Tang Yue untied his seat belt, put the photo frame on the center console into his pocket, and then jumped out of the cab of the Martian stray dog. The old cat grabbed his hand in the dark. Under the current weather conditions, they must not get lost to each other, but this time the old cat and Tang Yue no longer had a safety rope, and there was no rope to tie them together, so the old cat could only grab Tang Yue tightly.

The old cat held the small emergency light in his paws and shook it in front of Tang Yue, "Follow me! Tang Yue, can you hear me clearly?"

Although one person and one cat are close at hand, the quality of radio calls is still extremely bad, and the large amount of charged sand and dust suspended in the air seriously interferes with the radio signal.

"Can hear it." Tang Yue nodded, "It's very clear!"

"We have the last 3.5 kilometers left to our destination, in that direction... we need to go straight in that direction 3,500 meters." The old cat stretched out his claws and pointed forward, "How is your situation? How is the Mingguang Armor? How much oxygen and electricity are there to be rich?"

"I'm fine. I'm very full at breakfast and full of energy." Tang Yue brushed away the sand and dust on the terminal monitor of the Mingguang Armor control terminal. The terminal screen emitted a faint blue light. "The air pressure in the Mingguang Armor is normal. The emergency oxygen-making system can work for at least ten hours, and the eva battery can last for six hours."

"Okay." The old cat nodded, "I walked in front, you followed me, putting your hands on my shoulders."

Tang Yue put his hand on the old cat's shoulder. When the old cat took a step, he followed him. When the old cat took his left foot, he stepped on his left foot. When the old cat took his right foot, he stepped on his right foot, like an old zombie in the Qing Dynasty.

It took six hours to walk 3,500 meters. It was a piece of cake for Tang Yue under normal circumstances. He could jump with one foot in the entire distance within six hours.

But in dust storms, the situation is much more complicated.

For them, distance is second to distance. The biggest problem is to identify direction. If you accidentally get lost, the time spent in the dust storm will be greatly extended.

"Human walks cannot guarantee strict straight lines, so you must visually correct the direction. In the dark night when you cannot see the reference object, you will circle around in the same circle." The old cat said, "Many times, you think you are walking in a straight line, but in fact you unknowingly deviate from the right direction."

"Coriolis shift?" Tang Yue lowered his head and closed his eyes and moved forward step by step. The staggering little step looked like an emperor penguin. Since he could not see anything, Tang Yue simply closed his eyes, and the direction was completely guided by the old cat, like a blind man and its guide dog.

"The ground-turning bias force is one of the reasons. The main reason is that you cannot guarantee that the strides of the left and right legs are completely consistent." The old cat was wearing a cabin suit and walked with equal caution. Without lighting, the night vision instrument was not useful. The old cat could only grop and move forward. "Most people's right legs are slightly stronger than the left legs, so the strides of the right foot are larger than the left legs. This gap is very small, and you can't even see it in normal times, but when you travel a long distance in the desert, this slight gap will make you tilt your left side without knowing it, and finally go around a big circle and return to the original place."

"In other words, your left and right steps are equal?" Tang Yue asked.

"Yes." Old cat replied, "all are strict and constant 0.4 meters."

“The legs are so short.”

The old cat led Tang Yue forward, one foot deep and one foot shallow. There was a thick layer of floating sand on the ground, which could probably flood Tang Yue's ankles. Tang Yue turned his head again and could no longer see the Martian stray dog. The old dog disappeared into the darkness. Tang Yue knew that he might never have the chance to meet him again in his life.

Tang Yue pinched the old cat's shoulder hard. He couldn't see the old cat's back, but he could see the light in the old cat's hand. The latter raised the small emergency light over his head. This was the only light in the storm.

The old cat suddenly stopped.

Tang Yue also stopped, "What's wrong?"

"I have to make sure I didn't deviate from the right direction." The old cat stood there, "I am blind like you now. If you walk around in a mess, you will go to Antarctica."

"But you have a map in your mind."

"The map must also have reference objects to use." The old cat slowly bent down and grabbed a handful of sand. "Tang Yue, have you noticed that? The quicksand under our feet are getting thicker and thicker."

Tang Yue squatted down, and the sand that had only flooded his ankles had really reached his calves.

"what does that mean?"

"That means we are leaving the Ishi Plain." Old Cat replied, "The landform has changed significantly."

"This means we are heading right?"

