Photo: Courtesy of NASA / JPL-Caltech
LOS ÁNGELES – In three years, a new explorer will play the Red Planet. The wheels of agitation, the rotating machine, the rover is tied through the oxidized terrain, looking for rocks to send back to Earth: rocks that could prove there once was life on Mars.
It is the first time in history that scientists had a real shot by addressing one of the most profound questions of humanity: are we alone?
But first they must decide where to look.
There are three options: an old heat source that NASA visited once before, a dry river delta fed by a crater lake and a network of ancient plateaus that can have dark underground water layers.
Next week, after decades of dreams, years of research and a heated three-day debate in a workshop in Los Angeles last month, NASA's chief scientific officer will choose the place to explore. The site that he selects will set the stage in which generations of scientists prove the mysteries of our existence.
This operator, scheduled for its launch in 2020, is only the first phase of a sample return process of four thousand pounds. To put pieces of Mars into the hands of the scientists will require a shearer to recover the samples; a probe to bring them home; and then an ultra-safe storage facility that will keep Earth's life from contaminating the rocks of Mars and vice versa.
However, the discovery of fossils in these samples could illuminate the origins of life here on Earth. Could you indicate if someone is still there, waiting to find you.
"I want to know," said Matt Golombek, a NASA scientist in charge of guiding the search for a landing site. "No, I want to know what there is? I want to know the great accident that we are."
That hunger for knowledge is what has attracted hundreds of people to the recent workshop: veteran space explorers and aspiring doctoral students, a student of 18 years of age and a retired 80-year-old accountant, to evaluate the best plan . During days they discussed, fed by curiosity and weak coffee, aware that the outcome of their meeting could influence NASA and shape the story, very aware of what they still did not know.
So much about Mars remains a mystery. The same notion of alien life is just more than a guessed courage animated by wild hope.
They are hopeful
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On Earth, microscopic life is inevitable. Biology began nearly 4 billion years ago, when the planet was still being bombarded by leftovers of solar system formation. At present, small and tenacious organisms splash into the hot springs of Yellowstone National Park, flying through the clouds, freezing in Antarctica, about a mile and a half below the ground.
If it could happen here, why not?
Mars was visited by more than two dozens of satellites and rovers, which proved that it was not always the desert world we see today. Sleeping volcanoes and frozen lava floods show that the planet already had an active interior that was driving the tectonic activity. Empty canals, ravines and lakes suggest that liquid water once covered on the surface, which could mean a thicker existing atmosphere to prevent water from spotting.
But then the disaster struck. Less than a billion years in its history, most experts say the fused nucleus of the planet stopped hitting. This caused the fall of the carbon volcanoes and the loss of the magnetic field of protection of Mars. Cosmic radiation and solar energy particles have eliminated the planet's atmosphere, causing any surface water to evaporate. Goodbye, ocean; so long, lakes; farewell of humid soils and bubbles bubbles bubbles: all kinds of places that you like to live.
Now Mars is seen as a "failed planet," a frightening version of alternative reality in the world in which we live.
"It is the Earth where the Earth's environments went away," said Bethany Ehlmann, planetary scientist at Caltech, in the workshop. "So the question is, why? And when?" And, most important of all, "Was life the chance to go before?"
These questions can only be answered by bringing the rocks of Mars back to Earth, most scientists say. A human in a front-line laboratory would be able to analyze the atom of samples by atom, revealing small structures that a robot could not see.
The detection of even some unequal molecules left by a microbe would be historical. Knowing that biology arose in two neighboring planets would suggest that life is common throughout the universe. The environment where the Martians meet, whether it is a hot fountain, a river delta or an underground refuge, can provide a clue where life on Earth originated.
And the knowledge that a world could shelter life and then fails, would emphasize our own incredible fortune. The conditions for the continued existence of earthlings may not be so always ensured.
"We have to get these samples and they have to be the right ones," said Golombek.
On the back of the ballroom, an investigator turned to the person at his side and smiled: "Are you ready for the show?"
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One option for the mission is a hot springs field like Yellowstone explored by the Spirit rover between 2004 and 2010. Here, next to a rocky outcrop called Home Plate, the rover now disappeared discovered strange finger structures made from silica, an associated mineral with water and life. But the rover was not equipped with instruments capable of detecting complex organic compounds, so the mystery of these structures remained unresolved.
Seven years later, the spiritual instrument operator Steve Ruff received an impromptu epiphany through the volcanology journal: scientists discovered a field of geyser of another world in the Andes that contained structures such as those of Mars. In place, called El Tatio, heat-loving microorganisms produce silica deposits in filaments, mats and turns.
"This is the place that is the closest to Mars in any scenario that I've already been," said Ruff.
But reviewing a site may mean that there is less to learn, many scientists worry. What if Ruff is wrong with the silica structures?
Ruff's only response: "And if we're right?"
