### Author Topic: Meteor Strikes Chelyabinsk, Russia  (Read 165763 times)

#### rdale

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #360 on: 02/18/2013 07:45 PM »
but we can be certain that the \$4M/year we currently spend is unreasonably low.

No, we can't be certain. If we spent what was needed to prevent every threat to any human, there'd be no money left. That's why these threats are ranked based on risk and likelihood.

#### Robotbeat

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #361 on: 02/18/2013 07:50 PM »
Bottom line: spending \$1B/year on asteroid mitigation is not a waste of money from an actuarial perspective.

Well, if you were an actuary using actual statistics that might be true. But you aren't, and you made up the death rates, so your conclusion is completely wrong.

Hey, I was only aiming for an order of magnitude, BOTE, estimate of what would be reasonable.

It's true that the mortality rates I chose are conservative, but why shouldn't they be? On the other hand, assigning \$1M for the statistical value of a life is almost certainly an underestimate. For example, in 2001 the US Environmental Protection Agency (EPA) estimated the statistical value of a human life for the purposes of their cost-benefit analyses at \$9.1 each. This is nearly \$12M each in today's dollars.

So we can work it out another way: assuming dinosaur-killers hit the Earth at a rate of one every 70 ma, and the population is only 7 billion, but the statistical value of a human life is \$10M each, then it's still worth it to spend \$1B/year on asteroid mitigation. And this is still not taking into account city busting events. Nor does it take into account the premium that humans place on especially catastrophic events like mass extinctions.

Sure there are other games you could play.

One is to take the amount we actually spend (\$4M/year) and back-calculate the total worth the planet. If the risk of losing everything to a rogue comet is 1/65,000,000 per year, then \$4M * 65,000,000 = \$260T. To put this estimate of value in perspective, the world GDP is about \$80T/year. Thus NASA and the USG place the total value of nature and civilization at only 3.25 years worth of total economic output. To state it another way, NASA and the USG implicitly place the value of a human life at only \$37,142. This is certainly false.

Bottom line: we can quibble about whether we should spend \$1B/year versus \$100M/year on asteroid/comet mitigation, but we can be certain that the \$4M/year we currently spend is unreasonably low.
Agreed here.

But I think we can improve things somewhat by simply integrating it into all the other stuff NASA does instead of it being completely dedicated ONLY to asteroid mitigation. For instance, demonstrating a large SEP tug and staging it at EML1/2 (to support lunar, Martian, and/or NEO missions) would not only demonstrate the needed technology for a HSF mission to a NEO or Mars AND a large gravity tractor, but could also be put into place to provide a relatively quick emergency deflection capability.

Quick is relative here... We might be able to field a spacecraft in three years or so with an all-out effort until launch using an HLV, but if we already had a large SEP tug /with tractor capability/ out of Earth's gravity well, we could send it out almost as soon as we found out about the potential threat, even though the gravity tractor technique takes a while... This would cost way less than such an emergency effort and would be using a known-to-be-functional vehicle with lots of experience that has already traveled the riskiest portion of its mission (launch, deployment, and travel out of most of Earth's gravity well), plus would be able to be fielded and start tractoring far sooner.)

Such an ability wouldn't be free even if that's the sort of architecture we decide on for HSF anyway, but it also would provide a much more concrete justification for spending billions of dollars a year on an exploration program. And I don't think the modification itself would cost anywhere close to \$1 billion/year. And it could take advantage of commercialized logistics (including possibly ISRU in the future).
« Last Edit: 02/18/2013 07:54 PM by Robotbeat »
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#### Lar

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #362 on: 02/18/2013 07:52 PM »
but we can be certain that the \$4M/year we currently spend is unreasonably low.

No, we can't be certain. If we spent what was needed to prevent every threat to any human, there'd be no money left. That's why these threats are ranked based on risk and likelihood.
We can be *reasonably* certain it's too low though. That's what actuarial analysis is all about.

Note that a lot of the other threats are either over or underspent on, IMHO anyway.  Because people go with gut feeling instead of actuarial analysis.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

#### Warren Platts

##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #363 on: 02/18/2013 07:57 PM »
As impactor size increasesll rises more quickly, so that the average death toll per year is dominated by the largest impacts.  Years with any deaths at all due to impact events are rare, but once in a while the death toll in such an event will be huge.  When all sizes of impact events are accounted for, the average expected death toll per year from impact events is surprisingly large, concentrated in a small number of rare but catastrophic events.

I believe that is not correct. I believe that our NRC report said something about that:

http://www.nap.edu/catalog.php?record_id=12842

I'm too lazy to look in there, but I seem to remember that although everybody focuses on the dinosaur killer size, the real threat is from the smaller, but much more numerous asteroids. They may only kill a few thousands or millions, but they're far more likely to hit.

Thanks for the link.  While you are correct that the largest source is not the mass extinction dinosaur-killing objects of 10 km or greater, the peak mortality is associated with 1 to 5 kilometer asteroids that could still be expected to produce global catastrophes. These are not the mere city-buster IOW.

