The skies above Mars will witness some surprising aeronautical displays in the coming days, when three rival space robot probes reach the red planet after traveling millions of miles through space.
The United Arab Emirates Hope orbiter will arrive first on Tuesday, followed by the Chinese spacecraft Tianwen-1 the next day. Finally, the American Perseverance rover will make its dramatic descent to the surface of Mars on February 18.
It is a remarkable armada that reveals the growing desire of many nations to develop their own space technology and explore the solar system. How well they will be successful when they reach their goal this week and next week is yet to be seen, however. Mars is an unforgiving place to visit.
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Of the dozens of missions to Mars since 1960, about half have fallen or lost the planet completely, thanks to component failures, rocket engine accidents or software errors.
“It could be a heartbreaking business,” admitted British physicist Colin Wilson of Oxford University. “I had instruments on two missions prior to Mars – the Beagle probe from Great Britain and the Schiaparelli probe from Europe – and every time I was in the control room, holding my seat, during its descents. And on both occasions the probes stopped. “
Mars is a difficult destination for several reasons. First, it is millions of kilometers away, pointed out astrobiologist Susanne Schwenzer of the Open University. “It’s not like going to the moon, which is only a quarter of a million miles away. This is equivalent to a putt in a round of golf. In contrast, Mars is incredibly distant. In terms of golf, it is the equivalent of a complete and much more complicated starting shot. “
In addition, Mars has an atmosphere, but it is not dense. “This means that there is enough air to trigger dust and wind storms that sweep and push your landing module off course and into danger,” added Wilson. “On the other hand, it is not thick enough to allow the use of parachutes for the entire descent of the probe.”
In the past, space engineers in the United States relied on airbags on their probes, allowing them to jump and stop after being launched from a parachute. However, NASA’s new generation of rovers is too complex and cumbersome for such maneuvers, and Perseverance will instead rely on a rocket platform called the sky crane to lower it to the Martian surface.
This technique had already been used once, in 2012, to land the American rover Curiosity. Now Perseverance, a much heavier rover, will follow suit on a journey that has been dubbed NASA’s “seven minutes of terror”. That’s how long the SUV-sized space vehicle, which weighs more than a ton, will take to reach the surface of Mars after reaching the planet’s upper atmosphere at more than 13,000 mph.
Atmospheric friction will cause the first speed cut. Then, a huge parachute will launch automatically and this will reduce the probe’s speed to a few hundred kilometers per hour. Then the sky crane rocket engines will fire and the probe will slow down until it hovers about 20 meters above the surface of the red planet.
The crane will lower the rover over the cables until it touches the surface, the cables will be cut and the crane will fly to make its own uncontrolled landing at a safe distance from Perseverance. Only then will a message be sent to NASA engineers to inform them of the good news.
In contrast, the United Arab Emirates’ Hope spacecraft, the first interplanetary spacecraft in the Arab world, will have a relatively simple time this week. It was designed only to orbit Mars, which will be achieved by performing a 30-minute burn on its main engine.
If the firing is successful, it will slow the spacecraft down enough to be captured by Mars’ gravitational field and enter orbit around it. Hope will spend the next two years studying Mars to better understand how, over billions of years, he lost a thick atmosphere that was capable of sustaining water vapor on its surface, but which was slowly turning into a cold and arid world.
China’s Tianwen-1 is also scheduled to enter Martian orbit this week. He will study the planet for several months before launching a probe that will carry a 250 kg rover robot to the planet. If it works, China will become only the second nation in the world to successfully land a robot vehicle in another world, after the USA.
“China has already safely landed robots on the moon, but this will be a much bigger achievement and will really show what its space scientists can do today,” said Schwenzer.
Crucially, the three probes are part of a spearhead of missions that in the coming years should transform our knowledge of the planet, returning Martian rocks and soil samples to Earth for study. This task will be initiated by Perseverance, which is programmed to locate promising geological sites, extract soil samples and leave caches of them in selected locations. Future missions, involving Europe and the USA, will then retrieve these samples and return them to Earth.
“When we do that, we hope to get answers to the simple question: is there or was life on Mars,” added Schwenzer.
“It’s a crucial question – because if life evolved on Mars, regardless of life on Earth, it means that life evolved twice, separately, in the same solar system and is likely to be common in the cosmos.”