It's reasonable for me to have a two-way foil for a second-level civilization, right?

Chapter 88 The Weird Black Circle

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 threw it at the moon rock 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 the shovel collided with the moon rock, a powerful shock force came along the shovel.

The shock force that seems insignificant on the earth is like a nightmare on the moon.

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

The hook used to fix Bai Yixuan's body instantly collapsed, pulling his body back to the original place.

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

so close……

It seems that I am still working too hard.

He carefully adjusted the strength of his swing of the shovel.

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

Just when he was about to inquire about Hong Fan's situation through the radio, a piercing scream came from the helmet!

"This is!!"

Bai Yixuan's heart throbbed instantly.

Before he had time to think, he directly turned on the radio call function in the spacesuit: "Wanyi! What happened?"

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

"We...we found a strange thing!"

Hearing Xia Wanyi and Hong Fan's description, Bai Yixuan's pupils shrank slightly, and immediately said: "You two don't move around, I'll come right over!"

After interrupting the communication within the team, Bai Yixuan lightly gritted his molars, and quickly connected to the communication channel on Earth.

"Call the ground command center!"

"An abnormal situation was found! Repeat, an abnormal situation was found!"

……

Two 10 minutes later.

Panting, Bai Yixuan found Xia Wanyi and Hong Fan who were standing beside the crater.

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

fine……

"Ground command center, I found them!"

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

A few seconds later, Lu Yongchang's dignified voice came from his earphones.

"Got it, what's the specific situation?"

"Wait a minute, I'm connecting the camera." While speaking, he turned on the camera on the top of his head.

"drop!"

A crisp notification sounded in his helmet.

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

Hong Fan didn't speak, but just pointed to the inside of the crater.

The crater is very small, not even 1 km in diameter.

On the moon, it is considered a relatively small crater.

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

The moment Bai Yixuan 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, and Bai Yixuan estimated that the outermost circle has a diameter of at least 20 meters!

……

Earth, ground command center.

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

After more than ten seconds, Cao Liangcai said tremblingly, "This... what is this..."

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

After all, he had already been mentally prepared.

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

"I want to know the diameters of these concentric circles, and whether their center positions are standard!"

This approach is also to rule out the natural formation of concentric circles.

After all, there are all kinds of wonders in the universe, what if it is really the pattern that was smashed out when the meteorite fell?

Although this probability is very small, but to do science, you have to be more rigorous.

The analysis results will come out soon.

"Professor Lu, the positions of the centers of the nine concentric circles are very standard, not only that, but their curvature is also very standard!"

A researcher ran to Lu Yongchang with a report sheet 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 expression turned ugly for a moment.

"Old Cao, take a look, these nine concentric circles are as standard as if they were drawn with compasses!"

Cao Liangcai leaned over to the side.

The moment he saw the data on the report, Cao Liangcai's expression changed slightly: "From this point of view, this concentric circle should not be a naturally formed pattern."

"Could it be left behind from America's last moon landing?"

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

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

"Look, according to the diameter of the crater and the scale of the picture, the largest concentric circle has a diameter of 20 meters."

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

Speaking of this, Lu Yongchang's voice paused slightly: "I don't know if you feel that this black concentric circle is a bit like the jet port of the Hall thruster?"

Cao Liangcai's pupils suddenly shrank!

It doesn't mean he hasn't noticed yet!

The nozzle of the Hall thruster of Xuannv-[-] is also composed of several regular concentric circles!

Hall Thruster

He swallowed slightly, and said softly: "Could it be that... besides us, there are other countries on Earth that have mastered the mature Hall propulsion technology?"

Lu Yongchang shook his head solemnly.

"will not!"

"Before mastering the small fusion reactor technology, Hall's propulsion technology is basically equivalent to chicken ribs."

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

"The Hall thruster nozzle with a diameter of 20 meters... In my opinion, this is definitely an engine that a spacecraft that crosses the star system will have!"

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

The current situation is completely beyond his control.

He looked anxiously at Lu Yongchang beside him: "Professor Lu, let's now..."

Lu Yongchang's expression turned serious, and he turned to the researcher at the side and said: "Report this matter to the chairman of the congress, remember, it must be fast! Also, take measures to keep it secret!"

Seeing the researcher leave, Lu Yongchang's eyes gradually became tangled.

"Perhaps, we can only know the truth of the matter if we get close to that black circle!"

Chapter 89 The Traces Left by the Hall Thruster?

Lu Yongchang's words obviously startled Cao Liangcai who was on the side.

"Professor Lu?"

"Are you sure you want to let three astronauts take such a big risk?"

"How about... let them come back, let's have a long-term plan?"

Lu Yongchang looked at the data on the report with an uncertain expression.

The danger is certain.

After all, no one knows what the black circle is.

In case it is some kind of high-intensity radioactive substance... Even with the protection of spacesuits, these three astronauts will confess to being on the moon.

However, the current situation Xia Guo is facing does not allow them to think long-term!

Lu Yongchang gritted his teeth, a flash of determination flashed in his eyes, and then he lightly pressed the radio communication button.

"This is the ground command center, please answer if you receive it!"

……

Bai Yixuan stared at the black concentric circles in the crater, and a chill came out of his back involuntarily.

"You said, could this be a trace left by an alien civilization?"

silence.

There was no response in the team voice.

After a long time, Hong Fan's unique hoarse voice sounded on the radio channel: "It should be."

"Maybe, we are being watched by this alien civilization right now..."

Xia Wanyi at the side shivered suddenly, and subconsciously raised her head to look at the sky.

Total darkness.

Except for a little bit of starlight, she couldn't see anything strange.

"laugh……"

Just when Bai Yixuan was about to say something, a burst of electric current came from the radio.

"This is the ground command center, please answer if you receive it!"

Bai Yixuan's expression suddenly became serious: "Bai Yixuan received it, please tell me!"

After a few seconds of delay, Lu Yongchang's slightly tangled voice came from the radio: "Captain Bai, after technical analysis, we basically confirm that the black concentric circle pattern in front of you is a man-made object."

Bai Yixuan's pupils dilated slightly, and his breathing became a little short: "Then...Professor Lu, what do we need to do?"

The massive secretion of adrenaline made his voice a little hoarse.

Lu Yongchang's sigh came from the radio.

"Captain Bai, we need to analyze the truth of this black circle, so I hope you can go to the black circle to check."

"Of course, it's not mandatory."

"After all, we don't know if it's dangerous or not."

"Once there is danger, maybe..."

Speaking of this, Lu Yongchang's voice suddenly paused: "So, everything follows the principle of voluntariness."

Bai Yixuan's breathing became more and more rapid.