. CASE FOR MOON FIRST - 10 Searching for a non confrontational way ahead

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SEARCHING FOR A NON CONFRONTATIONAL WAY AHEAD

At the moment, there's a tremendous impetus amongst Mars advocates to get to Mars as soon as possible. Elon Musk even hopes to send humans to the Mars surface as soon as the 2020s, recently suggesting a first human mission in 2024, with NASA talking about the 2030s. I think it would be wrong though to suggest that Elon Musk doesn't care about the science impact of introducing Earth microbes to Mars. Here he answers a question on this topic, in the 2015 AGU conference in San Francisco, 30 minutes into this video:

Q. "I am Jim Cole from Arizona State University. I was listening to Chris McKay, another advocate of humans to Mars, and he was talking about how if we do go to Mars and we find life either there or extinct, we should consider removing human presence so that we can allow the other life to thrive. I was wondering what your thoughts on that were. "

A. "Well it really doesn't seem that there is any life on Mars, on the surface at least, no sign of that. If we do find sign of it, for sure we need to understand what it is and try to make sure that we don't extinguish it, that's important. But I think the reality is that there isn't any life on the surface of Mars. There may be microbial life deep underground, where it is shielded from radiation and the cold. So that's a possibility but in that case I think anything we do on the surface is not going to have a big impact on the subterranean life.".

So, it's clear (as I'd expect actually), he does think it is important we don't extinguish any native Mars life. But he thinks there isn't any present day life on the surface. But is that right?

I did a survey of the scientific literature, to see what there is by way of proposed habitats and to investigate the range of views on the topic:

Are There Habitats For Life On Mars? - Salty Seeps, Clear Ice Greenhouses, Ice Fumaroles, Dune Bioreactors,... (long detailed survey article with many cites)

It's also available as a kindle booklet, and also online here with table of contents

As you see, there's an almost bewildering variety of suggestions for habitats on Mars for life. The main ones are (these links take you to the online booklet)

• Warm Seasonal flows (Recurrent Slope Lineae)

• Sun warmed dust grains embedded in ice

• Flow like features

• Life able to take up water from the 100% night time humidity of the Mars atmosphere

• Deliquescing salts taking up moisture from the Mars atmosphere

• Advancing sand dunes bioreactor

• Droplets of liquid water on salt / ice interfaces

• Shallow interfacial layers a few molecules thick

There's a wide variety of views also on the topic of whether any of these are habitable, and whether they actually have life in them, from almost impossible to very likely, see Views on the possibility of present day life on or near the surface, and for the idea that they may be inhabitable but uninhabited, see Uninhabited habitats.

So when will we resolve this? Well not for some time. Most of these potential habitats would be hidden from view, a few millimeters or centimeters below the surface. Some of the habitats might be quite productive, for instance methanogens in warm humid locations deep below the surface heated by geothermal processes. There might be enough life there to cause obvious effects on the atmosphere, such as the methane plumes. But as Mars changed from a warmish wet planet to a cold dry planet, any surface life would probably become more and more sparse, and have less and less effect on the atmosphere.

As Mars slowly changed from the warmish humid planet on the left to the dry cold planet on the right, then any surface life may have become more and more sparse, and had less and less effect. Image from NASA (Goddard space center).

So, if the life from early Mars still lingers but is sparse, it might easily have almost no effect on the atmosphere by now. The most habitable areas of Mars such as the warm seasonal flows, if we are lucky, might be about as habitable as the Antarctic dry valleys or the high Atacama dry desert. If that's the way of it, life in those few square kilometers of the Martian surface would have almost no effect on the atmosphere. Mars already has small amounts of oxygen (0.145% as measured by Curiosity). The signal of oxygen from photosynthetic life on the surface, at such low levels, would just be hidden in the noise.

Indeed, even if the entire surface of Mars is as productive of oxygen as Antarctic ice covered lakes - and even if all that oxygen ends up in the atmosphere, the signal from all of that photosynthetic life would still be lost in the noise and not noticeable in the atmosphere (I made it about 0.0002%, in a very rough calculation, by just assuming a residence time of oxygen in the Mars atmosphere of 4500 years, the same as for Earth - at any rate it would be a tiny, surely undetectable, signal).

Why Mars Surface Life May Leave No Traces In Its Atmosphere: Our Rovers May Need To Go Up Close To See It

also my Our Spacecraft Could Look Straight At an Extraterrestrial Microbe - And Not See a Thing!

VALUE OF A NON CONFRONTATIONAL APPROACH

You might think, why not go out and out, confront the issue head on, and whoever wins the confrontation gets the prize? Well, yes, sometimes confrontation can be good. Sometimes you have to do it. Or sometimes it's good to tackle an issue head on and 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, which you could only get to by clearly exposing the differences. Or you might be able to go different ways after the confrontation, with a bit more clarity. But sometimes you are "in it" together and can't just continue your separate ways, and sometimes after battling away at a confrontation, you find it is going nowhere.

At other times, you can compromise, find an approach that lets you accommodate both views at once to some extent. But sometimes a compromise satisfies nobody. It would satisfy nobody to pass a compromise law to let fruit importers import Hawaiian fruit into California on the first day of each month. The fruit importers would be severely restricted in what they can do, and every month there would be new opportunities for crop infestations by the oriental fruitfly, so the law wouldn't be much help to the fruit growers.

Sometimes then, confrontation isn't wise, as it only entrenches views, and it makes it harder to look at the good points of what the other person is saying. And sometimes compromise is impossible because it is a situation that just doesn't have a natural compromise that would satisfy both. 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 or in some way just takes a detour around the confrontation that was looming up. That can then be satisfactory to both.

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). But I do think it's a situation where a non confrontational approach is possible, satisfactory for both. 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.

"OVER PROTECTION OF MARS" - THE IDEA THAT WE NO LONGER NEED PLANETARY PROTECTION - REBUTTED

This is an argument you often get from keen Mars colonization advocates. They've heard Zubrin speak about this and probably read the "Over protection of Mars" which got a lot of publicity as it suggested that we don't need to have any planetary protection of Mars because, they claimed, it has the same lifeforms as Earth in the same habitats already. The idea is that life gets back and forth between Earth and Mars on meteorites.

Now, that's certainly a decent hypothesis, panspermia, that some microbes might get from Earth to Mars and vice versa. But the case is not nearly as simple as you might think from those arguments. First, the "Over protection of Mars" by Alberto Fairén and Dirk Schulze-Makuch was immediately rebutted by a paper by the present and past planetary protection officers, Cassie Conley and Jim Rummel, called the "Appropriate protection of Mars". That got almost no publicity. The papers are behind paywalls, but you can read a summary of the arguments both ways in The Overprotection of Mars? in the NASA Astrobiology online magazine.

It's understandable that any proposal to reduce or drop planetary protection requirements would get so much more publicity. It's much more exciting for Mars advocates to learn that there are no planetary protection issues for humans to Mars. It's not nearly as interesting to learn that there are planetary protection issues. So any papers or articles suggesting that there will be no issues will get more publicity. So we need to bear this in mind, that the media is bound to be biased on this topic.

Why then is the situation not so simple as it seems? The problem with Zubrin's argument, and the arguments in "Over protection of Mars" is that

• We have no proof at all that life is transferred from Earth to Mars or from Mars to Earth. There is no consensus here either. Charles Cockell, astrobiologist, for instance has explored the possibility that Mars could be currently uninhabited, even if it has habitats for life there. Panspermia is a hypothesis with some experiments that seem to suggest it is possible, but you couldn't say that it has been proved, that it happened at all.

