posted
By the way, it was 1999-AN10 that first got me thinking about this, as reported in the free Spanish language weekly paper given out at the local Mexican restaurants. I was puzzling out the text, and it was using words like "apocalyptico" . So it has been 7 years now. We could have made significant progress, if we had decided to make it a priority. I'm sure when we see one heading down our throats, Bush will say nobody could possibly have forseen this. Posts: 6246 | Registered: Aug 2004
| IP: Logged |
posted
I don't find it strange as much as stupid that we're gambling our planet's entire future on the hope that we will never be hit by something of a mass-genociding size.
An Earth-shattering asteroid collision would be pretty much comparable to playing a video game for hours, and then suddenly the power goes out, and you never bothered to save it. Then you have to restart from the begining.
Posts: 879 | Registered: Apr 2005
| IP: Logged |
posted
I was reading the Bad Astronomy Blog (a very cool astronomy resource), and I saw a link to this incredible video of a massive asteroid impact. Fortunately, an impact of this size is incredibly unlikely. Additionally, something that size is going to be pretty visible, so if one like that were headed our way, we'd already know about it. This is very much a "what if?" scenario.
posted
Wow, that was really amazing! It's true that the larger the impactor, the less likely the event, but there have been near misses of 1 km in diameter since I've been keeping up with things. That one looked bigger than 1 km but much much smaller than, say, the moon. In fact, they now have good evidence showing that the moon was formed when a Mars-sized body struck the proto-Earth off center. So it may be unlikely, but it's happened before that something very much bigger than the one they showed has struck the Earth.
Anyway, there's little chance any life more complex than bacterial could survive an impact as large as the one shown. Life is just too delicate and too dependent on the atmosphere. We'd probably have to start over from bacteria after that one. Unless we avert it, of course! I hope Japan does have it under control! Surely the U.S. is dropping that very important ball!
Thanks for the links, Shigosei!
Posts: 6246 | Registered: Aug 2004
| IP: Logged |
posted
I thought it looked to be about 1000km across. Anyone elses opinion? Wouldn't something like that seriously crack the entire planet, alter it's orbit and revolution, things like that?
That was a really cool video, Shigosei. Thanks for posting that.
Posts: 2907 | Registered: Nov 2005
| IP: Logged |
quote:Originally posted by Juxtapose: I thought it looked to be about 1000km across. Anyone elses opinion? Wouldn't something like that seriously crack the entire planet, alter it's orbit and revolution, things like that?
That was a really cool video, Shigosei. Thanks for posting that.
Dr. Phil Plait (the bad astronomer guy Shigosei was talking about) estimates it at about 500 km
Posts: 168 | Registered: Jul 2006
| IP: Logged |
quote:Originally posted by Shigosei: [QB] I was reading the Bad Astronomy Blog (a very cool astronomy resource), and I saw a link to this incredible video of a massive asteroid impact. Fortunately, an impact of this size is incredibly unlikely. Additionally, something that size is going to be pretty visible, so if one like that were headed our way, we'd already know about it. This is very much a "what if?" scenario.
Edit: By the above I mean that an asteroid impact 1,000 of that size could cause the end of human civilization. It don't take much.
In fact, no. There is a fairly good chance we would not see a meteor that was big enough to cause global devastation. We know this because we have caught glimpes of meteors big enough to cause terrible damage, only after they have passed very very close to the Earth, and are receeding-- which means we didn't see them approach. Some of these have been quite large- asteroid wise.
And BTW- a comet this big (more like a moon), hits the Earth and the tower of London survives the initial shockwave? The wind alone would take it to peices I would expect. Then there is the smaller matter of the impact having to transfer momentum into the earth, nocking it in its rotation and spewing ejector flap from the other side of the planet.... hmmm
Posts: 9912 | Registered: Nov 2005
| IP: Logged |
quote:Originally posted by Orincoro: [In fact, no. There is a fairly good chance we would not see a meteor that was big enough to cause global devastation. We know this because we have caught glimpes of meteors big enough to cause terrible damage, only after they have passed very very close to the Earth, and are receeding-- which means we didn't see them approach. Some of these have been quite large- asteroid wise.
