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This artist print image published by the United States European Space Agency (ESA) shows Mars Express in orbit around Mars. ESA / Illustration by Medialab
Wow Mars, you're really pretty right now. You probably thought this if you recently looked at the night sky, and have noticed the appearance of a bright and shiny copper orb that is watching you. It's Mars. Our neighbor, and the fourth rock of the sun, is incredibly close to the Earth right now. In fact, on Tuesday, it will be closest to Earth's orbit since 2003. (So be sure to take a look at it.)
Because of its proximity and the Since the 1970s, a slew of robots has graciously explored the red planet, Mars has easily been at the center of the biggest question of humanity: Are we alone?
For decades, scientists have been staring at Mars, looking for the best places to find a trickle of water or a sign that the dry, dusty planet once greeted life. Mars was not always the sorry and desert planet we see today. Billions of years ago, the climate was warmer and wetter, welcoming a lush landscape where life had taken root.
As a matador teasing a bull, Mars has strung scientists for decades with nothing but a tantalizing trickle of water. here and there. Evidence of Mars' aquatic past is scattered across the reddish surface of the planet, with valleys and ponds showing the mark indicating the fleeting presence of water. (There was even condensation on some landers.)
Evidence suggests that ice tanks are hiding under the Martian surface, but there has never been any direct evidence of water liquid on Mars until now. Well, maybe.
The Mars Express orbiter has been serving humanity diligently for more than a decade. He keeps a watchful eye on Mars, probing the planet so carefully to learn more about his interior. Using radar, the orbiter has detected what appears to be an underglacial lake beneath the red sand surface of Mars.
The water reflects radar signals more strongly than rock or sediment, and the analysis shows that the radar profile detected by Mars Express closely matches the radar signals of the subglacial lakes of our planet, like those of the Antarctic and Greenland icecaps. This reinforces the notion that Mars is indeed home to lakes of liquid water beneath its surface.
But it seems that every year there is a new story about the discovery of water on Mars, and although it is a fascinating journey, not everyone is convinced that Mars should be the ultimate astrobiological destination. Here are some other interesting candidates for the billion dollar question from where will we find life beyond the Earth?
All these worlds are yours except Europa
The artist concept of a plume of water vapor thought to be ejected from the cold and icy surface of the Europa jovian moon. NASA / ESA / K. Retherford / SWRI
Perhaps Arthur C. Clark was channeling his inner cheerleader from Mars when he made such a statement. Or perhaps, he knows what is hiding in the icy depths under the healed surface of the ice-covered moon and warns us to stay away? Only time will tell.
For now, we know it: NASA (and scientists around the world) think that this Jovian moon could be one of the best places in the solar system to seek life beyond the Earth. in the honor thanks to its wet entrails. Located under Europa's thick and icy crust, this could be the largest known ocean. And despite Clark's warning, the space agency is scheduled to launch not one, but two multi-billion dollar missions into the icy world to look for signs of life.
Recently, the call of Europa exploded with the publication of an article detailing that scientists have finally found evidence of water plumes – something that has eluded the detection for many years. Buried inside data collected by a former spacecraft (Galileo), hid a hidden gem. Although it was collected for the first time in 1997, scientists continue to delve into the treasures of information that the probe has collected during its stay in the Jupiter system.
It took a cosmic inquiry to discover the exciting revelation: Galileo flew through a panache on Europa!
"If the plumes exist, and we can directly taste what comes from within Europe, we can more easily know if Europa has the ingredients for life," explains Robert Pappalardo, researcher at NASA. "It's what the mission is after – it's the big picture." (Pappalardo is currently working with a team of people to build a spaceship that will fly to Europe in the coming years. .)
For some time scientists have strongly suspected that water plumes emanate from the surface of the moon, and despite this discovery, the case is not fully resolved. The attraction of Europa is based on the fact that its feathers come from a global ocean of salt water that hides under the crust of the moon – and that life could thrive in its depths brackish.
