Space exploration is not a job for the impatient. When Rosetta he managed to intercept Comet 67P / Churiumov-Guerasimenko, in 2014, had already been a decade since its launch from French Guiana and ten more years since its construction was approved. To those two decades we would have to add the design time of the mission itself. A few days ago, Günter Hasinger (Oberammergau, Germany, 1954), the new director of science of the European Space Agency (ESA), presented in Madrid the next Rosetta, that is, the vision of Europe for the future of space exploration. The next month of November, in Seville, will be held the meeting of ministers of the member states of the agency that will decide their objectives for the coming years.
Among the great missions already approved stands out Juice, which plans to leave for Jupiter in 2022 to study its moons. The oceans that seem to exist under the surface of Europa, Ganymede or Callisto are among the places where there could be life within the Solar System. Later, as early as the 2030s, they will arrive Athena Y Lisa, a space observatory of X-rays and another of gravitational waves that promise to see as never before the fusions of black holes or neutron stars and along the way can solve dilemmas of physics more than a century old. Hasinger also mentioned the possibility of planning a mission to visit Uranus and Neptune, two planets that have never received the attention of their own space mission.
Question. Do you think that finding some type of extraterrestrial life in the next decades is something probable?
Some people say that the atmosphere of comets stinks like a horse stable
Answer. In the first place, we have to make clear what we consider life. We have to differentiate between simple life forms, such as algae or bacteria, that have made our planet a habitable planet by terraforming the Earth for billions of years and producing oxygen so that other life forms can exist, and intelligent life . A few hundred million years after the formation of the Earth there were already the first forms of life, but the appearance of more complex forms required 3,000 million more years, so the first ones will be much more abundant.
On the other hand, on Earth we have found life in many unexpected places, in the ice of the glaciers or under the earth's mantle. We now know that the total biomass below the surface of the Earth is greater than the biomass above us. There are bacteria and other organisms that live from radioactive decay so they have life cycles completely different from what we are used to. And there is another factor: when we have studied comets, a large number of organic molecules has been found. Some people say that the atmosphere of comets stinks like a stable of horses and for me that means that the basic bricks of life, the small elements necessary to create life, already exist in comets and other places.
I think there should be simple ways of life out there, the problem is how to detect it. For example, we believe that there was life on Mars billions of years ago, that there was liquid water on the surface, but today it is sterilized by cosmic radiation, so all life forms that might have existed on the surface have disappeared. To find life, you have to drill the ground. And something similar happens when you look, for example, to Enceladus or Europa, the icy moons of Saturn and Jupiter. We believe that there could be life under a layer of one kilometer of ice, in a liquid ocean that is very difficult to reach. The question is not so much whether we will discover life but how difficult it will be to discover it.
I think there's intelligent life out there, but it's so far away that there's no possibility of communicating with it
When we speak of exoplanets, the mere existence of oxygen in an atmosphere already indicates that some type of terraforming has occurred and that there must be bacteria that create oxygen because oxygen does not come from outer space. In the next ten or twenty years I think we will find signs of simple life forms outside the Earth. The question of whether we will find intelligent life is completely different. I believe that there is intelligent life out there, but it is so far away that there is no possibility of communicating with it.
P. What specific missions can perform these detections?
R. I think the first opportunity we will have is the recovery mission of Phobos samples [la luna de Marte] with MMX. In the coming years we will bring material from the Martian system. I believe that Exomars 2020, when we have the rover, it will also be a start. Another possibility is to analyze the plumes of moons such as Europa or Enceladus that arise through cracks in the ice and geysers in which the water could drag some type of organic material, although at the moment we do not have instruments to make those analyzes.
After, there are missions like Ariel, that make spectroscopy of the exoplanet atmospheres and that could find biomarkers. I would bet that this can happen in the next ten or twenty years.
It is speculated that black holes are actually part of dark matter
P. What great discoveries can we expect from Lisa Y Athena?
R. I believe that Lisa Y Athena They tackle fascinating questions about the nature of black holes, dark matter and the entire dark universe. Now, with the interest aroused by terrestrial gravitational wave observatories, there is a renewed interest in how black holes are formed and what happens when they melt. This can also serve to understand dark matter. We know that it exists, but we have no idea what particles form it. We also do not understand where black holes come from, we see primitive quasars, in the early universe, where there are already black holes, and we do not know where they come from. And there is a speculation that is exciting, although there is no agreement on whether it is plausible, and it is whether black holes are actually part of dark matter, whether black holes are contributing or even are basically dark matter.
These are issues that can be studied by Lisa Y Athena. Why Lisa Y Athena They will find mergers of black holes in the universe very early and can estimate how many there are and if they are connected to light and normal matter. I think the next two decades will be dominated by the study of extrasolar planets, but the next twenty will return the gravitational science that will help us understand what happened at the origin of the universe.
P. You are interested in Oumuamua, the first object arrived from outside the solar system that has been observed. Do you agree with the Harvard researchers who claim that it is probably an artifact built by intelligent beings?
R. I think that if you read the article they published, they do not really claim that it is artificial, but that it can not be ruled out that it is an artificial object. But then the press took this statement and said that Harvard astrophysicists said that. From my point of view, they referred to an idea that has been discussed for some time about the possibility of traveling to other planets with a solar sail. Something related to the initiative Breakthrough Starshot in which Stephen Hawking, before he died, he was also involved. It consisted of sending an artifact as a smartphone with a large solar sail. When you push it with a laser beam, you can accelerate it to a fraction of the speed of light and you could reach the nearest star in a short time.
The factor that will determine if we are able to populate the galaxy is the longevity of our civilization
I am skeptical about this technology, because the sail has to be an extremely fine and very large structure, hundreds of meters long. You have to propel it with a laser beam and the amount of energy you need to accelerate it is so great that you would basically fry the candle instead of accelerating it. But suppose there is a civilization that has overcome this problem of the solar sail and does not burn. Then, in principle, you could send a probe to another star. But if this were so, Oumuamua would be moving too slowly. It moves at about 30 kilometers per second when with a solar sail it would be moving at about 10,000 kilometers per second.
In addition, there are quite credible natural explanations. We have not seen a comet tail, so it must be a special type of comet that we have not seen in the solar system. That could be explained by the fact that it has been traveling for millions or hundreds of millions of years, and perhaps it has lost most of its gas because it is passing by a new star every million years or so. There are natural explanations for the phenomenon although we do not fully understand them.
P. Even if in the next few years we find signs of life on an extrasolar planet, in the universe everything is so far away that we could never visit it.
R. If you think of a human scale, it is impossible for you in a lifetime to get anywhere. But if you have an intelligent civilization capable of building robots and these robots go to another planet, and then these robots can build a factory that builds more robots, you can produce a snowball effect and in a few hundred million years you could populate with robots all the planets of the galaxy. So some people think that since these robots have not reached Earth, we can think that there is no civilization in the galaxy with that capacity, because if there were, they would already be here. But in principle it would be possible if you do not think of populating the galaxy in a human generation but during life a complete civilization. So the final factor is the longevity of our civilization. If we kill our planet a thousand years from now, there will be no possibility of communicating with other civilizations, particularly if they do not know how to take care of their planets either.