And BTW- a comet this big (more like a moon), hits the Earth and the tower of London survives the initial shockwave? The wind alone would take it to peices I would expect. Then there is the smaller matter of the impact having to transfer momentum into the earth, nocking it in its rotation and spewing ejector flap from the other side of the planet.... hmmm [/QB]
I think Shigosei's point was that we would most probably see a 500-1000 km asteroid approaching in advance. A much tinier asteroid, or meteorite, could cause global devastaion yet still be easy to miss until it was right on top of us.
Of course, just spotting a 500+ km object on a collision course would do us little good beyond affording us some quality looting and anarchy. We are decades if not centuries away from dealing with something that big. An object in the 10km or less class we have some hope of coping with, in the near future if we really tried (which we won't).
Wouldn't ground shock waves travel much faster than the atmospheric shock waves? That would ice Big Ben first.
Posts: 6316 | Registered: Jun 2003
| IP: Logged |
posted
Morbo's right--I don't discount the idea of a sudden, devastating impact. I was just saying that an asteroid as big as the one in the animation would probably have been spotted already if it were going to hit us anytime soon. I'm also not certain that there are any earth-crossing asteroids of that size. I think that even most of the asteroid belt objects are smaller than that one.
quote:The wave of superheated steam and magma engulfing the Himilayas was scary!
Yeah. I also thought the part where the ocean looks sort of normal and then becomes steamy and starts boiling away was chilling. Pun sort of intended.
Posts: 3546 | Registered: Jul 2002
| IP: Logged |
posted
Mile wide chunk of rock to pass within 2,100,000 miles of earth (about as far away as the moon). If you're interested in observing it, the data is all given in the link.
Posts: 6246 | Registered: Aug 2004
| IP: Logged |
posted
This is really cool but it should be noted that the moon is ~ 240,000 miles from the earth so this chunk of rock will be nearly 10 times further away than the moon.
Posts: 12591 | Registered: Jan 2000
| IP: Logged |
posted
We might lose Arecibo which would make it harder to look for near earth objects, and potential impact threats. That's shortsighted and unfortunate.
Posts: 6246 | Registered: Aug 2004
| IP: Logged |
posted
"Go outside after sunset and face north. The green Comet Linear VZ13 is gliding through Draco a few star hops from Polaris. Too dim for naked eye, but easy to see in 7X35 binoculars." [/paraphrase] For more info. Check out the 3D-orbit link, and play with the Java scroll bars to shift viewpoints. Coulda been one HECKUVA space SPECTACULAR. And we just missed it.
On 15Augus2007, the Comet/2006 VZ13 (Linear) nearly passes through the point which Earth occupied on 27May2007. Since aphelion was on 7July2007, Earth was somewhat close to that apehelion (farthest distance from the Sun) of 1.01671AU on 27May2007. CometVZ13 will cross nearly the same point at ~1.018AU from the Sun on 15August2007.
ie On 15August2007, VZ13 will come within ~0.002AU of a point that Earth occupied on 27May2007.
Another cute factoid, VZ13 will be between 1.015AU and 1.016AU from the Sun between 9August2007 and 12August2007; less than Earth's aphelion distance, but at a point above Earth's orbital plane.
Fortunately, that 2&1/2 month difference and steep orbital inclination means that the closest VZ13 will get to Earth is 0.575AU on yesterday and today.
Lest we get complacent, the 2006 in C/2006 VZ13 is the discovery year. If that Earth-crossing comet had come 2&1/2 months earlier on a slightly altered trajectory allowing intersection with Earth, there would have been nothing that we could have done about it in the time frame between discovery and impact.
Couldn't find a mass estimate, but comets tend to be large, much larger than the Earth-crossing asteroids that we've fretted about. Now consider the results of a Chicxulub-sized cratering event on our civilization.
posted
I think on all these repeat earth-orbit-crossing bodies, we should act to neutralize the threat for the benefit of future generations. The motions of the bodies in the solar system are chaotic (in a mathematical sense) and inherently unpredictable in the long run. Any asteroid or comet that repeatedly crosses the earth's orbit is a threat from now on. We should, while we can, take those threats out. The best way would be to deflect them to impact the moon, I think. This way, they're totally gone, nothing is harmed, and we get the bonus of possible nickel-iron deposits for lunar mining down the road. Eventually when we have lunar bases and stuff we can't do this anymore. So now is the time!
