Officials say debris from an Indian anti-satellite weapons test conducted earlier this week will likely burn up and ‘vanish’ in a matter of weeks, amid outcry over its potential to the already pressing issue of space junk in Earth’s vicinity.
Acting U.S. Defense Secretary Patrick Shanahan said on Thursday he expected debris from the destroyed satellite test to eventually burn up in the atmosphere instead of creating a lasting debris field that could threaten other orbiting craft.
The comments came after an estimation by India’s top defense scientist that the debris would burn up in about 45 days.
While Shanahan said he could not confirm any particular timeframe, he said the material likely wouldn’t survive long in the atmosphere.
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‘But in terms of threats to other objects, that’s consistent with what I’ve heard,’ that it will burn up in the atmosphere, Shanahan told reporters traveling with him in Florida.
The comments came a day after India said it used an indigenously developed ballistic missile interceptor to destroy one of its own satellites at a height of 300 km (186 miles), in a test aimed at boosting its defenses in space.
Few satellites operate at the altitude of 300 km, from which experts say the collision debris will fall back to earth, burning up in the atmosphere in a matter of weeks, instead of posing a threat to other satellites.
‘That’s why we did it at lower altitude, it will vanish in no time,’ G. Satheesh Reddy, the chief of India’s Defence Research and Development Organisation, told Reuters in an interview.
‘The debris is moving right now. How much debris, we are trying to work out, but our calculations are it should be dying down within 45 days.’
India says anti-satellite missile test will act as a deterrent
In 2007, China destroyed a satellite in a polar orbit, creating the largest orbital debris cloud in history, with more than 3,000 objects, according to the Secure World Foundation.
Since the impact altitude exceeded 800 km (500 miles), many of the resulting scraps stayed in orbit.
Asked whether he believed India, with a test at a lower altitude, had avoided a China-type scenario, Shanahan said: ‘That’s my understanding.’
The Pentagon said on Wednesday the U.S. military´s Strategic Command was tracking more than 250 pieces of debris from India´s missile test and would issue close-approach notifications as required until the debris enters the Earth’s atmosphere.
Lieutenant General David Thompson, vice commander of U.S. Air Force Space Command, said on Wednesday that the Indian test had hit the target vehicle.
A U.S. official, speaking on the condition of anonymity, said on Thursday that no new threats had arisen from debris yet.
The official added that there was no information so far to cast doubt on the claims made by Indian Prime Minister Narendra Modi.
Critics say such technology, known to be possessed only by the United States, Russia and China, raises the prospect of an arms race in outer space, besides posing a hazard by creating a cloud of fragments that could persist for years.
Shanahan said the Indian test was a reminder about how space was becoming increasingly contested, and underscored the necessity of creating a Space Command – a stepping stone toward President Donald Trump goal of creating a Space Force.
‘It really speaks to: Why we need to stand up Space Command. Think about the importance now of rules of engagement, the authorities, the tactics, techniques and procedures,’ Shanahan said.
Simulation shows what happens if satellites crash into each other
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 of space infrastructure.
But only 22,000 are tracked, and with the fragments able to travel at speeds above 27,000kmh (16,777 mph), 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.
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.