You might think, why not go out and out, confront this issue head on, let's have a grand debate or a contest of some sort, and whoever wins the confrontation gets the prize?
Well, yes, sometimes confrontation can be good. Sometimes you have to do it. Or you tackle an issue head on and though neither side "wins", you get more clarity from clearly exposing your differences from another person. If you are lucky, you may find that something new comes up that transcends either of your views or the things you knew, something which you could only have found out by clearly exposing the differences. You might not convince each other, but you might be able to go different ways after the confrontation, each with a bit more clarity.
Sometimes, though, you are "in it" together and can't just continue your separate ways. Sometimes after battling away at a confrontation, you find it is going nowhere. In this case, Zubrin has been battling with those who want to protect Mars from contamination by Earth microbes (and Earth from Mars) for many years. It doesn't seem likely that this is going to end by anyone "winning the argument" or conceding defeat. To his keen supporters, Zubrin may seem to have won all the debates, but to those who care about planetary protection, he hasn't won any of them, as we've seen.
At other times, you can compromise. Perhaps you can find an approach that lets you accommodate both views at once to some extent. But sometimes a compromise satisfies nobody.
Let's see an example of a situation where a compromise just can't work. Travelers from Hawaii have to be careful not to bring the oriental fruit fly Bactrocera Dorsalis into California because it would devastate the crops.
Bactrocera dorsalis - a female oriental fruit fly. Travelers from Hawaii to California have to be careful not to introduce it, as it makes fruit unfit to eat. Similarly microbes from Earth introduced to Mars may have harmful effects on whatever is on Mars.
It would satisfy nobody to try a compromise solution to import fruit from Hawaii to California only on the first day of each month. That would mean the fruit importers are severely restricted in what they can do, while the fruit growers are not protected from the oriental fruitfly, so it satisfies nobody.
Sometimes, confrontation leads to a resolution, but as often, it entrenches views and may make it a little harder to look at the good points of what the other person is saying. Or they do listen to each other, but nobody wins, or both sides say they have won. Sometimes compromise is impossible because we are in a situation that just doesn't have any opportunities for a natural compromise that would satisfy both parties in the confrontation.
When that happens, it's time to look for a non confrontational approach, a way ahead that while accepting the differences of views, leads maybe in an unexpected direction. Perhaps, somehow, it just takes a detour around the confrontation that was looming up. That can then be satisfactory to both. This is often possible when confrontation has failed and compromise is unworkable.
That is what I'm attempting here. I think it's a situation where direct confrontation will only polarize positions and entrench ideas, I don't myself think that the compromise approach of sending humans to Mars with some extra precautions is adequate (highlighted by the problem of a human crash on Mars which would effectively end all possibility of planetary protection). That's like the compromise of taking no precautions against the oriental fruit fly on the first day of each month.
This depends of course on what we find out about Mars as we study it further. But for as long as we continue to need to take precautions to protect Mars from the microbes on our rovers, I don't think it's going to work as a compromise to give the microbes on human occupied ships a "special pass".
But I do think it's a situation where a non confrontational approach is possible, and can be satisfactory for both. Not a head on conflict, not a compromise, but a search for a new direction for humans in space exploration. That can give us some breathing space, which can lead to new ideas, discoveries and solutions for the way forward in the future, whatever it is.
So, to try to see this in perspective, first lets try to look at something much smaller. Suppose you want to build a house and need to fill in a pond. You get an assessment done, and you are told that this pond is the breeding ground of a rare form of amphibian. In the UK it could be the great crested newt.
You might not give it a second glance, but this is a European protected species. Your would not be permitted to build on its pond, nor can you try to move it (apart from exceptional circumstances). Instead, you would have to preserve the pond and build somewhere else.