At any rate, on page 23, they show two sources that estimate that the annual expected mortality rate at 1,254 and 1,168 deaths per year due to asteroids and comets. (Which is very close to my own BOTE estimate of 1,000/year--yes, I admit I was right for the wrong reasons). Therefore, the amount we should be spending on asteroid mitigation is:

Optimal cost = 1200 * the statistical value of a single human life

So if one thinks that the value of a human life is \$12M (EPA), then we should be spending \$14.4B/year on asteroid mitigation.

If you think the value of a human life is only \$120K (Russian opinion poll), then we should be spending \$144M/year on asteroid mitigation.

Take your pick as you like, but no matter how you slice it, \$4M/year is much too low. In effect, the current level of spending places the statistical value of a single human life at only \$3,333.
« Last Edit: 02/18/2013 08:04 PM by Warren Platts »
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#### Robotbeat

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #364 on: 02/18/2013 08:01 PM »
WISE was a primarily a science mission, for instance, but it also served to detect NEOs (and is partly why its mission was extended). WISE isn't a perfect example, but I do think that we can probably get the most bang for our buck by including NEO detection goals in any relevant science missions and relevant science goals in any NEO detection missions.

This is like how KEPLER, while primarily an exoplanet mission, is providing excellent astrometry data and data used for studying the interior of stars (using asteroseismology).
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#### Warren Platts

##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #365 on: 02/18/2013 08:09 PM »
WISE was a primarily a science mission, for instance, but it also served to detect NEOs (and is partly why its mission was extended). WISE isn't a perfect example, but I do think that we can probably get the most bang for our buck by including NEO detection goals in any relevant science missions and relevant science goals in any NEO detection missions.

This is like how KEPLER, while primarily an exoplanet mission, is providing excellent astrometry data and data used for studying the interior of stars (using asteroseismology).

Agreed, but an interesting question is whether the awareness raised by the Chelyabinsk event will result in fresh, new monies being appropriated for NASA. I think an actuarial justification for that can certainly be made. These monies would serve the primary purpose of asteroid risk mitigation--but would also serve other, fun,"dual-uses"!
« Last Edit: 02/18/2013 08:12 PM by Warren Platts »
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

#### Danderman

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #366 on: 02/18/2013 08:16 PM »
I would imagine that a simple I/R detector in a tundra orbit would be useful in detecting incoming objects from the sunward direction. After all, if they are baking in the sun for a long time, they should be very visible to a decent i/r detector.

#### JimO

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #367 on: 02/18/2013 09:33 PM »
I didn't realize until I read this second post that you were not simply talking about radio interference, but rather ordinary objects acting as crude receivers...is that right?

http://forum.nasaspaceflight.com/index.php?topic=31118.345

#### iamlucky13

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #368 on: 02/18/2013 10:30 PM »
I didn't realize until I read this second post that you were not simply talking about radio interference, but rather ordinary objects acting as crude receivers...is that right?

http://forum.nasaspaceflight.com/index.php?topic=31118.345

Sorry...I missed noticing the previous link. Thank you.

And amazingly - the shock effect is quite mild

Found another video of Korkino. But the windows were broken. The delay 89s too.  0:07 flash,  1:36 shock wave.

Incredible. None of the other videos really make clear how much brighter than the morning twilight it was.

#### DLR

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #369 on: 02/19/2013 03:58 AM »
The orbits of most large NEOs are known. The real unknown are comets swooping in from the Oort Cloud. By the time we notice that a comet is on a collision course, it may already be too late to deploy something like a gravity tractor. We would need to pummel it with nukes.

First step: get rid of the space nuclear test ban.

#### Robotbeat

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #370 on: 02/19/2013 04:05 AM »
The orbits of most large NEOs are known. The real unknown are comets swooping in from the Oort Cloud. By the time we notice that a comet is on a collision course, it may already be too late to deploy something like a gravity tractor. We would need to pummel it with nukes.

First step: get rid of the space nuclear test ban.
SEP tugs can put a lot of mass on target and could be used as a good first stage for a deep-space interceptor (if it had time, it could make a sunward swoop to pick up speed, could even use a heck of an Oberth effect if the payload fired a solid near perisol on a very close pass by the Sun). To do better, we'd need nuclear-electric, which would help with HSF exploration of the outer planets (this is a late-century capability anyway... We won't be able to tackle those sort of threats for quite a while).
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To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

#### Hyperion5

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #371 on: 02/19/2013 04:17 AM »
It had the yield of the largest warhead carried by US nuclear submarines.   Lucky that it detonated high and wide of that town.

Yeah, 500 kilotons is nothing to joke about for sure.  I believe I read it hit the atmosphere at a 20 degree angle, which was why it broke up far overhead (thank goodness).  Does anyone know what angles would have seen this meteor survive atmospheric entry and smash into the ground?  Just how much would the entry angle have had to change for us to now be marking a dark day in world history?

#### Warren Platts

##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #372 on: 02/19/2013 04:49 AM »
The orbits of most large NEOs are known. The real unknown are comets swooping in from the Oort Cloud. By the time we notice that a comet is on a collision course, it may already be too late to deploy something like a gravity tractor. We would need to pummel it with nukes.

