Plasma tunnel vaporizes satellite in simulation to see how space junk burns up upon reentry

The European Space Agency (ESA) is testing temperature thresholds of satellites in a test chamber that could help could help engineers design spacecraft to burn safer in the atmosphere. 

The experiment used a plasma wind tunnel to mimic reentry conditions by heating gas in the test chamber to more than 12,000 degrees Fahrenheit and creating winds that are flowing thousands of miles per hour.

Researchers first created a virtual representation of a satellite to test different melting points.

A solar array drive mechanism (SADM), which is part of the satellite that directs its solar panels, was then placed in the chamber and completely vaporized in just seconds.

‘When a spacecraft reenters on an uncontrolled basis, the spacecraft operator has to prove that the on-ground casualty risk posed by its satellite is lower than 1 in 10,000,’ ESA shared in a statement.

‘So last year SADM manufacturer Kongsberg Defense & Aerospace (KDA) started an investigation supported by ESA, Hyperschall Technologie Göttingen GmbH (HTG) and the German Aerospace Center (DLR) to demonstrate the ‘desmisability’ of one of its satellite products.’

The team developed software models of the SDAM, which allowed them to test different melting points prior to using a 3D model in the plasma wind tunnel.

The virtual design includes a final shaft, gear box, motor, crown wheel and main bearing, all of which are found on a real SDAM.

The experiment used a plasma wind tunnel to mimic reentry conditions by heating gas in the test chamber to more than 12,000 degrees Fahrenheit and creating winds that are flowing thousands of miles per hour

However, scientists used a new aluminum screw that they believed would melt easier upon reentry.

Once the researchers had a better idea of the melting-point, they constructed the 3D model with the new screws and placed it in the test chamber where it was exposed to wind speeds of thousands of miles per hour, Live Science reports.

In a matter of seconds, the SDAM was vaporized – just as the software predicted, ESA said.

‘The main conclusion was that the demise phenomenology observed in test matched quite well the test predictions obtained through the simulations,’ ESA shared in the statement.

A solar array drive mechanism (SADM), which is part of the satellite that directs its solar panels, was placed in the chamber and completely vaporized during the process

ESA says that by testing the temperature thresholds of satellites, engineers can design spacecraft that cannot only perform well in space, but also burn safely in the atmosphere as they fall to Earth

‘However, due to some uncertainties in certain parameters, such as material properties and heat flux, the models needed some tweaking to match the tests and to be verified. This will be further detailed in the Test correlation section.’  

At least 26,000 of millions of pieces of space junk orbiting Earth are the size of a softball, which are moving 17,500mph, according to NASA.

Due to the size and speed, the debris is capable of ‘destroying a satellite on impact.’

NASA also notes that more than 500,000 pieces are a ‘mission-ending threat’ because of their ability to impact protective systems, fuel tanks and spacecraft cabins. 

Most of the space debris, if not all of it, will eventually fall to Earth and ESA hopes its simulation can help each piece burn up faster and safer upon reentry. 

WHAT IS SPACE JUNK? MORE THAN 170 MILLION PIECES OF DEAD SATELLITES, SPENT ROCKETS AND FLAKES OF PAINT POSE ‘THREAT’ TO SPACE INDUSTRY

There are an estimated 170 million pieces of so-called ‘space junk’ – left behind after missions that can be as big as spent rocket stages or as small as paint flakes – in orbit alongside some US$700 billion (£555bn) of space infrastructure.

But only 22,000 are tracked, and with the fragments able to travel at speeds above 16,777 mph (27,000kmh), even tiny pieces could seriously damage or destroy satellites.

However, traditional gripping methods don’t work in space, as suction cups do not function in a vacuum and temperatures are too cold for substances like tape and glue.

Grippers based around magnets are useless because most of the debris in orbit around Earth is not magnetic.

Around 500,000 pieces of human-made debris (artist’s impression) currently orbit our planet, made up of disused satellites, bits of spacecraft and spent rockets

Most proposed solutions, including debris harpoons, either require or cause forceful interaction with the debris, which could push those objects in unintended, unpredictable directions.

Scientists point to two events that have badly worsened the problem of space junk.

The first was in February 2009, when an Iridium telecoms satellite and Kosmos-2251, a Russian military satellite, accidentally collided.

The second was in January 2007, when China tested an anti-satellite weapon on an old Fengyun weather satellite.

Experts also pointed to two sites that have become worryingly cluttered.

One is low Earth orbit which is used by satnav satellites, the ISS, China’s manned missions and the Hubble telescope, among others.

The other is in geostationary orbit, and is used by communications, weather and surveillance satellites that must maintain a fixed position relative to Earth.