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Picture this - an astronaut has just found life on Mars. How do you think it happens? I expect most of us will answer "Found a fossil" as in the painting by Pat Rawlings used as the cover for my new kindle book. However, Curiosity is exploring a lake bed that has been dry for three billion years. That's long before there were any easily recognizable fossils on Earth.

So astrobiologists focus their hopes instead on ancient microbes. That may seem boring, but in the best case, these would not be ordinary microbes, but microbial versions of ET. They may be so ancient that they predate DNA, or maybe their life is based on different principles from Earth life. This could be the biggest discovery in biology of our century, revolutionizing our understanding of evolution, of how life works, and perhaps medicine, agriculture, and who knows what else.

These astrobiologists design exquisitely sensitive miniature instruments to detect faint ancient degraded biosignatures. Hopefully some of these instruments will fly one day. Perhaps life still exists on Mars, right through to the present, perhaps even early life hardly changed for billions of years, long extinct on Earth. If we aren't careful, something as vulnerable as that could be made extinct by whatever made it extinct here. Sadly, humans can't be sterilized of our trillions of microbe companions. As we try to touch Mars we may lose the most precious thing we could find there. As our microbes spread in the global dust storms, the native Mars life might be gone before we know it was there.

It would be so wonderful if we could just reassure everyone that Earth microbes on human crewed spaceships will cause no problems on Mars. If only real life were like the movies, built on the imaginations of authors and using evolving dramatic tropes. However, this time, we don't get to write the script for the sequel. Star Trek doesn't give us any real experience in exploring planets. We often make mistakes when we try something new, sometimes huge ones, It's time to look at this carefully. At last we are getting a few journalists and TV presenters who touch on the subject briefly, but we need more awareness as it is so often treated as a minor matter, soon dismissed. It's time this discussion moved from the specialist papers and workshops on planetary protection to the general public.

If we decide to keep Earth microbes away from Mars, at least for now, what happens to all our plans to explore the red planet? Well we can continue to use our robotic eyes and hands on Marx. . Meanwhile our astronauts can start extraterrestrial fossil hunting on the Moon. We should find meteorites there from early Earth, Mars and perhaps even Venus, wonderfully preserved deep in the extremely cold ice deposits at the lunar poles. Later, as we learn to send humans safely further afield, to Mars orbit, and its moons, they can explore it using "telepresence" in immersive 3D virtual reality. All of us back on Earth can join in, exploring a landscape built up from the hours of binocular HD video streamed from the surface. I will also cover searches for life in the oceans of Europa and Enceladus, and more exotic places, ranging from the molten sulfur lakes of Io through to liquid nitrogen geysers of Triton.

The book starts by comparing Mars with the Lascaux cave paintings, damaged by microbes from human visitors. I hope this book will bring these issues to the attention of a wider audience, now that it seems that we may have technology to send humans to Mars within a decade or two. This is a decision for all of us, not just scientists and space enthusiasts. This book has hyperlinks throughout which take you to the scientific literature. Many of the papers are open for anyone to read , so it's easy to follow through to find out more for yourself.

In more detail

How often have you seen this scenario in movies, artist's renderings and science fiction? Bold and brave astronauts explore Mars, setting out from their base in pressurized rovers and spacesuits. They scale cliffs, adventure into caves, and dig deep. They search for past, and present day life. And one of them has just made a great discovery, a fossil!

However there is another side to this picture. As these brave astronauts explore Mars, their bases and rovers leak Earth microbes into the dust, every time they open an airlock. Their spacesuits also leak air constantly (they have to be able to bend their arms and legs at the joints and the spacesuit designers achieve that by leaving tiny gaps which the air leaks through). They leak a trail of microbes, wherever they go.

Then, the ground they walk on is covered with dust as fine as cigarette ash, light and easily moved, even in the near vacuum winds of the Mars atmosphere. These particles can travel hundreds of kilometers in a few hours during the fast winds of the seasonal dust storms. Every decade or so, these storms combine and spread to cover the entire planet and last for weeks. The dust blocks the sun and turns day into night, and it takes months for all the thick clouds of dust to fall back out of the atmosphere. Carl Sagan once remarked, that the iron oxides that make up these dust particles are perfect to shield a microbe from the sterilizing UV light of the unfiltered sun. Such a microbe, imbedded in a minute crack in a dust grain, could eventually fall to the surface undamaged, thousands of kilometers from its point of origin. Trillions of hardy microbial spores will stream out from a human base in the winds, and if there are any Mars habitats for them to find, they would surely get there eventually. For more on this see How could this work on Mars with dust storms and a globally connected environment? (below).

That's especially so if humans crash on Mars. After all the space shuttles Columbia and Challenger crashed. Minute fragments of the astronauts bodies, food, air, water and the spacecraft itself would spread in the dust and could irreversibly contaminate Mars with Earth life. If that happens, then it will impact on all nations on Earth with an interest in exploring Mars, and also our descendants, and all future civilizations in our solar system. For the entire billions of years future of Mars, nobody would ever again have the opportunity we have now to study the present day pristine planet. Why don't explorers of other planets in Star Trek and the many movies, books and TV series have these same problems? Perhaps it is because they are the result of the author's imaginations. They aim is to entertain, after all, and over many films and movies, through collaborations of script writers, directors and sometimes ideas from the actors, they build up movie tropes that reinforce each other. Eventually the audience come to expect the films to be done this way. These are often things which help move the plots forward, and make the stories more dramatic. However, none of this is based on any actual experiences at all of exploring other worlds.

