Tech UPTechnologyFrancisco Anguita:

Francisco Anguita:

On the wall of his office in the Faculty of Geology of the Complutense University of Madrid, full of lunar maps and photographs of Mars, hangs a dedication that Francisco Anguita considers very special: “The Planetary Society, due to its extraordinary and efforts to support the exploration of the Solar System and the search for extraterrestrial life, awards Francisco Anguita with this certificate of appreciation “. The congratulation is signed by Carl Sagan.
“At 10 or 12 I had a tremendous fondness for cheap science fiction novels. If someone told me at that time that you could make a living studying planets, I would not have doubted it for a second,” says Anguita.

However, that early hobby lingered for years. Anguita turned to geology after abandoning her intention to become a chemist; “I didn’t like the way the labs smelled.”

Now, he teaches his students unconventional subjects that deal with volcanoes on Martian soil or frozen oceans of methane on a distant moon of Jupiter. He likes to consider himself a planetologist, a discipline of which he is the founder and pioneer in Spain. This trade seems to be like a mixture of detective who investigates the history and evolution of bodies in the Solar System and a forensic trained to certify the death of something as big and mysterious as a planet.

Anguita is one of the clearest exponents of a new generation of scientists emerged under the protection of NASA’s Pioneer and Voyager missions, who astonished locals and strangers with the bluish face of Neptune, the volcanic feathers of Io or the unknown frosts of Europa, the most fascinating moon of Jupiter.

Recently, Edward Stone, director of NASA’s Jet Propulsion Laboratory (JPL), has claimed that the search for life in the Solar System is actually the search for liquid water. Do you agree?
-In part yes. The biochemistry of life that we know needs water. But what about the one we don’t know about? I have my doubts, because I think the concept is a bit anthropocentric. For the same reason, all the planets in the Solar System would have to have plate tectonics and lithospheric recycling like Earth’s, and we now know that this is not the case. What will happen when we start exploring other extrasolar planets? There is no doubt that the life we know is linked to water, but I would not bet anything that this was the case for all possible life in the universe.

You have suggested that Mars may have changed its morphology much earlier than previously thought, as a result of studies on the nature of the Chasma Boreale canyon. Does it mean that the planet could have supported water, and perhaps life, a few million years ago instead of billions of years ago?
-That’s my impression. In fact, NASA believes that the areas to find hypothetical remains of life on Mars are those with deep hydrothermal activity, that is, they contain gaps through which the internal heat of the planet has escaped, in sufficient quantities to melt the ice and generate liquid water. We think that one of those areas is at the head of Chasma Boreale. It is a perfect place to send a probe. The bottom of the canyon is clogged with sediment, and the erosion that we see cannot be explained unless we go to large amounts of liquid water, and not in very ancient times. The canyon floor is free of craters, which tells me it could be a few tens of millions of years old. In geological terms, this is like talking about what happened months or years ago.

In any case, it is indirect evidence. It is also possible to conceive that Mars has been a dry and lifeless planet for its entire existence.
-I agree that this is indirect evidence. But much of what we know about Earth’s history is based on indirect evidence. For example, Newfoundland and Galicia were united 300 million years ago, but there was no one there to confirm it.

What are the latest discoveries that support your ideas?
-The most recent images from the Mars Global Surveyor probe show that a third of the surface of the red planet is a perfect plain. Scientists who have studied it say that it is the most perfect in the entire Solar System, something like the abyssal plains of the equatorial Atlantic Ocean. Such a flat ground occurs when there is sedimentation. There are no impact craters on the plain. And the so-called channels of Mars flow into it, but they do not continue: they disappear when they reach the edge, where there is a slight slope. If the channel does not follow, it is because there would presumably be a body of water, an ocean that covered a third of the planet. These are all indirect arguments, although they are undoubtedly quite convincing.

