This continues from my earlier article "Ten reasons not to live on Mars, great place to Explore." Many of the ideas in that article apply not just to Mars but to the solar system generally.

I believe that the best attitude to the solar system is to go into space in a process of open ended exploration and discovery, with no end date. We can also go there to find solutions to problems on Earth itself. I firmly believe however that we shouldn't go into space hoping to make a fresh start and to escape disasters on the Earth.

This is just because it turns out we live in a solar system with no other place anything like as habitable as the Earth.

I think the way to achieve a practical and sensible human space program is to recognize this, as our starting point. There is no escape available in space. We need to find solutions to our problems here to survive.

Perhaps, instead of structuring our human space programs around colonization, or some aim to have humans set foot on more and more distant locations in the solar system, we should take exploration and discovery as its main goals.

Earth is the only planet in the entire solar system that's easily habitable for humans. Venus and Mercury are far too hot, the others are far too cold. Nowhere else has an oxygen rich atmosphere.

There is only other place in the solar system with atmospheric conditions at all similar to Earth, and that's the upper atmosphere of Venus. There is a layer high in the Venus cloud tops with almost identical temperature and pressure to Earth sea level.

In many ways this is the most Earth like habitat in the solar system; still, it's no second Earth.

So, let's fill out the details to explain why that is.


Many people do have this idea of going into space to escape from the Earth. What tends to be forgotten is that there are many places on the Earth that we don't colonize. It's not an imperative that we have to colonize everywhere.

So, for instance, nobody has set their sights on the summit of Mount Everest as a place to colonize. We all understand that it's not an ideal place to set up home because you would need to import oxygen continually just to keep breathing. To make it a more exact analogy for colonies on Mars, or in space, or in Venus or whatever, you would need to make all your oxygen from the ice and snow on the summit of Mount Everest, and can't import it from anywhere else or extract it from the atmosphere.

Nobody has that as an aim and they are not frustrated because they are not permitted to do set up home there. It just isn't something that people even think of, to try and live permanently on the summit of Mount Everest.

Tibetan prayer flags on the summit of Mount Everest, which the Sherpas call Sagarmatha meaning 'Head Touching the Sky'

The summit of Everest is far more habitable than anywhere else in the solar system outside of Earth. But nobody has their sights set on the summit of Everest as a place to set up home and live permanently.

There are many other places on the Earth like that, much more practical places to live than Everest, but people don't have the idea to colonize them either, though you do get permanent settlements.

Scientists tend to be the ones most interested in living in these places long term, like Antarctica, the high Atacama desert, and high mountains in Hawaii. You have astronomers with their telescopes, and life scientists, biologists studying extreme forms of life. But even they only stay for months or years at a time usually.

This is Princess Elizabeth research station in Antarctica - Belgium's station, and the first "zero emission" research station in Antarctica; it generates all its own power.

Space colonies, I believe, are likely to start as research stations like this, inhabited mainly by scientists, who are there because they find the solar system utterly fascinating. They will probably have visitors also - tourists, journalists, adventurers and so on, there for shorter periods of time - plus staff who are there to help keep the station running. But for ordinary people, there won't be much of interest to keep you there for months and years on end, and they are certainly not an easy place to set up home in the near future.

I think that's the sort of human presence we will get as exploration of the solar system continues. We shouldn't, and don't have to encourage lots of people go to these places, as there is nothing there for the ordinary person, except to visit it, as somewhere interesting to go for a short time. If we have a human spaceflight program based on exploration, then people who are ideally suited to those places will go there naturally, just as they go to research stations in Antarctica.


I think this is where we went wrong with Apollo. The Apollo astronauts were not scientists and the mission as originally envisioned was just to get humans on the Moon, not to explore the Moon particularly. Originally there was practically no science component to it. Scientists came up to mission planners and said "What are you planning to do about returning rocks from the Moon?" and they hadn't even thought of this. That shows how little it was science orientated.

The science was an add on to the aim of getting humans to the Moon. Indeed the aims of the scientists were in conflict to some extent with the aims of the mission planners - who, tasked with the job of sending humans to the Moon and back, as safely as possible, ideally, would want to return the astronauts immediately, as soon as they had set foot on the Moon to reduce the risk of accidents to a minimum.

