I live in the Martian wilderness!

[Second Stage (10:30 AM - 17:10 PM): High-temperature sintering of Mars bricks.]

[Task]: Produce 80 "mortise and tenon interlocking structure bricks" for bricklaying.

[Single block specifications]: 500mm × 250mm × 150mm (0.01875 cubic meters)

[Single piece weight]: 54.3 kg

Total weight: 4.35 tons

[Working Time]: Estimated 6 hours and 40 minutes.

Gu Yu looked at the 54.3 kilograms in the data column. "Wow, a brick weighs over 50 kilograms? A concrete block of the same size on Earth only weighs about 20 kilograms, right?"

"The data is correct, Lieutenant Colonel. Please do not use Earth's experience to judge alien materials."

Xuanjian immediately pulled up a comparison chart on the side of the screen labeled "[Historical Archives: 2025·China Space Station·Lunar Soil Brick Exposure Experiment]".

"As early as 22 years ago in 2025, Chinese scientists had already confirmed this when they sent the first batch of lunar soil bricks into space using the Tianzhou-8 spacecraft."

"The mortise and tenon structure lunar soil brick developed by Huazhong University of Science and Technology has a density of over 2.9 g/cm³, a compressive strength of over 100 MPa, and can withstand a weight of 1 ton per square centimeter."

Xuanjian projected the data onto the Martian brick model and explained:

"The basaltic soil on Mars is rich in heavy elements such as iron and magnesium. After the Shengong module is microwave sintered, its internal porosity will be compressed to the limit, and the density will be close to 3.0 g/cm³."

"Simply put, what you are firing is not bricks, but 'artificial stone' that is close to the hardness of granite and has a density three times that of water."

"Although its volume is only equivalent to 12 standard red bricks on Earth, its weight is equivalent to that of an adult woman."

"In the 0.38G gravity environment of Mars, its perceived weight is about 20 kilograms, which is the golden weight for individual soldier carrying operations."

"I see..." Gu Yu suddenly realized, looking at the dark brick model with a look of understanding in his eyes.

Xuanjian retrieved the energy consumption model of the Mars brick:

"Mars bricks require basalt powder to be heated to over 1100℃ to undergo a 'geological polymerization reaction' and become ceramic. Its energy consumption is more than ten times that of the 'carbon-sulfur' process."

Gu Yu looked at the clear comparison chart of energy consumption and time and nodded.

"Very good. First, use a low-temperature process to quickly print the panels for the pool, and then use a high-temperature process to slowly fire the bricks."

"In this way, while the bricks are being fired this afternoon, I can go into the backyard first and start assembling the pool ahead of time using the carbon plates that were printed this morning."

"Perfectly correct procedure, Lieutenant Colonel."

"Let's get started!" Gu Yu stood up. "Let's begin with the carbon fiber plates. I'll provide the materials."

He walked to the control panel of the Divine Craft Module and activated his [Carbon Control] ability.

Strands of black carbon powder, like an endless stream of black quicksand, fell from his fingertips into the filter of the filling port, mixing with the yellow sulfur powder.

Today will be the first "mass production day." The bricks for the pool's running track and walls will be forged one after another on the same machine.

By the time it got dark today, Gu Yu was not only able to prepare all the bricks, but he was even able to complete the construction of the pool ahead of schedule!

......

While firing bricks, Gu Yu was not idle; he began preparations for building the wall—cutting sealing strips.

First, using a handheld laser rangefinder, several key positioning points were marked on the ground and the top of the cave.

Then, from cargo hold number two, they took out a metal disc the size of a car tire.

This is the portable deployment tray for the "high-elasticity fluororubber sealing strip".

A roll of dark brown fluororubber strip, hundreds of meters long and with a circular cross-section, is neatly wound around the core.

Gu Yu firmly fixed the deployment plate to a multi-functional mounting point on the side of the Tissot vehicle.

He pulled out the head of the sealing strip and passed it through a small square metal box that came with the deployment disk.

This small box is the core of this system: the "photoelectric fixed-length thermal cutting unit".

Gu Yu entered a few simple parameters on the touch screen on the side of the small box.