• If it was transferred, the last time this happened could well have been billions of years ago, some primitive form of early life. That would be the best opportunity for it, with both Earth and Mars covered in oceans, impacts on both planets by huge 100 kilometer scale impactors towards the end of the late heavy bombardment. If the early life was robust enough to withstand the transfer, maybe there was a lot of cross transfer back then.

• We don't know what happened when the life was transferred, if it did happen. It might well have made many species extinct on one or the other planet. We've had unexplained mass extinctions on Earth, and if you look at the record, you can't rule out the possibility of extinctions caused by life arriving here from Mars.

• If some Earth life was transferred to Mars, it doesn't mean that all species of life that could live on Mars got transferred there, since to survive the transit they need to be able to survive total vacuum, and the much colder space conditions, for a century, both capabilities that they wouldn't need on Mars. They also need to get onto the meteorite on Earth, and need to find a suitable habitat on Mars. With the population also reduced a lot by the transit, many species might not have made it at all.

In more detail, then first it's true that there are meteorites going back and forth between Earth and Mars and that tons of Mars meteorites reach Earth from Mars every year, and probably from time to time many tons of meteorites get to Mars from Earth. But they don't leave Earth or Mars continuously. Most of those meteorites have spent several million years in transit.

It's easiest to see this for the Mars to Earth direction as we can look at empirical data here. You can tell this from the cosmic radiation ages of the meteorites - how long they were exposed to this radiation during the crossing from Mars to Earth (while geological age shows the age since the rock first formed). The youngest meteorite we have, EET 79001, left Mars 730,000 years ago. So it was thoroughly sterilized by the time it got here. The oldest meteorite is around twenty million years old (as expected, because Earth clears its orbit over around a twenty million year time frame). These meteorites come to use from impacts of asteroids of the order of 1 kilometer across at an oblique angle on Mars, such as he one that created the young Zumil crater, and you get one of those every one or two million years on Mars.

The young Zumil crater, strong candidate for source of some of our Mars meteorites - impacts like this happen on Mars roughly every one or two million years. Most of the material spends millions of years in transit from Mars to Earth but some may get here within the first century.

So, the opportunities are rare, not nearly as frequent as you might think from the amount of material that gets to Earth from Mars. Then next, you have to show how the life gets from Mars to Earth. First, it has to be hardy enough to withstand a century in transit, with vacuum conditions, the cold of space, cosmic radiation, and solar storms. But as well as that, the habitats suggested for life on Mars surface life are shallow (top few cms) and many of them are fragile as well, salts, dusts, thin films of brine, and ice / salt interfaces in the top few few cms of the Mars surface. And the most habitable areas are likely to be rare, a few patches here and there. There may be spores in the dust, but how likely is it that an asteroid impact will send the Mars dust to Earth? Actually, detailed models show that the material sent into space after a big impact typically comes from a few meters below the surface. So in short, it seems very unlikely for any surface or near surface life to get from Mars to Earth in present day conditions, though it could have happened in early Mars when there were large seas or later on when there were floods and lake conditions.

In the other direction, we don't have any examples yet of Earth meteorites on Mars, but they leave Earth much less frequently. You need an impact large enough to send material at escape velocity through our thick atmosphere, against the Earth's gravity. The last time this happened perhaps was the Chicxulub impact 66 million years ago, an impact into a shallow tropical ocean, not the most optimal for microbes likely to survive the vacuum and cold of the transit and on Mars once they get there.

So, does Mars have any life from Earth from 66 million years ago? Or from earlier than that? Well it's quite hard for Earth life to get to Mars also. Assuming it's the first species to get from Earth to Mars, you need:

• Polyextremophile for the transit, needs to withstand the vacuum, cold of interplanetary space, cosmic radiation during the transit for a century (for fastest transit) and able to withstand shock of impact on Mars.

• Polyextremophile in other ways once it arrives on Mars - able to withstand, or even eat, perchlorates, able to survive in very salty brines (probably), or able to make use of the 100% humidity at night without water, or able to cope with the hydrogen peroxide - or one way or another, needs to be able to survive in one of the niche habitats on Mars. Also needs to be resistant to UV light when blown around in the dust unless it is lucky enough to reach a habitat almost right away.

• Anaerobe - if it depends on oxygen, then no good even if it survives the transit for a hundred years, it won't find much oxygen on Mars.

• Capable of forming a single species ecosystem for the first microbes to get to Mars - unless it can make use of native Mars life.

• Has to find one of the habitats it can survive in on Mars.

The best candidate to fit all that might be something like Chrooccocidiopsis, a radioresistant polyextremophile that can also survive in ordinary conditions too, does fine in the tropics. I could see it surviving the impact into a tropical ocean, making it to Mars and making its way to a habitat there. So, if we do find Earth life there, that would be my personal favourite for a top candidate. It would have evolved independently on Mars for at least 66 million years, but it has been around on Earth since right back to before the great oxygenation event, one of our oldest lifeforms, so could also have got to Mars billions of years ago.

Nevertheless, it's not proven that there is any life from Earth on Mars. And the life that gets to Mars from Earth could play nicely with whatever there is there native to Mars. For instance my example of early RNA based life, if there is nothing from Earth to eat it, then perhaps it can get on fine with Chroococcidiopsis, might be a mixed Earth / Mars originated life ecosystem. Or maybe there's some life form on Mars that is so much better at photosynthesis, some method not yet explored on Earth, that it outcompetes Chroococcidiopsis, which if true would not mean that all Mars life out competes all Earth life, it might just be that it can do better than Earth life in the realm of photosynthesis only. Maybe even that it's RNA based life, highly vulnerable to Earth secondary consumers, but better at photosynthesis than Earth life, just to throw out an idea there.

I gave the example of Arctic terns. They fly over Europe and also fly over Australia and cause no harm to the native Australian life. But that doesn't make European rabbits safe for Australia. In the same way there could be shared life from Earth on Mars, maybe a mix of Earth and Mars life there. But that wouldn't make all Earth life safe for Mars, or Mars life safe for Earth. And so far panspermia is just a hypothesis and is completely unproven though many think it is possible or even likely.

NATURAL CONTAMINATION STANDARD - WORKS FOR COMETS AND ASTEROIDS - BUT NOT FOR MARS

There is another argument like Zubrin's, which does work and is used in planetary protection calculations. That's the natural contamination standard. If you can prove that what you are doing is equivalent to what happens naturally, then the mission is not a biological issue. That's used for sample returns from comets and asteroids to Earth. Since fragments of comets and asteroids hit Earth all the time, then it's not adding to the hazard, whatever there might be. If there is any life on comets or asteroids, which is not ruled out, then we've evolved to be able to cope with its influx into our atmosphere, so there's no problem returning those samples.

The problem with Mars is that sending humans to Mars or returning samples from Mars to Earth is not like the processes that happen naturally. The natural contamination standard would involve simulating somehow the equivalent of 100 years of interplanetary cosmic radiation, and vacuum and the cold of space. And even then, those are events that happen only every 100 million years or so. While in the reverse direction from Mars to Earth, it might not have happened at all for billions of years.

