Deep Impact?

[akpe]

By Dr David Whitehouse

BBC News Online science editor

 

An asteroid discovered just weeks ago has become the most threatening object yet detected in space.

 

A preliminary orbit suggests that 2002 NT7 is on an impact course with Earth and could strike the planet on 1 February, 2019 - although the uncertainties are large.

 

Astronomers have given the object a rating on the so-called Palermo technical scale of threat of 0.06, making NT7 the first object to be given a positive value.

 

From its brightness, astronomers estimate it is about two kilometres wide, large enough to cause continent-wide devastation on Earth.

 

Many observations

 

Although astronomers say the object definitely merits attention, they expect more observations to show it is not on an Earth-intersecting trajectory.

 

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.

 

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.

 

Could an asteroid be deflected?

 

By Ivan Noble

BBC News Online science staff

 

 

It will take weeks or even months before astronomers will be able to confirm their suspicion that asteroid 2002 NT7 will pass very close to but not hit the Earth early in 2019.

 

"As further observations accrue, we'll probably find that what is currently a possible hit will become a near miss," Professor Mark Bailey, director of the Armagh Observatory in Northern Ireland, told BBC News Online.

 

In the very unlikely event that 2002 NT7 did turn out to be on a direct collision course, astronomers would have plenty of time to make accurate predictions about the time and location of the impact, and, with luck, to come up with a plan to deflect it.

 

"It's not like dealing with space debris, where the object may be irregularly shaped and tumbling and where even hours before impact you don't know exactly when and where it's going to come down," said Professor Bailey.

 

"With an asteroid impact, it's more like when Shoemaker-Levy 9 hit Jupiter.

 

"There we were able to calculate the exact time of impact almost to the second," he said.

 

Asteroid rendezvous

 

In the most unlikely event that it were on collision course, there would be no more important project than to try to deflect it, he added.

 

"It orbits roughly every 2.2 years, so there would be several opportunities to rendezvous with it.

 

"There'd be opportunity to assess what it's made of, find out whether it's made of rock and ice, or iron, whether it's a rubble pile or a solid body.

 

"It would make sense to put a beacon on it so that you'd then have a very precise knowledge of its orbit," Professor Bailey said.

 

No-one has yet seriously tried to come up with a plan to deflect an incoming asteroid, but given years of warning and an asteroid which orbits relatively frequently, giving it a small nudge early on might do the trick.

 

"Relatively benign deviations imparted years ahead are magnified each time the asteroid goes around the Sun and would hopefully be enough to turn a projected impact into a near miss.

 

Solar option

 

"One could even imagine landing on it and firing a rocket engine.

 

"People have talked about some kind of a mass driver, where pieces of rock would somehow be broken off the asteroid and cast off into space.

 

"Even a solar sail might be a possibility," Professor Bailey told BBC News Online.

 

Such a device might catch the solar wind - a constant stream of particles emanating from the Sun - and use the small but significant energy they carry to cause a tiny deflection in the asteroid's path.

 

Source: BBC (http://news.bbc.co.uk/1/hi/sci/tech/2147879.stm)

[Lucifer]

ʼντε καιρός ήταν... Πάντως εντάξει... Αν ζούμε ως τότε θα αποχωρήσουμε φαντασμαγορικά! Προσωπικά την βρίσκω με την ιδέα... <img border="0" title="" alt="[smile]" src="images/icons/smile.gif" />

[andreaslfc]

Αστεροϊδής 2002 NT7

 

Με διάμετρο 2.060Km.

Με μάζα 1.2e+13 kg.

Η ενέργεια που θα απελευθερώσει θα είναι ίση με 1.2e+06 Μεγατόνων.

 

Περισότερα από την NASA: Τα πλήρη χαρακτηριστικά του 2002 NT7.

 

Για την Palermo scale αν το νούμερο είναι μικρότερο του -2, δηλ. -2.89 δεν είναι τίποτα σοβαρό. Αλλά αν είναι από -2 έως 0 (στην περίπτωσή μας είναι -0.06) αυτό δείχνει κατάσταση που αξίζει τον προσεκτικό έλεγχο.

 

Αυτό που δείχνει τον κίνδυνο και τις συνέπειες που θα ακολουθήσουν είναι η Torino scale από 0-10 (όπου 10 σημαίνει: Μια σύγκρουση ικανή για μια σφαιρική κλιματολογική καταστροφή. Τέτοια γεγονότα εμφανίζονται μιά φορά ανά 100.000 έτη, ή λιγότερο συχνά.)

Ο 2002 NT7 έχει Torino scale 1.

1. Η πιθανότητα της σύγκρουσης είναι εξαιρετικά απίθανη, σχεδόν ίδια όπως ένα τυχαίο αντικείμενο του ίδιου μεγέθους που χτυπά τη γη μέσα στις επόμενες μερικές δεκαετίες.

 

Για αυτό κοιμηθείτε άνετα και Καλό Καλοκαίρι.

 

<small>[ 24-07-2002, 23:44: Το μήνυμα επεξεργάστηκε από: andreaslfc ]</small>