The skies over Mars will witness some startling aerial displays in the coming days as three rival space robots reach the red planet after traveling millions of miles through space.
The UAE’s Hope orbiter probe will arrive first, on Tuesday, followed by the Chinese Tianwen-1 spacecraft the next day. Finally, the American rover Perseverance will make its dramatic descent to the surface of Mars on Feb. 18.
It is a remarkable armada that shows the growing desire of many countries to develop their own space technology and explore the solar system. However, how well they succeed if they reach their goal this week and the following week remains to be seen. Mars is a relentless place to visit.
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Of the dozens of Mars missions since 1960, about half have crashed or missed the planet altogether, due to faulty components, missile engine accidents, or software errors.
“It can be a heartbreaking case,” admitted British physicist Colin Wilson of Oxford University. “I’ve had instruments on two previous Mars missions – the British Beagle lander and the European Schiaparelli probe – and every time I’ve been in the control room, my seat clamped, on their descents. And on both occasions, the probes have crashed. “
Mars is a difficult destination for several reasons. First, it is millions of miles away, noted 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. That’s the equivalent of a putt in a game of golf. Mars, on the other hand, is incredibly far away. In golf terms it’s the equivalent of a full tee shot and a lot more tricky. “
In addition, Mars has an atmosphere, but not a thick one. “That means there is enough air to create dust storms and high winds that put your lander off course and endangered,” added Wilson. “On the other hand, it’s not thick enough to use parachutes for the entire descent of a probe.”
In the past, American space engineers relied on mounting airbags to their probes, which would allow them to come to a stop after falling from a parachute. However, NASA’s new generation of rovers is too complex and heavy for such maneuvers, and persistence will instead rely on a rocket platform called an aerial crane to lower it to the surface of Mars.
This technique was used once before, in 2012, to land the American rover Curiosity. Now Perseverance, a much heavier robber, will follow suit on a journey dubbed Nasa’s “seven minutes of terror.” That’s the time it takes the SUV-sized rover, which weighs more than a ton, to reach the surface of Mars after hitting the planet’s upper atmosphere at more than 13,000 mph.
Atmospheric friction causes the first reduction in speed. Then a huge parachute will be released automatically and this will reduce the speed of the probe to a few hundred miles per hour. Then the overhead crane’s 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 lowers the rover on cables until it touches the surface, the cables are cut and the overhead crane flies off to make its own uncontrolled landing at a safe distance from Perseverance. Only then will a message be sent to NASA engineers to let them know the good news.
The spaceship Hope, the Arab world’s first interplanetary spacecraft, on the other hand, will have it relatively easy this week. It is designed only to orbit Mars, which it will achieve by running a 30-minute burn of its main engine.
If the combustion is successful, the spaceship will slow down enough to be caught by Mars’ gravitational field and orbit around it. Hope will spend the next two years studying Mars to better understand how, over billions of years, it lost a thick atmosphere capable of trapping water vapor on its surface, but slowly transformed into a cold and barren world.
The Chinese Tianwen-1 will also enter orbit around Mars this week. It will study the planet for several months before dropping a lander that will transport a 250kg robotic rover to the planet. If it works, China will only become the second country in the world to successfully land a robotic vehicle on another world, after the US.
“China has already landed rovers safely on the moon, but this will be a much greater feat and really show what their space scientists can do today,” Schwenzer said.
Crucially, the three probes are part of a spearhead of missions that should transform our knowledge of the planet in the years to come by returning rock and soil samples from Mars to Earth for study. This task will be initiated by Perseverance, which is planned to locate promising geological sites, extract soil samples and leave caches of them in selected locations. Future missions, involving Europe and the US, will then retrieve these monsters and return them to Earth.
“If we do, we will hopefully get an answer to the simple question, is there or was there life on Mars,” Schwenzer added.
“It’s a crucial issue – because if life on Mars were to evolve independently of life on Earth, that means that life evolved twice separately in the same solar system and is likely to be common in the cosmos.”