We'll only be able to fill in the gaps in this picture once we have life detection from Mars, if there is life there. From the evidence so far, we might well find habitats on Mars without Earth life in it, habitats that Earth life could inhabit.

There's another way also that Earth life might not be in those habitats. That is if they are very rare on Mars and form for a few centuries then go away. Maybe the Earth life just doesn't get there in time with a few spores spread in the dust storms before the habitat disappears again. It might be in some of the habitats and not in others. That happens on Earth also in newly formed lava flows but it only takes a few weeks for Earth life to colonize them. On Mars maybe it takes centuries or millennia.

So anyway - Zubrin and a couple of exobiologists have put forward a thesis according to which they think that habitats on Mars will have exactly the same lifeforms that the sam habitats have on Earth. But they don't go into details about how it would happen. It's largely "hand waving" arguments, and it's by no means proven and is rather controversial. I think many exobiologists would be very surprised if that's what they found. And would be bound to be some differences which you'd want to explore and understand, if he was right, to learn which lifeforms got to Mars, how they got there, and how they survived when they got there, what was the first lifeform to get there, and how they evolved and changed after spending tens of millions of years, perhaps billions of years, in Mars conditions.

But could also be that it just never happened. Or that there's a mix of Earth and native Mars life that gets on fine on Mars but won't work any more after you introduce more Earth species. Or perhaps Zubrin is right and somehow all the Earth lifeforms that could survive in those habitats are already there. If so that would be an extraordinary event that you'd want to understand well before introducing more present day Earth life to Mars. Or there might be habitats but no life, as Charles Cockell talks about, and again you'd want to understand that well too. It could give us insights into exoplanets that don't have life, and into the role of life in geological processes on Earth as a "control" and tell us something about how far complex chemistry can get on its way to life on a planet without life.

One way or another, I think it is just far too soon to say that it is okay to introduce Earth life to Mars.

For more on all this see my:

Does Earth Share Microbes With Mars Via Meteorites - Or Are They Interestingly Different For Life?

Could Microbes Transferred On Spacecraft Harm Mars Or Earth - Zubrin's Argument Revisited

No Simple Genetic Test To Separate Earth From Mars Life - Zubrin's Argument Examined

WHY QUARANTINE WON'T WORK - PROTECTING EARTH, AND HUMANS SENT TO MARS, FROM MARS LIFE (IF IT EXISTS)

Mars life could also be hazardous for Earth (this question about whether microbes from one planet can harm life on another goes both ways). If you haven't come across the scientific papers and workshops and studies on this issue before, chances are you're first thought will be of the "Andromeda strain" or some other science fiction scenario. In that case it's viruses from outer space. But viruses aren't a likely problem for humans going to Mars, because they have to be adapted to their host. Any life on Mars has never encountered humans before so can't be adapted to us.

There are many other ways though that Mars life could be hazardous to humans and also to the biosphere of the Earth.

• Gene transfer agents. These are much smaller than viruses, and they can transfer small fragments of DNA from one species to another to give them new capabilities. It's an ancient mechanism, and works between distantly related species. GTAs can transfer capabilities between species as unrelated as fungi and aphids (example of a GTA that gave an aphid the capability to create carotene, from a fungus). Also it works very quickly between microbes in sea water, if the GTAs ever got into the sea. In one experiment a GTA conveyed antibiotic resistance on 47% of the microbes in sea water, all types, just the microbes you have in sea water naturally, after they left them exposed to the GTAs overnight. This is relevant if Mars life is distantly related to Earth life. Even if the life got transferred from Earth to Mars or Mars to Earth billions of years ago, it could still exchange capabilities with Earth microbes readily using GTAs.

• Life not based on DNA which has chemical signatures that Earth based life is not designed to respond to. Our defenses would only respond to the trauma, not to the cause of it. This is a point made by Joshua Lederberg, Nobel prize winning microbial geneticist, in Parasites Face a Perpetual Dilemma and also in Exobiology: Approaches to

• Life beyond the Earth and a nice quote here:

• "If Martian microorganisms ever make it here, will they be totally mystified and defeated by terrestrial metabolism, perhaps even before they challenge immune defenses? Or will they have a field day in light of our own total naivete in dealing with their “aggressins”? in his "Paradoxes of the Host-Parasite Relationship" (he also gives an interesting analogy there with symbiosis with mitochondria)

• In the worst case, of total naivete on the part of Earth microbes, lifeforms like this could live on our bodies, in our guts, and produce chemicals that are poisonous to us or take the place of microbes that we need to survive. Or just eat us. And our defenses might not respond.

• Life from Mars could harm us in many other ways, not just directly as diseases of humans. If the life from Mars has a major effect on microbes that we depend on (like the algae in the sea) or on the plants we depend on for food, wood and so on, or on the animals, it could be just as disastrous for the environments on the Earth. As an example, cyanobacteria produce toxins that kill cows. There's no evolutionary advantage in this as far as we know, the cyanobacteria can't eat the cows and it's unlikely to be a measure to deter predation by cows. It's just a case of toxins that are effective over a large evolutionary distance. See Alien Infection (Astrobiology magazine, 2008).

• For another example, cyanobacteria produce BMAA which is implicated in Alzheimer's. This is a chemical that resembles L-serine and can be misincorporated in its place and cause folding disorders in proteins, amongst other effects. Again there is no advantage to the cyanobacteria to cause Alzheimer's in humans. And another nice example, cocoa plants produce theobromine which kills dogs if they eat too much chocolate. The cocoa plant doesn't need to defend itself against dogs.

• In a similar way, microbes from Mars could easily produce toxins that have adverse effects on Earth life.

• Life that out competes Earth life. One example here, what if Mars has some fourth form of photosynthesis different from the three main types on Earth.

• Our three types are:

• Green sulfur bacteria, which use light to convert sulfides to sulfur, which is then often oxidized to sulfur dioxide

• Normal photosynthesis which splits water to make oxygen, also taking up carbon dioxide in the process. (basic equation 6CO₂ + 12 H₂O → C₆H₁₂O₆ + 6O₂ + 6 H₂O where the oxygen atoms in bold are the same ones on both sides of the equation - see Plants don't convert CO₂ into O₂, and Notes on lamission.edu)

• The photosynthesis of the haloarchaea which works similarly to the receptors at the back of our eyes, based on a "proton pump" which moves hydrogen ions across a membrane out of the cell using bacteriorhodopsin similar to the rhodopsin in our eyes, with no byproducts such as sulfur or oxygen, just creates energy directly from the proton gradient.

• What if Mars life uses a fourth form of photosynthesis is more efficient at making use of sunlight than the methods used by the green algae in our oceans? The space of possibilities is so vast, there is no way that DNA based life on Earth has explored even all the possibilities for DNA. For instance, over many millions of years, higher lifeforms in Australia never developed the placenta or anything resembling a modern mammal, and so it was vulnerable to introduction of rabbits, which were not at all adapted to Australian conditions, but still easily out competed the native Australian marsupials. Similar things could happen at the microbial level for transfer between planets instead of continents. Mars microbes could have capabilities never explored in the entire history of evolution on Earth.

• For another example, if not based on DNA, it could be able to do more with less. The microbes might be smaller, the encoding more efficient, less need for error correction, enzymes much smaller to do the same thing, it could be all round more efficient, and so able to manage on less by way of resources, with a more efficient metabolism. It might out compete Earth life everywhere where it can survive on Earth, by making do with less.

