Photos taken by ISRO's Chandrayaan-2, which taken a month after the crash and released publicly last week (July 8) showed two craters, one 18-metre wide crater partially overlapping with another 16-metre wide crater to its west

Late last year, astronomers mapped a rogue rocket booster on a collision course with moon. While a debate on the origins of the piece of space junk ensued, the astronomers set March 4 as the date of crash.

On schedule, the rocket hit the lunar surface near the Hertzsprung crater on March 4 this year. Photos taken by the Indian Space Research Organisation’s (ISRO) Chandrayaan-2, which taken a month after the crash and released publicly last week (July 8) showed two craters, one 18-metre wide crater partially overlapping with another 16-metre wide crater to its west.

NASA (National Aeronautics and Space Administration) made a similar finding on June 24 and described the double crater as “surprising” and “unexpected”.

“Typically, a spent rocket has mass concentrated at the motor end; the rest of the rocket stage mainly consists of an empty fuel tank,” NASA said. The space agency added, “the double nature of the crater may indicate that the rocket body had large masses at each end”.

At least 47 of NASA’s robotic or crewed rocket bodies have crashed into the moon, according to the data from its Lunar Reconnaissance Orbiter Camera maintained in collaboration with Arizona State University.

But “no other rocket body impacts created double craters”, the NASA statement said.

A stage, in spacefaring parlance, refers to one of multiple rockets that are strapped together to propel the main payload to the destination orbit. Payloads can be a shuttle, a collection of satellites, an orbiter or even a lander.

In this case, experts now believe the culprit is a part of a Chinese mission launched in 2014, bringing back into focus the dangers of space debris and how they can keep posing a threat for years.

Astronomer Bill Gray, who first spotted the rocket in its trajectory to the moon, initially identified the object as part of the SpaceX Falcon rocket that launched the US Deep Space Climate Observatory, or DSCOVR, in 2015. He later clarified that he identified the rocket incorrectly, and it was likely from a 2014 Chinese lunar mission — an assessment NASA has since agreed with.

“The SpaceX id (identification) was just a mistake. Those of us who proposed that id are now confident it is the Chinese stage,” Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Centre for Astrophysics, told HT in an email.

That Chinese mission was the Chang’e 5 T-1, which was launched via China’s homegrown Long March 3C rocket. What is stark about this incident is that the projectile — the booster component of the Long March 3C, never re-entered the Earth’s atmosphere, which they are typically designed to do so that they burn up.

The Chinese government issued a denial shortly after the assessment was first made, saying the Chang’e 5’s rocket booster had been tracked burning up in the Earth’s atmosphere.

Astronomers say Beijing is merely mixing up two missions — the T-1 was launched in 2014 as an experimental precursor to the Chang’e 5 mission in 2020, experts explained.

The object is “quite conclusively identified as the Chang’e 5-T1 booster”, Gray said in his latest post after NASA issued its statement. The CE-5 booster was tracked coming back from the moon and hit the middle of the Pacific less than a week after launch. The CE-5-T1 booster spent over seven years wandering around the earth-moon system, before hitting the far side of the moon on March 4, 2022,” he wrote.

Why the impact led to the unique double crater, however, continues to be somewhat of a mystery. NASA, while supporting the China-origin attribution, said it will analyse the matter further, McDowell said a conclusive determination may never be possible.

The incident spotlights the growing risk in space, where orbital room is being crowded out by an astronomical race in which nation-states as well as private companies are increasingly active.

Behind it are projects like Elon Musk-owned SpaceX’s Starlink constellation and rival Amazon’s Project Kuiper. Both companies want to create a web of low-earth orbit (LEO) spacecraft that will beam down internet connectivity to anywhere on the planet.

Additionally, several countries – Russia and India being the most recent – have carried out tests of satellite-killing missiles, generating millions of pieces of debris.

Scientists have warned such developments not only increase the risk of collisions, but – particularly the satellite constellations -- raise the chances of interference with astronomical research.