The knotty problem of human quarantine - and what about exposure of humans during a robotic sample return?
This section may seem controversial, because, after all, the idea for Apollo surely was that quarantine would protect Earth. But as we saw, the Apollo regulations have never been debated publicly, as they were published on the day of launch to prevent the delays that would result from a public discussion of them. So, even if those were applied perfectly, with present updated knowledge, would they protect Earth?
You might well think this is only an problem for humans returning to Earth. How is human quarantine an issue for a robotic sample return?
Well, when you think it over some more, we have to think about what we do in the case of accidental exposure of humans to the materials returned from Mars. This could happen in many ways:
- Accidental breach of the container before it reaches the facility. Or in the facility after it gets there.
- Sabotage, or terrorism
- Someone decides to ignore the protocols.
- Human error
- Failure in the design of the facility leading to breach of confinement
- Natural events - hurricane, tornado, earthquake, meteorite impact
It doesn't matter much how they got in contact with the Mars samples, whether that happens on Mars or on Earth, so the situation is rather similar actually. If that happens to anyone, surely they would have to be quarantined too just as for astronauts that contact the materials on Mars?
It's the same also if the sample is returned to the ISS or to the Moon and examined by astronauts there. An astronaut exposed in the ISS or on the Moon is much the same as a sample handler exposed in a facility on Earth. If they contact the Mars sample, they become a potential carrier of any life that is in it. It's an issue in any scenario that has humans in close proximity to the samples and with some possiblity of an accident or intentional act leading to them contacting the samples.
So you can't really separate out the procedures for return of astronauts from Mars and for robotic return of a sample, unless you can guarantee that there is no possibility at all of human contact with the materials in the sample.
An example of a return that could keep this clear separation between robots and humans would be a return to a satellite above GEO. So long as it is studied only robotically and any material returned from the satellite to Earth is sterilized, then there is no way humans can contact any life in the sample. I cover this in the section If likely to be of greater astrobiological interest - return samples to above GEO
But, so long as humans can contact the sample, accidentally or through intent, then there will have to be provisions in place to deal with that situation. So then, the ethical and legal issues are similar to the case of an astronaut who visits Mars.
First, what kind of a hazard are we talking about here. If you haven't come across the scientific papers and workshops and studies on this issue before, the 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 as we've seen in this book, viruses aren't a likely problem for humans going to Mars, because they generally have to be adapted to their host, or something closely related. Any life on Mars has never encountered humans before so can't be adapted to us (though it may be capable of genetic transfer to our microbes)
The situation is rather similar to the forward direction of contamination of Mars by Earth life, with the additional complication that we have to look at effects on higher animals and humans, as well as human activities.
We have already looked at the many ways that Mars life could be hazardous to humans and also to the biosphere of the Earth, so here is a quick summary.
- Life not based on DNA which has chemical signatures that Earth based life is not designed to respond to. In that case, our bodies' defenses would only respond to the trauma, not to the cause of it. As we saw, 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.
This is not just a problem for life returned from outer space. It's also an issue for XNA studies in the laboratory. The situation is rather similar. Escape of XNA from a Mars sample is not unlike escape of a sample of non DNA based XNA life constructed in a laboratory. The main difference there is a chance of exobiology that is more different from Earth life than anything we can engineer in a laboratory. Not just the XNA but every detail of its biochemistry may be different. Some biologists studying XNA based life think that we should take extreme precautions, and ensure that any chance of accidental release is basically impossible. If you agree with them, the same surely applies to XNA from Mars. I discuss this in more detail in Hazards of XNA from Venus (below)
- Life from Mars could harm us directly through toxic byproducts, or indirectly through effects on our agriculture, or our pets or other creatures we value. 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, including higher animals, and so on ourselves, and our pets. It could also impact on the plants we depend on for food, wood and so on, or on the animals we keep for agriculture or for transport and recreation. Or on rare species that we value in their own right, or that have medical significance. I go into this in more detail in Many microbes harmful to humans are not "keyed to their hosts" (above)
- Life from Mars could harm us indirectly through effects on our or environment - for instance if it harms or replaces the algae in the sea or the microbes in our soil, it could have major effect on micro-organisms that our ecosystems depend on. Perhaps also on small creatures such as earthworms, or anything of that nature which we seldom think about, but depend on all the same.