This moon definitely ranks at the top of a list of the most desirable destinations, but there is another world even deeper in the solar system that could be our best hope for finding life. A tiny snowball, just wider than the state of Arizona, is an even more enticing target. This small world also has a key feature: an underground ocean
Enceladus Is So Fetch
The rendering of this artist shows a cross-sectional view of Saturn's moon Encelade. NASA / JPL-Caltech
In the vast darkness of space hangs a small icy snowball. Enclosed in an orbital dance with Saturn, this tiny and modest moon could hide a big secret. Thanks to NASA's intrepid NASA explorer, the Cassini spacecraft (little RIP robot), we know that Enceladus not only has plumes, but we have an idea of what they are made of.
During his many years exploring the wonders that have hidden Saturn and his family of moons, Cassini was able to fly through the Enceladus' water geysers and taste the ocean that hides beneath its surface ice.
Cassini's gravity measurements indicate that there is a local ocean and (possibly a global ocean) under the icy crust of Enceladus, feeding the geysers. The plume samples also show us that some of the emitted grains are high in sodium salt, which means that any body of water would be salty. Coupled with the evidence that silicate-rich grains have also been found, this supports the idea that Enceladus hosts hydrothermal vents on its ocean floor. (What other planet has these same types of events? The Earth!)
The existence of vents would definitely strengthen the case for life on the distant moon. On Earth, hydrothermal water sources are an oasis of life that abounds with all kinds of inhabitants, from microbial life to shellfish to cephalopods (and many more).
This near-infrared color mosaic of NASA's Cassini spacecraft shows the shining sun of North Titan's polar seas. NASA / JPL-Caltech / University of Arizona / University of Idaho
Perhaps, pale blue dots (and other aquatic worlds) are not the only type of celestial bodies that we should look for. Recent research has shown that we should include pale orange dots – misty worlds similar to Saturn's moon Titan – in our quest for extraterrestrial life. After all, Titan has an underground ocean made of liquid water similar to those of Enceladus and Europa.
Even our home planet has not always been the hospitable and lush world we inhabit today. The Earth looked very different 2.5 billion years ago, and as such, scientists developed computer models to illustrate how different our piece of rock was. The atmosphere of the Earth during this particular period – known as the Archean Era – was an air source mostly rich in methane, far removed from what we see today.
Scientists like to think that the Archaean Earth is the most "extraterrestrial" planet for which we have real geochemical data. Which means that it's not just Earth 1.0, it's a completely different world.
Today, our atmosphere protects us from the intense glare of the sun, preventing harmful particles and harmful rays from disrupting our daily lives. But if we had to go back in time, we would need to carry oxygen bottles to breathe and pack special space suits to protect ourselves from the intense radiation of the sun.
This is because the early Earth did not have this same protective layer. Instead, it relied on a thick layer of oil mist to protect it from damaging sun rays. This same haze also helped cool the Earth by reflecting solar heat in the space. Gradually, over millions of years, the climate and the environment have changed, evolving towards what we see today.
So, NASA, stop doing Mars already
A landscape of Mars is seen in a photograph taken by the panoramic camera on the Mars Exploration Rover Spirit. NASA / Jet Propulsion Laboratory / Cornell University via Getty Images
Space is expensive, so agencies like NASA need to plan their missions with great care. Mars is the planet (apart from ours) that we know the most. After all, we spent several decades studying it closely. But that should not count on other interesting worlds.
Mars is also very close to Europe or Enceladus, but if water is vital to life on Earth and if we see conditions (as evidenced by the plumes and fans hydrothermal potential), should not we explore these places? The plumes provide a window into the waters below the ice, so maybe scientists do not really need to send a spaceship to land on the moon and drill in its icy surface; they can simply send a vehicle to cross and sample their plumes – a mission type that is much easier to achieve.
The rules of astrobiology say that we should follow the water to find signs of life. But when it is omnipresent throughout the solar system, the best thing we can do is keep searching.
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