Of course some people couldn't care less about protected species. It's not a big deal if you don't care for great crested newts. You accept that others do, and as a law abiding citizen, you just build somewhere else. I gave the example also of the oriental fruit fly which makes fruit unfit to eat and so you can't import some fruit and flowers into California from Hawaii. It's an annoyance I'm sure for fruit importers, but it is something they understand the need for, and so most will just keep to the regulations.
For another example, the Kakapo, a flightless parrot, is very trusting and vulnerable to cats, dogs, etc.
I think most people would understand and accept that you can't have cats and dogs on islands inhabited by the Kakapo. There are many examples of invasive life, of course, which can cause problems on Earth. The best known ones are the higher animals and plants, but as we'll see, there are invasive microbes as well. So let's have a look at invasive species next, then I'll come back to this theme of looking for a non confrontational way ahead, not a compromise that can satisfy no-one, but a way ahead that can be satisfactory to everyone, at least to some degree, and for a while.
There's a long list here of examples of invasive species on Earth, and more here, and more in Wikipedia article on invasive species. Here is a selection from those sources.
(I have left out any that are only pests or diseases of particular plants or animals)
Many of them make native species extinct by changing the habitat in various ways, or by smothering the area with their form of life. This doesn't require the invasive species to be adapted in any way to attack the species it overwhelms. The same may happen with microbes from Earth on Mars. There is no need for Mars life to have encountered Earth life before, for it to cause problems. It's the same in the reverse direction from Mars to Earth. Also, microbial adaptations can evolve quite quickly, so they may evolve to be a nuisance on the other planet when originally they were not.
Although these are multicellular lifeforms, still, perhaps they may give us useful lessons for ways that microbes could cause problems too.
You could perhaps try to argue that only higher animals, plants and insects can be invasive. So, what about microbes, can they be invasive too? Well, the answer is "Yes they can".
Until recently most people thought invasive microbes just can't happen on Earth, because with its connected oceans and atmosphere, they could be spread so easily. But as it turns out, microbes can be invasive too, most easily in fresh water lakes and inland seas that are not physically connected.
These invasive microbes rarely hit the news, except for one particularly well known single cell invasive species, "rock snot" (didymo diatom) - it forms large easily visible structures like a multicellular plant, but it can spread from contamination by a single cell.
As it turns out, there are many other examples of invasive diatoms. This problem is very much under reported. Since most researchers didn't think this form of invasive species was possible until a couple of decades ago, probably there have been many invasions before then that nobody noticed. They just assumed that the problematical diatoms were native ones.
Here I'm summarizing Diatoms as non-native species, by Sarah Spaulding, Cathy Kilroy and Mark Edlund. Diatoms are microbes that form cell walls of silica, rather unusually.
Here are some of the more notable examples:
Then, there is one recent and very clear example, Dydimosphenia geminata. This diatom has been widespread in the northern hemisphere for at least a century. Until recently, microbiologists assumed that it was always there and had spread to those places naturally. It started to behave in unexpected ways, when it began to form large blooms in Iceland in 2000, central Europe in 2003, and the US in 2009. But though unusual, these still weren't treated as invasions because everyone assumed it was a native species to these areas already. They just assumed that it had to be something to do with local conditions.
But then, it suddenly appeared in New Zealand in 2004. That was a wake up call because there was plenty of evidence to show that it was not a native New Zealand species, because the lakes in New Zealand were well studied, and it simply wasn't there before.
It now forms large blooms in New Zealand and the government are trying to stop its spread. It may well be spread in some way by humans, and perhaps that explains the other blooms in Europe too. Maybe those were due to a variant with new capabilities for instance. It's too late to know now.
New studies showed that its cells stay viable for weeks if kept in cool wet conditions. That suggests that it could spread rather easily on damp sports equipment from place to place in a country, and even from one country to another. It's remarkable for its ability to form blooms in low nutrient waters. It can have economic impacts by blocking water intakes and interfering with angling and other recreational activities.
