Dead on Mars

The five Raptor 10D engines could provide more than 400 tonnes of thrust, and after the dismantling, Orion had a mass of 330 tonnes. Based on the conservation of momentum, the rocket engine had to expel enough high-speed mass to effectively reduce Orion’s high speed.

Orion’s computer precisely controlled the engine via a flight program that Tomcat had written. However, to reduce the errors in the Raptor 10D’s thick nozzles to the level of millimeters was impossible. Their original use case was not meant for the vertical descent of the spacecraft. For instance, the rockets that allowed the Falcon 9 to descend vertically relied on sensitive sensors and specialized feedback control mechanisms.

Tomcat didn’t have any of this, so it could only use the most brutal and simplest method. It directed the rocket engines’ nozzles outward to their maximums, crazily pushing the safety redundancies to the limits. This allowed Orion to hang in midair like a tumbler.

At this moment, if someone looked up from beneath the spacecraft, they would see the rocket’s exhaust drawing a gigantic cross in midair.

This was a Tomcat Cross.

In the final twelve seconds before the atmospheric entry.

“Flight-path angle adjusted again! Angle of attack leveled!”

“Raptor-05 at 85% thrust. The trajectory of flow increase for 01, 03, 07, and 09 is going as expected,” Tang Yue reported. “Orion’s speed at 4872.23 m/s… The pressure on the engine is too great. It’s just too fast.”

“Tomcat?”

“Got it.” Tomcat’s voice was heavy. “I’m monitoring it.”

The workstation’s heat-dissipating fans began to whirl crazily as the CPU fired up all its cores to indicate that not only was Orion under stress, it was also being stressed.

The five curves on the monitor rose, indicating that the five Raptor engines were increasing their thrust. To save propellant, Orion’s nine engines were ignited at different stages.

If this was the true descent, Orion would be hanging 12 kilometers high in the sky. It would decelerate by relying on the rocket engine’s reverse thrust while stabilizing itself.

Once it left orbit and began an atmospheric entry, there was no turning back.

Tang Yue and Tomcat stared at the monitor. At this point, they could do nothing but stare. Once the atmospheric entry began, most of the control was in the hands of Orion’s computer. Mission Control couldn’t easily intervene, nor could they do so in time.

Hold it.

Hold it.

Tang Yue whispered.

35 seconds into the atmospheric entry.

The Orion stably descended.

Kunlun Station remained silent in the heavy atmosphere. Only Tang Yue’s and Tomcat’s hurried, terse voices would occasionally sound.

“Take note, the IMU’s ¹ errors are accumulating. The gyroscope drift has deviated beyond our initial estimates.

“The wind-facing surface’s atmospheric density is increasing. The resistance numbers are rising.”

As the atmosphere thickened, the situation faced by Orion and the workstation became complex. Flight in a vacuum and in an atmosphere were completely different. The air didn’t provide any deceleration properties to Orion and only made the environment more thorny. For the workstation, the fluid dynamical simulations were taxing, and the CPU was slowly unable to keep up.

Tang Yue swept his gaze across every number on the monitor. The numbers and diagrams that didn’t look obvious on the surface combined together to form a complete spacecraft that flew in his mind.

The altitude indicator on the monitor kept jumping. If it were a mechanical watch, the spinning gears might even produce sparks from the friction. Instead of describing the Orion as landing, it was more like a crash. A controlled and deliberate crash.

The HP workstation was unable to precisely simulate the environment of Orion’s atmospheric entry. Orion’s massive body, spanning tens of meters long, made the force distribution and work environment extremely complex. It was truly difficult for the workstation to simulate reality. After all, it wasn’t a supercomputer that physically occupied more than a hundred square meters.

In fact, Tomcat had simplified the workstation’s workload. Certain details were temporarily replaced with fixed ideal values that would be tested individually in the future. This wasn’t safe or precise, but it was a choice made from not having any options. Otherwise, the computer might really explode in protest.

“The GNC system probably still needs to raise its adaptability and robustness.” Tomcat frowned as it rapped the table. “The RCS tri-axial attitude stability can still be optimized. It can still be optimized further…”

Seventy-five seconds after the atmospheric entry.

Mai Dong sat silently in her seat, raising her hand from time to time to look at the time.

Tang Yue had told her that the atmospheric entry would be a terrifying period of sharp deceleration during the real descent. The immense pressure would press her down against her seat, preventing her from moving. During this period of time, she wouldn’t be able to raise her arm. Only after the deceleration was complete, allowing the spacecraft to reach a uniform speed would she be able to move her body.

That six minutes of deceleration was a critical period that determined life and death. If any problems were to happen to Orion, it would most likely be then.

“Tang Yue?”

