(CNN) – A portion of a rocket that has been orbiting in space for years will collide with the moon on Friday, the first time a piece of space debris has inadvertently crashed onto the moon’s surface.

The moon is expected to hit around 7:26 a.m. ET at about 5,500 mph (8,851 kph), but the event will not be visible from Earth because the impact is expected to occur on the moon’s far side.

said Bill Gray, an independent researcher focusing on orbital dynamics and developer of astronomical software. He was the first to discover the trajectory of the booster rocket.

The only way to know exactly where the missile landed is through the pictures. The agency said that NASA’s Lunar Reconnaissance Orbiter would not be in a position to monitor the impact as it occurs.

However, the orbiter mission team is evaluating whether it can make observations of any changes in the lunar environment associated with the impact and then identify the impact crater.

“This unique event represents an exciting research opportunity,” NASA said in an emailed statement.

“After the impact, the mission can use its cameras to locate the impact, and compare old photos with photos taken after the impact. The search for the impact crater will be difficult and could take weeks or months.”

India’s Chandrayaan 2 orbiter can also locate the crater, which can be up to 65 feet (20 meters) in diameter, Gray said.

It will be far from the only crater on the Moon, which does not have a protective atmosphere. This means that the impact craters occur naturally when they collide with objects such as asteroids, which they do regularly. The craters were also caused by a spacecraft deliberately colliding with the Moon.

There is the potential for biocontamination at the crash site, because parts of the rocket are not sterile when launched, said David Rotheery, professor of planetary geosciences at the UK Open University.

“Most of the microbes will die, but maybe not all of them. They may not reproduce, but it’s a very small risk,” he said.

Unclear origin

The source of the missile part is unclear. Gray initially identified it as the stage of the SpaceX Falcon rocket that launched the US Deep Space Climate Observatory, or DSCOVR, in 2015, but later said it was wrong and that it was likely from a 2014 Chinese lunar mission. An assessment through which NASA agreed.

However, the Chinese Foreign Ministry denied that the booster missile was from the Chang’e-5 mission on the moon, saying that the missile in question burned up when it re-entered Earth’s atmosphere.

There is no agency that systematically tracks space debris away from Earth, and confusion over the origin of a rocket’s stage has emphasized the need for official agencies to closely monitor deep space debris, rather than relying on the resources of limited personnel and academics.

However, experts say the biggest challenge is space debris in low Earth orbit, an area where it can collide with working satellites, creating more debris and threatening human life on manned spacecraft.

There are at least 26,000 pieces of space debris in orbit around the Earth the size of a baseball or larger and can destroy a satellite on impact; More than 500,000 marble-sized pieces are large enough to cause damage to spacecraft or satellites; And more than 100 million pieces the size of a grain of salt, tiny bits of debris that can nonetheless puncture a spacesuit, according to a NASA report released last year.