Didymosphenia geminata in South Island, New Zealand. The two asterisks at lower left show where it was found in 2004. The triangles show where it had spread to by 2005-2006. The open circles show its locations for 2006-2007, and finally, the +s show its locations in 2007-2008. The government of New Zealand has run eradication programs to try to get rid of it. But it is still spreading.
These studies probably are just the tip of the iceberg because it's only recently that researchers realized that invasive microbes could be a problem. Because of that, this is a topic that has not been studied previously, Any previous symptoms of invasive microbes would be ascribed to other factors. For instance, were those earlier blooms of Dydimosphenia geminata in the US, Iceland and Europe due to an invasive species or not? We just don't know, and probably will never know.
This next example gives us quite a close analogy to the planetary protection measures for Mars. Antarctica is at particular risk from invasive microbes, because it is so isolated. Also, there's intense interest in the lakes trapped beneath the ice sheets, such as lake Vostok, the only remaining major pristine body of water on Earth. It's not only pristine, but it may well be unique too, with lifeforms found nowhere else. It's far more isolated than any lake in New Zealand.
The aim for lake Vostok is to keep microbes from the surface of Earth out of the lake altogether. So it's a rather similar situation to Mars. Here I'm summarizing some of the material from this paper: Non-indigenous microorganisms in the Antarctic: Assessing the risks. Scientists take great care not to introduce any non native species into its waters. They would dearly love to explore it. It's got highly oxygenated waters, surprisingly. The oxygen gets there in a kind of conveyor belt. First snow falls on the surface, with air trapped in it. Over thousands of years the ice gets packed under new layers of snow and ice. This ice then moves deeper and deeper, and eventually reaches the lake where it melts. This conveyer belt of bubbles of air brings oxygen at very high pressure into the lake. As a result they expect it to be the most highly oxygenated lake on Earth.
The ice above the lake acts as a thick blanket to keep it insulated which is why it's able to be warm enough for liquid water even in Antarctica. It's hard for ice to melt, but at that depth, once liquid, it can stay liquid indefinitely just heated from below by the warmth of the Earth itself. It may also have hydrothermal vents, and if so, then as for other hydrothermal vent communities, it may well have unique complex multicellular life. It may have evolved there for millions of years independently from the surface. We might find sea life there that is as isolated as the complex indigenous land life in Australia, perhaps with its own unique adaptations to those unusual circumstances. How we'd love to go down there and explore it and see what is there, but we just don't know how to sterilize our equipment to do that yet.
When the Russians drilled, they didn't know there was a lake there originally, and when they realized it was there, they they stopped drilling 120 meters short of the lake itself. Their drill penetrated into ice that they knew had melted and refrozen at some earlier time, but stopped short of the liquid water itself.
After analysing their drilling fluids the scientists found a large number of microbial contaminants which would get there in the fluids. That made the results of analysis of microbes in the ice controversial, and it underscored the need to keep the lakes themselves free of surface microbial life. So the Scientific Committee of Antarctic Research has drawn up a code of conduct for Subglacial Aquatic Environments in Antarctica designed to prevent introduction of non indigenous microorganisms to these subglacial lakes.
Subglacial lakes and rivers on the Antarctic Continent.
Since then, the Russians have drilled all the way through to the lake but in a way that triggered a geyser that rushed up the drill hole for hundreds of meters, then froze from below. They believe that this let them sample it without introducing any invasive microbes or other life from above. Their first attempt in 2012 lead to sample contamination by the drilling fluids, so they tried again in 2015. It's a rather similar situation to Mars. They hope to find out if Vostok contains life and what forms of life it contains.
So, what if, like Elon Musk, you are a multibillionaire and for some reason you have set your heart on the project to melt through the ice above the Vostok lake, put a human occupied submersible into it and cruise around looking for hydrothermal vents and perhaps strange forms of life. Even if you were a multibillionaire, you just would not be permitted to do this.
