NASA-International Space Station

A report released on Friday by the National Academy of Sciences claims almost nothing is being done to discover and destroy smaller objects in space that are perhaps a more likely threat that bigger asteroids and obvious threats.

The National Academies report says it is extremely probable that the next destructive impact will be something less than 50 metres (164 feet) across. This happens about once every 1,000 years. The last one hit over Tunguska, in Siberia, in 1908, destructing forests. If one hit a populated area today, it would cause destruction akin to a severe hurricane or tornado.

The term given to space matter that could potentially intimidate the planet is 'Near-Earth Objects' - asteroids, comets or really big pieces of rock that may wander close to Earth. About 6,200 near-Earth asteroids have been recognized, the largest being 1036 Ganymed, which is 20 miles (32 km) across.

Like the moon and Mars, which are covered in craters, the Earth is also often bombarded. But erosion, the association of continents, the oceans and even forests obscure them over time.

Objects one kilometre (just over half a mile) across hit the Earth about once in a million years. Something this big could harm a large region or cause a vast tsunami if it hit an ocean.

Objects of about 5 km (three miles) or larger could kick up enough dust to cause inclusive damage for years, perhaps decades of cold and dark conditions, and could cause mass extinctions.

"Luckily such events are exceptionally rare, the last known being about 65 million years ago," the report reads.

Your own possibility of dying in a large cosmic impact is 1 in 40,000, not because it is likely but because such an impact would kill so many people that it raises the odds. In contrast, your own risk of dying in a flood is 1 in 30,000, while the risk of death from a motor vehicle accident is 1 in 100.