The 3-tonne debris that crashed on the far side of the moon on March 4 will not affect the moon's environment or a space mission, according to Yang Yuguang, vice chair of the Space Transportation Committee at the International Astronautical Federation. 

The rare incident caught stargazers' attention and created a controversy regarding the origin of the debris. Astronomers estimated that the crash would form a new crater with a diameter of 20 to 30 meters in the naturally existing 520-kilometer-wide Hertzsprung crater, according to the National Geographic. The crash was out of view from the telescopes on Earth.

A "passivation" process that's widely adopted by global rocket developers is essential to making debris danger-free in deep space, Yang said, explaining that it is a process that involves the removal of leftover propellants and batteries from a used rocket after it has sent satellites into their designated obit. The process ensures that the rocket debris does not explode, which could create large amount of smaller debris that may endanger nearby satellites.

"The rocket debris does not pose much danger once it's passivated," Yang told CGTN.

In January, astronomers discovered a piece of rocket debris that was on track to slam into the moon. The piece was originally believed to be part of a SpaceX rocket launched in 2015. In mid-February, NASA claimed that the rocket part was more likely from China's Chang'e-5 mission launched in 2014.

China officially responded to the claim a week later by saying that China's monitoring showed that "the upper stage of the Chang'e-5 mission rocket has fallen through the Earth's atmosphere in a safe manner and burnt up completely."

Does the crash matter?

However, despite the unrelenting debates on the origin, Yang said, "It actually doesn't matter much where the debris came from," as the crash won't have any significant impact on the moon. "In the past 4 billion years, so many meteorites have collided with the moon," he said.

Yang said it's also common practice that countries even deliberately crash the spacecraft into the moon for research purposes or at the end of their lunar missions to give way for future exploration projects.

China's lunar probe Chang'e-1 had crashed into the moon from an orbit 200 kilometers above the moon's surface at the end of its mission. Scientists took advantage of the crash to take closer images with more details.

"The crash was totally safe during the whole process," Yang said.

Can pollution on moon affect research?

Some argue the crashed debris could pollute the environment on the moon, which may mislead the experts' research on looking for signs of life.

"The moon shows no signs of life, no matter from the past or the present," Yang said. A conducive atmosphere and water are crucial to life but the moon lacks both, he explained. "This means if we ever find signs of life [on the moon], we will be sure it's not from the moon."

Yang said that scientists have made efforts not to pollute certain parts of the space where life could exist. Spacecraft launched by the U.S. for Mars and Jupiter were strictly disinfected, he said.

Additionally, some spacecraft were deliberately crashed into a lifeless planet or a moon to avoid their potential collision with the ones that may have signs of life at the end of their missions, according to Yang. NASA's Cassini spacecraft, a mission for studying Saturn for 20 years, plunged into the planet to ensure that Saturn's moons remain intact.