After watching the two of them get on the lunar rover and leave, Bai Yixuan turned around and fixed his body with a hook lock.

Then, he raised the special shovel in his hand and smashed it at Yueyan beside him.

Because the gravity of the moon is only one-sixth of that of the earth, Bai Yixuan's movements seem a little light.

But at the moment when the shovel collided with Yueyan, a powerful recoil force came along the shovel.

The insignificant recoil force on the earth is like a nightmare on the moon.

Before Bai Yixuan could react, his body was thrown away.

The hook used to fix Bai Yixuan's body collapsed instantly and pulled his body back to its original position.

Bai Yixuan subconsciously raised his hand to wipe the cold sweat from his forehead, but touched the slightly cold mask.

Very dangerous...

It seems that I'm still trying too hard.

He carefully adjusted the strength of his shovel.

After more than ten minutes, he slowly breathed a sigh of relief and put a few pieces of shattered moon rocks into the storage box beside him.

Just as he was about to ask Hong Fan and the others about his condition via radio, a harsh scream came from his helmet!

"This is!!"

Bai Yixuan's heart instantly tugged.

Before he could think, he turned on the radio call function in the space suit: "Wanyi! What happened?"

After a brief silence, Xia Wanyi's terrified voice came from her helmet.

"We...we found something strange!"

Hearing Xia Wanyi and Hong Fan’s description, Bai Yixuan’s pupils shrank slightly and he immediately said, “Don’t move, I’ll come here right away!”

After interrupting the communication within the team, Bai Yixuan gently bit his back teeth and quickly connected the earth's communication channel.

“Call the ground command center!”

"Discover an abnormal condition! Repeat it and discover an abnormal condition!"

...

Twenty minutes later.

Bai Yixuan panted and found Xia Wanyi and Hong Fan standing next to the crater.

Seeing that the two of them were intact, Bai Yixuan breathed a sigh of relief.

fine……

"Ground Command Center, I've found them!"

Bai Yixuan said with relief: "They are fine, they are just standing next to a crater."

A few seconds later, Lu Yongchang's solemn voice came from his headphones.

"Received, what's the specific situation?"

"Wait, I'm connecting the camera." He turned on the camera on the top of his head.

"drop!"

A crisp reminder sounded inside his helmet.

Seeing that the camera on the panel began to transmit signals normally, Bai Yixuan "jumped" to his teammates: "What's going on?"

Hong Fan didn't say anything, but just pointed at the inside of the crater.

The crater is very small, with a diameter of less than 1 kilometer.

On the moon, it is a relatively small crater.

In addition, the crater is relatively shallow, and the sunlight can shine on its bottom without any obstacles.

The moment he saw the scene inside the crater, Bai Yixuan's pupils shrank violently!

On the silver-white surface of the moon, a black concentric circle suddenly appeared.

There are nine layers of concentric circles. Bai Yixuan estimated that the diameter of the outermost circle is at least twenty meters!

...

Earth, ground command center.

The moment when the black concentric circle appeared on the screen, the entire command center fell into silence!

More than ten seconds later, Cao Liangcai, who was standing beside him, said in a trembling voice: "This... what is this..."

Compared with Cao Liangcai, Lu Yongchang's reaction was much more dull.

After all, he had been mentally prepared long ago.

He took a deep breath and said softly: "Let the technical department analyze the image."

"I want to know whether the diameters of these concentric circles and whether their center position is standard!"

This practice is also to eliminate the fact that concentric circles are naturally formed.

After all, the universe is full of wonders. What if it is really a pattern that was smashed when the meteorites fell?

Although this probability is slim, scientific ones must be more rigorous.

The analysis results came out soon.

"Professor Lu, the center position of the nine concentric circles is very standard. Not only that, their curvature is very standard!"

A researcher hurriedly ran to Lu Yongchang with a report in his hand and said in a low voice.

Lu Yongchang's expression changed slightly, and he quickly reached out to take the report.

Looking at the data on the report, Lu Yongchang's face suddenly became ugly.

"Old Cao, come and take a look. These nine concentric circles are standardly like they were drawn with compass!"

Cao Liangcai, who was beside him, leaned over.

The moment he saw the data on the report, Cao Liangcai's expression also changed slightly: "It seems that this concentric circle should not be a natural pattern."

"Is it possible that it was left by the United States last time it landed on the moon?"

Cao Liangcai's eyes moved slightly and he said softly: "Don't forget that this area is also the moon landing site of Apollo 11, the United States."

Lu Yongchang pondered for a moment, shook his head slowly and said, "No, it will definitely not be a trace left by Apollo 11."

"You see, based on the diameter of this crater and the picture ratio, the largest concentric circle diameter reaches 20 meters."

"The Apollo 11 command cabin is conical, with a diameter of 3.9 meters at the bottom. The service cabin is a cylinder with a diameter of 3.9 meters. The size difference between the two is too big."

Speaking of this, Lu Yongchang paused slightly: "I wonder if you feel that this black concentric circle is a bit like the jet port of the Hall thruster?"

Cao Liangcai's pupils shrank suddenly!

He hasn't noticed this yet!

The Hall thruster nozzle of Xuannv No. 1 is also composed of several concentric circles with regular shapes!

He swallowed slightly and said softly: "Can you say... other countries on earth have mastered mature Hall propulsion technology?"

Lu Yongchang shook his head with a serious expression.

"Won't!"

"Before mastering the technology of small fusion reactors, Hall propulsion technology is basically equivalent to being useless."

"What's more, there shouldn't be such a big spacecraft on Earth."

"The Hall thruster nozzle with a diameter of twenty meters... In my opinion, this is definitely an engine that only spacecraft across the star system will have!"

A drop of sweat slowly slid down Cao Liangcai's forehead.

The situation now is completely beyond his control.

He looked at Lu Yongchang on the side with a nervous look: "Professor Lu, we are now..."

Lu Yongchang looked shaking and turned his head to the researcher beside him and said, "Report this matter to the Chairman of Congress, remember, the speed should be fast! Also, take confidentiality measures!"

Seeing the researcher leave, Lu Yongchang's eyes gradually became entangled.
Chapter completed!