Video of the last humans to visit the Moon as their lunar module took off. We have never been back. filmed from a camera left on the surface of the Moon.

Interview with Joseph P. Allen, Astronaut, Apollo 15 CapCom

"I hope the history shows that there are two very different agendas that somehow found themselves on Apollo. One was to take an American to the Moon and return him safely. That was one agenda. And the other agenda, unwritten and uncommitted to, but kind of adopted increasingly as the missions unfolded, was a scientific agenda. “As long as we’re there, let’s get as much scientific information as we can.”

If you’re a flight controller and your highest priority is only to get somebody there and back, you just want him to step down onto the surface and then come back, because this is a very risky place, and the more time you spend in a risky place, the more chance there is for a catastrophe to happen, in front of everybody

If you’re a scientist, the more time you can spend and the more activities you can do, the higher the likelihood will be that you will learn something of fundamental importance, and you realize that these two agendas are mutually perpendicular, or maybe they’re opposed to each other.

The Apollo that resulted was a combination and a compromise of those two totally different agendas. Now, was the proper balance achieved? No one knows the answer. A balance was achieved, and each agenda was satisfied to a degree. Neither perfectly. To this day, the scientists would like to have spent more time on each of the journeys out, and they also would like to have flown Apollo 18, 19, and 20. And we had hardware to do it and people to do it. But every time you flew to the Moon you took a huge risk."

Then when the humans got there, to the average person who is not a scientist, the Moon is not really that interesting. It's quite fun to start with, bounding over the landscape. I dare say an average person could easily go over the days long stay of the Apollo astronauts, and enjoy a visit of a few weeks. But the astronauts, quite understandingly, were not utterly fascinated by what they found on the Moon - the rocks for instance - in the way a geologist would be.

They did collect the rocks of course, as they'd been asked to do, and they had geology classes on the Earth to train them to help them to spot rocks on the Moon; but it was only with the very last mission to the Moon that we sent our very first scientist and the only scientist to go to the Moon. This was Harrison ("Jack") Schmidt, the geologist who trained the Apollo astronauts. He got to fly on the very last mission to the Moon.

As a geologist, he was utterly fascinated by what he found there. It was like the most exciting geological field trip you could imagine, and the mission planners had to keep reminding him that he was running short of time, as he came up with new rocks to collect, then continued finding other rocks that he would love to be able to collect but didn't have time to, because they were a few hundred meters further away than the furthest point he could visit safely within the time restraints.

Here is one of the videos of his field trip on the Moon. The astronauts always began each day by going out to the furthest point they could in the rover, and for safety reasons always had to be close enough to their spacecraft so that they could walk back to it before the oxygen ran out, if the rover failed. Here he is at this furthest point.

Towards the end of this video segment he gets continual reminders from mission control about the need to head back soon. You can hear his enthusiasm and excitement about the mission. This is when he found the orange soil on the Moon which nobody expected.

Transcript here (from the Apollo 17 surface journal)

Schmitt summed up the day with
“Geologically the second day was far more exciting, it was almost a full day of geological exploration, with several important discoveries, particularly the so-called orange soil which turned out to be volcanic glass beads, concentrated in a pure form, and that was rather unexpected, not totally because we thought that it might be a volcanic crater – it was not; it was an impact crater – but it had exposed volcanic material. That was a very exciting day for me. It was pure exploration for the most part, and we made quite a number of discoveries at the base of the North Massif.”

This is how it is going to work in the solar system I think, at present, because it is of most interest to scientists, especially for long term interest. For them these missions will be immensely exciting, and this will communicate itself to us back on Earth.

It is the same for Mars - it may look really fascinating in the pictures, it may look a bit like the Arizona desert. But actually to human eyes it is much more like the Moon. Imagine the Moon but brown and rather dark in colour.

These pictures you see of Mars - if there is a slight hint of blue in the picture or bluish gray even, then you know for sure that the colours have been digitally manipulated, in fact just about every picture you see of Mars have been.

John Carter Movie image - Mars in the popular imagination of fiction with blue skies and bright sunlight bathing the landscape, and of course, oxygen rich atmosphere.

Of course most people realise it is not like that but may not realize quite how dim and dull the Martian landscape would be to human eyes.