• Life returned from Mars might have a different side to it, like harmless grasshoppers which some trigger can turn into locusts, some condition on Earth triggers a different behaviour or capability that never turned up when encountered on Mars or in transit.

• Life returned from Mars could be harmless at first, until it adapts to Earth conditions, but then evolve to be a major problem later. For instance it might need to adapt to warmth, or to water that is less salty than on Mars, or to lack of perchlorates (if it tends to depend on perchlorates for food) or the denser atmosphere.

• It could be a slowly developing problem even without adaptation. E.g. back to that example of photosynthetic life that is just slightly better than Earth life, then it might take decades before sufficient numbers build up to replace the green algae and other photobionts in the oceans. Nevertheless, with exponential growth, there might be nothing we can do to stop its inexorable advance.

• Mars life could also be totally harmless, as Carl Sagan said in Cosmos, "There may be no micromartians. If they exist, perhaps we can eat a kilogram of them with no ill effects. But we are not sure, and the stakes are high. If we wish to return unsterilized Martian samples to Earth, we must have a containment procedure that is stupefyingly reliable...here are nations that develop and stockpile bacteriological weapons. They seem to have an occasional accident, but they have not yet, so far as I know, produced global pandemics. Perhaps Martian samples can be safely returned to Earth. But I would want to be very sure before considering a returned-sample mission.”

With this background, then you can see that ideas for quarantine just wouldn't work to keep Earth safe. There's a great tendency to look back at Apollo and assume we'd handle it as they did, put the astronauts in quarantine for a few weeks on return to Earth. But those quarantine precautions never had any peer review. They were published on the day of launch. And they were not even applied properly at the time. Buzz Aldrin noticed ants found their way into the quarantine facilities while he was in quarantine. He writes, in his book "No Dream is Too High":

“The unit was comfortable, but there was little to do and nowhere to go, so we got bored in a hurry.

"One day, I was sitting at the table staring at the floor, and I noticed a small crack in the middle of the floor, with tiny ants coming up through it! Hmm, I guess this thing isn’t really tightly sealed, I thought. Imagine, if we had brought some sort of alien substance back with us, those ants could have contracted it and taken it back out to the world!”

Earlier, the command module hatch was opened when they landed, and dust from the Moon surely went into the sea at that point, and there were other breaches of protocols as well. But even if it was done perfectly, it wouldn't have protected Earth from microbes from the Moon on the remote chance that it had any.

If we were to attempt to use quarantine today, for samples or astronauts returning from Mars, then problems with this approach include:

• If any of the astronauts become seriously ill, they will be rushed to hospital and not permitted to die in the quarantine facilities. If you try quarantine in orbit, they will be returned to Earth as soon as they encounter any really serious health issue. This is clear from Apollo. The crane they had designed to pick the command module out of the sea had a problem. Rather than fix the problem and leave the astronauts bobbing in the ocean, getting seasick while the world watched, they sent a helicopter with divers, who took the astronauts out of the module, into an open boat, and put them into their suits. By then the dust from the module would be in the sea already and planetary protection was already compromised even assessed by the standards of their time. From this example to show how mission planners were ready to waive precautions just to prevent the astronauts from getting seasick for a few hours while they fixed the problem, it's clear that they would definitely not let their heroic astronauts die in the quarantine facilities if they became seriously ill. So the Apollo astronauts quarantine was a largely symbolic gesture which would have done nothing to protect Earth from any real hazard in the unlikely case that the Moon did have microbes hazardous to Earth.

• It's not clear you can ethically keep them inside anyway if they get seriously ill in quarantine facilities designed to protect Earth from unknown dangers. At the very least it's a very tricky ethical and legal area. Even if they consent beforehand to be left to die there to protect Earth, it's not clear you can hold them to that in the event that it happens, especially if you have no idea whether there is some extra terrestrial cause - when it might well be some Earth based illness that needs to be diagnosed in the advanced facilities of a modern hospital to save their lives.

• It only protects from diseases that affect humans or other lifeforms in the facility. You can't take all the higher animals we depend on, the trees, grasses, sea water, etc. etc. into the facility for testing

• You have to guess at the latency period. Some diseases of humans such as leprosy can remain latent for decades before anything happens. There was no scientific reason for choosing any particular quarantine period for the Apollo astronauts. It was just a guess and I haven't seen any reasoning to explain their choice. Quarantine does work fine when you know the maximum latency period, and if it is a reasonably short period. But it doesn't work if that period is very long or you don't know what it is.

• It gives no protection from problems that manifest later. E.g. quarantine won't help at all if the microbes that humans carry with them need some time to evolve to adapt - either to terrestrial conditions or indeed even, to adapt to humans.

For all these reasons I think there is almost no point in attempting quarantine to protect Earth or to protect humans on Mars. It's largely symbolic and would give a false sense of security. It doesn't matter where you do the quarantine either, on Mars, or the journey back, or in orbit around Earth, or on the Moon, or back on Earth, none of that helps.

Instead I think there is no substitute for knowing what is in the samples before they are returned to Earth. I also think that we shouldn't send humans to Mars until we understand Mars conditions very well indeed and have done a reasonably complete biological survey of the planet, or for some other reason have a high level of confidence that there is no life there, or that any lifeforms there are safe for humans and for Earth. That's for safety reasons alone, apart from any other considerations, to protect both the astronauts and Earth (after they return).

CURRENT REQUIREMENTS FOR SAMPLES RETURNED TO EARTH AND LEGAL SITUATION

The most recent ESF study on how to deal with samples returned to Earth from Mars recommends returning them to a new type of facility which has to contain them right down to the level of GTAs as well as the smallest size of microbe they think is possible using unknown extra terrestrial biology. Their recommendations are that it has to be capable of containing particles well below the optical resolution limit of 200 nanometers (ideally it shouldn't permit release of particles over 10 nanometers in diameter). In other words, the facility has to be able to contain particles only visible with electron microscopes or similar. This is well beyond the capabilities of a normal biohazard level 4 containment facility where the aim is to contain known hazards of known size and capabilities. It also has to protect the samples against contamination by Earth life, even by a few amino acids.

Also, there's all the extra legislation to pass. Margaret Race looked at it. You'd be astonished, there are many domestic and international laws, needing to be passed - which were not needed for Apollo because the world nowadays is legally far more complex. After reading her paper, I think it could easily take well over a decade just passing all the laws even if everyone agrees and there are no objections, and surely longer if there are objections.

SUGGESTION TO RETURN SAMPLES TO ABOVE GEO INSTEAD

I think that given that we have no experience at all in handling extraterrestrial biology, that it's better not to return them to Earth at all, but instead, to a telerobotic facility above GEO - furthest in terms of delta v from Earth or the Moon of any point in cislunar space.

We could return some samples to Earth right away so long as we sterilize them first. So that should satisfy the geologists. I suggest using ionizing radiation to sterilize them, as that happens anyway on Mars, and would still preserve some evidence such as chirality and complex chemistry to show that there was life there before it was sterilized, if that was the case. And easy to take account of for the geologists, who already disentangle the ionizing radiation effects of the journey from Mars to Earth when studying Martian meteorites.

If they are shown to be harmless quite quickly, we just return them as is, much as we did with the Moon rocks. This saves years of legislation (probably a decade or more to pass all the laws), and hundreds of millions of dollars of expense for designing, building and operating a facility that is never needed.