“Yea,” Tang Yue replied. “I’m here.”

“Am I still alive?”

“Yes,” Tang Yue said. “You are safely descending. Currently, you are at a height of 35,887 meters.”

“I heard you both mention that 10,000 meters is a chasm of difficulty?”

“Tomcat said that below 10,000 meters, the atmospheric concentration would rise, making the environment very complex. That’s extremely disadvantageous to the spacecraft’s attitude stability,” Tang Yue said. “But don’t worry. Orion has the ability needed to maintain stability… We still have plenty of fuel, and the engine is very reliable as well.”

“Raptor-01, 03, 07, and 09 deactivated! Take note, Raptor-01, 03, 07, and 09 are deactivated! Computer self-checks a-okay. All stations take note!” Tomcat shouted. “02, 04, 06, and 08 activated!”

Just as Tomcat said that, the system indicated the shutdown of four engines. At the same time, the other four engines were ignited.

It was time for the relay to happen. For Orion’s Raptor engines, this descent of 120 kilometers was a relay race. The first batch of engines had completed its mission and could take a well-deserved rest. They passed the baton to let the second batch of engines complete the final part of the 30,000 meter descent.

“If this simulation test succeeds, I’ll probably regret it,” Mai Dong said.

“Why will you be regretting it?”

“I feel regretful that I didn’t really head down.” The girl smiled. “The chances of success are so low, and for it to actually succeed against all odds, wouldn’t it be regretful that it was only a simulation and doesn’t count? Anyone would have such thoughts… Ah, if only I had headed down using this opportunity, right?”

“No simulation test can represent the actual situation. The workstation is limited in its ability, and is unable to fully simulate reality.” Tang Yue shook his head. “Orion’s flight control system still has many flaws and drawbacks. Under such a situation, we cannot rashly let you descend…”

Just as he said that, the monitor in front of Tang Yue suddenly had a pop-up window appear. It was a jarring red that alarmed him.

“Code 1028 alert!

“Code 1029 alert!

“Code 1170 alert! Tomcat!”

“Copy.” Tomcat glued its eyes to the monitor. “Copy… 1029 is a warning about the structural robustness. 1170 is the attitude stabilization warning. Damn it. Something’s wrong. Something is wrong with Orion.”

“Something is wrong?” Tang Yue was taken aback. In less than half a minute of the warning pop-up window, the screen was covered in red warning numbers. He couldn’t react in time at the speed they were popping up at.

“Tomcat! All systems red!” Tang Yue shouted.

“It’s all red over here too.” Tomcat typed on the keyboard rapidly, making it evident that its monitor was also covered in red alerts that tinged its face red from the monitor’s light. “Orion’s RCS attitude stability has errored out. It’s giving the computer incorrect information, causing the computer to instruct the engine’s nozzles to rotate away in an attempt to stabilize Orion. The spacecraft is deviating from the central axis, and I’m trying to find the problem at its source. I’m trying to find the problem at its source!”

The most worrisome matter had happened after all. The spacecraft was unable to stabilize its attitude and it was beginning to topple.

Before the test, Tomcat had emphasized that the spacecraft couldn’t deviate more than five degrees, because once that happened, Orion’s weak truss might break down as a result.

At that moment, the spacecraft was gradually reaching the five-degree limit.

“Can you stop it?” Tang Yue bellowed. “Deviation of 2° 30′!”

“I’m trying!” Tomcat said fiercely.

“Deviation of 3° 50′! 3° 52′! Haven’t you found the problem?”

“I’m checking through the program and sensors for any bugs, and am also fixing the engine’s control commands…”

“Deviation of 4° 47′! 4° 50′! 4° 55′!” Tang Yue broke out into a sweat. “The truss’s robustness is approaching its limits. The spacecraft can’t maintain its integrity any longer!”

Mai Dong silently listened to Tang Yue and Tomcat shout over the comms as she raised her hand to look at the time. 267 seconds had passed since the atmospheric entry. Based on the expected stages, this was the period when the spacecraft approached an altitude of 10,000 meters.

Even though the personnel on Mars were in a frenzy, the lander remained pitch-black and silent.

“The deviation has reached 5° 13′! Structural coefficient at 77%! Tomcat, if you don’t hurry, the spacecraft will crash! The spacecraft is about to crash!”

“5° 27′. Structural coefficient at 80%!”

“5° 43′. Structural coefficient at 88%!”

“6°. 93%! 95%… 97%! 98! 99!”

“Found it! F*ck, it was a tiny logic problem! When the system rectifies—” Tomcat slammed on the table as it stood up. Tang Yue had done so at the same moment as he pushed the keyboard and cut Tomcat off. “Orion’s truss cracked and has disintegrated.”