WASHINGTON • The head of Nasa has branded India's destruction of one of its satellites a "terrible thing" that had created 400 pieces of orbital debris and led to new dangers for astronauts aboard the International Space Station.

Mr Jim Bridenstine was addressing employees of Nasa, or the National Aeronautics and Space Administration, five days after India shot down a low-orbiting satellite in a missile test to prove it was among the world's advanced space powers.

Not all of the pieces from the satellite that was shot down were big enough to track, Mr Bridenstine said. He added that the objects currently being tracked are 10cm or bigger, and about 60 pieces have been tracked.

The Indian satellite was destroyed at a relatively low altitude of 300km, well below the International Space Station and most satellites in orbit.

But 24 of the pieces "are going above the apogee of the International Space Station", added Mr Bridenstine.

"That is a terrible, terrible thing to create an event that sends debris at an apogee that goes above the International Space Station," he said.

"That kind of activity is not compatible with the future of human spaceflight. It's unacceptable and Nasa needs to be very clear about what its impact to us is."

The US military tracks objects in space to predict the collision risk for the International Space Station and for satellites.

In total, it is currently tracking 23,000 objects larger than 10cm. That includes about 10,000 pieces of space debris, of which nearly 3,000 were created by a single event: a Chinese anti-satellite test in 2007 at 852km from the surface.

As a result of the Indian test, the risk of collision with the International Space Station has increased by 44 per cent over 10 days, Mr Bridenstine said.

But the risk will dissipate over time as much of the debris will burn up as it enters the atmosphere.

AGENCE FRANCE-PRESSE