The nearest place in the universe in which alien life could come is Mars, and human beings try to colonize this planetary neighbor in the next decade. Before this happens, we must admit that there is a very real possibility that the first human steps on the Martian surface will cause a collision between earthly life and biotic nature on Mars.
If the red planet is sterile, a person's presence in this front would not create moral or ethical dilemmas. But if life exists on Mars, human researchers can easily lead to the extinction of Mars' life. As an astronomer who explores these issues in his book "Living on Mars: What I Need to Know Before We Go", I argue that the Earthmen must understand this scenario and discuss the possible results of colonization of our neighboring planet in advance. Perhaps the mission that would bring people to Mars needed a time limit.
Where could I live?
Life, scientists suggest, has some basic requirements. It could exist anywhere in the universe, which has running water, a source of heat and energy, and a large amount of some essential elements, such as carbon, hydrogen, oxygen, nitrogen and potassium.
Mars meets the conditions, just like in two other places in our solar system. Both Europe, one of the great Lun Jupiter and Enceladus, one of Saturn's big moons, have these prerequisites for hosting home biology.
I suggest that scientists plan a research mission on these two moons, giving a valuable background in reflection on the exploration of Mars without the risk of contamination.
Under their thick surface ice layers, both Europe and Enceladus are global oceans, in which 4.5 billion years ago the original soup could provide a life that developed and roots. NASA spacecraft even showed spectacular geysers that eject water from space in these oceans.
To find out if life is every month, planetary scientists are actively developing the Europa Clipper mission for the beginning of 2020. They also hope to plan future missions directed against Enceladus.
Be careful not to contaminate
Since the beginning of the Universe, scientists have seriously compromised the biological contamination of other worlds. Already in 1959, NASA organized meetings to discuss the necessity of sterilization of space vessels that could be sent to other worlds. Since then, all planetary research missions have respected sterilization standards that balance their scientific objectives with restrictions on the harmfulness of sensitive equipment, which could lead to missions in the mission. Today there are NASA protocols to protect all bodies of the Solar System, including Mars.
Since the avoidance of biological contamination of Europe and of Enceladus is an extremely well understood, highly urgent requirement for all missions in the Jovian and Saturnic environments, their moons remain uncontaminated.
NASA's Galileo mission explored Jupiter and its moons from 1995 to 2003. According to Galileo's orbit, there was the possibility that spacecraft, formerly of rocket propulsion material and subjected to the tide of Jupiter's gravity trains and its many moons, would someday collapse and thereby contaminating Europe.
This collision may not happen until millions of years from now on. Nevertheless, even though the risk was low, it was also true. NASA paid special attention to the instructions of the Committee of State Academies for Planetary and Moon Research, which pointed to serious national and international objections regarding the possible accidental removal of the Galileo spacecraft to Europe.
To completely eliminate such a risk, NASA on 21 September 2003 used the last pieces of fuel on a spacecraft to send it to Jupiter's atmosphere. At a speed of 30 miles per second, Galileo evaporated within seconds.
Fourteen years later, NASA repeated this scenario to protect the moon. The mission of Cassini was orbiting and studying Saturn and its moons from 2004 to 2017. On 15 September 2017, when the fuel passed, NASA's Cassini operator deliberately dropped a spaceship into the Saturn atmosphere where it collapsed.
What about Mars?
Mars is the target of seven active missions, including two rovers, opportunities and curiosity. In addition, on November 26, NASA's InSight mission is expected to land on Mars, where it will carry out measurements of the internal structure of Mars. Then, with the planned start of 2020, both rotor ExaMars and NASA Mars 2020 rover are intended to search for evidence of life on Mars.
The good news is that robotic rovers represent a low risk of contamination to Mars, since all spacecraft are scheduled to land on Mars before the start of strict sterilization procedures. This was because NASA introduced "rigorous sterilization procedures" for Viking Lander capsules in the 1970s, as they would directly turn to the Martian surface. These rovers probably have an extremely small number of microbials.
Any Earthly biot that will succeed in reaching the exterior of these rovers would be very difficult to spend the half-yearly journey from Earth to Mars. The vacuum in space, along with exposure to sharp X-rays, ultraviolet light and cosmic rays, would almost certainly sterilize the exterior of each space ship that was sent to Mars.
Every bacteria that sneaked, drives within one of the rovers, could come to Mars lively. But, if they fled, a thin Martian atmosphere would not provide any protection against high energies, the sterilization of radiation from space. These bacteria would probably kill immediately. Because of this harsh environment, life on Mars, if it is currently located, almost certainly hides under the surface of the planet. Because no rovers have explored caves or dug deep holes, we have not yet had the opportunity to meet with all the possible martian microbes.
Given that the Mars exploration has so far been limited to unmanned vehicles, the planet is likely to remain without land contamination.
But when Earth sends the astronauts to Mars, they will travel with life support and energy supply systems, habitats, 3D printers, food and tools. None of these materials can be sterilized in the same way as systems related to robotic spacecraft. Human colonists will produce waste, try to grow food and use machines for extracting water from the ground and the atmosphere. Simply living on Mars, human colonists will pollute Mars.
After the contamination, it is not possible to return the clock back
Space explorers have developed a careful approach to the robotic exploration of Mars and hands toward Europe and Enceladus. Why, then, are we willing to overlook the risk of Mars' life of human exploration and colonization of the red planet?
Mars pollution is not an unpredictable consequence. A quarter of a century ago, a report by the National Research Council titled "Biological Contamination of Mars: Questions and Recommendations" confirmed that missions that transport humans to Mars inevitably pollute the planet.
I believe that it is crucial that any attempt be made with evidence of any past or present on Mars well ahead of future Mars missions that involve people. What we discover will affect our collective decision whether to send colonists at all.
Even if we do not take into account or worry about the risks that man's presence would represent for life in Mars, the question of Mars's revival on Earth has serious social, legal and international consequences that deserve debate before it is too late. What risk would the life of Mars live in our environment or our health? And does any country or group have the right to risk contamination if those Martian lifestyles can attack the DNA molecule and threaten all life on Earth?
However, NASA, the Mars 2117 project in the United Arab Emirates – and the private – SpaceX, Mars One, Blue Origin – are already planning to transport colonists to build cities on Mars. And these missions will contaminate Mars.
Some scientists believe that they have already discovered solid evidence of life on Mars, the past and the present. If life already exists on Mars, Mars now belongs to Martians. Mars is their planet, and Mars's life would endanger the human presence there.
Does humanity have the inalienable right to colonize Mars simply because we can soon do so? We have the technology to use robots to determine if Mars is populated. Does ethics require us to use these tools to finally answer whether Mars is settled or sterile before we place human traces on the Martian surface?
David Weintraub, professor of astronomy, Vanderbilt University
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