- Life that out competes Earth life (as for forward direction). For instance, 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. For more on this see Surprising distant cousins
What if Mars life uses a fourth form of photosynthesis? What if it 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, that 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 may have a more efficient metabolism. Maybe it has only one biopolymer. Maybe it can 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 hidden capability that it uses only in rare conditions, like harmless grasshoppers which in response to some trigger can turn into locusts. There could be some condition on Earth which triggers a different behaviour or capability that never turned up when the life was encountered on Mars or in transit.
- Life returned from Mars could be harmless until it adapts to Earth conditions, but then evolve to be a major problem later. For instance it might need to adapt to the warmth of Earth, or to water that is less salty than on Mars, or to the lack of perchlorates (if it tends to depend on perchlorates for food) or the denser atmosphere. It may be a polyextremophile with some capability inherited from an earlier Mars that needs to be unblocked, or it may get these capabilities by horizontal gene transfer from Earth microbes. Or indeed it could happen the other way, Mars life transfers a capability, say a novel form of photosynthesis, to Earth life via gene transfer, but not straight away, and that novel hybrid Earth / Mars life is what causes the problems.
- 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. GTA's 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 GTA's 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 GTA's 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 GTA's
- It could be a slowly developing problem even without adaptation. E.g. if we go back to that example of photosynthetic life, if it has an advantage, it might be slight. Suppose it is just slightly better than Earth life. It might take decades before sufficient numbers build up in our oceans to replace the green algae and other photobionts. Nevertheless, with exponential growth, however slow, the result may be inevitable. Once we notice that it's a major problem, there might be nothing we can do to stop its inexorable advance.
- Or, of course, 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.”
You might think "surely we know how to do this", looking back at Apollo. Couldn't we just 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, as we saw above in Example of Apollo sample return - learning from our mistakes in the past (above). Buzz Aldrin noticed ants found their way into the quarantine facilities while he was in quarantine. Earlier, the command module hatch was opened when they landed, and dust from the Moon surely went into the sea at that point, and before that, the vents were opened to the atmosphere after re-entry, and there were other breaches of protocols as well. It's thought nowadays to be more useful as an example of what can go wrong.
What if we did this today, better, applying the rules perfectly and using modern technology ? Would a three weeks quarantine, or even a ten years quarantine protect Earth? There was no opportunity for anyone to discuss such questions at the time of Apollo. But the situation is changed. These issues would have to be debated at length today. There is simply no possibility at all, in the world as it is now, of avoiding public debate, as they did for Apollo.
So what sort of issues are there?
If we were to attempt to use quarantine today, for humans who have been in contact with the returned samples, or for astronauts returning from Mars, then problems with this approach include:
- What do we do if we find, during the quarantine period, that they have been exposed to microbes that are hazardous to other humans or to the environment of Earth, and that they can't be sterilized of them? After all that's why they are in quarantine, because there is a chance of this happening. In that case, is the plan to confine them to the facility for the rest of their life? How could that work, legally and ethically?
- What happens if someone exposed to microbes from Mars needs immediate urgent medical help, for instance a heart attack or other life threatening condition, even if we know for sure that it is not due to exposure to the sample?
Perhaps they need surgery, even an artificial heart or a stent. Can they be taken out of the quarantine to be examined and treated in a better equipped hospital? Or do we equip the facility with a telerobotic surgeon?
Even with a telerobotic surgeon, there's the need for nurses and an anesthetist, and it doesn't seem too likely all that could be done telerobotically in the near future. Do we send in an anaestheticist and nurses too on condition that they remain in there after the operation until the sample is proven safe (if it is)?
- What do we do if they have a serious illness during quarantine and we don't know yet whether it is the result of their exposure to the sample? And what if we know it is due to exposure to the sample, but we are unsure what the long term prognosis is, or whether it can be spread to other humans? What do we do in these cases?
- What about their human rights to freedom of movement and not to be imprisoned? This is not such an issue if the quarantine period is short, like the Apollo three weeks, but what if we decide it has to be decades long or even indefinite?
After all the whole point in this process is that there is a risk, however small, that they have been exposed to something that can't be released from the facility. So what happens
f we prove that their bodies carry microbes that could severely impact on the environment of Earth if it is exposed to them?
We can't simply rule out that possibility in advance, as if we do, the whole thing becomes a pointless symbolic gesture that would be ignored in the rare and unusual situation where it proved to be necessary. It's not a precaution at all, if it is going to be ignored in the only situations in which it is needed.
