My Little Pony: My Little Pony The Martian

"Xiaowen, are you free now?"

Venkat put down his notepad filled with various data charts and MAV design sketches, raised his head and replied: "Of course Annie," he then asked, "What happened?"

Anne strode into his office and closed the door behind her. "Why do you think something happened?"

"Well, first of all, you just said two sentences in a row in a deserted environment with almost no grammatical errors, and you didn't use any swear words;" Venkat explained, "Secondly, normally you The content of greeting me is to directly make demands or complain about how troublesome the work at hand is. Due to your unusual behavior and serious tone just now, I have reason to think that you have serious bad news. Let me know, but maybe you want me to help you."

"You are really a good detective." Anne couldn't help but cursed, "Yes, you are right. I have to ask you for something. A reporter I know helped me before. Don't be busy, she recently wanted to have an exclusive one-on-one interview with the alien spaceship captain Cherry Berry, and I wanted to ask if I could find a way to free up a day for her on the Pathfinder."

After Venkat heard this, the pen in his hand slipped unconsciously. "Annie, do you have no idea about the current communication situation?" He replied, "The signal delay has already exceeded twenty light minutes, not counting the time it takes to type on both ends; the communication bandwidth has also dropped to every Less than one thousand bits per second. Which means that in order to prepare for this interview, we have to push everything aside, just to let your reporter friend ask ten questions at most? Is this necessary? Can’t she even send an email and wait for a reply?”

"She said she wanted to do a live interview." Annie also looked helpless, "Xiaowen, I know how bad the situation is now, and I haven't seen the timestamp of the Pathfinder conversation. But this time it's the Times of London. Berenice MacReady, she is now basically our main force in publicity in Europe. Do you need me to remind you how much rescue funding the ESA has provided? Xiaowen, you must know that this is all due to her. Ah, I can’t forget it even if I want to. She spent a lot of time praising us, and she could almost write a poem about it. She took so much pains to carefully package every corner of the rescue project and sell it to the public. We are now I already owe her a lot of favors.”

Venkat let out a long sigh and slumped back in his chair to think about the organizational coordination issues that would follow. "If we really want to set this precedent, other news organizations will definitely come in and ask for interviews." He asked, "Is it okay to deal with them?"

"It's okay, I've been fighting for several weeks." Annie was very confident in this aspect.

"NASA's attitude towards the outside world must at least appear to be impartial on the surface," Venkat continued, "which means that in order to avoid triggering public criticism again, we must do some tricks to create a Berry-berry initiative. It feels like asking Ying to conduct an interview. This secret mission is left to you."

"It's arranged."

"Your friend needs to come here, either here or at JPL," Venkat said. "Considering the mess in Pasadena, it's better to come to us. She's going to be here for a few days. God, we can only have an interview opportunity when there is nothing urgent one day. Can you accept it?"

"She's been stationed here for a while," Annie replied. "She lives in a small suite in a hotel in Texas. That's no problem."

"And it must be stressed to her," Venkat added, "that she realize that her time is extremely limited. The first two hours of the day are reserved for our daily work, and the next nine If there is no emergency situation that requires our intervention, she can do it by herself. It is best for her to get the information she wants quickly, because this opportunity will not happen again. "

"I'll tell you."

Venkat sighed, "Then we can start preparing. This time I have made a special exception for you. Don't forget to return this favor to me next time."

"It's on me." Anne didn't mean to be grateful, so she accepted Venkat's gift shamelessly. Then she accidentally glanced at the pile of drafts on Venkat's desk and asked casually, "By the way, what were you working on just now?"

"It's just a rough estimate of the data, just talking on a napkin." Venkat replied, "I want to get a rough idea of ​​the effect of installing the Pony rocket engine on the MAV landing stage."

"Shouldn't this be JPL's job?"

