In space no one can hear you scream... ‘look out!’

Tens of thousands of satellites. 170 million pieces of space junk. No wonder scientists are warning of cataclysmic collisions in the heavens at more than 17,000mph

In February 2009, two satellites collided 500 miles above the earth. a defunct russian military satellite and a u.S. communications spacecraft were passing over a remote area of northern Siberia — but the consequences were felt around the world.

The crash occurred at a ‘hyper-velocity’ of 26,000mph — so fast that colliding metals behave like liquids — with the impact creating a kind of cloud in space.

With at least 2,000 large pieces of debris, and many thousands more smaller ones, hurtling through space, scientists around the world hurried to work out what was at risk of being hit.

Down on earth, people as far away as Kentucky reported hearing sonic booms from falling satellite debris, while others in Texas reported seeing a fireball flash across the sky.

When — more than three years later — a small piece of the russian satellite passed by just 130 yards from the International Space Station, the six astronauts on board were forced to take refuge inside two docked Soyuz ‘rendezvous’ spacecraft until the debris had passed.

The fragments from the 2009 collision will remain in space as a potential hazard for decades until earth’s gravity drags it out of orbit.

The accident was said to have been the first such crash to occur between two intact spacecraft, but experts fear it won’t be the last.

now scientists are warning that the chances of such accidents — chillingly illustrated in the film Gravity, in which a space shuttle is hit by satellite debris — are rising dramatically in earth’s underregulated and increasingly crowded orbit.

With tens of thousands of new satellites being sent into space by technology companies, experts fear that owners will not be up to the task of monitoring their movements to prevent collisions.

Those warnings have taken on a new urgency after another potential disaster was avoided earlier this month.

The u.S. air Force, which keeps trace of spacecraft and debris in space, notified the european Space agency (eSa) and SpaceX, the commercial space company owned by the technology entrepreneur elon Musk, on august 28, that their satellites were heading for a possible collision around September 2.

at stake in the crash were the £400million european windmonitoring research satellite, aeolus, and new Starlink satellite, one of 60 launched by Musk in May as part of a plan to bring the internet to earth’s remotest places.

Satellites don’t always follow an unchanging orbit around the earth. Changes in the gravitational pull, solar winds and other factors can suddenly shift their course and make it hard to forecast with any certainty.

It can also increase the likelihood of collision with other spacecraft.

In the latest case, eSa engineers became increasingly worried when the satellite controllers at SpaceX didn’t respond to their warnings.

Finally, the agency realised that it had to act alone. engineers carried out an ‘emergency collision avoidance manoeuvre’, firing a thruster on its satellite, already travelling at 17,000mph, to take it out of the SpaceX craft’s path.

The eSa said it was the first time it had needed to take such evasive action.

alarmingly given what was at stake, SpaceX later admitted it had missed the increasingly urgent-sounding emails from the eSa because of a ‘bug’ in its communications system.

holger Krag, head of the agency’s space safety, has described the wider lack of coordination between companies operating in space as

‘frightening’, with the controllers of certain satellites having to look on the internet for the contact details of the operators of other satellites.Then they ‘phone its reception and hope that someone picks up’, said Krag, who added that an automated system is needed along with a new international network organising space like the one that exists for air traffic control.

he has a point. The idea of airlines having to dig out each other’s phones numbers every time their planes are risking a collision is inconceivable.

yet, remarkably given that humans have been sending craft into space for decades, there are still no firm traffic rules there. In the past, this mattered less, because relatively few people or vessels were whizzing around in orbit. but that is changing drastically. There are more spacecraft going up — 111 successful launches in 2018 compared to 66 a decade earlier — and a growing number are carrying multiple satellites. elon Musk alone plans to send up 12,000 satellites, amazon wants to launch another 3,000 and OneWeb, backed by Virgin entrepreneur Sir richard branson, will be responsible for an additional 650. and what goes up often doesn’t come down. It’s expensive to bring obsolete satellites and used rockets back to earth, so many owners simply leave them up there. using radar observatories and telescopes, the u.S. government currently tracks about 23,000 man-made objects in space that are larger than the size of a cricket ball. They may sound harmless until one realises they are travelling at more than 17,500mph — about ten times the speed of a bullet. There are millions more — an estimated 170million — smaller pieces of space junk that experts can see but are unable to track. even a fleck of paint travelling at that speed can disable a satellite.

ACCOrDInG to nasa, a hit by a 10cm ball of aluminium would be the equivalent to the detonation of 7kg of TnT. In all, there’s estimated to be 8,400 tons of space junk hurtling through orbit.

The worst-case scenario is the so-called Kessler Syndrome (named after the nasa astrophysicist, Donald Kessler, who developed it), in which a single collision sets off a chain of collisions that ends up creating a lethal field of debris around the earth that would make it too risky to send up spacecraft or satellites for hundreds of years.

Of course, there is another collision hazard associated with the rush into space — the debris

hitting people on earth. every day, a ton or two of space junk — old satellites and rocket parts, mostly — is pulled out of orbit by our planet’s gravity.

eighty percent of it burns up as it re-enters the atmosphere but the remaining fragments are potentially deadly.

Only six recorded victims, five of whom were Japanese sailors on the same vessel, are recorded to have been injured by falling space junk, though experts predict that population growth will make this more frequent.

an effective solution to this threat is to ensure the falling spacecraft lands in the socalled South Pacific Ocean uninhabited area, also known as the ‘spacecraft graveyard’, a vast expanse between new Zealand and Chile. however, such ‘controlled re-entries’ are very expensive.

another solution is to take the rubbish out of space before it falls to earth. Space agencies are looking at devices including harpoons, lasers and ‘giant nets’ to remove debris while it’s still in orbit.

In the meantime, navigating satellites in space remains, as one expert put it, ‘like driving on a highway in a dense fog’.

In space, it seems, nobody can hear you scream: ‘Get out of the way!’