Chapter 508 - 497 SpaceX Gains a Point_1

"Lift off!"

A newly manufactured Falcon 9 rocket carrying the spacecraft codenamed "Dragon-Gravity" soared into the sky from Cape Canaveral. It was an unmanned launch.

Nearly a year ago, Musk proposed the "flexible gravity solution," and after a lengthy development process, Lockheed and SpaceX made it a reality.

Actually, the most fundamental and important cable technology was easy to solve. Once the Dragon spacecraft, weighing less than 20 tons, splits, each end has a mass of less than 10 tons. The centrifugal force generated by the rotation was quite manageable.

It took only three months to solve the FGD section, but the spacecraft’s design needed major changes, which took over half a year.

The original interior design of the Dragon spaceship didn’t consider gravity issues. To provide astronauts with the proper direction of gravity, a re-docking had to be performed in space.

That is, after entering space, the command module would have to separate from the service module, then rotate 180 degrees, use the cable deployment module on top of the service module, and then start rotating by releasing the cable to the predetermined length.

Re-docking meant that the command module needed to be improved, and special emphasis had to be placed on the docking section, since it was to bear the significant centrifugal force during rotation.

Then there was the attitude control system, which is just as important as the cable system, namely a set of powerful RCS. Both the service module and the command module needed it. It provided the speed for rotating and stopping and had to be precise and able to work for an extended duration.

The last issue was the trimming of the entire system when it started rotating, which was the biggest trouble in the design.

Although the weight difference between the two parts was not significant, at a high-speed rotation of 2 turns per minute, even a slight weight imbalance or uneven distribution of the center of mass would cause the entire rotating body to exhibit attitude or orbital deviations.

But the mass and center of mass of both the service module and the command module are constantly changing—the former continuously consuming fuel and the latter having people living and moving around inside.

The mass shift of the two rotating bodies is unpredictable, so the RCS control computer needs to respond timely, intervening whenever the attitude exceeds set limits, but it generally doesn’t work unless there is a significant issue, as RCS fuel needs to be conserved.

The essence of the entire FGD system lies in this automated attitude control system, which is much more difficult than the material of the cable.

More than 10 months later, the "Gravity Dragon" spacecraft had an unprecedented launch mass of 19 tons, more than 30% heavier than the original Dragon with crew, so the Falcon 9 rocket launching it could not be reused, or else it would not meet the required capacity.

Musk initially planned to use an older Falcon 9 for the mission, but Lockheed, fearing the hard-won spaceship would be ruined by a used rocket, insisted on wasting a new rocket.

On the 22nd, Central time 8 o’clock, humanity’s first artificial gravity spaceship reached low Earth orbit.

Houston spent 3 hours checking the overall condition of the spaceship and then confirmed the re-docking process.

The command module gently separated from the service module. Where the two were previously linked by single-use explosive bolts, it was now changed to a ring-shaped docking interface capable of providing high strength. A lot of effort was put into creating this interface to leave space for the cable connection in the middle.

After separation, the command module, with the assistance of the RCS, turned 180 degrees, with its head facing the command module and ejected the cover on top, revealing the cable release port.

This was originally the docking interface of the spaceship, but now, obviously, it no longer had the capability to dock with other spacecraft. Lockheed’s solution to this issue was to convert the side exit to a docking port, but this "Gravity Dragon" did not have it.

It took another hour and a half to complete the docking.

Houston continued with various parameter checks, and only at 16:00 did they confirm to proceed with the rotation test.

The cable used by "Gravity Dragon" was of a woven mesh hollow design, characterized by being very space-efficient and with very high tensile strength; each thin cable was made of multiple layers of structure, with a design redundancy of 500%, and an even higher maximum instantaneous load capacity, so there was no need to worry about the cable breaking.

The two docked sections of the spacecraft began to gradually increase their distance under the action of RCS, and the gray-white cable was slowly released. It had a total length of 220 meters, capable of producing a comfortable gravity of 0.5G without causing noticeable dizziness to the astronauts, yet the combined weight was still less than that of Musk before his diet.

Releasing the cable was a slow and cautious process; doing it too quickly could cause the two parts to move irregularly in opposite directions under the stress of the released cable, so the release speed had to be controlled precisely. There were also devices on the release mechanism for measuring the real-time tension.

The entire release process took a long four hours, and it was already approaching America’s summer night.

Newly appointed Director Robert was present on-site. "Gravity Dragon" was, of course, strongly supported by NACA, and if it could win the first successfully operating artificial gravity device for humanity, it would definitely be a significant accomplishment to boast about in front of Congress.

Because the cable release process was very cautious, the relative positions of the command module and the service module were now quite good, almost perfectly in a straight line. The cable was basically straight but not under tension.

Musk, still in Florida, connected remotely via the control room there, and said over the phone:

"Let it spin, Director, I have faith in it—not just faith that we’ll get the experimental data, I’m certain it will work,"

Robert nodded, giving the order to reach a rotational speed of 1 turn per minute, and if about 0.1G of gravity could be produced inside the cabin, they could continue to increase the speed.

After the ground command was issued, the RCS systems of both the command module and service module first released gas in the outward direction to tighten the cable to the pre-set tension, and then, under everyone’s anticipation, created opposing thrust at an angle of about 85 degrees from the cable, starting to rotate around a non-existent central axis.

At 1 turn per minute, the motion speed of the rotating body was 11.5 meters per second, which was very easy to achieve. Even though the RCS was started at minimum power, it still quickly increased the speed of both modules, and after less than 20 seconds, they both shut off their RCS in the direction of motion.

In a 400 kilometers high orbit, two spacecraft, each weighing about 9.5 tons, were connected by a cable and rotated around each other like a binary star system.

A gravimeter, precise to the third decimal point, was installed inside the command module. Now its display number fluctuated between "0.121" and "0.127."

Looking at the overall stability of the rotating system, according to ground-based antenna array detection, there were no significant orbital deviations, indicating that the RCS successfully controlled the symmetry of the rotating body.

Now, humanity’s first artificial gravity system was officially in use.

In Houston and Florida, applause and cheers erupted simultaneously.