The recent discovery of the exoplanet Kepler-452b, which is very close to Earth in its characteristics, has once again spurred interest in a possible encounter with alien life. However, this problem has long been translated into a practical plane: at the dawn of the space era, the USSR and the USA developed a unified system for protecting the Earth from alien microorganisms - and vice versa.
What are the pros and cons of this system? And do the latest discoveries by astrobiologists and planetary scientists provide grounds for weakening the strict quarantine rules? Now we will try to figure it out …
You can’t let someone else’s life on our planet - and in the same way, you can’t infect foreign planets with your life, if there is even a suspicion of your own. This mantra, albeit a little in other words, sounded on Earth almost at the very beginning of the era of space exploration. In 1967, at the height of the Cold War, the USSR and the United States, at that time the only countries capable of such exploration, concluded the Outer Space Treaty ("Treaty on the Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies"), where, in particular, the principle of non-infection was proclaimed for the first time.
Chapter IX reads: “The States Parties to the Treaty shall carry out the study and exploration of outer space, including the Moon and other celestial bodies, in such a way as to avoid their harmful pollution, as well as adverse changes in the earth's environment due to the delivery of extraterrestrial matter, and for this purpose, in the event necessary, take appropriate measures."
It is curious that since then and to this day nothing like these consultations between the members of the rapidly expanding club of space states has ever been held - in any case, the public does not know anything about it. We dare to suggest that in what, in what, and in this, each space country was in full solidarity with the parties to the treaty.
What to do
The trouble is that half a century has passed since the signing of this treaty, and scientists still have not come to an agreement on how to comply with it. It is clear that if we suddenly stumble upon green men, and even equipped with weapons, we will try to stay away from them, unless we exchange embassies, reliably blocked from alien influences and, most likely, placed on the nearest satellites, devoid of any semblance of life. However, we are primarily talking not about this science fiction, but about the protection of terrestrial microorganisms from aliens and vice versa. Therefore, the pollution referred to in the Outer Space Treaty is divided by scientists into two categories - direct contamination of alien micro-life by our microbes (forward contamination) and reverse (back contamination).in which the infection of the Earth's biosphere by alien organisms is possible.
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Astronaut Neil Armstrong blows a kiss to his sons from quarantine in Houston after returning from the moon on July 27, 1969.
We emphasize: for all the time of our space voyages, no traces of alien unicellular organisms have yet been found, so it is possible that they are not at all. However, based on general considerations, it should still be assumed that they exist, and in abundance, so we cannot exclude the possibility of both direct and reverse pollution.
It is also possible that if there is a danger of pollution, then it is small - even if a foreign microbe, foreign spore or bacterium gets into terrestrial conditions, then among the myriad of unfamiliar microorganisms against which he has no protection, the stranger with a high degree of probability will die, as happened to the belligerent Martian aliens in HG Wells' War of the Worlds. However, if it nevertheless survives and begins to multiply, the situation will turn upside down, and it will already become a fatal threat to life on our planet. The same is true for terrestrial microorganisms that get to other planets, where presumably they can have their own life, and, therefore, the principle of "do not infect", with all the unlikely probability of unicellular apocalypses, must be strictly observed.
Reverse pollution
People are primarily concerned with reverse pollution: it is important to understand how to avoid deadly invasion from outside. Since alien microorganisms have not yet been found, scientists are working with terrestrial babies - extremophiles who are able to live and reproduce in extreme conditions - at very high temperatures, in space cold, at excessive pressures, high radiation. It is not known whether the extremophiles that exist in our country are capable of destroying the biota of an entire planet, which is not prepared for their attack, but the fact that these theoretical killers must be extremophiles is beyond doubt. And such extremophiles, it turns out, are quite enough on Earth.