Earth has had oceans of water for 4 billion years, but Mars is now a nearly dry body. Why has it changed so much in relation to our planet?
-It is the same as wondering why our planet is so stable with respect to its neighbors Mars and Venus. The Earth has suffered variations in climate, glaciations followed by warmer periods, but Mars had a past in which it was a cold oceanic planet, and now it is a body with a very thin atmosphere, without atmospheric pressure, where the liquid water that you throw boils and evaporates. Venus today is a hot and dry planet, but we have reason to believe that in the past it was wetter and that it harbored water. Mars is a small planet, with a weak gravitational field, therefore incapable of retaining a dense atmosphere like Earth’s, essentially formed by the volatiles thrown by volcanoes. As for Venus, we know that it has active volcanism, but it is too hot due to its closer proximity to the Sun.

However, you believe that Mars had liquid water at different times in its history. And Venus has such a dense atmosphere that we cannot see through it. Both aspects do not explain why they are so different.
-A possible cause of these divergent evolutions would be in plate tectonics. Mars’ weak gravity prevents it from retaining volatiles in the long term. Where do these volatiles come from? Of the volcanoes. In the Martian past, there were periods of intense volcanism that expelled carbon dioxide and produced an acceptable atmosphere and climate. Not necessarily warm, okay, maybe warm or cold, but enough to make a dense atmosphere with a greenhouse effect that allows for liquid water. What happened next? That carbon dioxide precipitated as limestone rocks, and essentially the planet was left without an atmosphere because it turned to stone. This could have happened on Mars repeatedly: volcanoes generate the atmosphere, but it is sequestered and turned to stone. On Earth, the ocean floors sink into the planet, are destroyed and recycled, and release volatiles that are returned to the atmosphere by volcanoes. But on Mars there seems to be no plate tectonics, nor therefore recycling of the ocean floor, and without destruction of these bottoms, carbon dioxide is sequestered as rock forever. On Venus, the greenhouse effect is too intense now. The key in both cases lies in the internal energy that the planet presents.

In this sense, can it be said that a condition for a planet to harbor life is that it itself be alive?
-Of course. A planet can freeze to death if it loses carbon dioxide and other greenhouse gases and is unable to recycle them. Mars could be a dying planet. Venus, on the other hand, is alive and well. The best models of the Solar System indicate that the Sun in its beginnings was colder, and it has been warming progressively, reason why the greenhouse effect in Venus has not always been this way. The magic date is 4 billion years ago. We have three planets, Mars, Venus and Earth that contain liquid water, and a priori I cannot find arguments to think that life could not develop on Venus and also on Mars.

How does the discovery of ice on the Moon alter this picture?
-In my opinion, it ratifies this -scenario. The three planets could receive water of extraterrestrial origin, through comets. The Moon is a completely dehydrated body, so in principle it is not coherent to find ice deposits of millions of cubic meters there. That frozen water had to be planted there, and the most plausible explanation is that it was brought in by comets. If they got there, they had to safely reach other nearby bodies like Venus, Mars, and Earth.

NASA is laying the foundations to create a new science, astrobiology, whose objective is the study of the origin of life and its distribution in the universe. Doesn’t this seem too daring an adventure, considering that there is no evidence of life outside of Earth?
-Absolutely. There is indirect evidence written in terrestrial rocks from 4,000 million years ago that suggests that life already existed at that time. And I can’t think that life was precisely such a casual phenomenon so early, or that it occurred because Earth is a special planet. Throughout my scientific career I have fought against this prejudice, perhaps a biocentrism applied to the origin of life. Those against evolution insist that life is something unique and unrepeatable, with as slim a probability as that of a monkey typist who bangs a typewriter and produces by pure chance theDivine Comedy. These arguments seem solid at first glance, but the facts say otherwise. Life arises easily as soon as it has the chance and if we have not been able to generate it in the laboratory it is not because it is so difficult, but because we are still clumsy. Therefore, our obligation is to go out there to look for it.

Luis M. Ariza


This interview was published in August 1998, in number 207 of VERY Interesting.

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