, all point to unusual and potentially unnatural events that occurred as the planet's resources were utilised.

There is a likelihood that long ago the Uranian system was the location of some intense activity by an ancient extra-terrestrial civilisation: perhaps from Venus or Mars, or maybe even from Earth many millions of years ago (see my article 'Pre-Human Technology in the Asteroid Belt'). A vast engineering project of some kind may have been implemented. The evidence of such activity, even if it ceased hundreds of millions of years ago, will still be there for us to discover. We need to know what was going on, and why.

The most likely place we'll find that evidence is on the planet's moons.

Miranda, the smallest and innermost of the major moons of Uranus

The moons would provide all the resources needed for a civilisation as it worked. The moon Miranda, the smallest of Uranus' major moons, certainly has the appearance of a moon that has been heavily mined. As it's composition is mainly water ice its surface could have been the main source of water, oxygen and hydrogen for fuel.

The planet's largest moons, Titania and Oberon, do not show signs of mining, but they would make ideal locations for habitats and deserve detailed surface investigations. Ulimately, a strong human presence is required for a thorough investigation (and of course for the more general reason of helping ensure the survival of our species if/when something catastrophic occurs on Earth).

At the very least, a human colony in the Uranian system would be an ideal base from which to explore the outer Solar-System.

Human colonists on Miranda enjoying ultra-low gravity recreational activities 

A small human outpost on Titania, the largest moon of Uranus

An orbiter mission to Uranus and landers for its moons are essential. Sooner rather than later we need to know what happened in the Uranian system. And ultimately we need to establish a permanent human presence there to help ensure our long-term survival.