Alejandro Cardesín knows what he is talking about when you ask him about space missions. He has been working for ten years in the European Space Agency (ESA), involved in several projects studying the Solar System, including the Rosetta mission to Comet Churyumov-Gerasimenko, and Venus Express. At the present time, this telecommunications engineer is part of the projects to explore Mars, such as Mars Express and Exo Mars, which was put into orbit around the red planet a few weeks ago. One of its objectives will be to examine the conditions for the development of life on the planet. But his career in space exploration will be going much further, because he also participates in JUICE (Jupiter Icy Moons Explorer) a mission which will take off from Earth in 2022 with destinations Europa, Ganymede, and Calist, three of the biggest of Jupiter’s moons, to see if there may be life in the oceans of liquid water below the surface. Someone with his profile should not be absent from the XXVIII Canary Islands Winter School of Astrophysics, organized by the Instituto de Astrofísica de Canarias (IAC).
By Elena Mora (IAC)
“Scientists have found many forms of life in all terrestrial environments, which shows that some of these organisms could survive in conditions very similar to those on the red planet.”
“The next step in the exploration of Mars will be to analyze its subsoil, because it is very probable that geological or biological processes, not so far known, may be found quite close to the surface, maybe in the presence of liquid water.”
“Understanding the history of Venus has strong implications for the study of climate change on Earth”
Question: On July 20th it will be 20 years since Viking 1 arrived at Mars and sent back the first pictures of the red planet. What did it mean for the world to see this planet for the first time? How much have we advanced since then?
Answer: Since the first telescopic observations in the XIX century, Mars has always been the objective of speculations about the possibility that it could harbour conditions similar to those on Earth, and suitable for life, which triggered science fiction about possible extraterrestrial civilizations with a big impact on society.
This curiosity was given an impulse by the space race in the 60’s and 70’s, which ended with the Viking missions with objectives which were entirely exobiological, and whose media cover could be compared only to the Apollo missions. Unfortunately for popular fantasy, those mission s showed that the Martian environment is very different from what had been expected, and that there wasn’t a trace of life, but they suggested a series of questions about the geological history of Mars which the scientific community is still trying to answer after several decades.
Planetary exploration came to a stop for some time after the space race was over, and we have had to wait for this new century to be able to continue with space research and to carry on supplying pieces of the big puzzle which is the history of the red planet.
Q: As the results of research on Mars move forward, especially those showing that there has been water present, more scientists support the idea that it may have harboured life. What is the evidence supporting this possibility? If there is, or was, life, how will the confirmation of this affect our perception of the universe and of our place in it?
A: Planetary exploration in general, and astrobiology in particular, try to answer one of the questions which is most important for humanity: where, and how did life emerge? We know that life on Earth has an amazing capacity to adapt to the most extreme conditions and on our planet it is very hard to find a place where there is no life, at least microscopic life.
Scientists have found many forms of life in all environments on Earth, from the sub-zero temperatures in the polar caps, to the deepest parts of the oceans, and in the hottest deserts, even in extreme environments such as the acid water of the Rio Tinto, or the salt pillars in the Atacama Desert. All of this shows that these organisms are capable of survival in conditions very similar to those on Mars.
It has also been shown that there are many micro-organisms, in particular some lichens, fungi, and above all spores, which can persist in the conditions of the vacuum and the radiation in space, so that they could survive an interplanetary journey. There is a scenario, “panspermia” one of whose consequences is that life on Earth could have an extraterrestrial origin. We know that there has been interchange of matter (transported via meteorites etc.) between Mars and Earth, so that there is a possibility that life could have travelled between the two planets. Researching the red planet is one of the few possibilities that we have of finding an explanation of this kind of life and, if we do find it, we will need to analyze whether it has emerged in paralled to life on our planet or not. On the other hand if we don’t find anything we will have to ask ourselves why, under similar conditions, life emerged on one planet and not on the other.
Q: What is the scientific community looking for with the Exo Mars mission?
A: The ExoMars programme consists of two missions, one in 2016 and the other in 2020, which cover two fields which are different, but inter-related: science and technology. On the science side the objective of both of them is to obtain more information about the conditions which may allow the red planet to harbour life. The first phase, in 2016, will analyze via the TGO (Trace Gas Orbiter) the trace gases in the atmosphere which could be indicators of recent biological or geological activity, and the second phase, in 2020, will be aimed at analyzing the chemical compounds on the surface and in the subsoil to explain how the planet has evolved during the most recent millions of years, and if there are biological indicators from previous epochs.