Well in practice, I think it is pretty clear that if anyone who has been exposed to the sample becomes 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, especially if it requires surgery.
Could you ethically keep them inside anyway, if they get seriously ill in the quarantine facilities? It's different perhaps if you know for sure that it is a hazard for Earth to take them out. But if you don't know that for sure?
In practice, they might well be taken out of quarantine just for cases of minor discomfort, if the chance of the sample being hazardous to Earth was still thought to be very low. This was another of the lessons from Apollo. Carl Sagan wrote about this, in his "Cosmic Connection"::
"The one clear lesson that emerged from our experience in attempting to isolate Apollo-returned lunar samples is that mission controllers are unwilling to risk the certain discomfort of an astronaut – never mind his death – against the remote possibility of a global pandemic. When Apollo 11, the first successful manned lunarlander, returned to Earth – it was a spaceworthy, but not a very seaworthy, vessel – the agreed-upon quarantine protocol was immediately breached. It was adjudged better to open the Apollo 11 hatch to the air of the Pacific Ocean and, for all we then knew, expose the Earth to lunar pathogens, than to risk three seasick astronauts. So little concern was paid to quarantine that the aircraft-carrier crane scheduled to lift the command module unopened out of the Pacific was discovered at the last moment to be unsafe. Exit from Apollo 11 was required in the open sea."
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, can you hold them to that in the event that it happens, especially if you have no idea whether there is some extra terrestrial cause? 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.
Then there's what Carl Sagan called "The vexing problem of the latency period", again from "Cosmic Connection"
"There is also the vexing question of the latency period. If we expose terrestrial organisms to Martian pathogens, how long must we wait before we can be convinced that the pathogen-host relationship is understood? For example, the latency period for leprosy is more than a decade."
- 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. The three weeks period was just a guess. At least, I haven't seen any attempt at a line of reasoning to explain this choice. Quarantine does work fine when you know the maximum latency period, and if that is a reasonably short period. It doesn't work so easily, if that period is very long or you don't know what it is.
Also though, all that is based on the assumption that we need to protect humans from diseases of humans and that nothing else matters.
- 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, fresh water, camels, horses, cows etc. etc. into the facility for testing
- 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. This is a bit different from a latency period. Suppose for instance there was a microbe that could live in our lungs, like Legionnaire's disease, but needed some time to evolve to adapt to the higher levels of oxygen on Earth before it coud? In that case it might have a very low latency period, but the problem doesn't raise until it has evolved. That evolution might include swapping genes with Earth microbes if it is related to us.
It only gives protection if you keep the astronauts in quarantine indefinitely, in the case that life is confirmed in the sample that could survive on Earth - indefinitely, or until you prove it is safe. Potentially for ever if it is proved unsafe. But that's ethically and legally problematical even if they agree to it.
If quarantine is going to be effective as a way of protecting Earth, we have to think through such questions. It's obviously not going to be an effective method to protect Earth, if we have a policy that mission planners can drop any of the requirements whenever there is any problem that impacts on the humans involved.
Yet, surely human rights and health have top priority? Even if all the scientists and workers with a risk of contacting a sample sign a voluntary agreement to not be taken out of quarantine in any circumstances, even in event of serious illness and threat to life, can they legally, be held to such an agreement? It seems to conflict with basic human rights.
What if they change their mind once their life is threatened, or if it becomes clear there is no way to sterilize them of a serious threat to the environment of Earth and they have to stay in there for the rest of their life?
Incidentally it's also similar for people who volunteer on a one way mission to Mars. Apart from issues of forward contamination, what if they want to come back to Mars later on? That's like someone who agreed to stay in the quarantine facility changing their mind once they discover they have to stay there for weeks, months, years or even the rest of their life to protect Earth.
For all these reasons I think there is almost no point in attempting to use 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, so long as you accept that the humans involved have to have the right to return to Earth and to get medical treatment and help in the event of life threatening conditions, or to change their mind and make the decision to exit any quarantine facilities whatever their previous decision was, and whatever legal documents they might have signed.
For the same reason, I can't see how it can work for robotically returned samples either, unless you can somehow ensure that there is no chance at all of accidental exposure of humans to the materials.
I think that the answer here is that there is no substitute for knowing what is in the samples before they are returned to Earth. For as long as you don't know if there is life in them, or don't know what it's capabilities are, then you need to sterilize any samples returned here.