"Pang, the establishment of mathematical models needs accurate data support, the amount of carbon dioxide produced by our daily breathing, the amount of carbon dioxide absorbed by photosynthesis after the potatoes in the planting cabin are removed from respiration every day, the difference between this, how many leafy plants need to be planted to maintain the carbon dioxide balance in the perching cabin, we have to accurately measure."

"In addition, planting new leafy plants requires water, fertilizer, and 500 liters of water in our water recycling system, from which we can take 300 liters in addition to our basic drinking and washing guarantees, and 100 liters of hydrazine in MDV can be used to make 200 liters of water. It takes 40 litres for one cubic meter of soil, so we can make about 12.5 cubic meters of soil. The biggest problem is fertilizer, and the plant seeds we have left, which are basically vegetables, can't provide us with a lot of calories. Therefore, once new leafy greens are planted, then the potato yield will definitely decrease, and then it will cause food shortages......"

Pang Xuelin frowned and was silent, and after a while, he said, "Watney, I was thinking, maybe we can consider moving to live in the rover." We also have 2,300 hours of small CO2 filters, and every day we work twelve hours in the perching pod, with the remaining twelve hours resting in the rover. On the one hand, this can extend the use time of the spare carbon dioxide filter in the perching chamber, and on the other hand, it is also convenient for us to experiment, and there is an air analyzer in the rover, so we can adjust our plan according to the change in carbon dioxide content! ”

Watney bowed his head and muttered for a moment, then said, "That's a good idea! ”

That night, the two moved into the rover.

During the day, they enter the perching chamber and start the water production work that they are familiar with.

It took only three days to convert 100 litres of hydrazine into 200 litres of water, and they used up nearly 100 litres of liquid oxygen reserves.

But they had planned to work 12 hours a day, but by the evening of the first day, they could not proceed.

Because the carbon dioxide concentration in the habitat capsule exceeded 2,000 ppm within 12 hours, it had a significant impact on Pang Xuelin and Watney.

The two had to activate the perch's back-up CO2 filter to absorb the carbon dioxide in the perch.

It wasn't until two hours later that the carbon dioxide in the perching chamber was reduced to a safe concentration, and they turned off the carbon dioxide filter again.

After three days of testing, Pang Xuelin and Watney found that the potatoes currently grown in the inhabiting cabin can only absorb carbon dioxide produced by two people breathing for ten hours a day, and the rest must be solved by carbon dioxide filters.

Because they are basically in a high-intensity working state in the perching cabin, the carbon dioxide produced in 12 hours is equivalent to two-thirds of the carbon dioxide content exhaled by two people in a day.

"This is good news, even if we don't do anything in the future, using the potatoes in the planting module can extend the working time of the carbon dioxide absorbers in our perching module to 30 days, and if we choose the right crops, maybe we can really keep the carbon dioxide produced by our breathing in a basic balance, and even if it is slightly exceeded, it can greatly extend our working time on Mars."

Pang Xuelin said.

Watney nodded, "I've already chosen the plants we're going to plant next, just plant tomatoes!" Although there are also C4 crops with high photosynthesis efficiency such as rice and corn, these plants have a harvest period and have relatively high requirements for water and fertilizer, which are not suitable for us to grow. Tomatoes are more suitable. Tomato is a herbaceous plant that likes light, with a light saturation point of 70,000 lx and a suitable light intensity of 30,000-50,000 lx. It has a strong carbon dioxide absorption capacity. Moreover, tomatoes are different from potatoes, as long as there is the right temperature and humidity, they can grow all year round, so that they can basically ensure 24-hour uninterrupted photosynthesis. It's a pity that we didn't carry single-celled algae this time, and the photosynthesis efficiency per unit volume of that thing is high, as long as it is well managed and arranged in the planting tank, it is enough for us to use! ”

Pang Xuelin smiled: "You are an expert, listen to you!" ”

Next, after consulting with the expert group on Earth, Pang Xuelin and Watney maintained their work and rest time at twelve hours in the rover and twelve hours in the perch.

In order to ensure communication, Pang Xuelin connected the communication equipment of the rover to the Mars Pathfinder landing module, so that not only the perching module can contact the earth, but also in the rover.

During the 12-hour rest period, the carbon dioxide exhaled by the two people is only equivalent to one-third of the day's breathing, and the 12-hour perched cabin work, and the two-hour perched cabin backup carbon dioxide absorber can basically maintain the carbon balance of the perching cabin.

In this way, the backup CO2 absorber of the perching module, which was originally only available for twenty days, can be extended to 240 Martian days.

The 2,300-hour small CO2 absorber can also be extended to 145 Martian days.

When the small CO2 absorbers run out, they go into the perching chamber and use the oxygenator to spare the CO2 absorbers and live for another four to five days at most.

150 Martian days.

That's the limit of how long tomatoes can survive after planting tomatoes, Watney can't be sure.

The situation is really bad.

But Pang Xuelin and Watney still adjusted their mentality as much as possible and devoted themselves to the cultivation of tomatoes.

It took half a month for the two to transform the original living cabin into a tomato planting cabin, a total of 50 square meters of soil, Pang Xuelin and Watney specially transplanted half of the cooked soil in the potato planting cabin to the tomato planting cabin, and the newly created soil was reburied in the potato planting cabin.

This is likely to have a very bad impact on the yield of potatoes in the second season, but in order to ensure the survival rate of tomatoes, the two of them can't care so much.

……

201st Martian Day.

[19:20] JPL: Xuelin, I'm Tian Mu, your latest data has been received, the earth has set up a simulation cabin that is basically the same as your environment on Mars, according to the tomato photosynthesis data provided by you and the laboratory, the simulation operation on the supercomputer, the results show that 50 square meters of tomatoes, after ripening and potatoes, can absorb five-sixths of the carbon dioxide you produce, and the remaining one-sixth must be solved through your carbon dioxide absorber. Excluding the reduced CO2 capacity caused by the potato harvest season, preliminary estimates show that you still have 400 Martian days to survive, and my colleagues are working overtime to launch supplies next month, including a large amount of food and spare molecular sieves to repair the oxygenator, which are tentatively expected to arrive before the 585th Martian day!

[19:42] Rover: Roger, I hope the results of the supercomputing are correct, thank you for your efforts, and I wish you all the best for the supply plan.