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MOBIUS
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Prifysgol Caerdydd
Dec 1999
time: 15:21
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quote:
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 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 2km wide, large enough to cause continent-wide devastation on Earth.
Although astronomers are saying 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, in the southern 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 its 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 28km 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 astronomers will soon have a very precise orbit for the object.
Dr Donald Yeomans, of Nasa's 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 kms," he said.
Dr Yeomans told BBC News Online that 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. |
http://news.bbc.co.uk/2/hi/science/nature/2147879.stm
Let's hope Bruce Willis and Ben Affleck are still around for this - we might need them!
I think this in itself is a good excuse to put more resources into space, with the first target being Mars. Being hit by a meteorite is a real threat - one devastating one is believed to have hit in Siberia only about 80 years ago (I can't remember the name!)
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Vesayen
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Mobius-you read the ac friends board dont you?
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ravagon
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Australia
Sep 1999
time: 13:21
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Rather amusing how they describe the uncertainties as "large".
With a projected collision date 17 years in the future (ie: the Earth will cycle through about 16.5 solar orbits before said body is even close) between two objects in the suns gravity well (ie: making it a many body problem with pretty poorly defined parameters to start with) a "large" degree of uncertainty is like describing the primary blast of a thermonuclear detonation as "slightly warm". And thats not really much of an exaggeration either.
There may be astronomical events in the future at a level of significance to cause genuine concern but, to coin a phrase, "this aint it".
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Bereta_Eder
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so when will it hit us?
im too bored to read the article just give me the date
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Bereta_Eder
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bah who lives who dies by 2017
we have time
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Bereta_Eder
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You are magnanimously forgiven.
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Bereta_Eder
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How come you always know what time it is in Greece and I don't know what time it is in Canada (Quebec is it?)
I'm writing stuff.
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Dr Strangelove
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So how big is this thing? The Tunguska rock was supposed to be only about 200 meters diameter. Even a big non-nuclear bomb would blow something that size into easily manageable chunks.
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ravagon
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Australia
Sep 1999
time: 13:21
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quote:
Originally posted by MOBIUS
Thanks Ramo - Tunguska was the one I was thinking of. Damned lucky it hit a totally unpopulated area, it was massive!
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The tungaska "meteor" (1908) never actually hit. No impact crater. It exploded in mid air and flattened/irradiated a few hundred sq km IIRC.
A 2km wide asteroid isn't really much of a threat in any case. Not enough mass to serious impact the planets axial tilt or orbit (which could annihilate virtually all life) hence the major threat comes from the primary impact and the projected dust cloud fallout.
High-yield fusion warheads have a blast radius > 2km so even a near miss should be capable of fracturing the body at the very least - hence increasing the surface area over which it absorbs heat entering the atmosphere, thus vaporizing and reducing the size of the fragments and further reducing the impact.
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Bereta_Eder
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I have a vague recolection of Greek time being 2 hours ahead of London time...
So we're 7 hours apart.
Memorized.
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Dr Strangelove
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It knocked down trees in an area 30 miles in diameter. Yes, you're right, it did not actually impact the earth.
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Dr Strangelove
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quote:
Originally posted by Frogger
Not really. You could detonate a few dozen tons of TNT against an asteroid of 200 metres diameter without breaking it up (assuming it's actually solid and not just a loosely-bound pile of rubble).
Remember how big 200 metres is... |
How solid would something with such a small gravitational field holding it together be?
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ravagon
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Australia
Sep 1999
time: 13:21
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quote:
Originally posted by Frogger
2 km is a serious amount of mass. I don't know if even a direct hit with, say, a 20 megaton thermonuke would actually do anything other than crack off a big chunk. I sincerely doubt it would shatter it. |
If 2km is the diameter of its major axis then it has a volume of a few million cubic metres. Assuming a relative density of about 5 (I don't remember how reasonable this is I'm afraid) puts the mass at a few billion tons. This shouldn't be sufficient to withstand the stresses of a multi-megaton blast.
Nickel-Iron asteroids may be a little more resilient than Stoney-Irons but not by a great deal.
I may be making too many assumptions of course but I don't think thats too far out.
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24-07-2002 06:32
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