The China National Space Administration released a statement reporting the current position of the Chinese Mars probe Tianwen-1, which has been flying towards the Red Planet since late July.
At the time of the statement, Tianwen-1 had been flying for a total of 144 days with a total distance of 360 million km. Although it is currently at around 100 million kilometers away from Earth and less than 12 million from its target, the probe had to go through serious orbital corrections and maneuvers.
Overview of the Tianwen-1 mission to Mars
On July 23, the Long March 5 launch rocket with the Tianwen-1 space mission successfully took off from the Wenchang Space Center. With its successful launch, China’s first independent robotic expedition was on its way to Mars! The mission is extremely ambitious and consists of three components – an orbiter, a lander, and a rover.
The instruments onboard the orbital compartment are:
• MRC – Medium resolution photo camera – 100 m/pixel from a 400-kilometer working orbit.
• HRC – High-resolution photo camera – 2 m/pixel from a 400-kilometer working orbit.
• MM – Martian magnetometer
• MMS – Spectrometer for studying the mineral composition
• OSR – Radar to study the structure of the Martian crust
• MINPA – Detector for ions and neutral particles
The instruments onboard the rover are:
• GPR – a powerful radar that will study the underground characteristics of Mars to a depth of 100 meters
• MSMFD – a device that will study the properties of the planet’s magnetic field.
• MMMI – meteorological station
• MSCD – a device for studying the chemical composition of the soil
• MSC – multispectral camera
• NTC – topographic camera
If all goes according to plan, “Tianwen-1” will arrive in orbit around Mars in February 2021. Two or three months later, the lander will separate from the orbital compartment and make a soft landing.
Why is landing on Mars so difficult?
Every landing on Mars is a real challenge – and indeed this is the riskiest moment for the current robotic expedition. Numerous failures in the study of the Red Planet have led journalist Donald Neff to invent the Great Galactic Ghost, a mythical monster living on Mars that feeds on manned spacecraft.
Some people seriously think that there are aliens on Mars who are sabotaging Earth’s attempts to reach the planet. In the history of a total of 18 attempts to land on the Martian surface, only 10 were successful. But the real reason Mars landings are so difficult is prosaic – it’s because of the planet’s thin atmosphere.
It is this atmosphere that causes engineers headaches. It would be better if she wasn’t there. As, for example, is the case with the Moon – to land on our natural satellite, only brake rocket engines are used. If Mars had a dense atmosphere similar to that of Earth or Venus, it would be even easier – only heat shields and parachutes could be used.
But the atmospheric pressure near the surface of Mars is about 600 pascals – only 0.6% of that on Earth. The air layer is dense enough to require the use of heat shields and parachutes. But they alone cannot slow down landing gear enough.
Therefore, an additional softening system must be used – e.g. retro-rockets or shock-absorbing airbags. The end result is, that the lander is complex – and everything has to work perfectly for the landing to be successful. In addition, engineers do not have much time – from the moment of entering the upper layers of the Martian atmosphere to reaching the surface takes only 7 minutes.
Within these 7 minutes, all systems must be activated at the correct time. Just a little deviation … and the device will turn into a pile of useless iron!
And this is where the conservatism of the Chinese teams manifests itself – the choice of the low-lying Utopia plain provides a bonus time for the descent of “Tianwen-1” by parachute.
If the Tianwen-1 landing gear succeeds, China will only become the second country after the United States to make a successful soft landing on the Red Planet with a working lander.
Will the Chinese succeed? It is difficult to predict – as I mentioned above, Mars is an insidious planet, and China has never tried to send a Martian mission on its own. It was only in 2011 that a Chinese microsatellite was attached to Russia’s Phobos-Grunt automatic interplanetary station, but soon after reaching Earth orbit, it crashed and the entire joint Russian-Chinese expedition failed.
So we are keeping our fingers crossed for China – the most interesting thing is yet to come in the spring of 2021. For now, it is good to know that Tianwen-1 is on track 100 million kilometers away from Earth.
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• Kramer, H. J. (n.d.). Tianwen-1 (China’s first Mars Exploration Mission).
• Update: China’s Mars probe over 100 mln km away from Earth. (n.d.).