Returning to above GEO simplifies all that as no new legislation is needed, can be done within all the existing laws. Also, you don't have any concern about the staff not using the right protocols because it is all operated from Earth and there is nothing the staff could do by mistake or laziness that would lead to life from the facility escaping into the environment of Earth.

Yes, a plan to return to a facility above GEO would add to the expense of the mission, but nothing like as much as to a surface facility. The orbital facility could just be a single spacecraft that receives the sample, and does preliminary studies. Since some of the plans involve sending a spacecraft up to collect the samples anyway, it might not cost that more at all.

Then it's an open ended future after that. So any stages after that, to study the sample once it is in orbit, can be treated as extended missions. So this also reduces the up front cost and makes it much more likely to be accepted for funding. So I think this idea that a mission to return it to a spacecraft in a safe orbit above GEO for preliminary study would be the simplest one and lowest cost and most likely to be approved.

While if we decide that the samples are potentially hazardous for the environment of Earth, then by the time we do this, in the 2030s at the earliest, then it should be easy to send hundreds of tons of equipment to above GEO to study the samples, and this could be the basis of an international operation to study them in orbit via telerobotics if they turn out to be potentially harmful to Earth.

In that case we would design the facility on Earth around understanding of what is in the sample, or maybe just continue to study the samples above GEO. Either way we save major expense on designing a facility to handle any possible form of exobiology, and instead design our facility, on Earth or above GEO based on whatever is needed to contain an already studied sample. And if we do decide that the material can be returned to Earth in viable form for study as living organisms on Earth, then this will be for a known biology, so the legislation needed could be passed more easily.

For instance if it is viable early life, based on RNA or even just primitive autopoetic cells, it might be easy to establish at an early stage that there is no possible hazard for Earth at all, in which case perhaps it doesn't need to be studied in a biohazard containment facility at all, but just protected to keep Earth life out of the sample.

About the only thing that could damage and release the sample above GEO is an impact but there wouldn't be any risk from spacecraft debris, as any debris in GEO or the graveyard orbit a few hundred kilometers above GEO wouldn't travel far - those spacecraft are pretty much stationary relative to each other.

You'd place it far enough above GEO can put it out of way of any debris from defunct GEO satellites. So the chance would be very low of an impact leading to release of the material from the sample, only from natural debris from asteroids and comets, and being a spacecraft it could also maneuver to avoid such hazards like the ISS.

For more details see my:

Will NASA's Sample Return Answer Mars Life Questions? Need For Comparison With In Situ Search

No Simple Genetic Test To Separate Earth From Mars Life - Zubrin's Argument Examined

How To Keep Earth Safe - Samples From Mars Sterilized Or Returned To Above Geostationary Orbit - Op Ed

Need For Caution For An Early Mars Sample Return - Opinion Piece

Concerns for an Early Mars Sample Return - background material

Mars Sample Receiving Facility and sample containment

Mars Sample Return - Legal Issues and Need for International Public Debate

If there is Life in Venus Cloud Tops - Do we Need to Protect Earth - or Venus - Could Returned XNA mean Goodbye DNA for Instance?

OR RETURN SAMPLES TO THE MOON

Hazardous Biology Facility on the Moon, telerobotically attended, surrounded by vacuum - Artist's impression, illustration by Madhu Thangavelu and Paul DiMare © from The Moon: Resources, Future Development and Settlement

If you return samples to a human occupied base on the Moon, then it's got the same issues as returning them to a human occupied facility anywhere.

As with anywhere else, like the above GEO idea, quarantine simply can't work unless you know what is in it and what precautions are needed. Even if they agreed, it's not at all clear you can ethically or legally commit humans to stay there for the rest of their lives, should it turn out to be potentially hazardous for humans or any other creatures or the environment of Earth (e.g. carried to Earth on the skin or inside bodies of humans). What do you do if they become ill and Earth is the only place they can be treated effectively?

But if you return it to a robotic facility on the Moon - well now, it's far better isolated than anything we could achieve on Earth, yet perhaps easier to build and work with than a large facility in orbit, especially if we develop infrastructure on the Moon. As with the facility in orbit, then it's fine to build it first, and then to send instruments to it, so long as it only goes that way, and any materials are sterilized in the reverse direction.

It could be useful for any hazardous biology generally, like an extra biohazard level above biohazard 4. So for instance if we wanted to experiment with synthetic biology using XNA in place of DNA, then we could use a facility like this on the Moon, to minimize any risk of it affecting Earth.

Even if the life did escape from the facility, e.g. after a meteorite strike, where would it go? About the only way it could be transported is via the levitating lunar dust, but that would surely be thoroughly sterilized by UV radiation before long. You could also turn the region around the facility into glass and remove any dust that strays onto that glass regularly.

You would have to think about the effects of larger meteorite strikes. And it would need to be evaluated by exobiologists, but seems very promising to me for hazardous biology!

One other suggestion, what about putting the hazardous biology facility in a lunar cave? There are many cave entrances discovered on the Moon now, and some of them might be not needed for human habitats and just lead to a small cave the right size for the facility. It might have smooth walls like a lava tube. Ideal for the facility. Protected from impacts by all except the very largest of the near Earth asteroids. And you could use a liquid airlock for the entrance, to have air inside as would be needed perhaps for some of the machines, but no risk of dust / air getting out onto the surface.

Returning samples to the Moon is a lot safer than returning them to the Earth's surface. However, the COSPAR guidelines for category 5 (sample return) missions currently say that

"(The Moon must be protected from back contamination to retain freedom from planetary protection requirements on Earth-Moon travel)".

So before samples can be returned to the Moon, that would need to be discussed and the guidelines altered. One issue I can see that would need to be looked into in detail is - what if the sample return mission crashes on the Moon somewhere different from its intended landing site?

HOW MANY YEARS ARE NEEDED TO DO A BIOLOGICAL SURVEY OF MARS?

This is a bit like asking how long a bit of string is. The surface of Mars is similar in area to the land area of Earth. If you had a couple of missions each to each of the Earth's main continents, how much would you learn about the makeup of Earth at ground level?

However, to make a start on it, Carl Sagan had to come up with a number of biological exploration missions, for one of his calculations. Writing in the mid 1960s, he assumed that about 60 missions to the Mars surface would occur before a human landing, giving enough time to get a first idea of the exobiology of Mars. He assumed 54 of those successful, and 30 flybys or orbiters, in a twenty year exploration phase before a human landing. So that's averaging nine missions for every opportunity to send spacecraft to Mars (See his "Decontamination Standards for Martian exploration programs").

So far we've had seven successful landers in the six decades since he wrote that: the two Viking spacecraft, the Mars Pathfinder lander (with its tiny Sojourner rover), Spirit, Opportunity, Phoenix and Curiosity. Of those seven, we have three landers able to travel kilometers, the Spirit, Opportunity and Curiosity rovers, and one tiny rover able to travel of the order of meters, the Sojourner rover. In addition, we've had 13 successful orbiters if I counted it right. And we have one extra lander and one orbiter on the way there right now (the ExoMars Trace Gas Orbiter and the Schiaperelli lander which is mainly just a technology demo and test for ExoMars, only able to survive a few days on the surface).

