Chapter 142: Sol Two Hundred and Seventy-Five, We Only Want Sixty Kilograms
âThe work that youâll be doing next will be complicated. Iâll need to explain it to you in detail, Miss Mai Dong.â
Tomcat sat up straight, looking serious.
âYeah, yeah. Iâm listening, Mr. Cat.â Mai Dong floated in front of the camera as she took on the look of an attentive student.
Tang Yue sat to the side at a loss for words. He stared blankly at the pen and paper on the desk, knowing that it was hopeless. Getting the Eagle to return to Kunlun Station was impractical. Regardless if a rocket engine was installed or not, the lander had no means of a successful landing.
The Orion IIâs Raptor 10D engines werenât designed for landing. Even Orion II itself wasnât capable of atmospheric entry. The massive but weak propellant reservoir tanks attached to it couldnât withstand much stress, so it was bound to suffer structural meltdown upon atmospheric entry.
As for the thought of dismantling the rocket engine, it was foolâs talk. It was possible with a team with all kinds of cranes. But Mai Dong only had a wrench, so any attempts would appear comedic. Orionâs massive rocket engine nozzles were thicker than Mai Dongâs torso.
Neither he nor Tomcat could give Mai Dong an answer that wasnât: âItâs hopeless, lady. We canât do it.â
âWe still have hope.â
Tang Yue was taken aback. What?
He turned his head in a bid to confirm that he wasnât hearing things. What did that cat say? Thereâs still hope? What hope is there?
It had just completely denied his plan, saying that it was completely unworkable.
Why was it now saying that there was hope again?
âMiss Mai Dong, you should have some basic understanding of a spacecraftâs atmospheric entry. In general, itâs a process of deceleration and landing. Even though the masses like to describe it as something very complicated and dangerousâand of course it is extremely dangerousâitâs essentially a deceleration process,â Tomcat said. âAs long as we successfully decelerate, lowering the speed to a sufficiently low speed⊠all the problems will be solved.â
âYeah, yeah.â
Tang Yue widened his eyes. Tomcat didnât seem as though it was joking. Did it really have a solution?
âDeceleration requires power, and only with sufficient power can we very simply and brutally resolve what seems unsolvable.â
âAre you referring to Orionâs engine?â Mai Dong asked.
Tomcat nodded.
âTang Yue, you just said that dismantling the engines is impractical!â Tang Yue roared. âYou said that all your simulations failed. Not a single one of them crossed the ten-thousand-meter altitude!â
âItâs obviously infeasible to dismantle the engines.â Tomcat rolled its eyes. âYouâve seen Orionâs rocket engines, right? Do you think that thing can be dismantled by human strength? You are trapped in a pattern of thinking. Itâs true that Miss Mai Dong needs to have the Eagle, but the Eagle isnât the key⊠Think about Apollo 13. Was the command module the one that saved everyoneâs lives?â
Apollo 13?
Tang Yue was taken aback as his scalp tingled.
He had been trapped in a blind spot. Because the Eagle was a lander, Tang Yue had subconsciously believed that the Eagle was key to everything.
Everything revolved around the Eagle lander, so he had the crazy thoughts of dismantling the engines to install on the lander; thus, having to rack his brains on how stabilize the landerâs attitude.
But the one to really save Mai Dong⊠had never been the Eagle!
âWhat we are dismantling isnât the rocket engines,â Tomcat whispered, âbut the Eagle lander and Orion!â
Tang Yue was instantly enlightened. It was a crazy plan, crazier than grappling the lander with the space station. The failure to land successfully was ultimately a lack of thrust. If the thrust was insufficient, more power could be given. If an engine couldnât satisfy their requirements, they could use all nine!
It was unknown if this train of thought was inherited from the Falcon Heavy or the N1 from years ago.
If it were the former, Tang Yue would still feel a little at ease.
But if it were the latterâŠ
âYou said that Orion would be destroyed during an atmospheric entry!â Tang Yue stopped Tomcat.
âThatâs right.â Tomcat wore a cold expression. âWe want it to be destroyed!â
A robot was a robot after all; it wasnât humane at all when it went nuts.
Later, Tomcat said, âIn human aeronautics, 99% of the problems faced were a result of insufficient power. As long as there was enough power, none of the problems were problems.â
The final 1% was the fault of conventional frameworks.
âŠ
âWe all know that if a body is thrown from the sky on Earth, it will be a free-falling body, but itâs not truly a free-falling body.â
âBecause of air resistance?â Mai Dong asked.
âYes, this object will keep accelerating, but it wonât go on forever,â Tomcat said. âAt a particular point in its descent, gravity and air resistance will achieve a balance, resulting in terminal velocity.â
Tang Yue and Mai Dong nodded. It was easily comprehensible as it was in high school physics.
âThis is influenced by the density of the air, and in physics, thereâs a term known as the ballistic coefficient. The Martian atmosphereâs ballistic coefficient is extremely low, which also means that the atmosphere can hardly provide enough resistance to achieve a balance of forces,â Tomcat said. âIf we throw a powerless Eagle down, its deceleration will happen extremely slowly. And when its height drops to 40,000 meters, its speed will still exceed Mach 15. The surface temperatures will rise to 2000°C. This is also why we need the heat-resistant tiles.
âIn the 20th and early 21st century, many Martian probes perished because of this. The speed was just too fast for them to land successfully.
Tomcat shrugged its shoulders.
What was destroyed in the descent was Martian probes. The most classic example was the European Space Agencyâs Beagle 2. The poor lander remained in the desert to this day.
âA landerâs normal descent is this: It enters the atmosphere from an altitude of 125 kilometers. At this time, its speed should be about 5 km/s,â Tomcat used a pen to demonstrate it to the two others. It raised the pen in its paw high before stabbing it down. â85 seconds later, it will inflate an entry device for the first stage of the deceleration. Within that 85 seconds, its altitude will drop to 90 kilometers, enduring the peak heating.
âThe entry device will reduce the Eagleâs speed to below Mach 2. This is a Mach number that can withstand the deployment of a parachute. At 10,000 meters, the lander will deploy a parachute with a diameter of thirty meters.â Tomcat spread its paw above the pen to indicate the parachute. âThe parachute will reduce the speed of the Eagle to subsonic speeds until the lander reaches a height of 1000 meters. It will then abandon the parachute and activate the rocket engines to change its attitude to begin a powered descent.â
Tomcat slowly placed the pen vertically on the table.
These were things Mai Dong and Tang Yue knew as well. During their training prior to the mission, they had been briefed in detail about the spacecraftâs operational principles.
Tomcat was repeating it again today.
âWhy is the process so complicated?â Tomcat asked. âWhy does it need to be so complicated?â
Before waiting for their answer, Tomcat answered, âItâs because thereâs not enough power. We lack the power from rocket engines to provide a reverse thrust the entire time. Chemical rockets are too inefficient,â Tomcat said. âA rocketâs thrust is mostly pushing itself, with tonnes of its mass being fuel, and the rounding errors are the load.
âIn an ordinary descent, itâs not practical to have the rockets produce a reverse thrust the entire time. That will require the Eagleâs cargo and command module to be filled with propellant. The lander will become a flying fuel tank,â Tomcat continued. âBut thatâs in normal circumstances. What we are going to do is an abnormal descent⊠We donât care about efficiency or cost, nor do we care about the hundreds of tonnes of fuel. All we care about is that rounding error!â
Tomcat raised its paw and pointed at Mai Dong, enunciating each and every word: âA rounding error of 60 kilograms!â