WOODEN SATELLITES:LIGNOSAT PROJECT MAY REDUCE SPACE JUNK

US and Japanese space agencies are teaming up to launch lumber in an effort to reduce space litter

- DR SARA WEBB

In 1957, the first human-made object successfully launched into space was placed in orbit around Earth. This was Sputnik 1, a beautifully simple, Soviet-made spherical satellite with just four antennas.

But this historic event also marked another, more unsettling first: humanity had deposited its first piece of space debris. Part of the 267-tonne, 30m-tall rocket that launched Sputnik was stuck in orbit. Suddenly the world had a problem that we didn't know we needed to solve: the littering of outer space.

Thankfully, Sputnik and that rocket remnant de-orbited and burned up in our atmosphere fairly quickly after launch.

That hasn't always been the case, however - far from it. Over the course of just 66 years of space exploration, a vast amount of detritus has been left in orbit around Earth.

Now NASA and the Japan Aerospace Exploration Agency (JAXA) have an idea to help solve this issue: satellites made from a widely available, biodegradable material - wood.

The problem the agencies aim to address is a big and complex one and finding out just how big was the first stage of the project. We know that at least 130 million pieces of human-made debris orbit Earth, most of them whizzing around at over 7km/s - eight times faster than a typical bullet. Although that's a staggering number, some scientists think it's a conservative estimate.