Mars as it would appear to human eyes with a dull greyish reddish brown landscape, grayish yellow or brown sky (a bit like sky under thick smog) and hard to pick out colours. click here for full resolution.

Mars as you normally see it in press photographs, with the white balance altered so you can see the colours of the rocks more clearly, often adjusted so far that you have blue skies as well. click here for full resolution. See A White-Balanced Panoramic Photo of a Martian Mountain, Courtesy of Curiosity

That's because there is a very fine dust in the upper Mars atmosphere, and unlike the dust in the Earth's atmosphere it filters out blue light and leaves only the reddish and yellowish tinges. So Mars is the opposite of the Earth - the sky is reddish - but rather dark because it is further away from the sun, and has a lot of dust in the atmosphere - and the sunsets and sunrises on Mars are blue. Not a big bright sunrise as we have on the Earth but a blue patch around the sun as it rises and when it sets, because it is the reverse of the Earth.

Sunset on Mars - this is the only time you would ever see a patch of blue sky, as a pale blue smudge around the setting sun

So if you were on Mars everything would seem this greyish reddish brown - and human eyes are not used to it - so we would not be able to see colours clearly on Mars with unaided eye. Everything would be pretty much the same colour.

That's why the photos are digitally enhanced - to make it seem as if it was illuminated by a normal Earth blue sky and sunlight, when in fact it is illuminated by this dark reddish brown, so it's very difficult for human eyes to pick out colours.

So we see the Mars surface at its very best through the eyes of our rovers there - much better than we would with unaided eyes - and again our rovers don't need to be encumbered by spacesuits, they just need to drive around without being encumbered by big clumsy gloves and so on. They can be built so that Mars is just fine for them; so they are in their element. Humans will never be in their element on Mars.

Curiosity self portrait, obtained by stitching together many separate photographs taken from one of its cameras on an extended arm.

Our rovers are perfectly at home in the solar system, designed to be in their element.

Curiosity doesn't need life support systems or spacesuits. Our rovers are our eyes on the solar system and with their digitally enhanced vision can also see things we wouldn't see with the naked eye.

This is the same throughout the solar system (except on Earth of course).


I argued in one of my articles that habitats floating in the clouds of Venus would give us the most Earth like habitats in the solar system. At a certain height in the Venus clouds you get a one atmosphere pressure, you get the same temperatures as on Earth, you have even got a respectable amount of nitrogen in the atmosphere, a respectable amount of water and sulfur - it is mixed up as sulfuric acid but you can separate that - and the building construction is easier there too.

Russian idea for Venus cloud colony
Russian idea for a cloud colony in the upper atmosphere of Venus, proposed in 1970s
original article (in Russian) - and forum discussion of the article - includes rough translation (I think anyway), probably by non native English speaker.

Our oxygen and nitrogen gas is a lifting gas in the Venus atmosphere with half the lifting power of a helium balloon here on Earth so habitats float naturally at the cloud tops. You get great views of the clouds - and temperatures and pressures are Earth normal. The pressure is the same inside and outside of the habitat, so habitats can be of lightweight construction - and most of the materials can be sourced directly from the Venus atmosphere (even building materials, as the wood in trees is 90% derived from water and CO2).

To find out more see Will We Build Colonies That Float Over Venus Like Buckminster Fuller's "Cloud Nine"?

This is the only place in the solar system, outside of Earth, where you can use lightweight and low engineering construction methods to make houses. It is also the only place where you can live permanently in the open, without the need for about 4.5 tons per square meter of shielding between you and the cosmic radiation from space. The Venus atmosphere provides this shielding by itself. But it is still nowhere as easy to live as Earth.

Anywhere else in the solar system, you couldn't just build a house as you can on the Earth. You can't just go to the Moon or Mars and build an ordinary house there.

If you've looked at the ISS, seen pictures of it, you know it is made of many cylinders with few windows. That's because the ISS has to contain many tons per square meter (it would be about nine tons if it was full Earth pressure) of pressure pushing out. So you need hugely strong robust buildings.

It is difficult to engineer anything which is not an equipotential surface - normally cylinders, or spheres - or something of that sort, very rounded surfaces.