And we are talking not only about bacteria that can live in deep space or inside nuclear reactors with millions of rad of radiation - organisms are even more complex resistant to "extreme". For example, the Moscow Institute of Biomedical Problems of the Russian Academy of Sciences has been carrying out experiments on the ISS for about ten years, during which containers with various organisms are installed on the outer surface of the station and kept there for months or even years. As a result, it turned out that in addition to the spores of bacteria - champions in survival - in conditions of vacuum and temperature changes from minus 90 to plus 90 degrees Celsius, some spores of fungi manage to survive, even after 31 months mosquito larvae come to life, radishes sprout and barley spikes.
Microorganism strains from the International Space Station.
The problem of protection against re-infection from the theoretical turned into a practical plane back in the 60s, when American astronauts visited the moon and returned with lunar soil samples. At that time, scientists did not know if there was life on the moon (of course, in the form of bacteria, not green men), and protection from supposed lunar inhabitants was very cumbersome and serious, although its main principle was simple: “when leaving, wash your hands and wipe your feet. While on the moon, the cosmonauts tried not to bring dust with them into the reentry module and not allow it to settle on the surface of the spacecraft. Returning, the members of the lunar expedition were in quarantine for three weeks, and the samples were studied in a special laboratory in Houston, taking all precautions until it was proved that they did not contain any lunar microorganisms.
NASA's methods of protection against contamination from possible delivery of soil samples from Mars to Earth are even more serious. The principle of "breaking the contact circuit" will work here, in which any equipment that had direct or indirect contact with Mars will not return to Earth. Before getting on board the ship, soil samples will be packed in a special container, and on Earth they will be studied in compliance with the precautions that are used today when working with the Ebola virus. In the meantime, laboratories equipped in accordance with these requirements, according to representatives of NASA, do not exist, and it is not known when they will be created.
True, there is still time. Firstly, there are most likely no microorganisms on the surface of Mars: many hundreds of millions of years of superdrought should have destroyed them. If they survived, it was deep below the surface, where the water was preserved, and, according to scientists, at those depths stunning surprises await us. Secondly, a return trip to the Red Planet is not yet being prepared, since today such a visit will be prohibitively expensive.
Flight Engineer Donald Pettit (ISS Expedition 6) collects water samples for analysis (water heater in the Zvezda module).
And here scientists are faced with a paradox. On the one hand, even today unattainable precautions do not give a 100% guarantee of protecting the Earth from an alien killer virus, because we simply do not know what we will have to deal with. On the other hand, if we cannot bring anything living to Earth, then, accordingly, we are not able to study this living thing. The system thus suffers from both incompleteness and redundancy.
Direct pollution
Direct pollution is not easy either. Although this part of the Outer Space Treaty is based on a noble desire not to harm other worlds, scientists are more worried about another aspect of the contamination of alien biota with terrestrial microbes. They fear the difficulties associated with such pollution with the search for Martian microorganisms, or at least chemical traces of their metabolism. The terrestrial bacterium is unlikely to arrange a massacre for the inhabitants of the Red Planet, but, having penetrated into the ground, it can mutate, adapting to new living conditions, and when it is found, it may not be recognized and mistaken for a local resident.
The procedure, which should prevent direct contamination, is sterilization. Before the start, NASA warms up all parts of the spacecraft to 110 degrees (above the boiling point of water), which destroys most microorganisms. Those parts that cannot be warmed up are washed with alcohol. Our specialists, preparing for the flight to Mars that never took place in 1994, exposed all the components of the spacecraft (except for the electronics) to gamma radiation. But neither this measure, nor additional "sterilization" during the passage of the ship through the dense layers of the atmosphere can destroy all microbes on its surface. It is believed that a ship can be planted on a planet if there are no more than 500 spores left on a square meter of its surface after processing. So what? So disinfection doesn't work?
If colonists appear on Mars, then their every exit to the surface will also be accompanied by sterilization, the procedure of which will be similar to that used when working with the already mentioned Ebola virus. This will significantly increase the cost of an already expensive mission of the future and will greatly complicate the work of researchers.
