Star Wars-style lasers could help future space missions to accurately pinpoint the location of space junk in Earth’s orbit and avoid deadly collisions.
Millions of pieces of space junk are currently whizzing around the planet at around 20,000 miles per hour — providing a threat to future rockets and space craft.
However a new system based on neural networks has provided a better way to keep track of these hazardous objects with telescopes.
The approach can detect debris as small as 3 feet wide and allow courses to be plotted to avoid them.
Star Wars-style lasers could help future space missions to accurately pinpoint the location of space junk in Earth’s orbit and avoid deadly collisions. Pictured, the Beijing Fangshan Satellite Laser Observatory where the new technique was tested
The new laser tracking system has been developed by Tianming Ma of the Chinese Academy of Surveying and Mapping and colleagues.
‘After improving the pointing accuracy of the telescope through a neural network, space debris with a cross sectional area of 1 metre squared and a distance of 1,500 kilometres (932 miles) can be detected,’ Dr Ma said.
Even at such relatively small sizes, collisions between such bodies and spacecraft could trigger catastrophic accidents — and even cripple the world’s orbital telecommunications networks.
The new detection technique improves on current methods by around 1,500 times and works by employing a system that mimics the human brain.
Keeping track of all the satellites orbiting some 24,000 miles (38,000 kilometres) above our heads is a NASA priority.
In 2017, more than 400 satellites were launched — more than four times the yearly average from 2000–2010.
The sudden burst is in part fuelled by the efforts of large companies like Elon Musk’s SpaceX, Boeing and Airbus.
These firms have plans to deploying thousands of communications satellites into Earth-encircling orbits over the next few years.
With the increase in orbital traffic, the risk of collisions increases in tandem.
In ‘Star Wars: The Empire Strikes Back’, humanoid robot C-3PO warns pilot Han Solo that h i s chances of guiding the Millennium Falcon spacecraft through an asteroid field were 3,720 to 1. Earth’s orbit is nowhere near as dangerous, even after more than 50 years of space activity
In ‘Star Wars: The Empire Strikes Back’, humanoid robot C-3PO warns pilot Han Solo that his chances of guiding the Millennium Falcon spacecraft through an asteroid field were 3,720 to 1.
Earth’s orbit is nowhere near as dangerous, even after more than half a century of space activity.
However, collisions between jettisoned engines and disintegrated spacecraft remains have formed a ‘planetary scrapheap’ we need to be careful navigating, experts caution.
Neural networks are computer models of the human brain’s sensory inputs, processing and outputs.
Combining these networks with laser ranging telescopes has been proposed before, but this is the first study to significantly improve the telescopes’ pointing accuracy.
Dr Ma and colleagues trained the network to recognise space debris using two special mathematical formulas called the Genetic Algorithm and the Levenberg-Marquardt.
These optimised the thresholds for recognition of space debris — ensuring that the network wasn’t too sensitive and could be trained on localised areas of space.
The team demonstrated the improved accuracy by testing against three traditional methods at the Beijing Fangshen laser range telescope station.
Data on 95 stars was fed into each method, which were then assessed for their accuracy in detecting 22 other stars.
The new pointing correction algorithms proved the most accurate — alongside being both easy to operate and having a good real-time performance.
With their initial study complete, Dr Ma hopes to further refine the method.
‘Obtaining the precise orbit of space debris can provide effective help for the safe operation of spacecraft in orbit,’ he noted.
State-of-the-art telescopes use laser reflection from objects to measure their distance.
But the echo signal reflected from the surface of space debris is very weak — reducing their accuracy.
Previous methods improved results — but only within a range of one kilometre (0.62 miles).
WHAT IS SPACE JUNK?
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.
According to NASA, more than 500,000 pieces of debris are currently being tracked as they orbit the Earth.
The speed at which these pieces of debris orbit is enough to seriously damage a satellite or a spacecraft in the event of a collision.
NASA estimates that anything larger than a baseball poses a potentially catastrophic threat to the International Space Station.
In fact, even tiny paint flecks can damage a spacecraft when travelling at the velocities involved, as proven by the cracking of the Space Shuttle’s windshield.
The full findings of the study were published in the Journal of Laser Applications.