"Yes, but I feel a little itchy waiting." Venkat looked helpless, "JPL is currently busy dealing with a lot of problems with Sleipnir, and it will take several more months before he can bother to deal with this matter. Just entertain yourself by doing math problems."

"And is this feasible?" Anne asked. "I feel that the situation is not getting better but getting worse. After all, for several years you have been asking me to explain to reporters that in order to save fuel, MDV and MAV should be as light as possible. How important it is to quantify, but now it seems that we are reversing the course of history.”

"How much do you know about thrust-to-weight ratio?"

"If the push-to-weight ratio is about one, you can levitate. If it's more than one, you can go up to the sky. If it's less than one, you'll fall down, or you won't be able to fly at all." Annie shrugged, "To be more detailed is within the scope of a nerd's ability. Anyway, I I can’t understand it.”

"Okay." Venkat took out a blank piece of scratch paper and began to scribble on it. "The thrust-to-weight ratio of the MAV landing stage..." He directly abbreviated it as TWR (Thrust-Weight Ratio), "...under the conditions of Mars gravity, it is 1.2. About. It is indeed not big, but it is completely enough to allow the MAV about to land to decelerate from more than meters per second to a level where it can safely land softly within three minutes."

"Why can't we increase the thrust? Change to a larger engine? How about adding more fuel? Will there be any problems?"

"The greater the initial weight of the aircraft, the more fuel we need to consume when launching from the Earth, and it will be more difficult to implement a soft landing after arriving on Mars." Venkat explained, "By the way, this contradictory situation also caused the MDV to land The process has become one of the most dangerous event nodes for astronauts in the Ares mission. Once the MDV enters the Martian atmosphere, there will be no retreat to terminate the mission. Failure or failure. If given during design MDV adds a Mars escape into orbit mode, and the final product will be similar in size to MAV."

"But having said that, this time we used MAV to escape from Mars. The fuel component of MAV is hydrazine, which is ignited through a catalytic grille. It is the same propellant used by MDV. If we collect the remaining Ares 4 MAV and Ares 3 MDV For propellant, we might be able to find a way to extend the working time of that stage to one minute. In theory, this can obtain a lot of extra kinetic energy early in the launch, which can speed up our speed into orbit."

"You're talking about theory," Anne interrupted, "That's obviously different from the actual situation. Why?"

"Under the conditions of Martian gravity, a TWR of 1.2 corresponds to an acceleration of only 0.76 meters/second per second, which means that the speed of the entire spacecraft after one minute can only reach about meters/second. If it is If you want to land, this data is not a big problem, because the drag parachute and air braking system equipped with the MAV can decelerate the aircraft running at orbital speed to less than meters per second, and then the remaining kinetic energy can be easily offset by the rocket."

"But this time Mark and his friends wanted to accelerate to a speed of six thousand meters per second, and they also had to leave room for inter-stage separation, so in theory this looks good at 45 meters per second. Once it reaches reality, it becomes a self-destruction. After a minute of deduction, it can be found that the height of the rocket will only just touch the edge of the Schiaparelli Basin. After that, it will start to fall in less than ten seconds. After another twenty seconds, it will start to fall. It will return to the surface of Mars in seconds. In other words, the MAV pilots must manually start the first upgrade engine and release the landing stage launcher in one go. There can be no mistakes, otherwise it will be a dead end. Even if they did not make a mistake, they just moved a few steps slower. Yes, in the end the fuel burned in the first stage may be greater than the amount used in a normal launch."

"So all in all, just the height and speed gained by reusing the descent stage are not worth the risk for our team members. But if we include the main engine of the alien spacecraft, the data will be huge. It’s different.”

"How could it be?" Anne was puzzled. "Wouldn't it be heavier instead of heavier?"

"It is true that the weight is greater," Venkat replied, "the thrust is much greater. Our current rough estimate is that these three engines can levitate forty kilometers on Mars at maximum thrust. A weight of five tons is equivalent to producing forty-five tons of Mars thrust with TWR = 1; but if the load is only themselves, such a TWR is actually much better."

