Asteroid heading for Earth needs UN plan say scientists

Stan Beer
Sunday, 18 February 2007 09:45

Science - Space

On a cosmological scale, an asteroid called Apophis is small. However, if the 250 meter wide space rock hits Earth in 2036, as scientists say it may, the consequences would be catastrophic. According to the Association of Space Explorers (ASE), a professional association for astronauts and cosmonauts, the world needs to wake up to the danger or suffer a disaster that would dwarf the Indian Ocean Tsunami of 2004.

Former astronaut Rusty Schweickart, chairman of the ASE's Committee on Near Earth Objects (NEO) and a member of the Apollo 9 lunar module crew, believes action needs to be taken under the auspices of the UN to minimize the threat from rogue asteroids heading our way.

"While such cosmic impacts between NEOs and the Earth are infrequent their magnitude is often far greater than any other natural disaster, with an upper bound resulting in global, rather than local or regional devastation. Historically the largest of such cosmic impacts have
led to the virtually instantaneous extinction of a majority of the species alive on the planet at the time of impact," Schweickart and his fellow NEO committee members wrote in an open letter produced by the ASE in 2005.

Now Schweickart and his team are calling for a new global organization, which will have the responsibility of coordinating and dealing with such threats. According to ScienceNoW magazine, published by the American Association for the Advancement of Science (AAAS), astronomers told the annual meeting of AAAS last week preventing a collision would require mounting a not-yet-planned space mission by a not-yet-identified governmental body.

While thousands of potentially dangerous NEOs have been identified by astronomers, Apophis has been singled out for attention because it is going to have two very close encounters with the Earth within a short space of time. The first on Friday April 13 2029 will see the asteroid pass within an uncomfortable 30,000 kilometers. However, it is the second pass seven years later that have scientists worried. They're not sure whether the first pass will see Earth's gravity drag Apophis into a direct impact trajectory in 2036.

The only modern documented case of a large space body impacting Earth was in 1908 when an object exploded in the air over the Tunguska region of Siberia. The resulting blast, equivalent to a 10 megaton nuclear bomb, flattened 2150 square kilometers of forrest. There is still conjecture as to whether the object was part of a comet made of ice and dust or a rocky asteroid similar to Apophis. If it was an asteroid, then scientists have calculated that it would have been about 60 meters in diameter, less than one quarter the size of Apophis.

Proposals being put forward to circumvent the threat posed by Apophis and other NEOs include have specially prepared spacecraft ready to launch which would impact the threatening asteroid and deflect it from its collision course. Another suggestion, is to deflect the asteroid's course using the weak gravitational field of a spacecraft hovering nearby.

Scientists generally don't favour the idea of hitting asteroids with nuclear missiles as they believe it creates the danger of the asteroid simply fragmenting into a number of smaller but still deadly Earthbound NEOs.