This shows the ISS from space. Note the massive construction of the living quarters, with preponderance of cylinder shapes and very few windows. This is necessary to hold in the many tons per square meter of internal atmospheric pressure humans need to live.

The ISS is designed as a temporary dwelling for humans, normally just a few months at a time. It doesn't have much shielding from cosmic radiation, and is partly protected from solar storms by the Earth's magnetic field.

A permanent home in space would also need an extra 4.5 tons per square meter of cosmic radiation shielding around the entire habitat to prevent astronauts from getting life threatening cancers, or the habitat has to be built underground. The same would apply also on Mars and the Moon. The upper atmosphere of Venus is the only place outside of Earth where you can construct homes without these massive levels of engineering and protection.

Also anywhere outside of Earth and Venus, you'd be limited to a maximum lifetime EVA, because it's impossible to shield spacesuits adequately to keep out the cosmic radiation. You'd have a certain number of months or years total permitted outside your habitat in your lifetime. Children would be particularly vulnerable to cosmic radation, and so not allowed to go out of doors in spacesuits as much as adults. Babies probably wouldn't be allowed outside the shielded habitats at all.

So anywhere in the solar system apart from Earth (of course) and Venus, all your buildings have to be built like this, have to withstand tons of pressure against every surface, and it is extremely difficult to build windows, these are very high tech.

Also greenhouses have to be very strong to hold in all the pressure of the air. You can't just build a normal greenhouse on Mars. It has to be some very robust construction, and probably bubble shaped as well (e.g. one idea is a spherical greenhouse with part of it buried in the regolith).

Early NASA artwork showing lunar greenhouses.These are normally bubble shaped equipotential surfaces and would be made of some strong transparent material to hold in the tons of atmospheric pressure per square meter - it's always going to be far easier to build greenhouses on the Earth

So there is nowhere in the solar system where it is as easy to build places as it is for instance on the summit of Mount Everest, or in Antarctica, or the Atacama desert, or anywhere like that.

I know that the enthusiasts have developed ideas for ways you could build habitats in these places, with the idea of eventually maybe becoming self sufficient, so that they don't depend on the Earth.

If that was possible in space, it would be far far easier to do it on Earth than in the space.

Idea for an inflatable lunar base - one of many ideas for creating habitats in space. If you have a good reason for being there - for instance mining, or tourism - or for scientific discovery - then this could work.

But if you are just there to find somewhere to live, then it's always going to be much easier to set up home anywhere on Earth, even in the most inhospitable deserts. Here, you have oxygen to breath, water vapour and nitrogen in the atmosphere, protection from radiation, and are able to use normal lightweight building construction methods.

Mars is nearly as inhospitable as the Moon as a place to set up home. It is far more like the Moon than it is like Earth. For more on this see my Ten Reasons NOT to Live on Mars, Great Place to Explore.

So I can't see it working at all to start a settlement in space and make a new fresh start anywhere in the solar system. That includes my favourite of Venus, which I think is the most Earth like habitat. But still it is nowhere like Earth.

You have to have some other reason for going there with present day technology. Otherwise, whatever you do there to make your habitats nice places to live and sustainable - then for the same amount of effort, same amount of human hours put into building your habitats, you could build many more of them on the Earth, in the deserts.

It's never going to make economical or practical sense to build habitats in space, as somewhere to live, so long as everything you do in space can be done far more easily on the Earth.


There are many places we can valuably colonize on the Earth, in the sense, of making them more habitable so that humans can live there comfortably. The process of increasing desertification and cutting down of rainforest is turning large area of the Earth into dustbowls, similarly to the disaster in the states which turned large areas of the Prairies into dust bowls in the 1930s.

Farmer and sons walking in the face of a dust storm in the 1930s (Cimarron County, Oklahoma, USA) when large areas of the Prairies in the States turned to dust. This same process of desertification is happening in many places on the Earth today.

Reversing desertification is a massive problem world wide. In fact I was born in Madagascar and this is a country that is suffering tremendously from deforestation and the soil being lost into the oceans.

The red soil of Madagascar washed into the sea as a result of soil erosion resulting from deforestation.

At the current state of technology and understanding, then rather than attempt to terraform Mars, which we don't know how to do and which might easily make things worse, we should terraform the Earth.