However, only two of those missions could really count as biological exploration - the two Viking missions. I think you could call the Trace Gas Orbiter, and Curiosity early stage pre-biological exploration missions. They could in principle discover life, but both would need a strong signal to have a chance to distinguish it from non life easily.

So that's only 4 missions so far with a strong biological focus: two stationary landers, one rover, and one orbiter. And only the Viking landers are really strongly focused on in situ life detection. You could say that Carl Sagan's planned "biological exploration phase " really started and then stopped immediately with the two Viking spacecraft. We have done no direct life detection tests on Mars since then, so I'm not sure if you can really include any of the missions since then as part of his biological exploration phase.

ExoMars in 2020 will probably be the first mission to be able to search for present day life in situ on Mars to some extent, and still is not as sensitive for this task as Viking was designed to be (with controversy of course about whether it discovered anything because of the unusual Mars chemistry). And even with ExoMars, its main focus is past life, with its search for present day life as a bonus. The area it's going to is not high on the list of candidates for present day life.

That's mainly because for about thirty years, most scientists thought that present day surface life on Mars was impossible. This is now changing, and on the plus side, our tools for investigating it have moved forwards by leaps and bounds since Carl Sagan's time, but the habitats on Mars have also turned out to be much more elusive than Carl Sagan could have imagined.

So I think we have to say that the biological search on Mars is just restarting, after a long pause after Viking in the 1970s. So, to venture a very rough guess, just based on Carl Sagan's numbers, it's at least a few more decades required. If we send, say, a couple of new landers for each launch opportunity, it would be 54 years to complete his preliminary survey, unless Mars exploration is stepped up hugely. If we can get it up to the levels envisioned by Carl Sagan or further, perhaps ten or more missions every two years, maybe we can do it in twenty years or less. Though, of course, in the other direction, if there is present day life on Mars, we might find it with the first mission to go to a promising habitat there. You never know.

SPEEDING THE SEARCH UP WITH MINIATURE ROBOTS - WHAT COULD WE DO IF WE HAD FUNDING FOR A PRELMINARY EXOBIOLOGICAL SURVEY OF THE WHOLE OF MARS FROM EARTH?

Miniaturization may speed it up also, if we can scatter lots of smaller robots over the surface of Mars. See my Soaring, Buzzing, Floating, Hopping, Crawling And Inflatable Mars Rovers - Suggestions For UAE Mars Lander.

However, a swarm of 54 identical probes all sent to explore a single cave or a single region on Mars, and 30 identical orbiters similarly wouldn't hack it. Also, Sagan was thinking surely of missions with capability similar to Viking, so several instruments and very sensitive. We can certainly do with a lot less mass than Viking, today, and maybe we could get dozens of landers into a single launch of something like the Falcon Heavy, but they need to be carefully planned missions.

Imagine trying to get a clear view of the biological diversity of Earth with 54 landers, so about eight per continent, or in terms of countries, one lander for every three countries. When you think about it that way, it's not a lot to try to find out about a planet with a total land area similar to Earth, and with a complex and diverse geology.

There are many places we need to explore and dedicated missions for each. But if small, many of them could go on the same launch perhaps, then sent to many different locations on Mars from a mother spacecraft in orbit around the planet. Perhaps it could even send later missions in response to results of earlier ones.

This is a survey I did of some of the proposed surface habitats on Mars as well as some of the near surface ones. Are There Habitats For Life On Mars? - Salty Seeps, Clear Ice Greenhouses, Ice Fumaroles, Dune Bioreactors,... which may give an idea of the variety of possible surface habitats that have been suggested, most of them new suggestions in the last decade or so, and of course, the RSLs now confirmed to have liquid water (almost certainly) though not yet settled whether they are habitable or not.

So, what could we do if the funding was available to do an exobiological survey of Mars from Earth? I'd think you need a few missions to each of these targets myself:

• The Recursive Slope Lineae (RSLs). You would need to send missions to more than one of those as they are especially interesting, geographically isolated and it's possible some have life and some don't.

• The flow like features in Richardson's crater near the south pole. This may consist of fresh water trapped under ice, so are especially interesting for viability

• Equatorial sand dunes. Levin thinks Viking discovered life already, and recently with discovery of circadian rhythms in the re analysed experimental data, others think there is a possibility of that also. Then, whether Viking found life or not, there are ways they could be habitable. So we need to check up on that to be sure. Also Curiosity found a liquid water layer a few cms below the surface of the sand dunes indirectly. Nilton Renno has suggested that microbes could find a way to create a niche in it, by transforming the environment as it can do on Earth even though the data suggests it is always either too salty or too cold for life. [ExoMars may give the first ideas about this - though it's not quite as sensitive as Viking's labeled release, it could find life in the Atacama desert core which Curiosity couldn't]

• Salt / ice interfaces. Nilton Renno's "swimming pools for microbes" in droplets of water that form where salt touches ice.

• Salt pillars and salt deposits, for deliquescing salts, and for water that can form in fine pores in salt pillars.

• Both of those could be combined with a visit back to Phoenix's landing site - a study from ground level there able to detect life could also detect whether any of the Earth microbes from Phoenix have been able to replicate as Phoenix was crushed. Hopefully not, but if they have best to know at an early stage. And gives us some ground truth for robotic exploration sterilization to show our measures are adequate.

• The Hellas basin because of the icy mists that form there and because it is the densest atmosphere on Mars which could make a difference to habitability.

• Caves need a visit. Not so much lava tube caves as other types of caves, for instance ones formed by slippage, or ones that formed through erosion by water or dry ice. The difficulty is, they are hard to spot form orbit. We do need survey not just orbital images, which are also limited to particular times of day and such like. E.g. miniature planes to fly along the Valles Marineres to photograph it up close.

• We should explore the surface itself for life, for lichens and cyanobacteria that might be able to grow in partial shade, using just the night time humidity, according to the DLR experiments.

• Study the Martian dust as it might have spores in it from anywhere on Mars.

• Check the polar ice caps for deep subsurface water, using radar, and if any is found, to drill down to search for life (if liquid water forms at depths of over 900 meters after a meteorite impact or through geothermal heating, it will remain liquid indefinitely through the flow of heat from Mars itself insulated by the ice above).

There may be other places to target, but those are the main ones I can think of right away.

The orbiters would be like the Trace Gas Orbiter, searching for traces of gases produced by life on Mars as well as photographing the surface. For instance our photographs of the RSLs from orbit are all taken in early afternoon, the very worst time to spot effects of liquid water on Mars. That's because the spacecraft that takes those photographs is in an orbit that takes it closest to Mars when locally it's early afternoon there. We need orbiters to photograph Mars close up at other times of day such as early morning. We also need orbiters dedicated to broadband communications with Earth (probably doing their own observations of Mars as well). These would certainly be in place for human missions for Mars, best done right away at the biological survey stage.

With broadband communications, then instead of communicating with Mars once a day as is the current situation you have delays of between 8 minutes and 48 minutes there and back. So, between 15 and 90 times a day, or if you have powerful lights and are fully powered at night, between 30 and 180 times a day. When Mars is closest to Earth then with broadband you could do as much communication and control in one day as we currently do in a year. Or even more if you use artificial real time.

(click to watch on Youtube)

There would be some building on previous expeditions so I think you definitely can't do it all in one mission. You'd have survey missions and preliminary missions first, but if we had the funding, say a dozen missions every two years for twelve years :). Each wave of missions building on the previous ones, refining the search. Or some other combination including maybe building up to more and more missions as we get an idea of which places to target.