"If one of the engines of Mars exploration is to answer this question:" are we alone? "And we found a place that could address that question and move it away because it is not guaranteed that we will find it, I think that's just:" He paused, looking for a term that would not offend any of his colleagues. "A conservatism," he finally said. "And that's not so characteristic of NASA."
This site near the Mars ecuador was explored between 2004 and 2010 by Spirit rover.
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If any version of sending a rover 50 million miles through space can be called "conservative", landing on Jezero Crater could be this. It is more similar to the types of environments where ancient fossils were discovered on Earth: deltas, where sediments are conserved from vast watersheds.
"Sedimentary rocks tell us the story of what is happening on a site," said Tim Goudge, a geologist at the University of Texas at Austin. "It is engraved on the layers and you can read them as a book."
Jezero also contains minerals that are associated with life on Earth, like carbonate, as well as clays called esmectites known to "kill" organic material.
But the site is full of wavy sand dunes: a potential danger for a rover.
"They scare the kisses from me," said Ray Arvidson, a scientist at the University of Washington at St. Louis. In a mission to Mars, there are no reboots.
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Ehlmann, Caltech's scientist, spent years looking at map tables in northeastern Syrtis. It is a clearly Martian environment, which could be the home of a unique Martian life.
"This would be an opportunity to become a geologist there," he said. "I want to look at the rocks, to understand them, to reveal the story they say".
The site calls on many scientists because of the diversity of ancient rocks it contains. The remains of ancient meteorite impacts, called "mega-breaches", would be some of the oldest rocks displayed on any planet in the solar system. The rocks one billion years younger could reveal how Mars became the world that is today.
The area also has minerals, such as carbonates, which suggest that once it has received an underground aquifer – a potential refuge for organisms that seek protection against the harsh and erratic climate of their planet.
But if subsurface life was scarce, even the most sophisticated laboratory instruments on Earth could not detect it. Scientists are more accustomed to looking for life on sedimentary rocks such as those of Jezero.
So Emily Lakdawalla, a geologist and principal editor of the Planetary Society, raised a question about all the sites that are being considered.
"And if the samples do not turn?" she said. "Can we think about it?"
There was a pause when people contemplated the possibility. NASA has not financed any of the three monitoring missions that are required for the sample's return.
Golombek picked up the microphone.
"We decided to stop governing that conversation," he said. "It all depends on whether you are an optimist or a pessimist, right?"
At the moment, he urged his colleagues to be optimistic.
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The last morning of the workshop, there was no consensus on the best place to land the rover. Some scientists said their minds changed with each presentation, their opinions were ping-ponging as they heard convincing evidence from the followers of each site. Others became more ingrained in their positions.
But what if they did not have to choose?
The science team of the mission project conceived an ambitious long-term mission centered on a new landing site on the northeastern edge of Syrtis called "Midway", not far from the edge of the Jezero crater.
It would take hundreds of Martian days (the equivalent of several years on Earth), but the explorer could get from one place to another, obtaining the best samples from both. The voyage would take the seller through steep mountain ridges, crowded rocky fields and dangerous terrain scorched by the wind.
"This is an incredibly large exploration," said Ken Williford, deputy project scientist for the mission.
Even with Mars standards, Midway was full of unknowns. Scientists were unable to perform detailed analyzes of the rocks it contains, and the 15-kilometer proposal crossed the limit of what could be achieved by a heavy truck.
There were many ways that this could end poorly, some worried.
"But," said project scientist Ken Farley, "there's more to fail."
"Personally," he continued, "I do not want to fail because we have not been sufficiently ambitious so that the sample cache is scientifically worthy."
The vote was taken in silent silence; There was scarcely a whisper because the results were projected on the screens of the room. Columbia Hills received relatively low ratings. But Jezero, the northeast of Syrtis and Midway were neck and neck and neck.
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In the end, the decision would go down to Thomas Zurbuchen.
As NASA's associate administrator for science, he oversees more than 100 missions aimed at understanding the solar system and beyond. But of all these efforts, he said, Mars 2020 is where NASA has more to lose and humanity has more to gain.
"This is the most risky one," he said of the $ 2 billion mission. "But I suppose that everything goes exactly as we expected … The landing site that I am the decisive officer will make history".
Days before he was scheduled to receive his final briefing on the landing options, Zurbuchen remained undecided. Participation in the landing workshop, but there is still much to consider: the safety assessors of engineers, the potential for monitoring missions, the need to balance astrobiology research with other scientific issues.
And then there was the vision that filled his mind when he closed his eyes to dream: a consideration that was neither financial nor scientific, but pure hope. A probe that takes Mars samples back to the Earth. Scientists retrieve the cache and get their first glimpse of parts of another planet. The laboratory where the rocks will be analyzed, the complex instruments that will look for signs of ancient organisms.
And a science class where their future grandchildren sit down, reading a textbook that bears the name of the place they chose: a place where humanity learned, for the first time, we were not always alone.