Die on Mars

Five Raptor 10D engines can provide more than 400 tons of thrust, and the mass of the disassembled Orion spacecraft is 330 tons. According to the conservation of momentum, the rocket engine must inject high-speed working fluid of sufficient mass in reverse to effectively offset Orion itself. of high speed.

The computer of the Orion spacecraft controls the engine accurately, and Laomao has written a very strict flight program. However, it is impossible to reduce the deflection error of a big, stupid, black and thick nozzle like the Raptor 10D to the millimeter-arcsecond level. They originally The purpose of the rocket is not to make the spacecraft land vertically - rockets that land vertically like the Falcon 9 rely on keen sensors and specialized feedback adjustment mechanisms.

The old cat doesn't have these, it can only use the simplest and crudest method - deflecting the rocket engine's nozzle outward as much as possible, wildly expanding the safety redundancy, and letting Orion stick in the air like a roly-poly.

At this time, if someone looks up from the ground under the spacecraft, they will see the rocket's jet drawing a huge cross high in the sky.

This is the old cat cross.

12 seconds after entering the atmosphere.

"The track angle is adjusted again! The angle of attack is trimmed!"

"Raptor-05 thrust is 85%, and the flow rate increase curve at 01, 03, 07, and 09 is in line with expectations." Tang Yue reported, "The speed of Orion is 4872.23 meters per second, Old Cat... The engine pressure is very high, and the speed is really too fast. "

"Old cat?"

"I know." The old cat said in a low voice, "I'm watching."

The cooling fan of the workstation was spinning fiercely, and Comrade CPU worked hard. It said that it was not only the Orion spacecraft that was under great pressure, but also its own pressure.

The five curves on the display are climbing upward, which shows that the five Raptor engines are gradually increasing their thrust. In order to save propellant, Orion's nine engines will be turned on in stages.

If this is a real landing, then Orion is hanging alone at an altitude of 12 kilometers at this moment, relying on the reverse thrust of the rocket engine to slow down and stabilize its attitude.

Once it leaves orbit and enters the atmosphere, it has no way out.

Tang Yue and Lao Mao stared at the monitor. At this time, they could do nothing but stare. Once they entered the atmosphere, most of the control rights were in the hands of the Orion computer. People on the ground could not interfere at will, and it was too late. put one's oar in.

Hold still.

Hold still.

Tang Yue said softly.

Entering the atmosphere for 35 seconds.

The Orion spacecraft descends steadily.

Kunlun Station was quiet and dull, with only the rapid and brief voices of Tang Yue and Lao Mao ringing.

"Note that the IMU (Inertial Measurement Unit) errors are accumulating and the gyroscope drift deviation is greater than expected."

“The density of the atmosphere on the windward side increases and the drag coefficient increases.”

As the thickness of the atmosphere gradually becomes denser, the situation faced by the Orion spacecraft and workstations begins to become complicated. Flying in a vacuum is completely different from that in the atmosphere. For the Orion spacecraft, the air does not have any decelerating effect and will only change the environment. It's complicated and tricky. For workstations, fluid simulation is very computationally demanding, and the computer's CPU can't keep up.

Tang Yue's eyes scanned every parameter on the screen. The combination of these seemingly unclear numbers and charts formed a complete spaceship flying in his brain.

The altimeter on the display was jumping wildly. If this was a mechanical watch, the rapidly rotating gears might cause friction and sparks. Rather than saying that Orion was landing, it would be better to say that it was crashing, a deliberate and controlled crash.

The HP workstation cannot accurately simulate the environment of the Orion spacecraft when it enters the atmosphere. Orion is dozens of meters long, has extremely complex stress conditions and working environment, and it is really difficult for the workstation to simulate it - after all, it does not occupy a large area. A supercomputer with an area of ​​hundreds of square meters.

Laomao actually simplifies the tasks of the workstation. Some details are temporarily fixed to ideal values, and then tested separately in the future. This is not safe and meticulous, but it is a helpless move, otherwise the computer may self-destruct in protest.

"The GNC system should further improve its adaptability and robustness." Lao Mao frowned and tapped the table with his toes. "The RCS three-axis attitude stabilization can be further optimized, and it can be optimized a little more..."

75 seconds after entering the atmosphere.

Maidong lay quietly on the chair, raising his hand to check the time from time to time.

Tang Yue told her that when she actually landed, she would experience a very scary sharp deceleration after entering the atmosphere. The huge overload would press Ophiopogon japonicus on the chair and make her unable to move. During this period, she would not be able to lift her arms. After decelerating and the spacecraft enters uniform motion, she can move her body.

The six-minute deceleration period is a life-and-death barrier. If there is a problem with the Orion spacecraft, it is most likely to happen during this time.

"Tang Yue?"

"Yes." Tang Yue replied, "I'm here."

