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NASA Downgrades Asteroid-Earth Collision Risk
coondoggie writes "NASA scientists have recalculated the path of a large asteroid known as Apophis and now say it has only a very slim chance of banging into Earth.. The Apophis asteroid is approximately the size of two-and-a-half football fields, and updated computational techniques and newly available data indicate the probability of an Earth encounter on April 13, 2036 for Apophis has dropped from one-in-45,000 to about four-in-a million, NASA stated."
Isn't four in a million the same as one in 250,000 ?
>two-and-a-half football fields
So is that US football fields or are we using the metric system (ie. Soccer fields) ?
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Even the chance of an apocalypse is being downsized.
I guess that means I'm still going to need to worry about the Y2k38 problem.
We won't have to file taxes by April 15 in 2036, or possibly ever again. Death 1, Taxes 0.
Hope is the currency of fools
Taken from: http://en.wikipedia.org/wiki/Rogers_Commission
"Feynman was clearly disturbed by the fact that NASA management not only misunderstood this concept, but in fact inverted it by using a term denoting an extra level of safety to describe a part that was actually defective and unsafe. Feynman continued to investigate the lack of communication between NASA's management and its engineers, and was struck by management's claim that the risk of catastrophic malfunction on the shuttle was 1 in 10^5; i.e., 1 in 100,000. Feynman immediately realized that this claim was risible on its face; as he described, this assessment of risk would entail that NASA could expect to launch a shuttle every day for the next 274 years without an accident."
Well, it has nothing to do with the topic, but I wouldn't trust a statement "four-in-a million" made by NASA... ;-)
There is no guarantee for a secure life on this planet. Asteroid impacts are a part of the nature, so everybody should be aware of those risks...
Posted too soon, I did. Should have checked the source of the picture first.
What we have accompanying the article on Apophis is a picture of Asteroid 253 Mathilde. Apparently pulled off the NASA website at random by the author's of TFA.
"I do not agree with what you say, but I will defend to the death your right to say it"
All the models are run according the 'standard dynamic model' at JPL which includes gravity from the Sun, planets, large moons and large asteroids. Perturbations caused by objects outside the solar system are negligible compared to non-gravitational effects such as direct solar pressure and the Yarkovsky effect. These effects are impossible to model without knowledge of material composition, mass and structure, which you can't really get without going there.
However, the uncertainty caused by these non-gravitational effects is very small compared with the uncertainty caused by the fact that we just plain don't know quite where it is and how fast its going. In order to know where the asteroid will be in 2036 to within an Earth radius requires us to know where it is now to within about a meter -- the 2029 close approach in particular magnifies uncertainties incredibly (100x).
These state estimate uncertainties overwhelm any small errors in the dynamic model, and these new and improved probabilities come from refining the current state estimate. So yes, it is still valid to make these kind of predictions. You have to start early (10-20 years) to be able to stop it as well, so its important to keep an early eye on it.
How about 1 in 250,000? And "two football fields" doesn't tell us much about the thing's actual size.
You're translating from Jock to Geek. The Jock's understand a million as "a really big number" and 4 as a really small one. 250 is compleltely beyond them, let alone 250 times 1000! Football fields is a much more natural unit to them than a meter. Never mind that they're different sizes - they can all relate to being exhausted running the length of a football field. The concept of a meter just hurts their poor roid ridden brains.
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Apophis had been downgraded to 4 chances in a million from 22 chances in a million. This new figure is clearly wrong, because it has 6 chances to impact between 2036 and 2103 (see http://neo.jpl.nasa.gov/risk/a99942.html ). Perhaps this means the actual metric is 6 chances per 1.5 million.
Also of note in the upgraded data is the second of the 2068 near misses, having a 0.00 Earth radius distance. This is likely a statistical artifact caused by the fact that a near miss is a hit (a miss is a miss or it isn't; something that comes close but doesn't hit is a near hit).
Since the distance is zero but the impact probability is 1.1e-07, they have almost certainly determined that it will pass by (and/or impact) almost perfectly edge on. Due to its size being equivalent to 2.5 football fields, and a football field being a 2 dimensional rectangle with no thickness, an edge on impact would have little effect, keeping all 510 megatons of impact energy confined within an area of 270 by 0.000... meters, ie. no area at all. Thus, the impact will have absolutely no effect unless you happen to be standing over that 270 by zero meter line when it comes down on you, or worse, up at you after having passed through the Earth (a zero thickness should be able to pass through the planet like a neutrino).
Hopefully we will also get updated figures on 2007 VK184. It has a 340 in 1 million chance of impact. It gets 4 attempts between 2048 and 2057. Four chances in 9 years gives it 2.25 million years to have its one million attempts, in which time it will only hit Earth 340 times, or once every 2417095.5882352941176470588235294 days. This was calculated with due attention paid to leap years, though it is uncertain at the time of publication whether the frequent legislating of time standards by the US will result in the figure being in standard leap years or daylight savings leap years.
Just to add a minor point of confusion, in case it has been so far missed: the question has been raised regarding the actual size of these objects, as 'football field' is ambiguous, there being two different kinds of 'football' using different size fields. The answer is that it doesn't matter. NASA has already proven themselves to be above and beyond the need for conversion factors, and so they need not differentiate between metric and non-metric football. In their usual excessively polite manner, Canada has repeatedly not pointed out that they too have 'football' similar to the US kind, but with yet another differently sized field. Their reticence is somewhat practical when one considers that fewer people watch Canadian football than watch curling, and nobody outside Canada watches that.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B