Sun Tan still has some distrust of Nina, after all, the two have just met, and they can't have any problems with their actions this time, and now in this situation, if they are caught, they will be dead. However, Mark still agreed to her request, although the two didn't know each other too well, but from the short contact, Mark felt that she was a sincere person, and what she said really touched him, the more important issue is manpower, although confidentiality is very important, but it is difficult to do anything with the two of them, and it is always good to have one more person to help.

So at Mark's insistence, Sun Tan still took her, the cockpit of the military armor was for two people, but several of them were relatively thin, barely able to sit down, and after Sun Tan launched his horsepower to escape from the pothole, Mark saw an amazing scene on the ground.

The ground is covered with intricate black networks, like blood vessels bursting on the skin, the white ground is torn apart, and it makes people feel broken at a glance, those are the ground that was cracked in the earthquake, stretching for dozens of kilometers, extremely spectacular, no one knows the cause of the earthquake, maybe it is related to the impact of the mysterious cube, but there is no doubt that this will not be the last disaster, after which more unexpected disasters will follow.

The group drove the military multi-functional self-propelled armor from the top of the subsidence, this mecha is equipped with ion thrusters, flying by jetting ion plasma, the endurance is not strong, but at least it can let them leave the area, Sun Tan is not very good at driving, if it weren't for the mecha with SEM and auxiliary piloting, he would definitely drive into the ditch, after Mark came up, he gave up the driving position to Mark.

"Alright, now tell me what your plans are." Mark asked Sun Tan as he familiarized himself with the console.

"Then I said, in fact, a few days ago I was at a loss, originally I have been thinking about how to simulate and enhance our transmission signal, but there is no breakthrough, depressed I went to read my grandfather's book, hoping to find some inspiration, I have to say, although the old man is very smart, but he doesn't like to talk about people, and few people can understand what he writes." Sun Tan said as he pulled out a worn-out paper book from his bag, with a few large characters printed on the faded cover - lunar conjecture.

"I didn't think you had anything older than that machine." Mark complained that paper books can really enter museums by now, and at the end of the 21st century, there are no paper books on Earth, let alone on the moon, which has no trees at all.

"Is it rare? I've got more old fun. Nina said with a wink.

"In short, he wrote some of his research and hypotheses about the moon in it, he collected and analyzed some moon rocks, and found that the rocks collected from different locations and different states have a surprisingly high density, and if there is a liquid core inside the moon, or a solid body composed of solid rocks, the mass should be several times larger than now!" Sun Tan took out a bunch of ancient pieces of paper from the mezzanine of the book, some were newspaper clippings and some were photocopied fragments of papers, "However, the moon does not have the high quality to match, it has been hanging on our heads for thousands of years, so we are accustomed to it, we never thought that it is abnormal, its mass is too light, if it is a normal satellite, the deflection angle of the earth will be greater, the four seasons will be longer, and the tidal activity will be more intense, but none of these, there is something hidden inside the moon, this is a hollow planet!" ”

"What?" It was the first time Mark had heard such a statement after living on the moon for so many years.

"It's really possible." Nina added: "I also noticed this strange phenomenon when I was doing geological research, when a solid object was impacted, two waves could be measured, one was longitudinal and one was a surface wave, while a hollow object could only detect surface waves. A longitudinal wave is a penetrating wave that can penetrate an object, and the surface wave can only be transmitted on a very shallow surface. I once worked in the geological base of the moon for a period of time, and the vibration detector placed on the moon, after a long period of recording, did not record longitudinal waves, all of them were surface waves. ”

"And then, what does that mean?" Mark felt that he was too young to know what he could come up with to save the planet.

"Next is the point, now the exploration of the moon has been very deep, scientists have used satellite technology to scan the entire lunar surface, draw a complete map of the lunar magnetic field, but there are still many places that are undetected areas, those places seem to be blocked by something, my grandfather recorded a news, an astronaut detected a metal signal underground in the no-signal area, he suspected that there was a huge amount of metal veins underground, but it was quickly denied, the signal came and went like a ghost, In the end, it had to be stopped. Sun Tan's expression suddenly became excited when he said this, he raised a finger and said: "That may be the traces left by other civilizations, although I don't know what they are, but we have to go and see, if we can find the spaceship or base station of the alien civilization, maybe we can use their technology ......"

"Use their technology to send a message to the hijackers, and if the aliens on the moon are advanced civilizations, they can deter each other!" Mark finally got to the point.

"I see, you're so smart!" Nina also suddenly understood their plan after listening to them.

"However, it is still a bit difficult to implement, and I have recorded all the unknowns at the moment." Sun Tan took out a tablet from his bag and opened a map software, on which were the places he had marked, a dense list, if they looked for them one by one, it was estimated that they would not be able to find it for several months...... Not to mention that they didn't have a few months, and the mech's fuel and supplies were limited, and they could only get to less than ten locations at most.

"Damn, why are there so many...... Are these all places to hide spaceships? Mark held the tablet with a shocked expression.

"No, there are some of them that we are looking for, and most of them are just disturbed by the magnetic field of the moon itself." Sun Tan said.

"That can't be helped...... You can only gamble! Go to the nearest one! Mark slapped the steering wheel and shouted.

"Let's go here." Just as they were about to make a desperate bet, Nina stretched out a slender jade finger and tapped on the map, and her crisp and moving voice gave Mark a revelation in time like Ganlin, "Remember the legend I told you? My ancestors drew a complete map of the moon hundreds of years ago, and even today they have records of many unexplored places, and the great prophet once told the place where he dreamed, and the place where the river gushed out of the moon, is here. ”

"It's too godly, I won't believe it." Sun Tan said with a disdainful expression.

"It's better than Meng, let's go!" Mark turned around and added a throttle and drove towards Nina's words.