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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 ?
Is it really that hard to use the same intial number for 2 ratios? I mean honestly... 1 in 250,000 is much easier to compare to 1 in 45k than 4 in 1million
a handful of selfish greedy people are no match for millions of selfish, greedy people -u4ya
Man, that's a lot of Astro-Glide.
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>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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How about 1 in 250,000?
And "two football fields" doesn't tell us much about the thing's actual size. Besides "football" having two different meanings, one of which has multiple field sizes, what kind of volume are we looking at here?
They better be careful with those odds... that's dangerously close to a one-in-a-million chance, which everyone knows happen ALL THE TIME...!
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.
Clearly 4 in a *million* must be a very very small number, not like 1 in 250000 - which has thousands on the right-hand side, so that can't be good.
In an attempt to make a new probability "less scary" the authors (or summary writers) also commit a specific error - there is only ONE asteroid so any probability related to it is ALWAYS 1 in something. It can never be 4 in something because there is only once chance of collision.
I thought we killed that asshole at the end of season 3?!
No one cares what your captcha was
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they crashed a $125 million orbiter into Mars because they mixed up metric and imperial units... so im not trusting their math ;)
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
Yes, in much the same way that Jame Cameron murdered 49 people. (See point #6)
$_ = "wftedskaebjgdpjgidbsmnjgcdwatb"; tr/a-z/oh, turtleneck Phrase Jar!/; print
Million-to-one chances crop up 9 times out of 10.
I mean, who knows if the path of the asteroid may deviate a little bit due to gravitational pull of different planets/stars etc
If there are any stars out there besides the sun close enough to affect this asteroid... we're pretty much fucked already.
This is like those COPS shows, where they are following a high speed chase from a helecopter. The announcer is always announcing how they nearly hit the pedestrians, who were on the sidewalk, on the opposite side of the street.
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
I mean, who knows if the path of the asteroid may deviate a little bit due to gravitational pull of different planets/stars etc.
Well they're pretty certain that it will deviate due to the variety of forces on it, which is exactly why the result is given as a probability, rather than a "will hit" or "will miss by X miles". It's also why the probability changed with further observation. Conditional probability is basically serving as a stand-in for what we don't know and the fact that we can't solve N-body gravitational problems. The more we know about the asteroid's trajectory, the more we can say about it's potential future paths and the likely hood of it hitting earth. At the end of the day (or the planet), it will either be nudged onto a path that will impact us or it won't, but right now it looks unlikely that it'll happen.
The enemies of Democracy are
The real question is, will Bruce Willis still be alive and fit enough for an emergency space mission?
Born: March 19, 1955. That will put him at 81 years old... We better freeze him now, so we can thaw him out in case of an impending asteroid strike.
What is the real use in this? When, within reasonable (I'm not a scientist, but lets use an 85% confidence interval) levels of knowing, would we be able to determine that in fact, yes, this thing is or is not going to hit us?
How's a 99.9996% confidence interval? Not the most obvious way to word it and it doesn't strictly apply, but you could say that in the population of hypothetical asteroid trajectories, 99.9996% of them don't hit earth. More study of its orbit is probably going to increase that number.
Not sure how saying it's odds of hitting us is 1 in 250,000 is less useful than saying it's definitely not going to hit us (with 85% certainty). :)
The article states that they aren't being given the funding to further fund research centers for adequate testing. Politics aside - is there any funding (and more importantly, scientific viability) for preventative action for any of this, or are we just providing confidence intervals of our ultimate doom?
Sadly, no in terms of funding. Even the agencies who could conceivably cobble together something at the last minute aren't getting enough funding. We aren't funding the finding of these object to see if we even need preventative action.
As far as viability... there are quite a few things that would work quite easily with today's technology. But it would take time to actually construct the solution. And they all take time. Virtually none of them would work with only a year before the impact. Even ignoring the silliness of the Armageddon Solution blowing apart a Texas-sized meteor with a nuke, all it would mean is that two California-sized meteors hit the earth instead. The solutions most likely to work are ones where we slowly push (or pull) it out of the way over the course of years.