Cutting length: 0.5 meters

[Number of pieces to be cut: 80]

【Mode: Automatic】

"implement."

As the command was confirmed, the deployment disk began to emit a slight motor hum, automatically and at a steady speed conveying the dark brown rubber strip outwards.

Whenever the photoelectric sensor detects that a length of 0.5 meters has passed, it will trigger a signal.

Inside the small square box, a "nickel-chromium alloy hot-cutting wire" that has been instantly heated to 400 degrees Celsius will "whoosh" down.

"hiss--"

With a slight sound, the tough fluororubber strip melted instantly, leaving a smooth, mirror-like cut, even with a hint of freshly solidified luster.

Send out -> Measure -> Cut off.

With the final rise and fall of the cutting unit, 80 sealing strips of exactly the same length were neatly stacked in the material basket next to it.

Gu Yu knew that the most crucial factor in building an airtight wall that could withstand the huge pressure difference between the inside and outside of this chaotic natural lava pipe was not how hard the bricks were.

Instead, the walls must be absolutely straight! In the face of high-pressure gas, even the slightest angular deviation can become a fatal leak point.

He had to draw an absolutely precise "skeleton" for this wall.

He pulled out a futuristic-looking "pistol" covered in optical lenses from deep inside Tissot's toolbox—the 3D laser theodolite.

"Lieutenant Colonel, the equipment has completed its self-test," Xuanjian reported concisely. "The laser ranging and physical marking modules are ready, and the AR projection error has been calibrated to the micrometer level."

"Great, let's go to the backyard."

Gu Yu hung the instrument on his waist, passed through the airlock, and strode to the designated construction point, which was about 10 meters away from the cave entrance, where he raised the "pistol" in his hand.

"Xuan, activate AR lofting mode and project the design drawings onto me."

"clear."

As soon as the command was given, Gu Yu's helmet vision lit up instantly.

A miracle occurred—a translucent "wall of light and shadow" composed of ghostly blue virtual light rose up from the rough ground without warning!

It stands perfectly in the dark void, straight and smooth, exuding the precise beauty of industrial geometry.

However, the problem becomes apparent when its top extends to the top and edges of the hole.

The upper edge of the light wall did not fit perfectly into the rock, but rather cut deep into the jagged basalt, or hung in the depressions, leaving huge gaps.

"Xuan, do you see that? The height difference is even more than 30 centimeters. If we directly lay the bricks on it, this will not be an airtight wall, but a sieve that lets in the air."

"Understood, Lieutenant Colonel. The top and surrounding areas must be repaired."

"That's right, we have to cut a groove in the stone to build this wall."

Gu Yu raised the theodolite and locked onto the top of the cave through the aiming scope.

"Now, I'll draw this groove line first."

He pulled the trigger, and a red laser beam struck the rock on the cave ceiling with pinpoint accuracy.

As he slowly moved his arm, the high-pressure nozzle at the front of the theodolite emitted a rhythmic hissing sound.

"Pfft—pfft—pfft—"

Clumps of highly adhesive red marker paint were precisely sprayed onto the black rocks.

If you look at them together, those red dots perfectly outline the contours of the "virtual light wall" cutting into the rock.

A few minutes later, a striking red dotted line was deeply imprinted on the previously messy cave ceiling and edges.

"Xuan, write down these coordinates. After the bricks are fired this afternoon, use your super-controllable shuttle to mill a perfect groove, 10 centimeters deep and 50 centimeters wide, along these red dots!"

"Coordinates locked, cutting path generated."

Once the most difficult part, the top, was dealt with, the ground layout became much easier.

Gu Yu quickly marked two clear red cross anchor points on the ground, which were the baselines for the base of the wall.

He took two steps back, looked at the striking red top line in the darkness and the cross on the ground, and nodded in satisfaction.

The heavens are round and the earth is square; the rules are already set.

The lines have been drawn, and the grooves have been ordered. Now, all we have to do is wait for the bricks to be delivered from the kiln outside, and then we can officially start building the walls.

Just as Gu Yu finished drawing the last cross anchor point, a crisp notification sound came from his headphones. It was the "completion alarm" he had set a few hours earlier.