In the technological field both missions will develop the knowledge and the necessary methods to take increasingly complex information to Mars, with the idea of bringing back samples of the planet in the coming years. In spite of the loss of the Schiaparelli module the technology developed during this interplanetary mission will serve as the basis for the next big step for mankind: the future human exploration of our neighbouring planet.
Q: One of the main objectives of Exo-Mars is to study the methane in its atmosphere, which could be an indicator of the biological processes which produce it, as happens on Earth. What is the origin of this gas? If there were a biological process producing it, where would this be?
A: The origin of methane on Mars is a major mystery, since on our own planet this gas comes mainly from biological activity or in some cases from active geological processes in contact with liquid water. However at the present time neither of these conditions is found on Mars.
Furthermore, methane cannot remain in the atmosphere during much time because it is degraded by the effect of radiation, oxidation, and recombination with other chemical components, so that the process which produces the variations observed in recent research must be occurring right now, or at the earliest within the last few hundred years.
Space missions continue to give us a lot of information about the chemical processes in the atmosphere and on the surface, but until now none of these has been able to give us the explanation of the variations observed. For that reason the first step in the exploration of Mars will be the analysis of the subsoil, because it is very probable that these geological or biological processes so far unknown, will be found just below the surface, maybe in the presence of liquid water.
Q: There are theories which say that Venus was a planet with an atmosphere very similar to that of the Earth? Is there a possibility that our own planet will evolve in a similar way?
A: Venus is our nearest neighbour, and has a similar size to the Earth, and according to the accepted theories the two planets formed under similar conditions, with a similar quantity of water and at a distance from the Sun relatively similar (only 30% different). But in spite of having a common origin, Venus has evolved in a very different way. The water has almost completely disappeared and the atmosphere has reached extremes of pressure and temperature which impede any type of life, and make exploration of its surface very difficult.
The main objective of Venus research will be to understand the evolution of the greenhouse effect produced by the atmosphere, and try to find out if there was a point of no return in its geological history, in which the thermal equilibrium was broken, causing the liquid water to evaporate, and gases to be lost to outer space.
Understanding the history of Venus has major implications for the study of climate change on Earth, because the increase of the greenhouse effect caused by human activity in recent decades is breaking the thermal equilibrium and we need to know if we are anywhere near this point of no return which could bring about the end of life on our planet.
Q: Could we talk about future missions, apart from Exo Mars and Venus Express, to conquer other planets in the Solar System?
A: The Space Agencies have Solar System exploration programmes planned far into the future, because interplanetary missions are very complex and need many years of development. As is the case of Exo Mars, they need the cooperation of several agencies to accomplish them.
Nowadays one of the most important subjects at international level is research in astrobiology, which is make great strides, not only in the programmes for exploring Mars, but also in missions to the icy moons of Jupiter. An example is the European mission JUICE, which will arrive at Europa, Ganymede, and Callisto in 2030 because there could belief in the oceans of liquid water below their surfaces.
In addition, the Rosetta mission has been a historic milestone in cometary and asteroidal research, which will give rise to the development of a number or international progammes in the coming years. These will not only produce a great deal of information about the origin of the Solar System, but will also serve to develop the technologies which could protect our planet from possible approaching asteroids. Such a mission is AIM, a European project which will study the impact and the deviation of an asteroid in collaboration with the Americans via the AIDA programme.
Q: The conquest of Mars, fiction or reality? Will it be many years before it occurs and is no longer merely a subject of science fiction? After Trump’s victory will there not be a long waiting list of people who want to go to Mars?
A: The international agencies continue working on Solar System exploration, and at the present time our technological development allows us to believe that we might be able to make an unmanned return visit to Mars during the next decade. Although this is a very complicate objective, the technology is on the right track, and with the required international support it should be possible to make manned journeys within 20 to 30 years.
It may seem improbable, right now, to make manned interplanetary journeys, but at the end of the XV century marine explorers, with technologies which seem rudimentary to us, made discoveries which were unimaginable for the society of their time, and which changed human history in only a couple of decades.
At the present time the next frontier in human exploration is the planet Mars, and although to the majority of people this may seem to be science fiction, manned journeys, or even the establishment of colonies on Mars may, within not so many years, become a reality.