The remaining rocket will crash on the far side of the moon at 5,800 mph (9,300 km / h) on Friday, away from the prying eyes of telescopes. It can take weeks, even months, to confirm the impact via satellite imagery.
It accidentally falls into space, experts say, since China launched it almost a decade ago. But Chinese officials doubt it is theirs.
No matter who it is, scientists expect the object to drill a hole 33 feet by 66 feet (10 to 20 meters) and send moon dust to fly hundreds of miles (kilometers) across the barren surface.
Low-trajectory space debris is relatively easy to detect. Objects that are launched deeper into space are unlikely to hit anything and these distant pieces are usually quickly forgotten, except for a few observers who enjoy playing a celestial detective on the side.
SpaceX initially got the rap for the upcoming lunar debris after asteroid tracker Bill Gray spotted the collision course in January. He corrected himself a month later by saying that the object of the “mystery” was not the upper tier of the SpaceX Falcon rocket since the launch in 2015 of a deep-space climate observatory for NASA.
Gray said it was probably the third stage of a Chinese rocket that sent a test capsule to the Moon and back in 2014. However, Chinese ministry officials said the upper stage had re-entered the Earth’s atmosphere and burned.
However, there have been two Chinese missions with similar names – the test flight and the 2020 lunar return mission – and US observers believe the two are confused.
The U.S. Space Administration, which monitors the space debris, confirmed on Tuesday that China’s top-level mission from the 2014 lunar mission had never been launched, as previously reported in its database. But he could not confirm the country of origin of the object that is going to hit the moon.
“We are focusing on objects closer to Earth,” a spokesman said in a statement.
Gray, a mathematician and physicist, said he was now confident that it was China’s rocket.
“I have become a little more careful in such matters,” he said. “But I really do not see it as something else.”
Jonathan McDowell of the Harvard and Smithsonian Center for Astrophysics supports Gray’s revised assessment, but notes: “The result will be the same. It will leave another small crater on the moon.”
The moon already has countless craters, ranging up to 1,600 miles (2,500 kilometers). With little to no real atmosphere, the moon is defenseless against the constant storm of meteorites and asteroids, and the occasional incoming spaceships, including some that were deliberately crashed for the sake of science. Without time, there is no corrosion and so impact craters last forever.
China has a lunar landing on the far side of the moon, but will be too far away to detect Friday’s impact just north of the equator. NASA’s Lunar Reconnaissance Orbiter will also be out of range. It is unlikely that India’s Chandrayaan-2 in orbit around the moon has passed by then.
“I was hoping for something (important) to hit the moon a long time ago. Ideally, it would have hit the near side of the moon at some point where we could really see it,” Gray said.
After initially defining Elon Musk’s upcoming SpaceX hit, Gray looked again when an engineer at NASA’s Jet Propulsion Laboratory disputed his claim. Now, he is “quite convinced” that it is a Chinese rocket component, based not only on orbital tracking since its landing in 2014, but also on data obtained from the short-lived ham radio experiment.
The JPL Earth Studies Center supports Gray’s reassessment. A team from the University of Arizona also recently spotted part of the Chinese Long March rocket from light reflected by its color, during observations of the cylinder with a telescope.
It is about 40 feet (12 meters) long and 10 feet (3 meters) in diameter, and makes mounds every two to three minutes.
Gray said SpaceX never contacted him to dispute his original claim. Not even the Chinese.
“It’s not a SpaceX problem, nor is it a China problem. Nobody is very careful about what they do with the rubbish on this kind of orbit,” Gray said.
Tracking remnants of missions in deep space like this is difficult, according to McDowell. The gravity of the moon can change the course of an object during flights, creating uncertainty. And there is no database immediately available, McDowell noted, other than those “assembled” by himself, Gray and a few others.
“We are in an age where many countries and private companies are putting things in the background, so it’s time to start watching,” McDowell said. “At the moment there is no one, only a few fans in their spare time.”
Associated Press video producer Olivia Zhang and Beijing-based video journalist Sam McNeil contributed to this report.
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