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...

Human Colony on Titan

Titan is Saturn's largest moon (and the second largest in the Solar-System after Jupiter's moon, Ganymede). It is unique in many ways, most notably for its thick atmosphere, weather patterns, including rain, and its lakes and rivers. It is one of the best places in the Solar-System for a large human colony. It has the potential to support millions, in fact.

And there is, of course, the potential to discover a completely different form of life and biology to that of our own.

Saturn's largest moon, Titan. Left: a true colour image. Right: overlaid with an infra-red view of the surface.

Here's why Titan would be a promising place to build a colony:

• Titan's thick atmosphere and air pressure, that's just above that of Earth's surface, would eliminate the requirement for bulky pressure suits. A suit would simply need to provide warmth and oxygen.
• The hydrocarbon lakes would provide the materials to make plastics that could be used to make all the required structures for living and working.
• The atmosphere would provide excellent protection from radiation and meteorites, and make any leaks or failures of habitats a problem rather than a lethal failure (the indoor and outdoor pressure would be the same and therefore any leaks very slow).
• Drilling into the surface would provide all the water a colony could ever want. And from that could be extracted oxygen, and hydrogen for fuel.
• The low gravity would make return to space relatively easy, and the thick atmosphere would make aircraft particularly easy and economical to fly. Human-powered flight is possible.
• If there is any life on the surface of Titan it is likely to be methane-based, which should mean it would be unable to survive in a human environment. The danger of either life-form infecting the other would be minimal. It's very likely they could coexist without any problems.

There are significant challenges to overcome, but none are in any way insurmountable:

• The surface temperature is extremely low at about -180 degrees Celsius. This is significantly colder than even the coldest locations on Earth. New types of clothing and insulation will need to be developed to cope with this.
• It is currently unknown exactly how detrimental to health living in such a low gravity environment would be. Those born and raised on Titan may well be unable to leave the moon due to the weakness of their bodies. They would certainly never be able to visit Earth.
• The journey time from Earth to Titan would be many years using conventional rocket technology. Unless the ship had a rotating section to generate artificial gravity, and effective radiation protection, the crew would suffer significant health issues. Nuclear propulsion would significantly reduce journey times (this has been researched heavily but never used).
• There is a possibility of water-based life existing in the subsurface oceans. The water extracted for use by the colonists would need to be thoroughly studied and sterilised to prevent contamination and infection.

A view of Titan's surface from an altitude of 70 kilometres

Creating a Self-Sustaining Colony

Landing on airless moons is always problematic due to the need to rely solely on rockets to slow down enough for a safe landing. A large amount of fuel needs to be transported each time. No such problem exists at Titan. The thick atmosphere and low gravity of the moon makes it easy to take advantage of aerobraking techniques and relatively small parachutes (compared to the large parachutes that would be required in the thin atmosphere of Mars).

Because of this very large landing craft, carrying hundreds of tonnes of cargo, or even hundreds of colonists, should be able to land quite easily.

Before colonists arrive in large numbers a sizeable 'town' of habitats will be needed, with power generation and crop growing facilities to enable self-sufficiency. It needs to be well planned, with plenty of redundancy, factories (making use if the liquid hydrocarbons), and with roads and airstrips, and space launch facilities.  There will be no chance of rescue for a colony so far from Earth.

The initial habitats will have to be sent by unmanned missions. They will be built robotically. The first humans will then arrive to expand the facilities and establish what will become the first self-sustaining colony. It's likely that this initial stage would take two or three decades to complete. Essentially, the first generation of colonists would be living in a frontier town, with limited but slowly improving comforts.

A shuttle takes off for a journey to an orbiting station around Titan. Once the colony matures and fuel and manufacturing factories are established there will be regular trips to and from the moon's surface to other colonies in the Saturnian system.

The second and future generations would benefit from the growing colony, with spacious homes, more recreation time, and a growing system of orbital facilities to support life on the surface including communications, and transit to and from the surface and to other colonies that will no doubt have been established elsewhere in the Saturnian system and beyond.

At this point, when survival is routine rather than the main task of each colonist each day, research and scientific discovery can take priority. And it will no doubt focus on the indigenous life that is quite possibly abundant on the moon. Such life could well be complex, with the lakes especially teeming with larger creatures that are just impossible to detect without a surface presence.

A large methane-based complex life-form living in one of the hydrocarbon seas on Titan. The actual life on Titan is likely to be less extravagant than that shown in this image, but it still could have evolved into an array of sizeable creatures.  

Titan could have a diverse ecosystem, far removed from what we know here on Earth. It is the most exciting location in the Solar-System to look for life. There will be no shortage of scientists willing to live there when the time comes to send them.

Robotic Exploration

Before any human colonisation of Titan can start we need to know much more about the moon and its surface conditions. We must send surface exploration missions there at the earliest opportunity.

Some missions have been proposed since 2008, such as the Titan Saturn System Mission. It's an ambitious proposal consisting of an orbiter, a balloon to explore the atmosphere and photograph the surface, and a lander that would splash down in one of the methane lakes.

Another proposal is the Titan Mare Explorer. It's a relatively low cost mission that would put a lander on one of Titan's seas. Unfortunately it did not receive funding, but the lander could end up as the lander for the Titan Saturn System Mission if that ever gets off the ground.

Kraken Mare, Titan's largest sea, seen from a high altitude. NASA is researching the possibility of sending a submarine to explore the sea's depths. If it goes ahead it would be a remarkable mission, and one that has the potential to encounter what could be a complex ecosystem of methane-based life.

Flying in Titan's atmosphere is easy due to it's high density and the moon's low gravity. AVIATR proposes sending an aeroplane that would spend a year flying aound Titan, before attempting a landing. And there is ongoing research into a submarine that would explore Kraken Mare, the largest sea on Titan.

None of the above proposals are ever likely to launch. But there is a proposal that has a reasonable chance of getting full approval. Dragonfly, as it is known, would send a rotorcraft (similar to a quadcopter drone) to explore the moon. It would have the ability to fly at speeds up to 10 metres per second and reach altitudes of up to 4 kilometres. It would land and recharge from its radioisotopic generator during Titan's long nights. While landed it would sample the surface composition. It’s an ambitious and cost effective proposal.

The Dragonfly drone: an essential mission to Titan, and one that could be launched in the next decade

In July 2019 NASA will select either Dragonfly or CAESAR (a comet sample and return mission) for launch in the mid 2020s.

Titan's huge importance cannot be stressed enough, both to help ensure the future of our species by being one of the best places for a sustainable human colony, and by being the likely home of a completely new form of life.

Both of those reasons must ensure that Dragonfly is chosen.

They simply must.