Posts: 6246 | Registered: Aug 2004
| IP: Logged |
quote:The best way would be to deflect them to impact the moon, I think. This way, they're totally gone, nothing is harmed, and we get the bonus of possible nickel-iron deposits for lunar mining down the road.
Another bonus is the PR that could go into a Planned Lunar Impact! I'd throw a party for that.
Posts: 684 | Registered: Jun 2002
| IP: Logged |
The B612 foundation. What a great name for it! Jeni will appreciate that, I'm sure.
quote: I think it's a very clear situation, not unlike Hurricane Katrina, where it's only a matter of time before this happens. It differs from Katrina because we can't accurately predict the future of a hurricane. But in this case, you can predict very precisely, and you can know decades ahead of time if there's likely going to be an impact. And you can't deflect a hurricane, all you can do is button down or evacuate.
In this case, we could literally prevent a disaster on the scale of 10,000 Katrinas. For humanity to have this capacity and not be prepared to use it is an anti-survival thing. You're rolling the dice -- you're saying, we could do something about it, but we'll take the risk of going the way of the dinosaurs. It seems to me that this is a very irresponsible act.
quote:Originally posted by Tatiana: I think on all these repeat earth-orbit-crossing bodies, we should act to neutralize the threat for the benefit of future generations. The motions of the bodies in the solar system are chaotic (in a mathematical sense) and inherently unpredictable in the long run. Any asteroid or comet that repeatedly crosses the earth's orbit is a threat from now on. We should, while we can, take those threats out. The best way would be to deflect them to impact the moon, I think. This way, they're totally gone, nothing is harmed, and we get the bonus of possible nickel-iron deposits for lunar mining down the road. Eventually when we have lunar bases and stuff we can't do this anymore. So now is the time!
Only there are Billions of such objects in the solar system. You could mess with as many as you want and never save yourself any trouble. Besides, there are near passes from asteroids so often that we often don't even know when they're getting close, until they've already passed us.
What, can someone tell us, would be the effect of a mile wide object impacting on the moon? I speculate it would be problematic at best.
Posts: 9912 | Registered: Nov 2005
| IP: Logged |
posted
I suspect that some debris would reach Earth, causing a good meteor storm. Most of the post-impact ejecta would likely stay near the Moon, likely obliterating some existing features, and any nearby moon landing sites.
I know quite a lot about this stuff, but you'll want to ask a professional because I can't be sure.
Posts: 684 | Registered: Jun 2002
| IP: Logged |
posted
Listen, I've only read the first page... Rather, half of the first page.
Here's my problem. The chances of *one* person (Me) dying because of a meteor crash is 1 in 25,000... But what are the chances that an asteroid large enough to wipe out all of humanity will hit the Earth? Or, even half of humanity?
I'm terribly sorry if this has been addressed in all of those links and I've missed it.
*******Edit*******
Sorry, I realize now the topic has drifted. Posts: 438 | Registered: May 2006
| IP: Logged |
posted
New scientific findings suggest that a large comet may have exploded over North America 12,900 years ago, explaining riddles that scientists have wrestled with for decades, including an abrupt cooling of much of the planet and the extinction of large mammals.
posted
Nathan, don't apologize. I'm delighted that you took an interest. I'm sorry I didn't see your question before now. The probability is low but the consequences are so great, our ability to avert the disaster is so cheap comparatively, that it makes good sense to do serious work on the problem.
For one thing, in general, we care more about larger scale disasters. We spend, for instance, many times the amount per annual death on airline safety than we do on traffic safety, because even though cars kill a whole lot more people, they kill them by ones and twos and fives. Airplane crashes tend to kill a couple of hundred at a time. This is a general rule in averting risk. Humans spend more per annual death on preventing things that kill more people at once. So asteroid impacts, which kill far more at once than airplane crashes, should be attracting more funds per annual death rather than less, as is the case. It's a simple concept but hard to put in words. Did I explain that in a way that it makes sense?