There are many simple things we could do on the Earth to reverse the effects of our actions and make it more habitable than it is, for instance actions to reverse deforestation. Earth is by far the most habitable and most easily terraformed planet in our solar system.

This is something which we could reverse much more easily than we could start up new colonies somewhere in space. We could use some of the same technology too. There are some ideas which are related to space settlements such as seawater greenhouses - which use seawater which cools down the greenhouse and evaporates the seawater. This is in desert places close to the sea - it creates fresh water for the greenhouse, fresh water for the desert, replenishes the aquifers, and creates salts as well.

Sundrop farms video

Find out more: Sundrop farm news

So this is a little bit like the space settlement ideas - but using seawater (which we don't have in space) and of course we already have oxygen in the atmosphere, but it is quite self contained with the way it circulates, with the sun and the seawater all working together.

I'm not saying we won't have any habitats in space. We will need them for our scientists out there apart from anything else - and in these habitats they will have to solve the problems of closed systems. Then you will also have the tourists and hotels in space - and miners getting resources for the Earth.

We may have other reasons for building them too. For instance maybe we will need them for building solar power satellites in space. This was the original reason given for the Stanford Torus design.

This is an artist's impression of the Stanford Torus design. This was an ingenious idea to create a huge habitat in orbit around the Earth. Despite its size, you could get all this material from the surface of the Moon. It's about ten million tons (equivalent to excavating one square kilometer of the lunar surface to a depth of about 3 meters assuming lunar rock densities of 3.4 tons / cubic meter). The idea then was to send it to the construction site using mass drivers on the Moon. All you need to send from Earth are the materials you need to create the mass drivers in the first place, plus hydrogen, which in their plan would be combined with oxygen extracted from the soil to make water, and nitrogen - the rest of the materials come from the Moon.

They estimated it would cost about 20 times the cost of Apollo, and by 28 years it would be paying for its annual costs, and could pay itself back entirely in 70 years. It would have ten thousand inhabitants and their main occupation was to make solar power satellites for the Earth. By reducing costs of electricity, it would benefit poor people and poorer nations more than the wealthy, as they spend a higher proportion of their earnings on power. (Details in chapter 6 of their study).

With 1970s technology then this was a process that needed many people in space. If they had built it then, perhaps we wouldn't have had the energy crisis or global warming and would have low cost electricity from space by now.

Perhaps it still is one possible way to deal with the energy crisis and global warming. But nowadays you wouldn't need as many as 10,000 people in space, surely

But a smaller settlement in space might well be useful if we do large scale mega construction in space, or move some of our Earth's industry into space

We might well build big settlements in space eventually. But we will need a fully worked out reason, like this, to build them. Without a good immediate reason for the colony to exist, it will make no practical or economic sense and the project will fail - because it costs so much less to build homes on Earth.

So, I'm not saying at all that we can't do this or shouldn't do this sort of thing.

I'm just saying is that it will never make sense to go into space with settlement there as your end goal. It will never be easier to live in space, than on the Earth at least with present day technology.


Now there may be some magical technology in the future which will change all this - and we will meet that situation when it arises. For instance 3D printers may eventually make a huge difference to this.

Amazing 3D Printer

We will actually send a 3D printer to the ISS soon.

How NASA Will Use 3D Printers in Space

Eventually we'll be able to do nanoscale printing also, of electronics in space.

These 3D printers will obviously transform spaceflight. But they will also transform life on Earth also. They will make construction and repair in space easier but will also make construction and repair on the Earth easier also. So when it comes to buliding places to live, then builders on the Earth will probably still have the edge over builders in space.

What we know about the future is that it is never as you predicted. Some things may be and some things not.


Very much the same thing applies to terraforming. In my "Trouble with terraforming Mars" I've talked about how very different Mars is from the Earth. It would be really hard to terraform Mars, I believe, because it is so very different from the Earth.

When people talk about making a fresh start and escaping disasters on the Earth, everybody acknowledges that Mars is totally not at all habitable like Earth at present.


It's pretty clear that you couldn't escape a disaster on Earth on present day Mars.