It would be great to be able to say that humans on Mars will cause no problems. It's what most of us want to be true. Anyone who writes or says that is likely to be more popular, and their articles and videos will get more widely shared. But our actions will have real world consequences, not just lead to movie sequels. We don't get to write the script for what happens next. We need to take a careful and thorough look at what might actually happen before we act.

Could we get a future news story: "Debate over Moldy Mars is a Tale of Human Missteps"?

We have made so many mistakes on Earth, already. I will start this book with an example of the many things that went wrong with our attempts to preserve the Lascaux cave paintings. Could the same happen some day with Mars? Might we some day read an article in the Washington Post,or New York Times, similar to a recent one about the Lascaux caves, but this time it says: "Debate over Moldy Mars is a Tale of Human Missteps"? If so, is this something we can foresee in advance and prevent?

At least nowadays scientific news stories about Mars sometimes mention these issues. But still, it's too often brushed over quickly. almost as an afterthought. Let's take an example from the scientifically highly respected Sky at Night program in the UK (hosted for many years by Patrick Moore until his death). In a recent episode,Life on Mars the presenters briefly covered the need to protect Mars from Earth life. They also talked about the impossibility of keeping Mars pristine with humans on the surface. But they treated it as a rather minor matter. The discussion starts about sixteen minutes into the program. The presenter ended by saying (around twenty minutes in)

In other words, the idea is that our present situation is frustrating, and once we send humans there. we will no longer need to be bothered about protecting the planet, because the die will be cast. With Mars irreversibly contaminated with Earth microbes, then you get the impression that with a huge sigh of relief, at last, we can go about exploring Mars much as we explore Earth (though in spacesuits of course).

That argument may seem convincing to you, if you haven't looked into it in detail. Who cares about a few bacteria when there may be far more exciting discoveries to be made there? Indeed even many scientists think this way. Kudos to the BBC for raising the issue at all however, as the idea of planetary protection is so often ignored completely as soon as the discussion turns from robotic to human missions. Another recent video raising these issues is this one from VSauce Is it okay to Touch Mars? which they did for the National Geographic series on humans to Mars. I got the idea for the word "Touch" in the title of this book after listening to their video, and this book is in a way a response to it. It covers some of the same issues that they cover (starting nine minutes into that video), but there is so much more to be said.

Raising awareness - fossil optimists and early life enthusiasts

We have a long way to go by way of raising awareness of these issues, and I hope to help with this book. Before we can make the right decisions for the future, we need a clear understanding of what the issues are.

Many of us, without thinking about it, are "fossil optimists" as I characterize it in this book. The cover photo shows this fossil optimism in artwork done for NASA by Pat Rawlings. After all, that's how it works on Earth. We are used to learning about past life from fossils, so it's not too surprising that we expect the same to happen on Mars. Enthusiasts, including scientists, even search the Opportunity and Curiosity photos for what they think may be fossils of past Martian life.They are usually searching rock formations from dried up lake beds that are unlikely to have seen any life for more than three billion years. Nearly all Earth macro fossils date from the last half billion years of our geological history, apart from some hard to recognize stromatolites and other fossils that are ambiguous and took a lot of proof before they were accepted as life. To look for clear unambiguous macrofossils in Gale crater is to show optimism that life on Mars had at least a two and a half billion year head start compared to Earth. Such fossil optimism is not absurd, indeed you can come up with some interesting reasoning in favour of it, but the case for it isn't very strong either, and you can argue the case both ways.

Many professional astrobiologists are "early life enthusiasts". Their professional focus and instrument design is mainly orientated towards life similar to whatever existed on Earth over three billion years ago. Such early life may very well even be so early that it predates DNA based life. It may consist of single cell organisms, so small that you can't see them at all, not just with a magnifying glass, but even with the best of optical microscopes. They don't expect to find easily recognizable macrofossils in these deposits. Instead they pin their hopes on the ability of the Mars conditions to preserve organics for billions of years. But they expect this signal too,to be weak, degraded, mixed in with organics from other sources, and only present in a few rare locations. They also expect that they will need to drill to depths of several meters to find it. For this reason they think that in situ searches with sensitive biosignature detectors are the way ahead for the search for past life. And even then it may also require a fair bit of detective work. Present day life is also likely to be elusive for different reasons.

With that background, the tiny microbes are the very thing you are looking for. Introducing Earth microbes and organics could be disastrous for ones hopes of finding out about life on Mars. So what then is the role of humans in this vision?

Value of humans in space - and fossil hunters on the Moon?

In my other kindle books and booklets, and my articles, I've written a fair bit about the value of space resources, and the many ways that humans can contribute in situ to exploring the solar system. I also argue strongly for the Moon as the obvious place to get started with human exploration. It's not just as a stepping stone to Mars. It's also a place of great interest in its own right, and with little by way of planetary protection issues to deal with.

