A spacecraft without an engine does not rely on its own power, but on the external power of the launch vehicle when it is lifted off.

From the International Space Station to a satellite, they basically rely on the initial power of the launch vehicle to operate in outer space. Of course, small spacecraft such as satellites, except for a very few satellites with small independent power systems, other satellites do not have the function of orbit change. Large spacecraft such as the International Space Station, although it also has a power system, but this power system is only used when the ISS adjusts its orbit, and the ISS does not rely on its own power system, but still comes from the initial power exerted by the launch vehicle.

However, the U.S. Space Shuttle, which has now been deactivated, and the current lunar spacecraft are different from ordinary spacecraft, whether it is a space shuttle or a lunar spacecraft, they all have a large-scale power system that can be carried by themselves, and they can make this spacecraft freely accelerate or decelerate in space.

Although the main power system of the lunar spacecraft is not a chemical fuel power system with stronger propulsion, the lunar spacecraft with four 900 mm ion thrusters has a more durable acceleration ability.

These four 900-millimeter ion thrusters are very different from the 900-millimeter ion thrusters that were just developed last year, and after more than a year of improvement, although the caliber of the ion thrusters has not changed, this improved ion thruster has more thrust.

In fact, in terms of the current human ion thruster technology, this kind of thruster that represents the future can only be used in space now, because space is basically out of a vacuum, so this kind of ion thruster with very small propulsion can be useful.

In 1998, the Jet Propulsion Laboratory in the United States launched a Deep Space 1 probe to test advanced flight technology. The detector is powered by an ion thruster with a diameter of 304 mm, and the total weight of the detector is 486.3 kg. These include 373.7 kg of detector dry weight, 31.1 kg of hydrazine propellant, and 81.5 kg of xenon for ion propulsion. The probe completed its 20-month mission on December 18, 2001, and has successfully provided a variety of useful data for a new generation of ion thrusters.

The "Deep Space 1" probe flew hundreds of millions of kilometers with just more than 100 kilograms of fuel, which shows how important the future of ion thrusters is. It's just that the ion thruster used by the "Deep Space One" probe at that time was only 304 mm, if it were on Earth. The thrust of this ion thruster is only enough to push a piece of paper

Last year, Dr. Schmitz's team succeeded in developing a 900-millimeter ion thruster, which is nearly 500 millimeters larger than the one used in the Dawn probe ten years ago, and the thrust is about seven times higher than that of the ion thruster.

However, the 900-millimeter ion thruster developed by Dr. Schmitz's team at the time was only the initial model, and after more than a year of improvement, this 90-millimeter ion thruster far exceeded the original model a year earlier, both in terms of size and effective power.

The current 900 mm ion thruster, named "Starry Sky", has nearly three times more effective power than the original model. What does this increase in effective power mean? Let's take an example to compare, and it will be clear at a glance.

Although the 300-millimeter ion thruster used on the "Deep Space One" only has the thrust of a piece of paper, it can increase the speed of Deep Space One by 32 kilometers per hour per day. If that little guy can work for 300 days straight, he can increase the speed of Deep Sky One to 9,700 km/h. And if the 300-millimeter-class ion thrusters are replaced by the current 900-millimeter-class "Starry Sky" ion thrusters, then the "Deep Sky One" will only take three days to reach a speed of 9,700 km/h, and if the four "Starry Sky" ion thrusters are installed on the "Deep Sky One", then the time required to increase the speed to this speed is only a little more than a day

And with the four thrusters working together, even a lunar spacecraft or a larger Martian spacecraft can fly at speeds of up to 20,000 km/h in space. It only takes five to six days. And if you want a lunar spacecraft or a Martian spacecraft to reach a second cosmic velocity, that is, a speed of 40,000 km/h. It doesn't take more than 15 days!

That's the power of the new ion thrusters, and the most important thing is that they can work continuously for a long time without interruption and consume very little fuel. If you were to use chemical fuels for propulsion a spacecraft, even if it was just a satellite, if you were to reach the second cosmic velocity. At least eight hours of engine work!

Not to mention whether an engine that runs on chemical fuel can last eight hours, and even if it does, where can you find so much fuel!

Therefore, the current spacecraft want to reach the second cosmic velocity. They all use the gravitational pull of the earth and the sun, and use the "slingshot principle" to make curves in space to achieve the goal of minimizing fuel consumption.

Just like the Apollo program back then, it took seven or eight days to go back and forth on the moon, and the moon is only 384,000 kilometers away from the earth. Why does it take so long? It is because the lunar lander needs to use the gravitational pull of the earth and the sun to accelerate, and it needs to fly around the earth or the moon many times to increase the speed to the corresponding speed. In this way, the spacecraft will have to fly for an unknown number of kilometers, and it will naturally take a long time.

Ordinary spacecraft, including the spacecraft in the Apollo program and the current "Chang'e" probe in China, must use this mode of constant orbit change to increase the speed of the spacecraft, but no matter how the orbit is changed, the purpose is to speed up the spacecraft.

In terms of the current technology of the lunar spacecraft, it also needs to go through such a mode, but as long as the lunar spacecraft determines the orbital route, it can use the function of the ion thruster to continuously accelerate, so that the spacecraft can reach the required speed in a very short time, so as to get rid of the earth's gravity and enter the Earth-Moon transfer orbit and reach the orbit around the moon in a very short time.

Because the moon spacecraft is the real virgin. After all, this kind of opportunity to enter space for field operations is precious, even with the current "Star-One" launch vehicle recyclable and reusable technology, it will take millions of dollars to send people into space.

Therefore, in addition to Tang Feng, the soy sauce maker in the explorer team, the other five astronauts are seizing the time to debug all the equipment, and strive to understand all the functions of the lunar spacecraft in a short time.

After nearly three days of tuning tests, Commander-in-Chief George . Anthony has finally announced that the mooncraft has been adjusted, and the next step is to conduct the all-important powertrain commissioning. This commissioning was carried out at the same time as the moon landing, which means that from now on, the lunar spacecraft will enter a continuous acceleration, and then use the gravitational pull of the Earth to enter the Earth-Moon transfer orbit and fly directly to the Moon.

During this time, the Starry Sky ion thrusters will operate for more than forty hours without interruption, directly increasing the ship's speed to the second cosmic velocity (to be continued). )