To get Earth at all like Mars you'd have to get rid of 99% of the Earth's atmosphere, and all the oceans, and you'd have to get rid of 80% of the ice in Antarctica to get down to the levels of ice there is on Mars. On Mars the ice in the ice caps is equivalent to about 12 meters of water over the surface of Mars, and if you got rid of 80% of Antarctic ice, then that would be equivalent to 12 meters of water over the surface of the Earth.

Then you'd have to get rid of the Earth's magnetic field (which protects us from solar storms), stop continental drift, and even then you are not done.

Then you have to reduce the sunlight to a half of what it is - then make it a more elliptical orbit (leading to bigger changes between the climates in the two hemispheres) and reduce the gravitational pull to a third of what it is.

The gravitational pull is important, because first, it means that on Mars you need three times as much of any gases in the atmosphere to achieve the same pressure at ground level - and also - nobody knows if humans can survive long term in low gravity. Our life expectancy might be less (life expectancy in zero g might be as low as two years according to the opinion of one space medicine specialist, from our experiences of zero g in space - but there is no way to estimate it in low g) and bones may be unable to grow in low gravity.

No credible human caused or natural disaster could make Earth as inhospitable as Mars in the near future. Even comets perturbed from the Kuiper belt are not at all likely to do this to Earth, as we can tell from the cratering record on Mars and the Moon.

Earth could certainly become as inhospitable as Mars in the far future - there is a remote chance that Mercury could hit the Earth a billion years or so from now, perturbed from its orbit by resonances with Jupiter then deflected by Venus. Also, over a similar timescale as the sun heats up the Earth's oceans would boil away. Mars might well be a useful place to escape to in the far future in those scenarios, but Earth is by far the best place to live right now.

To make Earth as inhospitable as Mars you'd have to remove 99% of it's atmosphere, all its oxygen, all its oceans, 80% of the ice in Antarctica, stop continental drift and its magnetic field, reduce gravity to about a third, and halve the amount of light so that the equatorial regions get as cold as Antarctica.

In any credible disaster on the Earth, the safest place to go to escape will be somewhere else on Earth., and the best thing for anyone on Mars to do would be to return to Earth to help with rebuilding after the disaster.


Because Mars is so very different from the Earth, terraforming is far from straightforward. If you could somehow magically transfer the Earth ecosystem to Mars it wouldn't work because the planets are so different, Mars needs its own solutions.

Also, terraforming is something that will take thousands of years to complete. People were more optimistic back in the 1970s with estimates in the region of centuries, but nowadays the most optimistic think getting on for a thousand years, and others think it would take 100,000 years, if you want to go as far as an oxygen rich atmosphere. That's if it works. We have never successfully terraformed a planet, of course, and nobody knows for sure if it would work.

This looks great, but what you might not realize is that the timescale from the beginning to end of the process is 1000 years. What advanced technological project have we ever undertaken that took centuries to completion?

And this the most optimistic of present day projections. Mars probably has many possible end states, it is not at all clear we know enough at this stage or can keep it in the desired end state without continuing mega-engineering into the endless future..

For more about this Why Mars is NOT a Great Place to Live - Amazing to Explore From Orbit - with RC Rovers, and Nature Inspired Avatars

The big issue is that there may be many possible end states of a planet. We on the Earth are only in one of them. It is no longer credible to suppose that you just need to add some life to a planet and it would automagically end up something like the Earth.

Mars as it is now may well indeed be an end state of a planet with life at Mars' location in the solar system - because it seems reasonably likely that it had life in the early solar system and may well still have life to this day.

If Mars as it is now is a stable end state for a planet with life at its location, you might have to fight against that to try to make it anything like the Earth.

You'd have to set up systems designed for Mars, a colder planet with less gravity (needing three times as much atmosphere for the same pressure), far less water, no continental drift or magnetic field, half the sunlight, and all the other differences. If that worked, it might then turn out that you have to have mega-engineering from now on into the endless future, in order to keep Mars terraformed. If you stop the mega-engineering, it might unterraform almost as quickly as it terraformed.

And what advanced techological project have we ever done which lasts centuries in order to reach completion?

For more about this see my Trouble with Terraforming Mars.

It's great to think about ideas like terraforming, and it could arguably be said that all the thought that has been put into terraforming Mars has been a great contribution to understanding how the Earth's ecosystem works and help us understand how exoplanets work.

