This star is going to the moon

Chapter 271: There are no "what ifs," but there is rebirth, and testing manned lunar landing technology on Mars.

Humans are very curious about Mars, so like the Moon, we have conducted a lot of explorations of Mars.

However, despite the exploration, the only country currently operating rovers on Mars is the United States.

As for Russia, it is incompatible with Mars and is the reason why Mars exploration has a lower success rate.

Just like the poor students in a class who drag down the average score.

Thanks to the experience of Americans using Mars rovers, the Chinese incorporated many design features to cope with Martian dust cover when designing their Mars rovers.

The person in charge said, "Firstly, it is based on the principle that lotus leaves are not wetted by dew, which is to add a superhydrophobic cell cover to the surface of the solar cell."

"This is a nanoscale microstructure that can reduce the contact area between Martian dust particles and solar cells, making the particles easier to be blown away by Martian winds, with a dust removal efficiency of over 80%."

"Based on the superhydrophobic battery cover, the solar panels on both sides of the Mars rover are designed as a four-piece structure resembling butterfly wings."

"They can rotate in one dimension to a vertical position, that is, stand up like butterfly wings, and then directly dump the Martian dust covering the surface of the solar panels..."

This also draws on the experience of previous Mars rovers. The solar panels of previous Mars rovers could no longer move after they were deployed, but they could tilt the entire body to dump the dust on the solar panels and face the sun with a larger projected area.

When the tilt angle is greater than the "angle of repose" of the dust, the dust can be removed by sliding off.

For example, the Rosalind Mars rover, which the European Space Agency has yet to launch, can tilt its body more than 30 degrees by finding suitable slope terrain, thus causing dust to fall off.

However, not every Mars rover has such terrain conditions.

For example, the solar panels of NASA's Mars rover Spirit were covered with a lot of dust. With winter approaching, NASA wanted to tilt Spirit to maximize its exposure to sunlight.

However, because its wheels were stuck on rocks tilted 5 degrees to the south, and the sun was near the northern horizon, the Spirit eventually lost power and ended its mission.

The solar panel design by Lao-Chinese engineers now features an active tilt angle that allows dust to slide off.

It was decorated with both "lotus leaves" and "butterflies," which could be described as quite romantic, but Lu Yun shook his head slightly.

Because in his previous life he knew how the Zhurong lost its mobility, and these technologies alone could not solve all the problems of dust cover.

Because Mars' thin atmosphere cannot block the sun's strong ultraviolet radiation, and strong winds cause dry dust particles to collide with each other and with the surface, the dust floating in the Martian atmosphere carries static electricity.

Once they land on the solar panel, they adhere to it, and sometimes even tilting the panel cannot completely remove the particles adhering to it.

The Zhurong Mars rover fell into a deep sleep for roughly the same reason.

Although its designed lifespan was three months, it actually worked for about a year, which can be considered as exceeding its mission.

It's quite a pity that he couldn't work after only one year.

The American Mars rovers Opportunity and Spirit also used solar panels and were designed to have a lifespan of three months, but one worked for several years and the other for more than ten years!
However, their ability to work for so long is not due to advanced technology, but simply because of incredible luck.

Because the Mars rover's dust removal work involves not only its own efforts but also "nature's cleaners."

Martian dust storms can not only cover the solar panels with dust, but if you're lucky, they can also blow the dust off the solar panels.

It is especially effective at removing dust when encountering small whirlwinds.

According to the Americans' own statistics, the Spirit encountered it once, while the Opportunity encountered it four times.

In addition to the "big cleaning", Opportunity also frequently experienced a sudden increase in battery power of 5% after just one night.

Scientists joked that Martians probably came out in the middle of the night to wash the car.

A more precise explanation, however, is that Opportunity was constantly probing craters, and the airflow within the craters and the large angles at which the rover climbed the crater walls played a role. Therefore, Opportunity became the longest-running rover in human history to travel on other planets, operating from 2004 until its mission ended last year when it was completely covered by dust, covering a total distance of 45 kilometers and serving for 14 years.

The future Zhurong was not so lucky. It was exploring the Great Plains and encountered excessive dust accumulation during the "winter" when the lighting conditions were poor, so it never woke up.

If the dust accumulation is too high during the summer, the strong sunlight during the summer can still ensure its activity, and it is even possible to remove some of the dust so that it can continue to be active in the winter.

Unfortunately, there are no "what ifs" in reality.

However... there is rebirth!

Lu Yun received the request to manufacture a mini Mars rover in mid-2018, because the "Golden Toad" mini lunar rover from the end of 2017 was so amazing.

Many people think that it would be good if it worked for one lunar day, which is 14 Earth days, but it actually worked for six lunar days!
So the Mars rover project approached him.

Instead of building a separate camera that can't move after landing, let Lu Yun think of a way to build a mini Mars rover that can work for a long time.

No matter how long it lasts, even if it can only work for one day, that's still a "long time" for a separate camera that can only work for a short while.

What's more, the mini Mars rover can move, which is its biggest advantage.

When Lu Yun designed the "Golden Toad" mini lunar rover, he was only at level 4 in aerospace engineering. When the higher-ups asked him to design a mini Mars rover, his aerospace engineering level had already reached level 5, so it was a piece of cake for him.

So they removed the weight of the camera, cut corners in other areas, and even removed the display boards for the Winter Olympics mascots Bing Dwen Dwen and Shuey Rhon Rhon.

Yes, the Tianwen-1 lander carried this.

(Engineers are installing a display board on the Tianwen-1 lander)
After removing so many things, Lu Yun finally got a weight of 10 kilograms.

This weight is about the same; the American Mars rover "Sojourner" weighed about the same.

(The Sojourner Surveyor)
It is several tens of centimeters long, about the size of a large toy car.

However, that's not important. What's more important is that Lu Yun made suggestions for further dust removal for the Zhurong Mars rover.

In the 1970s, NASA developed an electric shield system that uses electrostatic and dielectric forces to remove dust from solar panels.

Specifically, a transparent, electrically sensitive material is placed on a solar panel. With the help of a sensor, when the dust concentration on the panel reaches a critical level, the material is energized, causing the dust to become charged and float, thus removing it from the panel.

However, due to the problem of "electrostatic breakdown," this technology cannot be used on Mars or the Moon.

NASA later developed a method to prevent electrostatic discharge, which worked well in a simulated Martian environment on Earth. The panel only needed a small amount of charge to remove about 90% of the dust deposited on the panel within two minutes.

However, it was not used in the Mars exploration mission.

Because NASA no longer uses solar array rovers on Mars, but instead uses isotope batteries, also known as "nuclear batteries".

Lu Yun thought it would be perfect for the Zhu Rong.

Moreover, this technology is not only useful on Mars, but also on the Moon, because lunar dust also carries an electrical charge.

The Apollo moon landing missions of the United States had problems before. Astronauts wearing lunar spacesuits brought lunar dust into the lunar module, and when they took off their spacesuits, lunar dust drifted into their eyes or entered their lungs through their respiratory tract.

All 12 astronauts who landed on the moon inhaled a certain amount of lunar dust, and some even experienced strange symptoms known as "lunar hay fever."

It's important to know that lunar dust is different from dust on Earth. It hasn't been eroded by wind and rain; it's in its most primitive, broken state, with sharp edges, just like shards of glass or fiberglass.

If this electrostatic dust removal technology is verified on Mars, it can be used in future manned lunar missions.

(End of this chapter)