Annie shook her head, "I don't understand what you say."

Venkat tapped his chin with his pen, held his chin and thought for a while, "Okay, let's not mention MAV and ponies for the time being," he decided to change his mind, "Let's talk about Captain Frank Watney ( Buck Watney and his potato-powered spaceship."

Annie grinned, "Thunderspuds is ready?"

Venkat smiled knowingly, "That's more or less what it means. Leisu No. 1.2 weighed fifty-two tons when it took off, and the first stage can produce sixty-two and a half tons of thrust, with a thrust-to-weight ratio of about . But he didn't have much time. It is enough, so we need to add more thrusters to facilitate faster entry into orbit."

Annie nodded, "Okay, I can understand that. Probably like the space shuttle or Falcon Heavy, right?"

"That's right. If at this time a certain former president sold Falk Watney a few boosters with his name on them," Venkat drew several missile shapes next to the classic sci-fi rocket shapes on the paper. "If each of them weighs five tons and can produce four tons of thrust, then the TWR is four to five - less than one. This means that if these so-called boosters are launched individually, they will I had to burn more than half of my fuel before I could barely get off the ground."

"Tie these two boosters to Leishu-1.137, and the resulting aircraft will weigh tons, with a thrust of tons at take-off, and a thrust-to-weight ratio of ."

"In other words, it's not as good as 1.2." Anne nodded after hearing this, "Congratulations to Watney for squandering the Space Orphans and Widows Fund to boost the former president's self-esteem."

"Yes, but our Falk Watney is not such an idiot," Venkat continued to tell the story, "He would never do this if he was upright and honest. His plan is to use the Rainbow Mustang Sparkling Necklace System, which weighs Seven and a half tons, but it can produce up to forty tons of thrust. The situation now is quite different! After attaching such a series of systems to Leishu-1.72, the spacecraft weighs tons and takes off The thrust is tons, so the thrust-to-weight ratio is approximately..." This time Venkat took out a calculator and said, "...."

"This data is much better than 1.2, right?" Annie asked, "Fuck Watney looks promising this time."

"It's too early to draw a conclusion now," Venkat replied, "Let me give you an example. The thrust-to-weight ratio of both the Saturn V and the Space Shuttle was around 1.5 when they were launched, but as the fuel continues to be consumed, the load will also It decreases accordingly, so the peak thrust-to-weight ratio of both can eventually be close to around 3. In fact, the peak TWR when we launch unmanned aerial vehicles is generally above 15, because the loads such as detectors are much stronger than human skin, and the G force is large. It’s not easy to have troubles like broken bones, broken bones and bleeding of internal organs.”

"It's time to get back to the topic," Venkat became serious, "the data I just told you are not made up out of thin air. The weight of the MAV with the landing stage and fuel is fifty-two tons, and the thrust-to-weight ratio on Mars is 1.2; and the pony thrusters—the Rainbow Bronco Sparkling Necklace System—weigh four and a half tons, and about three tons of batteries are needed to drive them continuously for one minute. On Mars, this system can output about Forty-five tons of thrust, and a thrust-to-weight ratio of 1.72 roughly corresponds to a speed increase of about three meters per second. After one minute of acceleration, the MAV's speed will be close to about two hundred meters per second, and its altitude will reach about six thousand meters. ——This speed and altitude can safely separate the descent section and start the first upward upgrade engine, and they will be able to escape in a real sense."

"Okay, I understand now," Annie said, "But why can't we add more batteries or fuel?"

"First of all, the materials the ponies currently have are only enough for them to make about a hundred batteries at most," Venkat replied. "If they exceed this number, they will have to make the housing frame, control and connection components from scratch. "Secondly, we're not entirely sure yet whether they actually have the ability to synthesize hydrazine on their own, and the landing-stage engines won't be able to use any other kind of fuel they might have access to in the immediate area."

