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India says it has destroyed one of its own satellites in Earth orbit as part of a test of an anti-satellite missile.

A similar test by China in 2007 generated a huge cloud of dangerous space debris and drew international condemnation for potentially putting other nation’s satellites at risk. But the Indian satellite was in such a low orbit – 300 kilometres up – that any debris should soon fall to Earth, space researchers have told 51����.

“Things shouldn’t last long at that altitude,” says Craig Underwood at the University of Surrey in the UK, one of the leaders of the , which is studying how to get rid of space debris. “For orbits of 300 kilometres or less, any remaining material will quickly be removed by atmospheric drag.”

The Indian test was announced by prime minister Narendra Modi in a televised address on 27 March.

“In the journey of every nation there are moments that bring utmost pride and have a historic impact on generations to come,” . “One such moment is today. India has successfully tested the Anti-Satellite (ASAT) Missile.”

The US, Russia and China have all previously tested anti-satellite missiles. The last such test was in 2008, when the US used a ship-launched missile to demolish a defunct spy satellite that was falling to Earth. That satellite was just 250 kilometres up, so all the debris fell to Earth within a month or so.

But the satellite hit by China in 2007 was orbiting at an altitude of 835 kilometres. “The debris from this test remains a hazard,” says Underwood.

It appears India has tried to ensure its test doesn’t create a similar problem, although this has yet to be confirmed.

“There is no info yet,” says David Todd of satellite data company Seradata. “It really depends if there was a major, subsequent explosion and if any debris was boosted to a higher orbit.”

The UN’s 1967 Outer Space Treaty bans nuclear bombs or other weapons of mass destruction being stationed in space. But a proposed ban on other weapons has been blocked by the US and other countries.

Space debris is already a major problem. “The situation is critical,” says Underwood. We have already passed the point where collisions that generate space debris increase the likelihood of further collisions, and so on, creating a cascade effect, he says.

This Kessler effect was made famous in the film Gravity, although in reality it is happening over decades or centuries, not in hours – and there is still time to halt it by removing defunct satellites and debris from orbit.