The Moon can also help bring us with the biological search for early life, rather surprisingly, through remains of life that landed there in meteorites. It has extraordinarily cold conditions at the lunar poles. We might find fossils also, fossil diatoms are still recognizable after a simulated impact on the Moon, indeed the smallest ones are intact, complete fossils. There must be a lot of material from the Chicxulub impact on the Moon. Perhaps the Moon will be one of the best places for fossil hunters in our solar system, outside of Earth.

The Moon must have meteorites from Mars too, for us to pick up, also from early Venus too, from before its atmosphere became as thick as it is now. Early Venus might have had oceans and might have been as habitable as early Earth and Mars. For more on this see Search for early life on Ceres, our Moon, or the moons of Mars below.

In those books I also argue that with our lunar adventures, we will learn about what humans can and can't do in space, and how to stay healthy there. We can also learn how to be self sufficient for months and then years at a time, before resupply from Earth. If we can do that on the Moon it will reduce costs hugely. Once we've done that, it will also be much more practical and safe to send humans not just to Mars but to the Venus clouds, Mercury, asteroids and further afield. Even Jupiter's Callisto, just outside its dangerously intense radiation belt, is less than two years journey time on a fast Hohmann transfer orbit.

Once it is safe to send humans to Mars orbit, we can use this to explore the surface in an immersive way. This is similar to exploring a three dimensional virtual world in a computer game, but this time the world explored is real. Telepresence like this may be a great way to explore the Moon too, so we can gain experience of this on the Moon first. This virtual way of touching Mars is in some ways more immediate than touching in a spacesuit and is an exciting and adventurous alternative vision for humans in space. It is also safer, and has none of the irreversible and possibly devastating consequences for science of landing on the Mars surface directly with all the microbes that inevitably accompany us.

I thought it's best to say that from the outset as I've found in the past that my readers sometimes see my articles as an attempt to stop humans from exploring space. Far from it, I'm a science fiction geek and long term enthusiast for humans in space since the time of Apollo. As a teenager I found those missions exciting and followed them keenly. Humans on Mars are not the problem. The problem comes with the microbes that accompany us, in the air, in our water, and indeed on and in our bodies too, trillions of them, that can't be removed or we'd die. These include microbes capable of living in extreme environments, since many extremophiles retain their ability to survive in more ordinary conditions. They can manage just fine on and in our bodies, and on the surfaces of our spaceships. Even the organics that make up our bodies, and our food, human wastes etc could be a problem in the event of a crash on Mars, as we'll see. They could confuse those astrobiological searches for elusive degraded organics, with instruments sensitive to a single amino acid in a sample. If we explore Mars via telepresence, we can be there in person without these possibly devastating consequences of touching Mars.

Human settlement and exploration - hugely positive or hugely negative - it all depends how it is done

Of course many of my readers will be keen on human settlement in space. Though that's not the focus of this book, I should just touch on it. I argue in my Moon First books that this has potential to be hugely positive or hugely negative. It depends very much how it is done, and it may be a good thing that we are likely to have few humans in space to start with. Though I'm keen on humans in space, I'm no advocate for sending large numbers as fast as possible. After all think what the consequences would be if we had the likes of ISIS and North Korea in space colonies, with space technology far advanced over ICBMs. Once there are tens of thousands, and millions of people in space, we can't restrict this to the "good guys or gals" whoever we think those would be. I cover this in my Case for Moon First in these sections:

I argue also that settlement can have hugely positive consequences if done well. It can help protect and sustain Earth, move heavy industry into space and provide power and resources that may help us in the future.

It's a similar situation for human exploration without settlement, which is the main focus of this book. That also can be either hugely positive or hugely harmful. This book is about the especial case of the impact of in situ human exploration of the solar system on the scientific search for life. Mars is the one place in the inner solar system most vulnerable to Earth microbes. The same issues also apply for Jupiter's Europa and Saturn's Enceladus with their deep ice covered oceans connected to the surface, so I will cover those as well, also the Venus clouds, and some more exotic places we could search for life, such as Titan, Io, Triton even, but the main focus is on Mars as there are no plans to send humans to those other places in the near future.

Humans can probably help a lot with in situ exploration, because of our ability for fast and accurate on the spot decision making. But we have to be careful to look at the downsides as well as the upsides of humans "on location" in the solar system. We need to understand what could go wrong, as well as right, to decide how best to plan our explorations. By doing this we can make best use of both humans and robots, and preserve the science value and interest of the places we explore.

This is the preface to my new book "If Humans Touch Mars". So let's get on to the book. What are the possible consequences and ramifications if humans touch Mars?

At around 370 pages, it is too long to include in its entirety here. But you can read it online, and on kindle.

Touch Mars ? Like Moldy Lascaux - Tale of Missteps? - Kindle edition. Or read it online on my website (free).

Facebook group

I've made a new facebook group which you can join to discuss this and other visions for human exploration with planetary protection and biological reversibility as core principles. Case for Moon for Humans - Open Ended with Planetary Protection at its Core