It's not just an issue with subglacial lakes in Antarctica. There are issues with microbial life on the surface too. On average each person sheds a billion microbial cells each day, through hair loss, skin sloughing, sneezing, coughing etc (estimate from page 543 of this paper). On the plus side, most of these microbes would not be pre-adapted to Antarctic conditions. Also though microbes that are completely unrelated to each other can exchange genes readily through gene transfer, they do it more slowly in such cold conditions than they do in warmer conditions.
This shows a typical Antarctic dry valley field camp. It's perhaps the closest analogy we have to a Mars base:
The researchers stay within a fixed area around the camp in order to limit their impact, in a "corral" system. They give as a a typical example, a corral that's 50 meters square. After a ten day camp restricted to those 50 square meters, they will leave an estimated sixty billion microbes in the soil.
Assuming those sixty billion microbes are evenly mixed into the top one cm of the site, then that makes it around a hundred thousand microbes in each cubic centimeter, which is between 0.1% and 10% of the natural population of microbes in those sites. Calculations from page 4 of this paper: Non-indigenous microorganisms in the Antarctic: Assessing the risks
This is perhaps our closest analogy to the Mars planetary protection guidelines on Earth and helps underscore how invasive microbes can sometimes be an important issue even on Earth when we encounter situations here similar to Mars exploration. But we don't have any previous experience of something as new as exploring a new planet in this way.
We even have an analogy for the microbes carried in the dust storms on Mars. One of the big questions in Antarctica is how easily the microbes can spread in the wind. As an example, Aspergillus fumigatus was found in an Adele penguin colony and then later in a remote dry valley. This is a fungus found in soil and in compost heaps, which also causes allergic reactions in humans and sometimes serious diseases such as Aspergilliosis, and a frequent cause of hay fever in humans. Incidentally it's a useful example to show how a microbe not adapted to harm humans can still be a nuisance for us. Anyway they don't know if it was already present in the remote dry valley or it spread there in the wind from the penguin colony.
They conclude that though this may not be a serious threat at present that our instruments are getting much more sensitive and that in the future studies may let us notice microbes that we wouldn't have spotted before. They conclude:
"...To counter such threats might require a new tier of Antarctic Specially Protected Areas, essentially ‘no-go, no-fly zones’ where access would be permitted only under the strictest of conditions of biological protection, designed to provide rigorous protection of the environment from human dissemination of nonindigenous organisms. Such zones would, at the very least, provide control sites for future comparative analyses of the impacts and consequences of the anthropogenic introduction of microorganisms...."
It may be an interesting paper to read for anyone who is thinking through effects of non indigenous microbes on Mars or in the other direction from Earth to Mars. Remember that Antarctica is globally connected with the rest of the world through the atmosphere and the sea, and yet microbes are still an issue there. How much more of an issue would this be if the only way life could get from the rest of Earth to Antarctica was through transfer on meteorites, which may have never happened or may have happened only billions of years ago, and most recently 66 million years ago, and probably not photosynthetic life? That's the situation for Mars.
And also remember that Astrobiologists wish to send exquisitely sensitive instruments to search for life on Mars capable of being confused easily by just a tiny fragment of a single cell from Earth. Also, how much more of an issue would this be if the life on Mars is only early life, made extinct billions of years ago by modern DNA based life? Or in the other direction, if Mars microbes have evolved more rapidly and are billions of years advanced over Earth life in some or all of their capabilities.
