Asteroid 2002 NT7

Actual Photo Of 2002 NT7 Asteroid
It has been called the most threatening object in space

FROM BBC NEWS 24 JULY 2002

It was first seen on the night of 5 July, picked up by the Linear Observatory's automated sky survey programme in New Mexico, US.

Since then astronomers worldwide have been paying close attention to it, amassing almost 200 observations in a few weeks.

Could it be deflected?

Dr Benny Peiser, of Liverpool John Moores University in the UK, told BBC News Online that "this asteroid has now become the most threatening object in the short history of asteroid detection".

NT7 circles the Sun every 837 days and travels in a tilted orbit from about the distance of Mars to just within the Earth's orbit.

Potential devastation

Detailed calculations of NT7's orbit suggest many occasions when its projected path through space intersects the Earth's orbit.

Researchers estimate that on 1 February, 2019, its impact velocity on the Earth would be 28 km a second - enough to wipe out a continent and cause global climate changes.

However, Dr Peiser was keen to point out that future observations could change the situation.

He said: "This unique event should not diminish the fact that additional observations in coming weeks will almost certainly - we hope - eliminate the current threat."

Easily observable

According to astronomers, NT7 will be easily observable for the next 18 months or so, meaning there is no risk of losing the object.

Observations made over that period - and the fact that NT7 is bright enough that it is bound to show up in old photographs - mean that scientists will soon have a very precise orbit for the object.

Dr Donald Yeomans, of the US space agency's (Nasa) Jet Propulsion Laboratory in California, told BBC News Online: "The orbit of this object is rather highly inclined to the Earth's orbit so it has been missed because until recently observers were not looking for such objects in that region of space."

Regarding the possibility of an impact, Dr Yeomans said the uncertainties were large.

"The error in our knowledge of where NT7 will be on 1 February, 2019, is large, several tens of millions of kilometres," he said.

Dr Yeomans said the world would have to get used to finding more objects like NT7 that, on discovery, look threatening, but then become harmless.

"This is because the problem of Near-Earth Objects is now being properly addressed," he said.

2002 NT7 Orbit

THE REAL STORY OF 2002 NT7

(89959) 2002 NT7 (also written (89959) 2002 NT7) is a near-Earth object (NEO) that became the first object observed by NASA's NEO program to be assigned a positive rating on the Palermo Technical Impact Hazard Scale for a potential impact date of February 1, 2019. Despite inflammatory press reports, the object has a "low probability" of impact, approximately one in a million.

Further observations of the object have since re-rated the threat lower. As of July 25, 2002, the hazard rating on the Palermo scale had been lowered to -0.25. However, the discovery of an object with an initial hazard rating above 0.0 is still a significant event in the history of the NEO observation program.

On August 1, 2002, the object was removed from the list of objects that present a threat, at least for the next 100 years.