Also, we have the ability to actually do something about this threat, unlike many other threats to the planet as a whole like nearby supernovas, the sun going nova, super-volcanoes exploding, and so on. Because this would cost only a comparatively modest amount to make us safe, it makes a lot of sense for us to do this.
The rest of the arguments for why it is such a smart thing to do are on the first page or so of this thread. I hope I didn't wait too long to answer your question, Nathan. Once again, I apologize for not seeing it sooner. =)
Posts: 6246 | Registered: Aug 2004
| IP: Logged |
quote:So asteroid impacts, which kill far more at once than airplane crashes, should be attracting more funds per annual death rather than less, as is the case.
This is only true if you assume that our tendency to spend on avoiding big, splashy catastrophes is sensible.
Posts: 10645 | Registered: Jul 2004
| IP: Logged |
quote:Originally posted by Tatiana: I think on all these repeat earth-orbit-crossing bodies, we should act to neutralize the threat for the benefit of future generations. The motions of the bodies in the solar system are chaotic (in a mathematical sense) and inherently unpredictable in the long run. Any asteroid or comet that repeatedly crosses the earth's orbit is a threat from now on. We should, while we can, take those threats out. The best way would be to deflect them to impact the moon, I think. This way, they're totally gone, nothing is harmed, and we get the bonus of possible nickel-iron deposits for lunar mining down the road. Eventually when we have lunar bases and stuff we can't do this anymore. So now is the time!
Only there are Billions of such objects in the solar system. You could mess with as many as you want and never save yourself any trouble. Besides, there are near passes from asteroids so often that we often don't even know when they're getting close, until they've already passed us.
What, can someone tell us, would be the effect of a mile wide object impacting on the moon? I speculate it would be problematic at best.
There are billions of objects in the solar system, but only a small number of large repeat earth-orbit-crossing bodies. It makes sense to deal with them, because they pose the greatest risk to humanity. And the reason near passes are not noticed more is that no serious effort with large resources has been made to look for them.
Posts: 6316 | Registered: Jun 2003
| IP: Logged |
posted
Y'know, people, you probably want to be careful throwing around numbers like 'billions'. 10^9 is pretty big. If you want to say "Some large number", use 'zillions', which doesn't have any connotations of exactness; if you use 'billions', people might think you're being exact. I very strongly suspect that the number is only in the millions, at most, short of counting grains of dust. This is an important difference which is obscured by the careless use of 'billions'.
Posts: 10645 | Registered: Jul 2004
| IP: Logged |
posted
Seriously, Glynn? Unless you have some insult/joking relationship going on there I'm not aware of -- out of line.
Posts: 3516 | Registered: Sep 2002
| IP: Logged |
posted
Ah, how delightful! In that case let me introduce you to a clever feature that forums like this have. See on the main page that little column headed "topic starter"? The ones that say "Tatiana" or "ana kata" or "ak" or "aka" in that column, please don't let me impose upon you ever to click on those threads. After all, your blood pressure is obviously high and your patience short. It would seem to be a great boon to your health for you to simply forbear. I promise I won't be upset in the least. Posts: 6246 | Registered: Aug 2004
| IP: Logged |
posted
Leonide, thanks! As you see, Glynn and I don't have any relationship, joking or otherwise, he's just being his usual delightful self. Posts: 6246 | Registered: Aug 2004
| IP: Logged |
posted
How very unChristian of you, Glynn. A militant and/or apathetic atheist like me doesn't stand a chance against your firey asteroid vengeance.
Posts: 3516 | Registered: Sep 2002
| IP: Logged |
quote:Originally posted by Tatiana: New scientific findings suggest that a large comet may have exploded over North America 12,900 years ago, explaining riddles that scientists have wrestled with for decades, including an abrupt cooling of much of the planet and the extinction of large mammals.
Geez, Tatiana. Everybody knows that the abrupt cooling was caused by the flood.
Duh.
Anyway...
Thanks for answering. That does make a lot of sense... So... Now what?
Do we just raise awareness? (I feel that the answer is probably in one of those links... I hate dial-up!)