"However, the main problem is actually the weight." Venkat continued, "We can't extend the operation time of the pony thruster as long as the first upgrade. It is completely impossible to replace the first upgrade, and After the energy of these engines is exhausted, we have no safe and non-destructive way to remove them from the aircraft. If they are released directly, they may collide with other structures and damage the spacecraft. That is to say, unless we install these thrusters on the descent stage, Otherwise they would be completely useless for at least a minute during the flight, and we can't afford any liability on this mission."

"So, if we can find a safe way, we will connect the pony engine to the landing stage and work for about a minute, and then separate from the landing stage and free fall back to the surface of Mars." Venkat looked a little regretful, " This is indeed very wasteful, but unless we can find a way to replace part of the upper stage thrusters with pony engines, the current solution is already the most effective way to use it."

"Oh." Annie replied.

"In addition, Bruce will be responsible for optimizing the data from another aspect." Venkat continued to explain, "That is to say, he will find ways to remove all components that are not necessary for Mark and the others to survive, and do everything possible to reduce the weight of the aircraft. Heavy. Every bit of weight removed from the MAV acts directly on the TWR, increasing the efficiency of all thrusters. That’s where our key expectations for the rescue mission come from – and of course the Twinkle engines.” He shook his head and added, "God bless, it's better not to use this last resort."

"Oh," Anne read back.

"Annie, did you lose me again?"

"No, no," Annie said with a bad smile, "I was just imagining how Watney would react when he heard that we were going to rename the MAV to 'Thunder Su-1'."

"What?" Venkat was shocked and glared at Annie, "No. Don't, don't, never. Don't make such a joke to me..."

"Xiao Wen, see you later," Annie said, "I have a press conference to hold in seven minutes."

"Annie, I'm warning you, you must never tell him, seriously!" At this time, Venkat was too late to regret, "Did you hear me?! Come back!"

In the winding crystal cave beneath the surface of Mars' e-zone, the temperature is still rising.

The height of the alfalfa plant in the field is only about one foot above the ground, but it has a root system that drills several meters deep into the ground, penetrating the nutritious soil layer cultivated by the Martian refugees with all the hardships, all the way to the uncultivated original soil of Mars, and gradually Struggling to find weak spots in the melting permafrost. The criss-crossing plant root systems bring a large amount of soil bacteria into the shallow soil; although most of them are beneficial bacteria, a small number are not kind.

A recently reinforced layer of air-tight silica crystals and the concrete cave walls form an effective layer of insulation, allowing the heat generated by the solar lighting system, plumbing pipes and heaters to be maintained within the cave. A large amount of heat heated the air, warmed the plants, and gradually penetrated into the soil, roaming to the unknown depths of the ground.

Mars refugees have long believed that the magma tubes here have a symmetrical shape, continuously sloping downwards into the source of the cave at the center of the ancient extinct volcano. Unfortunately they guessed wrong. Weathering brought in a large amount of dust from the surface and accumulated it, forming the current downward-sloping landscape, but the rocks covered by the thick soil layer rose upward as the cave continued to deepen. In other words, the depth of the soil near the cave entrance is even greater than the vast interior space above.

Tracing deeper into the soil, there are a large number of ancient water-bearing mineral deposits hidden under the pure ice permafrost, which preserve the sediments of the years that did not gradually penetrate from the shallow sandy soil of Mars, but gush out from the source of the core of the earth. .

Over millions of years, these sediments have trapped many clusters of methane hydrates, which are simply ice crystals that store large amounts of methane in their crystal lattices.

The alfalfa roots continue to spread downward, carrying with them the warmth of the surface and various bacteria.

The first clump of methane thawed.

Small streams of methane gas gradually merge into rivers and begin to slowly seep upward along the plant roots, replacing the oxygen in the soil little by little. The beneficial bacteria begin to die off in droves.

Other bacteria smelled the smell of methane and happily took root.

They began to multiply and bear fruit.