You'd also be looking for habitats with no life. If there are surface habitats, whether there is life in them or not, those are vulnerable to Earth microbes meaning that sending microbes there is irreversible so you want to know that too even if they are uninhabited. They could be of great interest for exobiology indeed, especially if they have complex organics, but no life, or "almost life". So it is specifically a search for present day surface habitats and life - or ones that are reasonably easily accessible from the surface.

If it's possible to get humans to Mars orbit, then they could oversee all these rovers on the surface, rather similarly to the game of Civilization. Many of those 54 landers would be doing routine tasks at any time, things they can do autonomously. They could be controlled remotely from Earth using broadband. But from time to time they'd be doing something more challenging and interesting and that's where astronauts in orbit would step in. So in that way, a half dozen astronauts in orbit could work with all of those 54 landers and more using telepresence.

For more about the potential habitats, see my Are There Habitats For Life On Mars? - Salty Seeps, Clear Ice Greenhouses, Ice Fumaroles, Dune Bioreactors,...

A RAPID SURVEY OF MARS DOES SEEM POSSIBLE - HOWEVER NONE YET PLANNED TO GUIDE OUR DECISIONS BY THE 2020S

So, it's possible we could survey Mars more rapidly, but there aren't any planned missions yet to suggest we are going to do this in the very near future, as in, the next decade (say).

In the circumstances, if we send humans to Mars in the 2020s or in the 2030s, unless there is some big change, and someone does a large number of robotic missions first, we can't have anything like enough information by then to know what effect their microbes would have on Mars.

If you share Elon Musk's certainty that there is no life on the surface - which to be fair was the scientific consensus right up to 2008, then you may agree with his conclusions there. But ideas about Mars are changing fast, and we can't be so sure now about the apparent certainties of the early 2000s.

CLASH AND CONFRONTATION?

For this reason, I foresee a possibility of some kind of a confrontation, where experts who meet to make planetary protection guidelines for COSPAR just don't have enough information to say for sure if there is present day life or habitats for Earth life on Mars or not. So then it would come down to personal judgement. Experts who are skeptical about life on Mars might say to the Mars colonist advocates like Elon Musk, "Sure, go ahead, you probably won't do any harm". While those who are optimistic about the proposed habitats are quite likely to say "Slow down, we need more data". I wouldn't be surprised if the workshop was inconclusive with some saying it is okay and others saying it is not.

This potential confrontation was highlighted recently in my guest appearance on David Livingston's "The Spaceshow" on 3rd May 2016. I said, during the show, that it's possible that we might not have enough information for COSPAR to approve humans to Mars soon enough for Musk's plans, and also said that it is still a possibility that we could find out that there is vulnerable life on Mars. I was saying much the same things I've been saying in this book.

Anyway I expected this to be a controversial thing to say, knowing that many keen Mars advocates would be listening to the program - but I was surprised at quite how controversial it seemed. From the questions we got by email, it seems that many people would be very upset if their plans to attempt to colonize Mars were even delayed a few years because of issues such as this. David said that the possibility that planetary protection issues could delay their plans is never raised in the Mars colonization conferences at all, which are held every year in the States. So, if I'm right about this projection, it would be a great surprise and shock for them. What can we do to help defuse and resolve this possible future confrontation? This book actually came out of my deliberations after thinking over that show.

COMPROMISE ATTEMPTS

What's the way ahead? A compromise doesn't seem too likely to work, to me. If you try to reduce the number of microbes, but the exploration is still biologically irreversible, you haven't protected Mars from Earth life. Perhaps you've delayed its spread, and that's about it. That would be like responding to issues with the oriental fruitfly on imported fruit from Hawaii by saying that it must be kept out of California every day, except on the first day of every month. That would restrict the ability to import fruit and yet do nothing, or very little, to keep out the fruitfly, so nobody would be satisfied.

NASA is currently working towards the idea of an exploration zone, with the human occupied field station in the center, and robotic spacecraft heading off for in situ study around the perimeter, and returning samples to the center. This might seem a good compromise, with humans on the surface, but trying to limit the effects of the microbes by restricting human movement geographically.

see: Mars colony will have to wait, says NASA scientists

Here is another example, with the human exploration zone shown close to an area of special interest - the recursive slope lineae or warm seasonal slopes, which may have liquid salty brine seasonally, one of the suggested habitats for life on Mars:

from: Mission to Mars: The Integration of Planetary Protection Requirements and Medical Support

As you can see, the idea is that the human exploration zone is contaminated with Earth microbes and this is just accepted as a necessary part of human exploration of Mars, but only clean rovers are permitted to travel to the habitats that potentially could host surface life on Mars. They bring samples back to the human base for analysis, or are used to study the site remotely.

That could work just fine on the Moon. If humans don't travel too far from their base, they will preserve pristine lunar surfaces just a few kilometers away, untouched by human footprints or wastes or debris from the habitat.

But how can this work on Mars with the Martian dust storms? That's my main question here for the scientists who suggest this approach. The main problem here is that microbes can form hardy spores, and on Earth these can survive for long periods of time, hundreds of thousands of years, and in rare cases, millions of years of dormancy. On Mars, they can get into cracks in the fine grains of dust and be partially protected from the UV radiation. And the numerous rocks on the surface will totally protect any microbes that get into their shadows from UV light. Even in equatorial regions, some areas under rocks will be permanently shadowed from UV light.

And then you get these:

This is a Martian dust devil - they race across the surface of Mars picking up fine dust and would also pick up any microbes imbedded in the dust.

The microbes would be protected from UV radiation by the iron oxides in the dust. HiRISE image from Mars Reconnaissance orbiter, of a dust devil in a late-spring afternoon in the Amazonis Planitia region of northern Mars. The image spans a width of about 644 meters.

The winds are very feeble on Mars in the near vacuum of the atmosphere. The strongest winds on Mars would barely move an autumn leaf. But the dust is also very fine on Mars and easily lifted by these feeble winds. And it's made of iron oxides too, which would help to shelter any spores imbedded in cracks in the dust, from UV light.

Then from time to time dust storms will cover the entire planet.

Global Mars dust storm from 2001

This relates to an observation Carl Sagan made Carl Sagan raised in an old paper "Contamination of Mars", back in 1967.

"The prominent dust storms and high wind velocities previously referred to imply that aerial transport of contaminants will occur on Mars. While it is probably true that a single unshielded terrestrial microorganism on the Martian surface - even the most radiation-resistant variety - would rapidly be enervated and killed by the ultraviolet flux, this by no means applies to all contamination scenarios. The Martian surface material certainly contains a substantial fraction of ferric oxides, which are extremely strongly absorbing in the near ultraviolet. In fact, apart from the ferric oxide identification, the red color of Mars clearly indicates major electronic transitions at short visible wavelengths. A terrestrial microorganism imbedded in such a particle can be shielded from ultraviolet light and still be transported about the planet."

He continues:

"A single terrestrial microorganism reproducing as slowly as once a month on Mars would, in the absence of other ecological limitations, result in less than a decade in a microbial population of the Martian soil comparable to that of the Earth's. This is an example of heuristic interest only, but it does indicate that the errors in problems of planetary contamination may be extremely serious."

