Old Cat finished singing "Sailor" and then "Lighting the Stars", followed by "Blind Date", "Friends" and "Heavenly Road". It was like an old song jukebox, but Tang Yue did not have the right to choose the songs.

Can tolerate the old cat’s rough voice like a scrapped tape recorder with unstable voltage. Kuangsha Literature Network

It howled loudly all the way while driving. When the old cat sang "That's the Qinghai-Tibet Plateau, oh oh oh oh oh..." and let out a high-pitched bray, Tang Yue didn't know how he restrained himself from jumping out of the car and fleeing.

impulse.

After the old cat finished singing "Heavenly Road", Tang Yue thought it was finally going to stop for a while.

But it started humming again.

Tang Yue was about to say something when he was suddenly startled.

The melody that the old cat hummed was very familiar to him, and Tang Yue almost hummed along with it. It was the song "Tomorrow Will Be Better".

"The tune you sang traveled a distance of thirty astronomical units in two minutes, which is one hundred and fourteen times faster than the speed of light." Tang Yue said, "This must be the fastest thing in the galaxy.

"

After the Mars Stray Dog drove for an hour and a half, the old cat took off the accelerator, stepped on the brakes, and turned off the power.

At this time, the rover's battery still has 5% power left.

"That's it for today. We have traveled thirty kilometers, and we need to charge the stray dog ​​next." The old cat jumped out of the car, looked up at the sun, and walked around to the trolley to unload the battery panel.

Tang Yue got off the car and stood beside the wheel of the Martian stray dog ​​and looked around. He saw a vast expanse of salt-alkali flat wasteland with no village in front, no shop in the back, and not even a place to shade from the sun. Fortunately, this was

Mars, if it were on Earth, would definitely cause dehydration and heatstroke due to exposure to sunlight.

Fortunately, they have stray dogs, and the means of transportation in the desert are lifeboats. Otherwise, it would be difficult to get out of this arid sea of ​​death with human power alone.

From here, Kunlun Station can no longer be seen at all. Tang Yue knew which direction Kunlun was standing, but when he looked far into the distance, he could only see a dark gray line of sky and earth.

The old cat unfolded the solar panels one by one and set them up on the ground. All the more than forty solar panels would occupy an area as large as half a football field. The next whole day is charging time. Now it is Mars.

It was a quarter past eight in the morning, and Tang Yue and Lao Mao had to stay here until the sun set in the evening, waiting for the charging to be completed.

Tang Yue connected the transformer to the battery, took out the charging cable, and plugged it in to his Mingguang Armor.

It’s not just stray dogs that need recharging, but also old cats and extravehicular suits.

One person and one cat completed the installation of the solar panels, and finally the old cat pulled out two small horses from the experimental cabin like magic.

Tang Yue and Lao Mao, one each, sat side by side on small stools, both dragging black cables behind them.

"When can I move again?"

"Tomorrow morning." Old Cat replied, "It will take at least ten to twelve hours to charge. We plan to set off at seven o'clock tomorrow morning and proceed thirty kilometers northeast."

"The direction won't be wrong, right?"

"Deviations are inevitable, as long as we make corrections in time." Lao Mao returned to the cab and dug around, took out a roll of forms and handed them to Tang Yue.

Tang Yue glanced up and down. The table was densely packed with numbers. He couldn't understand what it was. The only thing he could understand was the English abbreviations on the top of the table, "on" and "tues".

"ed", "thur", "fri", "sat" and "sun", Monday to Sunday.

"What's this?"

"Star catalog." Old Cat replied, "Those numbers are celestial coordinates and calibrate the positions of celestial bodies."

"Star catalog?"

"The sextant can only determine our latitude, not the longitude directly." Lao Mao explained, "We need other means to determine the longitude of our location. The most intuitive way is to look at the time. There are time zones on the earth.

With the concept of time difference, you can know your longitude according to which time zone you are in."

"But this is too rough." Tang Yue said.

"Yes, it's too rough." Old Cat nodded, "Judging longitude based on time is essentially observing the height and position of the sun - in areas with different longitudes at the same time, the sun's position on the celestial sphere is different.

It’s the same, but in order to ensure accuracy, we’d better not use the sun, but use smaller and more accurate celestial bodies.”

Tang Yue spread the form on his knees, dragging the hem of the paper to the ground. It was really a very long and complicated form. Each number was accurate to four or five decimal places. It reminded Tang Yue of high school mathematics.

The natural logarithm table in the appendix at the back of the textbook.

"Smaller and more precise objects?"

"Yes." The old cat pointed to the top of his head, "We don't use the sun as the standard, we use Phobos and Deimos."

Tang Yue recalled the meaning of these two terms, "Phobos and Deimos?"

"Yes, we use the two satellites of Mars as the standard. The Kunlun Station has very detailed orbit data. They are very good markers. The star catalog in your hand is the celestial sphere of the satellites when observing them from the Kunlun Station.

Coordinates." Old Mao pointed to the table in Tang Yue's hand again, "Now that we have left Kunlun Station, when we observe Deimos and Phobos at the same time, their positions will deviate from the records on the star catalog... We

You can know the distance between your own longitude and the longitude of Kunlun Station."

Tang Yue pondered for a long time, Lao Mao's description was too brief, and he couldn't digest so much information at the moment.

"Give me an example."

"Okay, let me give you an example. For example, at 7:30 pm, when we observe at Kunlun Station, the position of Demos is 100." Old Mao further explained, "Then at the same time, at 7:30 pm, we observe here.

, the position of Demos is 101, and its coordinates have deviated - this is obvious because the observer's position is different... This deviation is equivalent to the time difference on Earth."

"Knowing the time difference, we can calculate the longitude."

Tang Yue nodded slowly. The old cat was really not kidding. It said that they were Captain Cook on Mars. Now it seems that this is true. Judging the position based on celestial bodies and time is a very ancient method. The oceans hundreds of years ago

Ships will even carry navigational clocks that are accurate enough for this purpose.

Now he only has this star catalog in his hand. There is no mobile phone, no radio, no gs, and no various navigation equipment. All he can rely on is time, stars and mathematics.

"Can it be accurate to this point?" Tang Yue asked.

He was a little concerned about navigation accuracy.

"Don't forget that this is Mars. The diameter of the planet under our feet is only half that of the Earth, and its total surface area is only equivalent to the land area of ​​the Earth." Old Cat said, "The distance of three hundred kilometers is negligible on the Earth, but

Here, enough deviations can be shown... As long as our calculations are accurate enough, we can determine the longitude to a very reliable value."

"But how does this thing work?"

"I will teach you at night. This thing cannot be used during the day."
Chapter completed!