Who knows, in the future maybe these ideas will be used, but I think we are a long long way away from being at the point where it makes any practical sense or is of any value to try to terraform Mars, or has any chance at all of success.

Whether it is possible or not, it's such a long term project that even the most optimistic would not expect to make Mars into a second home as habitable as the Earth in as short a time period as a few centuries.


What we should do instead is to use the ideas and thoughts behind this indeed, but should be focusing on terraforming Earth. So for instance reversing desertification and dealing with deforestation, and with the soil loss and all these thigns likethat.

In the solar system we should be heading out and seeing what we can discover there in a process of open ended exploration, with no end date, just as we explore Antarctica and other similarly inhospitable places. Actually given the amazing interest of Mars for biology I'd say there may be good reasons to leave it to open ended exploration even if it was as habitable as the Earth - but as it is now, I think there is no contest.

And there is much of tremendous value we can discover in space, particularly in terms of biology - a surprising gap of our knowledge.


If you work out all the evolutionary steps from amino acids to human beings, and you look at the most primitive cell we know, where do you think that would lie along the line from amino acids to ourselves?

This drawing shows the 21 amino acids found in  eukaryotes - the amino acids are the basic building blocks of life.

If you draw a line, with the basic amino acids, which you find in meteorites, at one end, and with us, humans at the other end, ordered by complexity of the DNA - where would you put the simplest known living cells?

It would be natural to think of the simplest living cells we know as almost the first step of evolution after the basic amino acids you find in meteorites.

But if you look into it more closely, it's absolutely impossible that you could mix different amino acids together and get a cell.

The smallest known cell - which is a tremendously complicated cell, has DNA, RNA, RNA polymerase, all the complex details of gene expression with error correction, proteins enzymes, the cell wall, a million different chemicals in a complex dance.

This shows how RNA Polymerase (RNAP) converts the DNA (black) into RNA (blue) in the process known as transcription. The RNA then goes on to construct proteins in the next step

This shows how messenger RNA (mRNA) is used to assemble proteins in the process known as Translation.

These are simplified diagrams of two of the main processes involved in gene expression.

And this in turn is only one part of the immense complexity that makes up a functioning cell, even the most primitive type of cell we know.

These amazingly complex chemical dances involving a million different chemicals go on in even the simplest cells we know.

Here is a video animation of part of the process - transcription and translation all the way from DNA through RNA to Haemoglobin (in this example).

It turns out that in terms of the evolving complexity of the DNA there must have been as many different steps in evolution between amino acids (simplest building blocks of life also found in meteorites) and the simplest cell that we know, as there are between the simplest cell and ourselves.

In fact so much happened between amino acids and the simplest living cells, that if you plot the line backwards you end up with this diagram suggesting that life must have originated nearly ten billion years ago, long before the origin of the Earth.

This diagram shows the complexity of the DNA as measured using the number of functional non redundant nucleotides.

This is  a better measure of the genetic complexity of the organism than the total length of its DNA. Some microbes have more DNA than a human being - much of that used for other purposes rather than for genetic coding, the so called C Value Enigma. Measuring it this way deals with that issue.

Then, we don't have actual DNA from nearly 4 billion years ago. The origin of the archaea in their present form especially is a matter of debate. But we have micro-fossils from that time that look like present day Archaea. Various lines of evidence suggest that they may be something of a living fossil from over 3 billion years ago.

This image shows some of the fossil evidence of the early microbes - at the top you see a sequence of micro-fossils arranged in an order thought to show cell devision.

Of course, archaea vary greatly genetically and adapt to different environments. The idea is just that some of them are generally similar, and that they are of similar complexity to their archaean era predecessors.
Either that means that life did evolve that long ago - or else - that evolution for some reason proceeded far more quickly in the first few hundred million years of the Earth's h istory.

Either way, there's the equivalent of developing a nucleus, going multicellular, developing a backbone, warm blooded, all the other steps to us - there's the equivalent of all those steps from the amino acids to the primitive cell, and we don't know anything about that gap.

It's a huge gap in our understanding, and particularly on Mars but also in other places in our solar system, it's possible to fill this gap.