"No, no matter which direction we go, we are leaving the Ishi Plain...Okay, we can continue to walk down. I have figured out my position." The old cat stood up and reported a string of numbers, "130.8,158.4."

"130.8?158.4? What is this?"

"Where we are on the coordinate system, I use the parking position of the Martian stray dog ​​as the origin to build the polar coordinates and Cartesian coordinate systems. I just told you that my stride is strictly 0.4 meters, so every step I take is 0.4 meters." Lao Mao explained, "From the start, I have taken 512 steps, and have advanced a total of 204 meters."

“So where is our goal?”

"Its location is probably at (2498.2, 2506.6)."

“Accurate?”

"Only as accurate as possible." The old cat shrugged, "Inertial navigation will always accumulate errors."

Every five minutes, the old cat has to stop and determine its direction. The equal footsteps can theoretically ensure that it walks in a straight line, but in reality, the situation is more complicated than the theory. Uneven terrain and obstacles sometimes force the old cat to go around the corner.

Tang Yue also followed him to count the steps. He closed his eyes and followed the old cat. Every time he took a step, he counted silently in his heart, but every time he counted to a certain number of steps, he would be interrupted. It might be because he encountered a stone or a ravine. At this time, the old cat would turn his head to remind him, and then find a way to overcome the obstacle. When Tang Yue got through all this and wanted to continue counting, he could no longer remember how many steps he had taken.

In the dark and lightless world, I can't feel that I am moving forward. I can't count how many steps I have taken will make Tang Yue lose his sense of distance.

"Are you tired?"

"It's okay." Tang Yue gasped, "How far have we walked?"

“Six hundred meters.”

"I only walked six hundred meters?" Tang Yue was a little surprised.

"Yes."

"I feel like I've walked that far away six kilometers." Tang Yue said, "It's strange... Why do you feel so tired even though you haven't walked very far?"

"Psychological pressure." Lao Mao said, "Normal people will suffer considerable psychological pressure when they completely lose their vision. After all, you are not blind and cannot adapt to this state in a short period of time."

The sand under the feet became thicker and thicker. When they were uphill, the old cat and Tang Yue were both slipping. They were climbing a tall sand dune. The higher the slope, the steeper it was. In the end, the man and the cat had to use their four legs. Tang Yue grabbed the old cat's two hind legs and crawled on the sand dune, and their limbs were deeply trapped into the sand.

It was extremely inconvenient to move in the quicksand and could not find the focus. Tang Yue tried his best to pull and still stepped on the spot. The sand flowed under him, just like a beginner swimming in the water. The old cat's situation was no better than him. It struggled hard in front of Tang Yue. After finally moving forward three steps, his feet suddenly slipped and returned to the starting point, rolling into Tang Yue's arms.

Tang Yue hugged it and lay on the sand panting.

"How are you?" Tang Yue's mask leaned against the old cat's helmet. He turned on the light inside the Mingguang Armor mask and illuminated his face. "Are you injured after falling?"

"I didn't fall, I just went down." Lao Mao said, "I just didn't control my left arm and couldn't use my strength... This arm is about to be scrapped."

"What's the situation now?" Tang Yue knew that the old cat's left arm was an old injury. He had problems more than once along the way, and the symptoms became more and more serious.

The old cat tried to move his limbs, pondered for a few seconds, and shook his head, "I'm afraid it's not optimistic. The joints of the limbs are very stiff. We have been in the storm for too long. When the temperature is low, the old legs will be offended."

"Then let's take a break?"

"No, the longer the drag, the worse the situation is. I may need to heat up to make the internal temperature of the body rise." said the old cat, "but we obviously don't have this condition."

It is impossible to heat up and increase the heat. The most lacking thing now is energy and electricity. Tang Yue’s Mingguang Armor has the function of insulation and heating, but Lao Mao does not have the cabin clothes. Lao Mao wears the cabin clothes just to prevent wind and sand, and does not even have a battery.

The old cat was silent for a moment, "Listen to Tang Yue, if you have to be alone..."

"Shut up." Tang Yue interrupted it, "I will teach you how to increase the heat, will friction generate heat? Mechanical energy is converted into internal energy, yes, it is rubbing hands. When we are outdoors in winter, we rub our hands to keep warm. Lao Wang Lao Tang and the others are so angry that they rub each other barely. You should start rubbing your hands now, rubbing hard!"

The old cat is stunned.
Chapter completed!