"Am I still alive?"

"Still alive." Tang Yue said, "You are landing safely. The current altitude is 35,887 meters."

"Have you ever heard that 10,000 meters is a hurdle?"

"What Lao Mao said is that when the density of the atmosphere increases below 10,000 meters, the environment will become very complicated, which is detrimental to the stability of the spacecraft." Tang Yue said, "But don't worry, the Orion spacecraft has enough ability to maintain stability... We still have plenty of fuel and the engines are reliable."

"Raptor-01, 03, 07, 09 is shut down! Attention, Raptor-01, 03, 07, 09 is shut down! The computer self-test is normal, all departments should pay attention!" Old Cat shouted across from the monitor, "02, 04, 06, 08 starts!”

As soon as Lao Mao finished speaking, the system showed that four engines were shut down, and at the same time, the other four engines were turned on.

It's time to hand over the baton. For the Orion spacecraft's Raptor engine, this 120-kilometer landing is a long-distance relay race. The previous batch of engines have completed their tasks and can rest. They handed over With his own baton, the next 30,000 meters of the race will be completed by the latter group of engines.

"If this simulation test is successful, I will probably regret it." Maidong said.

"What do you regret?"

"I regret that I didn't really get on with it." The girl laughed. "Isn't it a pity that the success rate is so low? It's hard to succeed once, but it's just a simulation test and can't be counted. Anyone would think so... Ah, it would be great if I took this opportunity to go down, right?”

"Any simulation test cannot represent real practice. The workstation has limited capabilities and cannot completely simulate the actual situation." Tang Yue shook his head, "The flight control system of the Orion spacecraft still has major flaws and flaws. In this case, we cannot let You landed rashly..."

Just as he was talking, a pop-up window suddenly popped up on the screen in front of Tang Yue. It was a dazzling red color, and he was surprised.

"Code 1028 calls the police!"

"Code 1029 calls the police!"

"Code 1170 calls the police! Old cat!"

"Received." Old Cat buried his head in the monitor, "Received... 1029 is a structural strength alarm, 1170 is an attitude stability alarm, hell, something is wrong, there is a problem with Orion."

"Is there a problem?" Tang Yue was stunned. Less than half a minute after the alarm pop-up window popped up, the full-screen parameters began to rush wildly, one after another, so fast that there was no time to react.

"Old cat! Everything is red!" Tang Yue shouted.

"Everything here is red." The old cat clicked on the keyboard, thinking that there were also layers of red warnings on the screen in front of it, and the white cat's face was reflected red. "The RCS attitude stability of the Orion spacecraft collapsed. It gave the wrong signal to the computer. The computer was commanding the engine nozzle to deflect in an attempt to stabilize Orion's attitude. The spacecraft was deviating from the central axis. I'm looking for the source of the fault. I'm looking for the source of the fault!"

The most worrying thing happened. The spacecraft could not stabilize its attitude and it was slowly capsizing.

Before the test, Lao Mao repeatedly emphasized that the deviation angle of the spacecraft cannot exceed five degrees. Once it exceeds five degrees, Orion's fragile hull structure may collapse.

At this moment, the spacecraft is gradually approaching the limit of five degrees.

"Can it be saved?" Tang Yue roared, "The deviation angle is two degrees and thirty minutes!"

"I'm working hard!" the old cat said viciously.

"The deviation angle is three degrees and fifty-two minutes! Three degrees and fifty-two minutes! Haven't you found the source of the problem yet?"

"I am troubleshooting program bugs and sensors, and am also correcting the engine control instructions..."

"The deflection angle is four degrees and forty-seven minutes! Four degrees and fifty-five minutes! Four degrees and fifty-five minutes!" Tang Yue was sweating profusely. "The strength coefficient of the main truss structure is approaching the limit, and the structure of the spacecraft will not be able to support it!"

Maidong listened quietly to Tang Yue and Lao Mao roaring back and forth on the channel. She raised her hand and glanced at the time. 267 seconds had passed since the re-entry into the atmosphere. According to the normal progress, the spacecraft was approaching an altitude of 10,000 meters at this time. .

Although there was a lot of activity down there, it was still dark and quiet inside the lander.

"The deflection angle is five degrees and thirteen degrees! The structural coefficient is 77%! Old cat, if you don't hurry up, the spacecraft will crash! The spacecraft will crash soon!"

"Five degrees and twenty-seven minutes, structural coefficient 80%!"

"Five degrees forty-three, structural coefficient 88%!"

"Six degrees, 93%! 95%...97%! 98! 99!"

"Found it! What a little logic problem! When the system was correcting errors -" the old cat slapped the table, Tang Yue stood up at the same time as it, pushed the keyboard hard, and interrupted it with a voice, "Orion spacecraft master The trusses broke and disintegrated.”