Asteroids Apophis's Deep Impact on Easter Sunday 13 Apr 2036

A blue-ribbon panel of scientists is trying to determine the best way to detect and ward off any wandering space rocks that might be on a collision course with Earth. US Congress asked the academy to conduct the study after astronomers were unable to eliminate an extremely slight chance that an asteroid called Apophis will slam into Earth with devastating effect in 2036.

Apophis was discovered in 2004 about 17 million miles from Earth on a course that would overlap our planet's orbit in 2029 and return seven years later. Observers said that the asteroid — a massive boulder left over from the birth of the solar system — is about 1,000 feet wide and weighs at least 50 million tons. After further observations, astronomers reported that the asteroid would skim by Earth harmlessly in 2029, but it has a one in 44,000 probability of slamming into our planet on Easter Sunday , April 13, 2036.

Small changes in Apophis' path could make the difference between a hit or a miss are possible. The chances are now supposed to be low, and its hazard potential has been reworked several times, but the actual chances of a Deep Impact will be known only by 2014, when more data is collected.

More than 5,000 near Earth objects, including 789 potentially hazardous objects, have been identified so far. A collision with one or more of these many objects littering the solar system is inevitable. For example, astronomers had only 24 hours' notice of a small asteroid that blew up over northern Africa on Oct 7. A larger, more dangerous object presumably would be spotted years or decades ahead, giving humans time to change its course before it hit.

The panel is also tasked to review various methods that have been proposed to deflect or destroy an incoming asteroid and recommend the best options. They include a nuclear bomb, conventional explosives or a spacecraft that would push or pull the asteroid off its course. Offbeat ideas are painting the surface of the asteroid so that the sun's rays would heat it differently and alter its direction, and a gravity tractor, a satellite that would fly close to the asteroid, gently nudging it aside.

The earlier that a dangerous asteroid is found, and the farther it is from Earth, the easier it will be to change its trajectory. A relatively small force would be enough while the object is millions of miles away.

The year 2029 could be crucial. When Apophis makes its first pass by Earth, its track can be more precisely determined. That will enable astronomers to judge whether Earth will escape with a near miss or will have to take swift action to avoid a blow that could devastate a region as large as Europe or the Eastern United States.