Posts: 438 | Registered: May 2006
| IP: Logged |
"You could ram it hard with a one-tonne spacecraft and it would change momentum enough to shift it.
If you leave it any later you either have to use much more mass or use a nuclear bomb to achieve greater impact."
Posts: 6246 | Registered: Aug 2004
| IP: Logged |
posted
Nope. The mirrors would act as solarsails, pushing themselves away from the asteroid. So ya'd hafta have more rocket power and trajectory-control programs to keep those mirrors in place than ya would for a gravity tug.
Asteroids tumble. So focusing mirrors on a spot long enough to raise temperatures sufficiently high to cause vaporization is problematic. That or ya'd hafta have a HECKUVA LOT more mirrors than they seem to assume. The vapor would then act as a mirror itself, greatly decreasing the rate at which asteroidal material would vaporize. If the vapor is hot enough, it'll act as a phase conjugate mirror reflecting the beams directly back into the mirrors, which would further deflect those "solarsail" mirrors.
Then the direction of thrust tumbles along with the asteroid. Which means at best chaotic thrust-vectoring pushing the asteroid in unpredictable directions.
Can't focus on a pole because asteroids tumble around more than one axis. And even if asteroids spun about one axis, unvectored thrust would cause it to begin nutating around another.
Posts: 8501 | Registered: Jul 2001
| IP: Logged |
posted
You are more correct than I : most asteroids do spin about a single axis with little-to-no nutation. Apparently, the strong impression left from watching videos of unusual asteroids such as Toutatis made me misremember tumblers as the rule rather than as the exception.
posted
Signs of a recent asteroid impact eventsuspiciously-near the end of the Upper Paleolithic and the beginning of the Mesolithic; and/or possibly forcing what would eventually become the Laurentide icemelt ("Noah's Flood")
posted
Any body rotates around exactly one axis. Tumbling occurs when that axis is not a symmetry axis of the body in question. For example, imagine an ellipsoid. Rotate it around its long axis; clearly it has a pole. Stop the rotation. Keep the long axis in mind, but tip the ellipsoid 45 degrees. Now start rotation again around the same axis as before, which is no longer a symmetry axis. Tumbling will ensue.
Posts: 10645 | Registered: Jul 2004
| IP: Logged |
posted
Tatiana: Have you ever read Carl Sagan's "A Pale Blue Dot"? In it he addresses his stance on the issue of shoving asteroids and comets around at that time(which may or may not be terribly valid anymore). To summarize it he says that before we go start shoving things around we should just LOOK and begin tracking close to all the potentially dangerous bodies, which is obviously difficult since they are very small against a very large background, and some could be very far away etc etc.(kuiper belt etc.) He notes that a preemptive strategy like what you propose--shove all potential future problem asteroids into the moon or some such eliminating course could be seen as rather foolhardy. If something were to go wrong with such a mission and the body missed the moon and smashed into the Earth or just got pushed into a course that after a few revolutions ended up hitting the Earth, then that's no good.
The sort of program you propose would require more tracking of all the Stuff flying around in our solar system, which would take more money that for some reason governments are unwilling to provide. I'd much rather decommission a bomber/not have built that bomber, and have an increase in space exploration budget. What we need to eliminate this issue is colonies on mars/the moon so that if a planet of ours is destroyed by an apocalyptic event we don't lose everything. That, coupled with a strong sky-searching program with action taken against probable threats, is really the best way to go... Really, the only thing we can do unless everyone decides that war hasn't gotten us very far and they'd like to put their billions into research and collaborative space exploration instead of war, is wait. and hope that we don't get snuffed out by a big ol' rock that nobody saw coming.
As a side note: Carl Sagan is awesome. I recommend Cosmos, Pale blue dot, Demon haunted world... Yeah.
Posts: 655 | Registered: May 2005
| IP: Logged |
Printer-friendly view of this topic
![[Smile]](smile.gif)
Isn't the illustration awesome?
![[Wink]](wink.gif)
![[Big Grin]](biggrin.gif)
![[Embarrassed]](redface.gif)
![[Roll Eyes]](rolleyes.gif)