Recently, a controversy has erupted in the scientific community about this. In 2013, Dirk Schulze-Makuch, an astrobiologist at the University of Washington, and astrophysicist Alberto Fairén of the SETI Institute published an article titled "Overprotecting Mars" in Nature. Scientists have proposed revising the costly procedure for sterilizing the spacecraft, as it "imposes unnecessary bans on the search for life on Mars." A few weeks later, the same journal published an article by Catharine A. Conley and John D. Rummel, astrobiologists at NASA, entitled "Defending Mars expediently," where they justified this defense. “We can find what we are looking for only if we do not infect Mars with life brought from Earth,” the scientists said.
It must be assumed that, unlike reverse pollution, from which there will always be protection, protection from direct pollution can become a temporary measure, acceptable only at the stage of studying Mars. But since humanity will not only study other planets, but also populate them, at this stage the colonists will no longer be up to sentimentality about the microlife being killed. Today, the idea of settling other planetary systems seems like a fairy tale, since today we are not even able to get to them, and the settlement of Mars seems to us a distant and unrealizable science fiction. But serious scientists are already building long-lasting plans to turn the Red Planet into a second Earth. And then, perhaps, from protecting someone else's life, people will move on to attacking it.
In general, it is clear about the Earth, but there is a different opinion about Mars
It makes no sense to protect Mars from contamination by terrestrial microbes and spend large sums on thorough sterilization of Martian automatic probes - terrestrial microorganisms entered the Red Planet billions of years ago with meteorites, American astrobiologists write in an article published in the journal Nature Geoscience.
Since the beginning of the space age, scientists have taken the most severe measures to protect alien "ecosystems" from potential contamination by terrestrial microorganisms. This practice is enshrined in the 1966 treaty on the principles of the activities of states in the exploration and use of outer space - it prescribes to avoid harmful pollution of the Moon and other celestial bodies. Measures for interplanetary "antiseptic" are developed by the International Committee for Space Research (COSPAR).
Particularly stringent requirements are imposed on landing probes going to Mars - on this planet, as scientists believe, microbial life can exist, and its collision with earthly "guests" can lead to unpredictable consequences. In addition, it is believed that the emergence of terrestrial microbes could make it pointless to try to discover "primordial Martian" life.
However, astrobiologists Alberto Fairen of Cornell University and Dirk Schulze-Makuch believe that these precautions have not made sense for several billion years.
“We believe that life on earth has most likely already been transferred to Mars. Life has existed on Earth for at least 3.8 billion years, so there was enough time for the transfer process to occur naturally - by meteor impacts … In addition, in the past, the frequency of meteorite falls was higher than today,”the scientists write. …
They note that at the moment it can be considered proven the possibility of transfer of microorganisms with "passing" meteorites. The process of interplanetary transfer begins with the impact of a large space body on an inhabited planet - this impact can knock out into space large enough rock debris, inside which microorganisms may appear.
Then these debris can fall to Mars - as the Martian and lunar meteorites fall to Earth. The chances of survival of "passengers" are increased due to the relatively thin Martian atmosphere, in which meteorites, when falling, heat up less than in the earth.
Fairen and Schulze-Makuch suggest that terrestrial microorganisms that came to Mars billions of years ago, when conditions on this planet were much more favorable, could have disappeared by now. In this case, it makes no sense to worry about contamination from space probes. If life on Mars arose independently of earthly life, it collided with earthly "guests" billions of years ago. Martian microorganisms, if they still exist, will not see anything unexpected when they encounter microbes brought by automated stations.
You can save
Scientists believe that with a very high degree of confidence, Mars can be considered already "conquered" by terrestrial microbes. “Therefore, it is already too late to defend Mars … and we can safely weaken the measures of planetary protection,” the article says.
Its authors believe that sterilization measures will be required only in cases where automatic probes will explore the environment where Martian life can exist now - and then, only so as not to confuse the aboriginal microorganisms and those brought with them.
"As interplanetary research around the world is now facing severe budget cuts, it is critical to avoid unnecessary spending and redirect taxpayer money to missions that can make the most significant contribution to planetary exploration," the scientists write.
They believe that measures to protect against potential contamination can be canceled for orbital probes and seriously revised for rovers and lander.
Vladimir Pokrovsky