I'm not really worried about an asteroid that we know about, and are tracking, that looks very unlikely to hit the earth. I'm much more worried about all the objects we don't know about, so we have no idea how likely they are to hit us. My biggest concern is that we discover an object that has a high probability of hitting earth in only a year or two.
More funding for finding and tracking, pls k thx.
The enemies of Democracy are
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...
There are three objects with higher probability of impact on the list, two of them much larger than Apophis (270 m diameter). Their diameters are 560 m and 780 m.
http://neo.jpl.nasa.gov/risk/
Scroll down to "Objects not recently observed"
Certainty is a funny word, but basically, the closer it gets the more confident you are in your prediction because small errors grow to large errors over time.
I would say, without significant funding you'd know for certain in the lead up to the 2029 close approach. During this event, the asteroid will pass within the geostationary satellite belt, and has the potential (1 in 250,000 now) to pass through a 'gravitational keyhole' that corresponds with a return impact trajectory. Note that the likelihood of impact in 2029 is zero (i.e. the 6-sigma boundaries of trajectory estimates are very far from the Earth).
Unfortunately, if you don't do something about it well before 2029, its unlikely you could do anything short of an Apollo-class-plus (Bruce Willis-class?) mission, in terms of funding, uncertainty, and national effort, to stop it. Put simply, its much easier to push the asteroid a kilometer (out of a keyhole) than it is to push it 3000 kilometers, but you have to do it earlier.
If you wanted to do very precise tracking to know if (and where) it was going to impact without waiting for the close approaches, you can do some of it with simply more observations with larger telescopes, and more ground-based radio ranging. However, you're going to get much better results (an order of magnitude) if you send a spacecraft out with a proper beacon. Two or three months in 2021 with this kind of tracking would give you 3-sigma (99%) reliability if it is to impact, and ascertain that it was not if it is not going to. A year of this tracking would tell you where exactly it was going to hit, within about 100km.
Of course, if you're already out there, its not too much more expensive to add the equipment to do a gravity tractor and move it away from a keyhole, since by 2022 it would be very difficult and very expensive to get a mitigation mission put together in time. A combined exploration and mitigation mission is estimated to cost about $350M, and in addition to improving knowledge about the unlikely but potentially imminent threat, would make it much easier to deal with future threats and contribute a lot to our understanding of near Earth asteroids in general. A pure exploration mission might be able to shave off $25M -- the only extra equipment is some Hall thrusters and a longer lifetime. I personally think there is political will for it at relatively low cost (Discovery-class mission), and scientific benefits beyond the mitigation of an admittedly small risk.
(Full Disclosure: Most of these numbers are pulled from a mission proposal I'm currently working on. The details aren't officially published yet, although they are being presented at a conference next week.)
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.
Yes, we are. Eventually. Might as well get it over with, eh?
Besides, you all are such pessimists. I like to think of it like this. If it hits us, dying will be the one thing that mankind finally comes together and actually achieves, something that everyone, everywhere can be a part of.
You'd probably have to apply a few km/s Delta-V (at least) to it in order to do that. All estimates show it entering the Earth's sphere of influence at about 5.87 km/s, which would be reasonable for putting it in orbit, if it were in the right place. Unfortunately, as it moves past the earth it gets sped up and moves on a hyperbolic orbit, it speeds up, so theres no real way to do it just by changing its position slightly (which could be done for ~$300M).
Basically, changing its position slightly in order to prevent an impact requires a very small amount of energy. For a 50 mN thrust for 1 year, 20 years ahead of time (which is enough to move it in 2036 by around 20 Earth radii), moves it about 500 meters and thus does about 25 Joules worth of work*. However, consider changing the velocity of something the size of Apophis (2.1e10 kg) from 5.8 km/s to say 3 km/s -- thats 2.5e17 Joules worth of work. Thats 800 MW over 10 years. I think there are probably better asteroids to capture in this case, and its certainly not an easy task by any definition.
*forgive me if the numbers are a bit off, but its the correct order of magnitude anyway
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