Chapter 81: Challenging Space Development
“Ten, nine, eight, seven…”
The countdown continued.
Today, a survey rocket was set to launch from a hastily constructed launch site over the ocean. Frustrated by the lack of useful resources, Commander Eve had finally ordered Ringo to allocate some resources for space development. This newfound flexibility was made possible by the increased resource shipments from the Second Fortress.
However, once a certain level of success was achieved, the launch site would be dismantled and repurposed for the construction of an underwater platform.
“Ignition… thrust at nominal levels. Two, one, lift off.”
The rocket being launched was a disposable solid-fuel rocket. It carried survey equipment at its tip and would accelerate as long as its fuel lasted. If it failed to break free of the gravitational pull, it would simply fall back down; if it succeeded, it was planned to operate as a makeshift satellite for several days. Since there were almost no propulsion devices capable of orbital control, it was expected to ultimately fall back into the atmosphere and burn up.
“Number One is ascending normally. Passing altitude of 5 kilometers.”
“Oh, it’s fast, really fast!”
The craft was lightweight, a straightforward rocket design. The second stage was also solid-fuel, with very few instruments aside from the fuel itself.
“Altitude reached 10 kilometers. Eleven, twelve…”
The rocket continued to ascend smoothly. Data from the early warning high-altitude plane confirmed that it could ascend without issue up to nearly 20 kilometers.
“Altitude 18 kilometers. Discrepancy confirmed between accelerometer readings and radar measurements.”
“…Here it comes.”
A decrease in ascent speed had been observed during previous rocket launches. Despite appearing normal, the acceleration was clearly diminishing. However, this time, the rocket was equipped with a precise accelerometer. This allowed the problem to be visualized as a discrepancy between the apparent acceleration and gravitational acceleration.
“No abnormalities detected in the rocket motor’s combustion temperature. No issues with the craft’s temperature, pressure, or vibrations. Based on the observations, it is possible that gravitational acceleration is increasing.”
“…Hmm? Wait, can gravitational acceleration change?”
“It does not change.”
“It doesn’t, right?!”
No abnormalities were observed in the burning rocket motor. Observations across various electromagnetic wavelengths found no issues. Internal sensors showed no strange readings, but the only anomaly was from the accelerometer. There were no significant changes in acceleration at various positions within the craft. Yet, the acceleration calculated from external radar measurements was visibly decreasing. This indicated that some external force was acting to suppress the rocket’s acceleration.
While one might simply attribute this to air resistance, it was hard to believe that the atmosphere would become denser as altitude increased. There was also a possibility of changes in atmospheric composition, but no significant issues had been found during previous high-altitude plane surveys up to around 30 kilometers. This left one other possibility: universal gravitation, specifically the gravity of this planet.
“I’ve had my doubts from the beginning. This planet has a diameter far greater than Earth’s, yet its gravitational acceleration is approximately 9.81 m/s², nearly identical to Earth’s. Gravitational acceleration is determined by diameter and mass, but for it to match to five decimal places is far too convenient.”
“…Well, that’s certainly true. It means the diameter and mass are balanced just right to yield the same gravitational acceleration, right?”
“Yes, Commander Ma’am. However, the likelihood of this planet coincidentally having the same gravitational acceleration as Earth is nearly zero. Moreover, this planet has water, life is thriving, and humans with almost no genetic differences dominate. It’s more natural to consider that there is some form of manipulation at play rather than attributing it to chance.”
Even as Ringo explained, the rocket continued to ascend. It was not gaining speed as initially planned, and consequently, its altitude was not increasing as expected. Still, the rocket had already surpassed an altitude of 60 kilometers and continued to rise.
“The first stage rocket has completed combustion. Burning ceased. First stage separation. Second stage rocket motor, ignition… combustion status good. Fairing separation. Success.”
Ringo carefully monitored the rocket’s trajectory. Observations of acceleration after engine shutdown, with the atmosphere thinning and only gravity acting as an external force. The values from the internal accelerometers and the speed calculations from radar measurements were being analyzed.
“Commander Ma’am. It appears that gravitational acceleration at high altitudes is several times greater than on the ground.”
“…Huh? I’m sorry, but I don’t understand.”
As one moved away from the surface, gravity should increase. This was, of course, a non-scientific phenomenon. Logically, one would expect gravitational acceleration, or universal gravitation, to decrease the further one was from a massive object. However, at around 100 kilometers altitude, this was within the margin of error.
“Commander Big Sister, um… I’ve finished the calculations… I think gravity is twice that of the surface…”
“Oh, thank you, Olive. Is that so? So, gravity doubles as we go higher?”
“Altitude 120 kilometers. Acceleration has stabilized. Gravitational acceleration is approximately double, and no further increases have been observed. Due to gravity, the planned speed has not been achieved. The required orbital velocity has not been reached.”
“Ugh…”
The required orbital velocity is defined as the speed necessary to maintain an orbit without returning to the surface if launched at the correct angle. Satellites must reach this speed; otherwise, they will eventually fall back to the ground.
It seemed that the thrust of the launched survey rocket would not be sufficient to reach that speed.
“Assuming the gravitational acceleration at the surface is 9.81 m/s², the diameter of this planet is approximately 20,000 kilometers. If we could accelerate to the required orbital speed of 36,600 km/h at an altitude of 300 kilometers, it would function as a satellite. However, at the current acceleration, we might only reach 25,000 km/h. Moreover, if gravitational acceleration is doubled, the required orbital speed exceeds 50,000 km/h. A fundamental redesign of the rocket motor is necessary.”
“…So, simply put, we need double the performance.”
“Yes, Commander Ma’am.”
While Ringo’s answer simplified the issue, it was not that straightforward. To increase thrust, the rocket motor would need to be strengthened or additional nozzles added. Either way, this would add weight to the rocket motor itself and proportionally increase fuel consumption. To compensate for this weight increase, more fuel would need to be added, which would further increase the weight of the fuel itself, leading to a compounding effect where the rocket’s weight increased exponentially without altering its launch capacity.
“Commander Big Sister, what should we do…?”
“…We could either invest more resources or give up at this point…”
If left to Ringo and Olive, they could likely develop the rocket with minimal resource expenditure. However, new developments typically consumed resources like water. This would completely halt the construction of the underwater platform and could even hinder the development of the Second Fortress.
“Hmm… For now, let’s freeze space development. We’ll redirect resources to the mining development at the Second Fortress and the construction of the underwater platform. Once the underwater platform becomes operational, we’ll have more resources available. We can reconsider at that time.”
“Yes, Commander Ma’am. Olive, the design for the solid rocket motor can be done at a lower priority, but let’s proceed with it. If we secure the resources, we can start testing immediately.”
“…Understood.”
As they were deciding on the future direction of The Tree, the rocket’s acceleration came to an end.
“Second stage rocket, combustion stopped. Second stage separation. Third stage engine, ignition… combustion commencing, all sensor values normal. Fuel tank pressure normal.”
The first rocket launched by The Tree ultimately reached an altitude of 400 kilometers. There, it exhausted its fuel and separated the observation device. The device continued to ascend due to inertia but eventually succumbed to gravity and began its descent.
“…Observation device, surface temperature rising. High temperatures due to adiabatic compression are occurring.”
The observation device collected various data before ultimately burning up. The data gathered would be utilized across various fields in the future.