The moment has come. After seven and a half months of travel, the red planet appears huge through the hatch of the ship. The crew members see it so close that they feel they can touch it with their hands.
That is the goal. At a speed of more than 20,000 km / h, the spacecraft must initiate a series of braking maneuvers that will allow it to land on Mars. They are the seven minutes of terror that will be lived from Earth on a delayed basis. However, the crew will experience them, for the first time in history, live.
First, the entry into the Martian atmosphere and the braking produced by friction with the heat shield to supersonic speeds. Then the deployment of the large parachutes. These will slow the spacecraft further until, finally, the firing of retrorockets will allow a soft landing on the Martian surface.
At that moment, once the engines have been turned off and with the dust still depositing around the ship, the historic milestone of the arrival of human beings to another world will have occurred. Humanity will be on Mars.
This short story, which seems like science fiction, is about to come true. The members of the first crew that will travel to another planet have already been born. Preparations for human exploration of Mars have already begun. In fact, humans are expected to set foot on its surface in a couple of decades.
Why is going to Mars so important? What is the point of human exploration of the red planet?
The answer is clear. Mars is currently considered the most habitable of the planets within our grasp. This makes it the best scenario to confirm the existence of life outside of Earth. In short, the answer to the riddle of life could be found on Mars.
Its exploration, first through the telescope and later by means of orbiting spacecraft and robots on the surface, has revealed a fascinating planet. Despite being half the size of Earth, this younger brother of our planet has colossal landforms, the largest in the Solar System.
It has the largest volcano, Olimpus Mons, with an altitude of 23 kilometers. Also the largest canyon system, Valles Marineris, with a maximum depth of 7 kilometers and a length that runs a quarter of the Martian equator. In addition, it has the largest known impact basin, Vastitas Borealis, which occupies 40% of its surface.
It is precisely this basin, which occupies the most northern areas of the planet, which establishes a clear difference between the two hemispheres. On the one hand, the so-called northern lowlands; on the other, the southern highlands.
This is what is known as the Martian dichotomy, a clearly visible distinction between the northern hemisphere, depressed with respect to the Martian zero level (or datum) and practically without craters; and the southern hemisphere, higher and riddled with craters.
The reason why Mars is a planet with two faces is still unknown. However, the absence of craters in the lowlands could be due to the presence in the past of a large ocean that protected the surface from impacts.
The presence of liquid water on early Mars is also deduced from dry channels observed in situ or from orbit. Also the confirmation of the existence of lakes that filled craters, as in the case of Gale crater, the study site of NASA’s Curiosity rover.
To date, this has been, without a doubt, the most important find of Martian robotic exploration. It confirms that Mars and Earth were quite similar, both having abundant liquid water on their surface. The appearance of life on Earth at that time leads us to raise the possibility that it could also have started on Mars.
Methane in the atmosphere of the red planet
Another of the great discoveries on Mars, although it has yet to be confirmed, has been the detection of methane in its atmosphere.
In the terrestrial, practically all the methane is of biological origin. It comes from methanogenic organisms, but also from geological processes, such as serpentinization.
The presence of methane on Mars, therefore, could be interpreted as a result of the existence of life, past or present.
Currently, the study of the origin of Martian methane is one of the great challenges of astrobiology. At the moment, detection has occurred only on the surface. Specifically with the instruments on board the Curiosity rover. Still, it hasn’t been detected in the upper atmosphere, which is strange.
The expectation would be that methane detected at ground level would accumulate in the atmosphere. That it was captured by the sensitive instruments on board orbiting spacecraft before solar radiation destroyed it by photodegradation in a process that takes several centuries.
There must be a mechanism, yet to be discovered, that rapidly destroys methane on the surface and does not allow it to accumulate in the atmosphere in sufficient quantity to be detected from orbit.
The most recent finding relative to Mars has been the confirmation that it still maintains some seismic activity. The more than 480 earthquakes detected so far by the seismograph on board the InSight platform are unequivocal proof that the red planet still has a beating heart. It has also been found that the global magnetic field of the planet is greater than expected. This reinforces the idea of that increased activity.
Such discoveries are helping to elucidate the process that Mars underwent in the past. The one that made it go from being a planet with an atmosphere presumably more dense than the current one, warmer temperatures and abundant liquid water on its surface, to being the cold, dry and arid planet that it is today.
The great robotic landing of 2021
All these findings make Mars the main astrobiological target today. Even more so if we have the three missions that will reach the red planet during the month of February 2021. Each of them constitutes a milestone for space agencies and the countries that send them.
The Emirates Mars Mission (EMM), also known as Hope (Hope, in English), is the first interplanetary mission of an Arab nation. It is an orbiter whose main objective will be the study of the Martian atmosphere.
The Tianwen-1 mission (search for the celestial truth, in Chinese) is the first Chinese mission. It consists of an orbiter and a rover, called the HX-1. The first will carry out studies of the magnetic and gravitational field. The second will analyze rocks and soil and record environmental values.
The US Mars 2020 mission consists of a rover, the fifth NASA has sent to Mars. Christened Perseverance, it is practically a twin of the Curiosity rover. Its landing, scheduled for February 18, will take place in the Jezero crater.
The landing zone is an old river delta. It is an ideal place to search for evidence of past life on Mars, the main objective of the mission. In addition, soil samples will be collected for the first time, which will be sealed and brought to Earth on a future mission.
Different technologies will also be tested to prepare for future human exploration of the red planet. This is the case of obtaining oxygen from atmospheric carbon dioxide. Also the test of a flying device, a small helicopter baptized as Ingenuity.
Mars, while jealously guarding its secrets, has undoubtedly provided answers to some of the great enigmas of science. In fact, it has had a profound impact on culture and decisively driving the advancement of science in recent centuries. The next few decades will be crucial for its exploration.
Observed, imagined and explored, the moment is finally approaching when it is visited by humanity in search of life.
With the dust already deposited and the hum of the engines muffled, it will be time to set foot on Mars. After treading on its surface, we will become a planetary species. We will have taken the final step to unravel the enigma of life.
The red planet is sure not to disappoint us.
Juan Ángel Vaquerizo Gallego is coordinator of the Scientific Culture Unit at the Astrobiology Center (INTA-CSIC)
This article was originally published on The Conversation
George is Digismak’s reported cum editor with 13 years of experience in Journalism