Moon crash: Discarded rocket part to hit Moon in hours, say scientists

Image source, Peter Birtwhistle

Scientists who first predicted the collision of a rocket and the Moon in January say that a discarded part of the rocket is hours away from crashing into the Moon.

The three-tonne rocket part is expected to hit at 12:25 on Friday.

The rocket part was thought to have been launched by Musk's programme, but then they said it was Chinese.

The impact on the Moon is expected to have a small effect.

Scientists hope to study the impact crater and moon dust.

The rocket part was first seen on Earth. A space survey in Arizona spotted the object, but lost interest when it was shown not to be an asteroid.

Space junk is hardware discarded from missions or satellites without enough fuel or energy to return to Earth. The booster is thousands of miles away in high altitude, far from the Earth's atmosphere.

The European Space Agency estimates there are over 30,000 pieces of space junk.

There is no space programme that tracks deep space junk. The risks to humans from high-orbit debris are low and monitoring space is expensive.

It falls to a small group of volunteers who spend their time making calculations. They send emails and alert each other if someone is in the best place on the planet to spot an object in space.

Six weeks after the booster was seen, Peter Birtwhistle was watching the skies for asteroids from his garden in the south of England.

A tiny dot of light was picked up by his telescope. He told the news that it was part of a rocket.

Space junk can fall in and out of view. He didn't see the rocket part for seven years.

He explained that he grabbed some images when it passed close to Earth.

Bill Gray is an astronomer and data scientist on the east coast of the United States. He was the one who identified it as a SpaceX booster heading for the Moon.

The news that part of a space mission was going to be destroyed made global headlines.

Tracking space junk is often a detective work. Astronomers have to piece together the identity of the rocket by tracking its route through space. They match it to dates and locations of rocket launches.

Some space missions do not publicise their routes.

We know the launch date for a Chinese mission because they are on TV. I guess it will get to the Moon in four or five days. Mr Gray explains that he computes an approximate orbit.

Sometimes he makes mistakes. Mr Gray's identification was impossible after another observer sent him new data.

He ran the numbers again and concluded it was the third stage of a rocket from China.

Image source, Getty Images

China denied that the upper-stage had reentered the Earth's atmosphere.

Mr Gray is sticking to his guns. He thinks China has mixed up the tracking of two rocket parts.

We will never be certain.

Hugh Lewis says the scientific value of tracking deep space junk is limited. He says it is important to keep an eye on what is there as human settlement in spaces becomes more likely.

It is the mess we have created. He says that objects that we think are safe can return to Earth unexpectedly.

We won't see the last moments of the booster when it hits the far side of the Moon.

It could be days or weeks before it is confirmed. Two satellites will take pictures of the crater left on impact.

Evidence of its true origins will be lost as the booster breaks into thousands of pieces. The estimates made by Bill Gray and the volunteers are the best we have.