Of course we know much more about Mars than they did back then. But the situation is still the same, the dusts do indeed contain large amounts of iron oxides. We have also found out that some microbes are far more UV hardy than realized in the 1960s. The dust storms and high wind velocities are the same as in the 1960s. The dust does contain perchlorates, which they didn't know back then, but microbes can survive exposure to perchlorates at the low temperatures on Mars.

If the spores can survive a few hours of exposure to UV within a dust storm, as some experiments suggest, they could be transported considerable distances. Those results suggest they could survive at least twelve hours of being blown over the surface within a Martian dust storm. See also Survivability of Microbes in Mars Wind Blown Dust Environment. Also, I think it might be worth considering the possibility that in addition to those twelve hours of daylight, spores could be transported at night during a dust storm, when there's no UV light, yet still dust suspended in the atmosphere.

With wind speeds of 10 to 30 meters per second average for the faster winds during a dust storm, then the spores could travel 20 to 60 miles in an hour, or 240 to 720 miles in twelve hours. Also, if they end up in a shadow at the end of that, they will then be protected from UV radiation until the next time they get transported by the winds. If the human habitat is positioned close to a special region as in the suggestion by Jim Rummel above, these figures suggest that they might get to a vulnerable region in a dust storm in much less than twelve hours.

So it would seem that Carl Sagan's concern still applies when you take into account this modern research into survivability of microbes in dust storms. My question for research here is, can a Mars exploration zone be kept biologically isolated through a Martian dust storm? As far as I can see, this plan could only slow down the advance of Earth life over Mars. The accidental introduction of Earth microbes would still be biologically irreversible after a human landing, if there are viable habitats for Earth microbes on Mars.

If there are any habitats for it to spread to, then it would get there eventually, carried in the dust. And that is the very thing we can't know by the 2020s or even the 2030s probably, except in the positive direction by confirming one of the many suggestions for habitats on Mars. So, a compromise solution like this wouldn't really work I think.

Then as well as that you have the issue of a crash. It doesn't seem too likely that we'll achieve 100% reliable spacecraft to land humans on Mars in the next few decades. So what happens if the spacecraft crashes? That would seem to mean an end to planetary protection of Mars. I'll look closer at this human spaceship crash on Mars scenario later in the section: What if there seems to be no alternative? - we must have Mars!

There is another kind of compromise, to put the human base in orbit, and we'll come to that later (in Telerobotics as a fast way for humans to explore Mars from orbit). That could be just fine for planetary protection. But the Mars colonization enthusiasts are dead keen to send humans to the surface, not just to orbit.

MOVING YOUR HOUSE TO AVOID A POND FOR GREAT CRESTED NEWTS

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 just build on its pond, but would have to preserve the pond and build somewhere else.

Of course some people couldn't care less about whether it goes extinct. But others do, and it's accepted, that we have to have laws like this to protect endangered species. It's not a big deal if you don't care for great crested newts. You accept that others do, so 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. And similarly it's easy to understand why you wouldn't be able to get permission to melt through the ice above the Vostok lake in Antarctica to put a human occupied submersible into it and cruise around. That's perhaps the closest to Mars planetary protection, because there, the aim is to keep microbes from the surface out of the lake.

WHAT IF THERE SEEMS TO BE NO ALTERNATIVE? - WE MUST HAVE MARS!

But where it gets much harder to cope with is if there seems to be no alternative. 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. 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 this booklet:

Can We Risk Microbes From Human Crashes - On Mars? If Not, What Happens To Dreams To Colonize The Planet?

The only way humans could be permitted to go to Mars surface under COSPAR recommendations in the near future would be if they had a consultation that reduced the planetary protection requirements to much less than that needed for robotic spacecraft. Also they would have to just choose not to investigate the effects of a crash of a human spacecraft on Mars (because that would count as an immediate fail of planetary protection). And if a human occupied spacecraft did crash on Mars, I think that would pretty much be the end of planetary protection for Mars.

The result seems inescapable to me -, if humans go to the Mars surface, we would probably have to relax the requirement of biological reversibility. Even if the microbes did not encounter any habitats on Mars, the spores would be spread over the surface in the dust, and 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 (ecopoesis), these pesky spores could scupper all our plans.

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). And 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.

PONDS AND FLIGHTLESS PARROTS AGAIN - BACK TO THE MOON

So - it's like the example of the island of the flightless parrots, the Kakapos, or the pond for the great crested newts, except that it is now a planet sized "pond", and a planet that some humans want to attempt to colonize. And there seems to be nowhere on Mars that would be truly isolated.

Anyway - this becomes a confrontation when you think there is no way ahead. If you can just move your house to avoid the pond with the great crested newts, no problem. So that's when I realized, that what is needed is an alternative vision, somewhere else in the solar system that is as good as Mars. You can use the asteroids, and Phobos and Deimos for materials to build habitats, and some space advocates are very enthusiastic about such ideas. But for others similarly minded to Elon Musk, the asteroids don't quite cut it. Mars may seem a lot easier in some ways than building habitats from asteroids. At any rate, it may seem a rather different direction of space settlement, a different kind of vision.

But what about the Moon? Could that help defuse the situation? I was already a "Moon firster" and was aware of some of the material on the subject. But until I wrote this book, as I've said, I had no idea quite how many points there were in favour of the Moon as a place for human habitats and ISRU. Depending on what we find when we explore, study and prospect further, the Moon might actually be better than Mars for this. So - like the house builder moving the position of their house to deal with the issue of the great crested newt pond - is it possible that the Mars enthusiasts can move their base to the Moon, and use much of the same ideas for ISRU there, instead? For the first few missions at least?

Meanwhile also of course, we would explore Mars, and eventually send humans there, to explore it from orbit. We can also use many of the ideas for Mars Direct, and other Mars architectures to send robots to the surface - highly capable fast moving rovers fueled by the methane fuel that are used for humans in those designs. Similarly, use the Mars stationary satellites over the base to relay signals back to Earth via broadband.

In this way we can get some breathing space, of a few decades, hopefully, to find out about Mars on a scientific level. To find out if there are habitats there for Earth life and search for exobiology. Meanwhile, you are also building up an infrastructure on Mars and in Mars orbit that would be useful if we did ever decide to send humans to Mars. Or indeed, it could be useful for other things too, anything we might do on Mars. Perhaps you decide to try ecopoesis (duplicate the biological transformations of early Earth on much faster timescales), or turn the clock back to early Mars, or transform it in some other way, or even grow plants there (plants could be grown on Mars using sterile hydroponics without impacting on any native Mars life, since seeds can be sterilized). There would be many possible futures still open to you at that point.

Also meanwhile we can work on space habitats, closed systems, eventually build city domes on the Moon and large closed systems in the lunar caves, continue to explore ideas for creating larger and larger self sustaining habitats. Whether we eventually get to the point of terraforming entire planets, I think can be left to later, until we have much more understanding than we have now, with these early experiments. So, then it becomes an open path, where instead of closing off futures, we open out to more and more possible futures, and wider vistas at every step. These vistas don't just include Mars either but many destinations for humans in the solar system.

If this approach is valid, I'm sure it will still be a slow process. People don't change their ideas overnight, especially if they have been working for decades to try to get humans to Mars. And this is just one vision, which has to be part of a debate, to explore possibilities. But I hope perhaps that with this book I'm helping provide a greater diversity of visions for the future. :).

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