London, Nov 19: A new study by scientists suggests that asteroids which are deflected on a collision course with Earth, are likely to return for another potential clash.

According to the study presented to the US House Science and Technology Committee last week, methods like nuclear explosions might deflect an asteroid temporarily, but it does not guarantee safety next time its orbit brings it close.

Rusty Schweickart, who heads an asteroid research group, told the committee that the effects of powerful blasts are hard to predict, especially if the Earth's gravitational pull acts on the object.

"An asteroid could pass through one of the 'keyholes' that would nudge it back onto a collision course with Earth," New Scientist quotes Schweickart as saying. "So once diverted, it might need to be steered past Earth to prevent this," he added.

At the same hearing, members attacked NASA for ignoring smaller asteroids.

This indifference was evident from the fact that when Congress asked NASA to plan a programme to identify dangerous objects as small as 140 metres across, the space agency said that it preferred to work from other surveys. (ANI)