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Comment by bpicolo | Hacker News Reader

You have to wonder when a large piece of space rock will hit somewhere inhabited. That said, with 3% of earth's land being urban (3% of 29% of Earth), and reasonably infrequent falling rocks, it's really not that likely to happen in any given lifetime. I suspect we're keen enough these days to be able to predict and evacuate the right areas, though. This paper references another that suggests a "Tunguska Event" is a once in 200-300 year deal: http://articles.adsabs.harvard.edu//full/1994Metic..29..864Y... (Man I am so far into the rabbit hole now)

Looks like 15th century China had an event that probably had a number of casualties (though apparently modern researchers dispute the details). Wasn't aware of that. https://en.wikipedia.org/wiki/1490_Ch%27ing-yang_event

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In 2013 in Russia, a meteor exploded over a city and injured thousands of people.

https://en.wikipedia.org/wiki/Chelyabinsk_meteor

Something extra interesting about this is the number of videos that recorded it due to the prevalence of car dash cams. This helped scientists quickly reconstruct what happened and is amazing footage to have of such a rare event.

> Russian authorities stated that 1,491 people, including 311 children, sought medical attention in Chelyabinsk Oblast within the first few days.

Yeah, I saw that. Looks like the shockwaves were the primary mode of injury, though I guess that will always be the primary mode of injury in a large explosion. No deaths that I could see, which is good. I remember seeing the dashcams back then

> Looks like the shockwaves were the primary mode of injury

Not the shockwaves, but things damaged/knocked over by the waves. If you were standing in a field, the shockwave would do nothing to you. It was harmless. But if you are standing beside a poorly-designed glass building, pieces are going to fall off that building. This was Russia. I would expect that other countries, with different building practices, might suffer far fewer casualties.

Right, things damaged BY shockwaves, if we're being pedantic

Do countries legislate shockwave standards in buildings like they do cyclones/hurricanes/etc?

I would imagine that people would think that's a serious waste of money given the odds. Of course after it happens, someone will go "See!!!".

No, but most anti-earthquake measures, especially in regard to glass falling from buildings, would seem applicable. So too with codes meant for safety during hurricanes, tornadoes and other strong winds.

Russia has the worst luck with asteroids.

They're the largest country by area, so it makes sense they'd get hit the most.

Well, Canada is pretty big too, but we don't get any asteroid action. Canada is like "oops, sorry, didn't see you coming. Let me rotate out of your way" and then Russia gets hit.

Russia: "So nice of you Canada, let me thank you with this radioactive satellite". https://www.wikiwand.com/en/Kosmos_954

You might think that, but you've taken a few hits: https://en.m.wikipedia.org/wiki/Manicouagan_crater

Russia has 4x number of people, so I'd expect also a much higher % of the area to be settled.

Are poles more or less likely to be hit than equatorial regions? My google flailing is not getting me anywhere.

Aren't most things in space, well most of the closer things like asteroids, spinning around the sun on the same plane as Earth?

If that's the case then the poles would have a smaller cross-sectional area than equatorial regions.

Maybe the poles would be a good place to build evacuation shelters. Getting there in a hurry could be an issue.

Meteoroids and asteroids generally come from well-known directions since the asteroid belt is relatively confined within the plane of the solar system, with inclinations less than 30 degrees on average. But due to the Oort cloud being spherical, comets can come at us from nearly any direction.

Russia is also pretty big :)

Arguably, the Yucatan peninsula's luck is even worse...

The funniest part about the video in this article is that nobody gives a shit. I mean, look at pedestrian crossers.

Speaking of, what is it with the Russians and the dash cams? There seems to be a subculture of recording while driving and posting videos of road rage, fistfights, etc.

Apparently there was/is a scam where people would walk in front of your car and then sue you for hitting them. So everybody started putting in dash cams to be able to provide evidence against the scammers.

I have heard it's due to the corrupt traffic police. Everyone wants their own record of what happened.

Same thing as the British and CCTVs

Insurance purposes. Russia is a strange country. It wouldn't be too uncommon to have a drunk Russian jumping onto your car angrily while you're parked at a stop-light, or someone knocking you off the road on a highway.

I once saw a small meteor falling, sometime in the early 2000s. I had no idea what it was, just a giant bright sparkling object in the sky...it was kind of terrifying.

For days I looked for any information in the news about it and never found anything reported. I never quite knew what it was, and nobody else really believed by description, until all the dashcam videos about this incident showed up on the internet.

I once saw something during bright, sunny summer day - it looked like a small object that hit the atmosphere pretty much head on (as in it's velocity was perpendicular to the surface). It lasted a second or two, looked like a turbolaser shot or something

It wouldn't have to hit somewhere inhabited. If it landed in say, the Pacific Ocean you could see massive tidal waves on multiple population centers at once. Arguably a bigger threat than if something of equivalent size were to hit land.

http://www.astronomynotes.com/solfluf/s5.htm

Agreed, if something fairly small hit say Gran canaria then it's goodbye large parts of the UK and low-lying parts of Europe.

