"Pang, if the landing module doesn't stay, I'll drive the rover to the Schiapallelli impact crater, and use the Fubos navigation on the way, and the approximate location should not deviate."

Pang Xuelin shook his head and said: "No, if you have enough time, you can still do this, but now you only have fifty days, as long as there is a slight deviation in the direction, it may take a few days to correct, and then the carbon dioxide absorber you carry will not be able to support the rover to reach the Schiaprelli impact crater." ”

"But I took the landing module away, what about your communication with Earth? The circumferential probability deviation of the landing position of the supply module reaches five kilometers, the landing area is almost fifty kilometers from the perching module, and without satellite navigation, you may find it difficult to find the supply module! ”

Pang Xuelin's brows furrowed deeply.

This is indeed a big problem.

The rover was originally designed for short-distance travel without taking into account the problems of long-distance travel, and the roosting module could emit radio navigation beacons, so it was not equipped with a navigation system.

In general, if you want to make a long-distance trip on Mars, you either use satellite guidance or an integrated SINS/CNS navigation system.

The SINS/CNS integrated navigation system is mainly composed of strapdown inertial navigation subsystem and astronomical navigation subsystem.

Strapdown inertial navigation is inertial navigation, and the core equipment is a laser gyroscope, but the accuracy of this navigation method will gradually diverge over time.

Astronavigation is the process of calculating the relative position of the rover and Phobos (Phobos) for navigation.

But the accuracy of this navigation method can also be problematic.

Therefore, the engineers combined strapdown inertial navigation and astronomical navigation, the strapdown inertial navigation subsystem provides the mathematical platform and position matrix to the inertial navigation attitude measurement information construction unit, and also provides the latitude and longitude information to the inertial navigation position measurement information construction unit, and the astronomical navigation subsystem transmits the inertial attitude matrix to the integrated navigation filter, which will provide attitude and position estimation errors according to the astronomical navigation subsystem and the strapdown inertial navigation subsystem respectively.

The accuracy of this navigation is high, almost no less than that of satellite navigation.

But now, the two of them don't have a working navigation system at all, and it is impossible to make their own.

Without the Mars Pathfinder landing module, if something happens to his side, he won't get any support.

And the supply module is related to how he will survive on Mars in the future, and if he can't find the supply module, it will be a big trouble.

"So the Pathfinder landing module has to stay here, and we've got to figure out a way to get to Skiapallelli in fifty days," Watney said. It's a pity that we don't have enough CO2 absorbers, otherwise as long as I set off early, even if the navigation accuracy of Föpos is not high, there is enough time to reach Schiaparelli. ”

Pang Xuelin was stunned for a moment, and a flash of inspiration suddenly flashed in his mind, and he asked, "Watney, what did you just say?" ”

"I said the Pathfinder landing module had to be here......"

"No, no, it's the next ......"

"We don't have enough CO2 absorbers, otherwise it's okay to leave early......"

"Yes, why didn't I think of it, you can leave early!"

Pang Xuelin clapped his hands and laughed.

Watney was stunned and said, "But we don't have enough CO2 absorbers!" ”

Pang Xuelin laughed and said: "Watney, we are all stuck in a mindset, our carbon dioxide absorber is not enough, but our liquid nitrogen and liquid oxygen reserves are enough." The rover is not a perching pod, and the space in the car is limited, so you can wait for the carbon dioxide content in the car to exceed 2%, and then put on an EVA spacesuit, and then release the air in the car, and re-use the nitrogen oxygen tube to make up the pressure, so that you don't have to worry about how to absorb carbon dioxide? ”

“what？”

Watney's eyes lit up, and he clapped his hands and said, "That's a great idea, if that's the case, I don't even need to bring so many carbon dioxide filters!" ”

Pang Xuelin smiled: "You still have to bring carbon dioxide, after all, this way is a waste of liquid nitrogen and liquid oxygen, if you only rely on the navigation of Ferbos, you can reach Schiaparelli in eighty days, right?" ”

Watney said, "That's totally fine! ”

Pang Xuelin said with a smile: "Okay, then I will prepare 50 liters of liquid oxygen and 50 liters of liquid nitrogen for you, which is enough for you to use for a hundred days, and the food is also well stocked for you, you set off on the 370th Martian Day and arrive at the Schiaparelli Impact Crater on the 450th Martian Day." The only pity is that you have never returned on this trip, and you have wasted a lot of biofertilizer! ”

Watney laughed and said, "When you return to Earth, I'll take care of it for you!" ”

"Get out!"

……

After Pang Xuelin communicated his idea to the Ares Project Command, he was quickly approved by the Command.

This also has the advantage that if Watney has a problem during the journey and is discovered by the satellite, Pang Xuelin can also drive another rover to the rescue.

Such a plan is important for high-risk space activities.

……

Time passed.

The two of them prepare for this long journey every day, and their lives become busy and orderly.

In the living cabin, the tomatoes also grow and bear fruit one after another, and this thing is made into ketchup by Watney, which solves the problem of potatoes not being seasoned after eating.

During this period, Pang Xuelin and Watney harvested the third crop of potatoes, which was even less than the second crop due to insufficient fertilizer, only 180 kilograms.

However, as long as the supplies can arrive smoothly, Pang Xuelin does not have to worry about food problems, so the two of them have no need to save food in a short period of time.

After successfully planting the fourth season of potatoes, it was finally time for Watney to set off.

370th Martian Day!

Early in the morning, Pang Xuelin prepared baked potatoes, a fried rice with Kung Pao chicken, a tomato mixed with the little white sugar left, and two large cups of aerospace polypeptide protein powder drink.

Both of them sat at the table in some silence, and Pang Xuelin showed a smile on his face and said, "Eat!" ”

Neither of them spoke during the meal, but gulped down these carbohydrate-rich foods.

Finally, Pang Xuelin raised his glass and said, "Watney, have a good trip!" ”

"Thank you!"

Watney raised his glass and touched Pang Xuelin, and drank it all.

Subsequently, both men put on EVA spacesuits and exited the perching chamber from Airlock 2.

In front of the rover, the two were silent.

Watney stepped forward and hugged Pang Xuelin, reached out and patted his helmet, and said, "Pang, take care, I'm waiting for you on Earth!" ”

As he spoke, he got into the rover without looking back.

Pang Xuelin didn't speak, just stood in place, watching the rover hatch close, watching the rover engine start, watching the rover gradually fade away and disappear into the depths of the horizon.

An unprecedented sense of loneliness swept over Pang Xuelin.

Pang Xuelin muttered to himself: "Next, I'm alone!" ”