When you think about how important life is for us, of course we are alive, medicine is very important, but also we are surrounded by the products of life. Just take a look around you and chances are you'll see some wooden things, paper, plastic, oil, cardboard, cloth, we are so dependent on the products of life.

Think about what understanding the process of evolution of primitive cells could do, and maybe some life that has gone in a different direction from life on the Earth. Think about what new things could arise - maybe even new technologies, new nanotechnology, new biological products.

We have no idea what we are going to discover in the solar system, especially now we realise there is at least a very strong potential that we will find out things about life, evolution, and the origin of life all the way back to amino acids.


But it is likely to be a very difficult and long process to find this out. Science takes a long time anyway, and then there are various reasons why this is really hard to discover because the life is expected to be very elusive.

We are talking about traces of organics from billions of years ago that may still remain on Mars to this day, very much degraded but still plenty for us to learn a lot about what life was like back then.

For more about this, see my article Where Should we Send our Rovers to Mars to Unravel Mystery of Origin of First Living Cells?

We are also talking about very hard to discover present day life, a few microbes per ton of soil maybe, very sparse slow growing, maybe each microbe will live for a thousand years before it reproduces.

So it's going to be really hard for the scientists to discover things, but amazing things for them to discover. So I think we should think about it like that and when we have projects in space, think in terms of open ended exploration, and also thinking, what are these projects doing for the Earth?

So we need to be patient and give the scientists the time they need. For instance, I'm pretty sure that just as we have had many announcements that our rovers have discovered signs of water on Mars - the next stage will be similar announcements about amino acids, and chiral signatures. Unless very lucky, we will get announcements one after another that scientists think they may have found ancient life on Mars - but nobody is sure if they have - and then the same perhaps for present day life also if it is elusive. There may be many expeditions and experiments before we have a clear picture of what early Mars or present day Mars is like from a biological point of view. This is how science works, is normal and not something to be surprised at.


We will go there for its own sake to make discoveries, or to return something to Earth. Also adventurers, explorers and tourists going there for fun, recreation and just to have a good time and see the sights. There is nothing wrong with that, and maybe some day it will be as easy to visit places in space as it is to visit places on the Earth.

But I think the idea of setting up a colony when you don't know what it is for - I think that's when you are going to go all wrong. Because it just isn't a good place for the likes of ordinary people like ourselves to head off there - if you are not a scientist - and really very interested in what you are doing there.

If you are interested in what you are doing - then you build your colony around that interest. So you might have an orbital colony around Mars in order to explore Mars and you design it in such a way that it is a very good research station and that's why you build it.

In the case of Mars particularly,surely you will design your research station with humans in orbit, controlling robots on the surface. This lets you explore Mars more thoroughly, at less cost, increased safety, and most importantly, without increasing the risk of contaminating Mars and confusing the sensitive scientific experiments. See my Why Mars is NOT a Great Place to Live - Amazing to Explore From Orbit - with RC Rovers, and Nature Inspired Avatars.

In the case of the Moon, it might well turn out that it is worthwhile to have humans on the lunar surface to explore it, though we may also make considerable use of rovers controlled from Earth and the L1 and L2 positions. And as for Mars (and also some places on Earth such as lake Vostok), there may be some places on the Moon also (perhaps the ice in the craters of eternal night at the poles) and other places in the solar system which need to be kept pristine and uncontaminated by Earth life.

The main thing is that you design your missions and research stations around the need to explore and make discoveries, instead of the Apollo type approach where you design them around the need to let humans set foot on some particular spot in the solar system.

That way your human space program has a sound basis and we can settle into it for the long term, instead of a short term program that lasts for only a few years like Apollo.


You don't build a colony on the Moon, or in orbit around Earth or Mars or on Mars or in the Venus clouds, or Mercury or anywhere like that just as a place for someone to go to live. That just makes no sense at all.

It makes no sense at all to go into space as somewhere to live, because you can build your homes far more easily on the Earth. That would be just like going to the summit of Mount Everest to build a house because you think that's a great place to live.

North face of Everest looking towards base camp. Going into space to find a new place to live is like going to the summit of Mount Everest to build a house because you think that's a great place to live.
(this is edited from a transcript of my video talk Why Open Ended Exploration of the Solar System is More Practical than Directed Colonization on my MarsandSpace Youtube channel)." />