You may have heard of Schuerger and Lee's Humvee journey through the Arctic, and wonder how that fits with this. After all, they found hardly any contamination. Well, they were looking at a different question. They wanted to know, how far does the microbial contamination spread? They found that at a distance of 10 meters from a rover driving over pristine terrain, there would be hardly any microbial contamination. But they specifically did not look at regions that were contaminated by humans directly through their various activities. Also they only looked at short term, not long term effects, such as whether any of the microbes spread to the Arctic habitats. They also only looked at cultivable microbes and not at archaea. Of course, they must have left thousands of microbes per cubic centimeter, as for the Antarctic bases. For details see Humvee journey through the Arctic - contamination study (below)
It's easy to accept that you should keep non-native species out of an island inhabited by flightless parrots, as after all we have no shortage of islands on Earth. It's also easy to accept that you should choose a different place to build, if your new house endangers some species of amphibian. Again usually you can find an alternative house site. It's the same with the Hawaiian fruit. There are many other places to get fruit. Where it gets much harder to cope with is if there is something you are very keen to do and there seems to be no alternative, no way to keep your non-native species out of the place you want to build on or colonize, and nowhere else to go.
The Mars colonization enthusiasts want to colonize Mars. If the planetary protection rules were enforced as strictly for humans, as they are for robots, it would certainly keep humans away from Mars altogether. I think everyone would agree with that much, the enthusiasts included. There is just no way you can sterilize a human occupied lander to robotic standards, because of the trillions of microbes that live in and on the human body, also in our food, and in the air. Also, if you assessed human landings on Mars in the same way you do for a robotic mission, you'd have to do planetary protection assessments of the effects of a "hard landing", i.e. a crash on Mars, as I looked at in one of my earlier articles and kindle booklets and also in the section on Why do spacecraft crash so easily on Mars? (above):
This is my short kindle book and article on it:
Can We Risk Microbes From Human Crashes - On Mars? If Not, What Happens To Dreams To Colonize The Planet? - also available to read online.
So COSPAR would have to just choose not to take into consideration the effects of a crash of a human spacecraft on Mars (because that would count as an immediate fail of planetary protection). Also, the NASA mission planners or whatever space agency does the final planning would have to not take it into consideration either, as any mission to Mars right now with humans on board is bound to have a significant risk of a crash. If a human occupied spacecraft did crash on Mars, well I believe that just about everyone would agree that that would be an end for planetary protection for Mars. Sooner or later, so long as there are habitats for Earth life on the surface of Mars, or connected to it, life from the crash would get there. And whenever you detect traces of present day life on Mars, your default assumption would be that it's life that got there somehow from the crash site.
There is just no way we can achieve anything like parity with the robotic missions. So, the only way humans could be permitted to go to the Mars surface under COSPAR recommendations in the near future would be if COSPAR reduce the planetary protection requirements for humans to much less than their requirements for robotic spacecraft. Also, it seems that if humans go to the Mars surface, we have to relax the requirement of biological reversibility. Even if the microbes did not encounter any micro-habitats on Mars to their liking, the spores would be spread over the surface in the dust, in such large numbers, that it would probably be impossible to "put the genie back in the bottle".
Spores last for a long time, especially if they can get into a shadow, protected from UV light, and even more so if they get into a cave. They can sometimes last for millions of years on Earth. Eventually, in the global dust storms, some of those spores would encounter habitats, if there are any at all on Mars. They'd still be there thousands of years in the future also, to potentially cause problems with plans to transform Mars. For instance, if we try to roll back to early Mars, or to do step by step terraforming, or other transformations based on introducing some species before others (ecopoiesis), these pesky spores could scupper all our plans.
For the details see: Biologically reversible exploration of Mars (above)
It would still not be a confrontation if you could land humans somewhere on Mars isolated from everywhere else. But the Martian dust storms turn the whole planet into one connected system, apart from a few places perhaps, like the crater at the summit of Olympus Mons (on short timescales of thousands of years anyway, so long as it doesn't erupt).
Even if you aim for the crater at the top of Olympus Mons, there's a possibility that the spacecraft crashes somewhere else on Mars during the landing attempt. And it might not be totally isolated even at that height surrounded by the rim of the crater. We simply don't have any current spacecraft or plans for the future that could permit humans to land on Mars in a biologically reversible way, whether or not it is theoretically possible. We'll come back to this in more detail in the section on Could we send humans to the Mars surface in a biologically reversible way? (below)
