Tang Yue stopped what he was doing. "Girl, you have to trust us. Rescue …"
"Rescue will arrive in time, right?" Mai Dong said. "You have told me this many times."
Tang Yue was speechless. He had indeed said this many times. He did not know if he was cheering for Mai Dong or encouraging himself. No one knew if rescue would arrive in time. According to the rules of Hollywood movies, the cargo spaceship had to arrive in time, and it had to arrive at the most critical moment. It had to rescue the little girl at the last moment before the space station was about to crash. The male and female leads would successfully reunite and usher in a happy ending.
But reality was not a movie. There was never a perfect ending set by the screenwriter in advance.
The principle of mediocrity was everywhere in this universe. Any result was normal and reasonable.
Old Cat lowered its head and knocked on the stretcher with a pair of pliers. It did not want to say anything. If it did not make any promises, it would not have to bear any responsibility. But Tang Yue kicked it.
"Ahem … Miss Mai Dong, let me teach you a rough way to determine the height of the orbit." Old Cat cleared its throat. "Can you see the Isidis Planum now?
Or the Endeavour crater?
The Gale crater?
The Victoria crater?
It doesn't matter what the crater is. Find a reference point directly below you. "
"Hmm … Endeavour crater … Endeavour crater … Let me see. It should be on the Meridian Plateau. The Meridian Plateau is near the equator … I can see it. I can see the Endeavour crater, Mr Cat," Mai Dong replied. "Mr Cat, can you hear me?"
"Yes, Miss Mai Dong. Can you find a pencil or ruler over there?
If you can't find it, take off the glove of your spacesuit and give me a thumbs up. "
Mai Dong looked around and reached out to grab a pencil that floated in front of her. She opened the lid. "Mr Cat, I have a pen in my hand."
"Okay, now listen to me and follow my instructions. Straighten your right arm in front of you and hold up the pen."
Old Cat instructed, "Close your left eye again and stare at the tip of the pencil with your right eye. Let the tip of the pencil coincide with the left edge of Endeavour's crater. Make sure that the crater, the pencil, and your right eye are aligned. Do you understand?
They must be in a straight line. "
The girl followed Old Cat's instructions. She held the middle of the pencil, straightened her arm, and held it straight in front of her. She closed one eye and slowly turned her body so that the tip of the pencil pointed at the shadow on the edge of the impact crater on Mars.
"Okay, Mr. Cat."
"Now open your left eye and pay attention to keep your body, arm, and pencil still. Then close your right eye and look at the tip of the pencil with your left eye." Old Cat said, "Tell me where the tip of the pencil is now."
"Hmm … It's pointing at the center of the crater."
"Okay."
Old Cat nodded. "Okay, Miss Mai Dong. You can open your eyes now. The current altitude of the Mars United Space Station is about one hundred to one hundred and twenty kilometers."
Tang Yue and Mai Dong were both stunned.
Tang Yue stood on the side and watched the whole process. He was curious to see how Old Cat was able to calculate the altitude of the space station with just a pencil.
"How did you calculate it?"
"This is a very old method of distance measurement. It's called 'eye skipping.' Before the invention of advanced optical sights and radar, eye skipping was commonly used for artillery to measure the distance of targets."
Old Cat explained, "The principle is actually very simple. Just use your eyes, a pencil, and a reference object to construct two similar triangles. The distance between the pupils of an ordinary person is about six centimeters, and the length of an arm is sixty centimeters. This is a triangle with a height ratio of ten to one. Similar triangles must have a height ratio of ten to one as well."
"We will use the crater of Endeavour as a reference object. The crater of Endeavour has a diameter of twenty-two kilometers. The distance that the tip of the pencil moves is half the diameter of the crater, which is twelve kilometers."
Old Cat continued, "The base of this large triangle is twelve kilometers, so its height is one hundred and twenty kilometers … This is the distance between Miss Mai Dong and the ground."
Tang Yue was a little surprised. He was not surprised by the eye skipping, but by the fact that the cat knew the height of the Joint Space Station. It always knew how to measure the height of the orbit, but it had never told him.
"The current altitude of the Joint Space Station is in the upper atmosphere of Mars, which is the bottom of the ionosphere," Old Cat said.
"Have I entered the atmosphere?" Mai Dong asked.
"The nominal atmosphere is actually no different from a vacuum."
Old Cat said, "The atmospheric density will only increase significantly below sixty kilometers, so this height is relatively safe. There is enough buffer space. I think the space station will be able to hold on until Tianzhou 37 arrives."
Old Cat's promise was more reassuring than Tang Yue's, because Tang Yue's encouragement was based on a certain kind of confidence. Its theoretical basis included, but was not limited to, ancestral philosophies such as "man can conquer nature," "where there is a will, there is a way," and "human subjective initiative is the driving force that determines the direction of history." These ideas could be used to shout slogans, but using them to calculate orbital dynamics was like having epilepsy.
But Old Cat was different. Everything it said was necessarily based on rigorous mathematical and physical calculations.
Now, what Mai Dong needed was not slogans, but calculations.
The girl breathed a sigh of relief. Although the eye skipping method's estimation was very rough, it was still the only reassurance that they could take in their desperate situation.
"Thank you, Mr. Cat."
Old Cat did not say a word as it continued to work on the screws on the stretcher. It used so much force that it was like the screws were screwed to death, as though it had a grudge from its previous life. Following that, Old Cat pressed down on the stretcher's frame to confirm that it could withstand the weight of an adult. This time, it did not fall apart.
"I told you a long time ago that rescue will arrive in time."
Tang Yue heaved a sigh of relief. He now had the confidence to say those words. "You still have a long life ahead of you, lass. You still have a lot of things to do. You can have a happy and meaningful life. Your future life might be very dull and monotonous. After all, Kunlun Station is not a good place, but I believe you can still find happiness there."
"Thank you for your kind words." Mai Dong smiled. "If I can go down, I will take wedding photos with you."
"I'm not joking." Tang Yue curled his lips. "You can stop joking about wedding photos."
"I'm not joking either."
Tang Yue paused and stopped.
"Really, I'm serious …" The girl looked at the Martian ground beneath her feet. She raised the pencil in her hand, closed one eye, and said in a sly tone, "Tang Yue, if I can land safely, let's get married."