That article describes the effects of an event a million times more energetic that Tunguska. (6e7 vs 10-15 Megatons)

> You have to wonder when a large piece of space rock will hit somewhere inhabited. That said, with 3% of earth's land being urban (3% of 29% of Earth), and reasonably infrequent falling rocks, it's really not that likely to happen in any given lifetime.

Suppose the probability was close to 1 for this century instead of a long line of zeros with a 1 at the end.

Why would that be the case?

I'm not going to say it explicitly here but you should be able to figure it out. If you do, probably better not to elaborate. Merely reply with 'ZOG' or 'Oh Shit' and never get a good night's sleep ever again! ;-)

I wouldn't bet on us noticing the meteor sufficiently early for an evacuation. We have mapped only a tiny portion of asteroids in our solar system and, iirc, the budget for that program keeps getting cut.

Luckily, there are new companies springing up to do work like this because it will be profitable some day. Planetary Resources is specifically looking for big rocks to do mining operations on, but is taking it into their own hands to map for unknown objects with Near Earth trajectories. That doesn't take away from how sad it is that our governments have cut the already-small budgets of important research like this. That's a crime, really.

Edit: here's the startup pitch I added to our last YC application in the "other ideas" section (I wonder why it didn't get funded):

-------

4) Planetary defense network to protect from asteroid impact. Build small satellites to search for and redirect dangerous asteroids. Rather than last-minute warning systems or explosion/impact-based protection, it would work by slowly gravitationally changing dangerous asteroid orbits so that they will not hit Earth. Build it so that it’s gravitationally self-sufficient and can use captured asteroids to deflect incoming dangers. This is similar to the recent work at Planetary Resources in Seattle - while they prospect for minerals we would direct asteroid orbits. In February of 2016, NASA announced the creation of the Planetary Defense Office to coordinate these efforts globally. Now is the right time to start working on this.

[1] http://www.scientificamerican.com/article/nasa-s-new-planeta...

But those efforts are mostly focused on the big asteroids that wipe out huge areas, right? Spotting an asteroid the size of a minivan or so is really hard, but if something of that size hits a city, thousands die.

> Spotting an asteroid the size of a minivan or so is really hard

Its really not; as I understand, our current technology is sufficient to find things much smaller than that at the distance of the inner edge of the Kuiper Belt.

The problem, at any size, is that we scan very little of the sky, not that its hard to find objects of any size that would be dangerous.

Not feasible as all governments of this planet suspect one another to use the captured meteors as ballistic weapons.

Also planetary defense needs constant maintenance, so what if there is some crisis, and a prolonged downgrade of civilization?

Perhaps I haven't explained my idea very well. I'm imagining millions of small robotic spacecraft, self-constructed by self-mining asteroids that they have found on their own. The little asteroid spacecraft would roam the solar system on huge orbits and search for potential Earth impact-bound objects. If it finds something, over the course of hundreds of years, or thousands of years, the network of small asteroid spaceships could send a probe to the offending target and adjust its orbit so as not to impact. It could then use the offending targets to create new nodes in the system. Theoretically the defense network could last as long as the sun does.

I do agree that the law of unintended consequences might mean that building such a system would instead ensure the destruction of the Earth rather than save it. But it's an idea.

That's a fun idea, and obviously a long way out, but there would have to be a lot of advances to make it possible.

Not all asteroids are made of the same stuff, so the robots would have to know many possible materials that the robots could be made of and how to process the raw materials into those refined materials and how to actually build the equipment to do that refining. That means that they would also have to know many ways to build refining equipment depending on what materials are available. It's a lot of variables and very difficult.

For instance, how can they create circuit boards if silicon and carbon and copper aren't available?

I think it makes more sense to build a robot factory in one location (a low gravity moon for instance) and send out the first few thousand robots to known asteroids. They could attach and shift orbits to where they crash on the other side of that moon where robots go and harvest raw materials to bring back to the factory.

Your current proposal is like telling 100 people to go to 100 specific locations on earth and build a bicycle with what is at that location. One guy in the desert might end up with a bike made of glass fired from the sand. Someone in the jungle might end up with one made with ivy and bamboo. While it's theoretically possible, it would be easier to send them out and tell all 100 to bring back all the materials they find to a central location and build bicycles out of the pile of stuff. The large amount of materials would render bicycles that are made of the best possible materials for each part.

P.S. If you're working at a startup that's pitching long-shot ideas like this, I really want to join you guys!

Which program are you referring to? LSST is fully funded.

https://www.lsst.org/science/solar-system/potentially-hazard...

https://en.wikipedia.org/wiki/Large_Synoptic_Survey_Telescop...

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