A leftover rocket part that has been hurtling through space is about to smash into the moon. The mysterious hunk of metal is set to make its violent mark on our lunar neighbor Friday around 7:25 a.m. Eastern, marking what's believed to be the first time a manmade space missile has unintentionally hit the moon.

While experts say there's no potential threat to us here on Earth, it does highlight a growing problem around our planet — space junk.

Observers say the rocket part, which is expected to hit the surface while traveling at roughly 5,800 miles per hour, is likely a piece of a Chinese spacecraft launched in 2014. Now, it's on a path to become yet another lunar crater.

"If you were there on the moon, it would look like a meteorite hitting the moon — a rather large one — or a small asteroid," says Philip Metzger, a planetary scientist at the Florida Space Institute.

The moon, unprotected by a thick atmosphere like Earth's, is no stranger to cosmic beatings. More than a dozen spacecraft have crashed into its surface, including the intentional crashing of NASA's LCROSS mission in 2009, which was on the hunt for lunar ice. And the moon is constantly bombarded by asteroids and meteors.

"Crater upon crater, there's not a single spot of the moon that hasn't been churned over many times in the past like this," says Metzger.

Unfortunately, astronomers won't get to see this most recent impact happen in real time. The collision is happening on the far side of the moon, outside the scope of Earth-based telescopes. It could take weeks or months to confirm the impact using imaging satellites orbiting the moon.

Still, scientists say they hope to learn something about the crater created by the junk's collision and the amount of heat it generates.

A problem closer to home

For now, space junk is not a huge concern for the moon — but it is a growing problem closer to home in Earth's orbit. Moriba Jah is an aerospace engineer at the University of Texas Austin and chief scientist at Privateer, a company aimed at tracking space debris. He says that of the 50,000 pieces of debris his company is tracking, only about 5,000 are operating.

"Everything else is garbage," says Jah. "So 90 percent of what we track is junk."

We rely on those working satellites in space for service down here on Earth like GPS and communication. Tracking space junk is key to keeping those satellites working and preventing collisions which could turn parts of that orbiting infrastructure into even more space junk.

Objects in space travel at incredibly fast speeds, something like 15 times the speed of a bullet.

"Nothing is protecting these satellites from getting swept by a piece of junk and then the capability goes away," says Jah.

Tracking dead satellites and space trash presents its own challenges. Because they no longer transmit radio signals that may identify what they are or where they came from, astronomers here on Earth look for clues in the light reflected off of their surfaces.

"The materials that you build something out of have this wavelength dependency," says Jah. Different materials will reflect slightly different wavelengths of light, resulting in a unique "fingerprint" that astronomers can use to identify what an object is made of — and who probably made it.

That led to initial confusion when first identifying the piece of junk about to smash into the moon. An initial analysis suggested the debris was from a SpaceX rocket, then determined it was more likely from the Chinese space agency. Both parties have denied ownership.

Tracking space trash

Space is big and the chances of collision are low, but the more and more stuff we put in space, the higher the risk. On November 15, 2021, the Russian military blew up a defunct satellite in space with a missile, producing thousands of pieces of debris that threatened to strike the International Space Station. The U.S. government condemned the move.

Both government agencies and the private sector are now taking a greater interest in keeping space clean.

"Just like we polluted the surface of Earth and in our waters, we have also polluted the skies," says space policy analyst Laura Forczyk. "It's one thing that we now need to clean up for the benefit of all humankind."

The White House is bolstering its efforts to control space debris and better manage traffic in orbit, thanks to a directive from the National Space Council, a group dedicated to steering the Biden administration's space policy. In a document outlining its priorities in space, the administration said it seeks to "enhance the security and resilience of space systems that provide or support U.S. critical infrastructure from malicious activities and natural hazards."

Private companies like Privateer are working to track this debris. Others are looking at ways to service defunct satellites in space, preventing them from becoming hunks of junk floating around in orbit.

This focus on junk both from the government and private section is a step in the right direction, experts say.

"I'm glad to see more capital and more attention brought to it," says Forczyk. "We need that. We also need to mitigate against creating future debris."

Back at the moon, NASA is planning a handful of human missions in the 2020s, along with science missions on the lunar surface and even a moon-based space station — providing a growing list of reasons to keep space junk under control.

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