First step: get rid of the space nuclear test ban.
SEP tugs can put a lot of mass on target and could be used as a good first stage for a deep-space interceptor (if it had time, it could make a sunward swoop to pick up speed, could even use a heck of an Oberth effect if the payload fired a solid near perisol on a very close pass by the Sun). To do better, we'd need nuclear-electric, which would help with HSF exploration of the outer planets (this is a late-century capability anyway... We won't be able to tackle those sort of threats for quite a while).

I agree with DLR. The real wild cards are the Oort cloud comets. We've already found the vast majority of large NEA's that pose a potential global catastrophe. These aren't the real threat: if they were headed for the keyhole, we would have years of heads up time to figure out something.

A comet that's barreling down on a collision course at hyperbolic velocities is a completely different animal. Not sure what it would take to dissuade such an animal, but gravity tractors are probably not it IMHO....
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

#### Robotbeat

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #373 on: 02/19/2013 05:46 AM »
You didn't read what you just quoted.
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#### DLR

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #374 on: 02/19/2013 07:21 AM »
The orbits of most large NEOs are known. The real unknown are comets swooping in from the Oort Cloud. By the time we notice that a comet is on a collision course, it may already be too late to deploy something like a gravity tractor. We would need to pummel it with nukes.

First step: get rid of the space nuclear test ban.
SEP tugs can put a lot of mass on target and could be used as a good first stage for a deep-space interceptor (if it had time, it could make a sunward swoop to pick up speed, could even use a heck of an Oberth effect if the payload fired a solid near perisol on a very close pass by the Sun). To do better, we'd need nuclear-electric, which would help with HSF exploration of the outer planets (this is a late-century capability anyway... We won't be able to tackle those sort of threats for quite a while).

Space-based nuclear reactors are not a late 21st-century technology. Whether one will be built and flown in the next ten to twenty years is a question of political will. In addition to comet defence it would be useful to all sorts of programmes (planetary outposts, rapid interplanetary travel, high-capability deep-space probes ...). I don't think space reactors really are a controversial issue.

The real problem is the Nuclear Test Ban Treaty. It prevents us from experimentally verifiying the effect of nuclear explosions on various types of asteroids/comets.

If you want to deflect hyperbolic comets and small, previously unknown asteroids heading towards a populated area (too little time between discovery and impact to employ a GT), nukes are the only option we have. If we want to get real about planetary defence we'll have to acknowledge this and amend the treaty.

This is quite an interesting paper:

it would be possible to sufficiently disperse an asteroid with the same orbital and physical parameters as Apophis using a 300kt subsurface nuclear explosion up to 15 days before impact.

With only a few days lead time and a nuclear interceptor on station in orbit, the Chelyabinsk Meteor could have been dispersed into harmless fragments.

#### A_M_Swallow

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #375 on: 02/19/2013 08:35 AM »
The real problem is the Nuclear Test Ban Treaty. It prevents us from experimentally verifiying the effect of nuclear explosions on various types of asteroids/comets.
{snip}

Before we start changing treaties things like finding and docking to an asteroid can be tested using conventional explosives.  When we can steer small asteroids then we can ask permission to steer big ones.

#### suncity

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #376 on: 02/19/2013 09:29 AM »
It had the yield of the largest warhead carried by US nuclear submarines.   Lucky that it detonated high and wide of that town.

Yeah, 500 kilotons is nothing to joke about for sure.  I believe I read it hit the atmosphere at a 20 degree angle, which was why it broke up far overhead (thank goodness).  Does anyone know what angles would have seen this meteor survive atmospheric entry and smash into the ground?  Just how much would the entry angle have had to change for us to now be marking a dark day in world history?

I understand that such a meteor will not reach the ground, independent of the entry angle. There was a nice article in Sky and Telescope about the Tunguska event explaining how they “explode” at altitude and devastate wide area with the shock wave.
If I remember correctly, Chondrite asteroid are brittle; when entering the atmosphere, they face a massive aerodynamic force, proportional to air density, on their leading side. The body of the meteor is subject to compressive stress. When the meteor reaches lower and lower altitudes, it sees higher and higher aerodynamic resistance due to increase in air density, and when the compression stress become greater then the body resistance, it breaks into pieces. The fragments in the trailing side ram forward and create a larger leading surface that further increase air resistance and give rise to the “explosion”.

This will likely happen when it reaches a certain air density/altitude, irrespective of the angle of entry. But I guess the damage on the ground will be much more concentrated if a meteor strikes at 90° and the shock wave is not spread over a long flight path.

#### Maciej Olesinski

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #377 on: 02/19/2013 10:28 AM »
New compilation (just in case anyone haven't seen it yet)
liveleak.com/view?i=3b9_1361266537
« Last Edit: 02/19/2013 11:23 AM by Maciej Olesinski »

#### smoliarm

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #378 on: 02/19/2013 11:13 AM »
...
#1
By the time we notice that a comet is on a collision course, it may already be too late to deploy something like a gravity tractor.
...
#2
We would need to pummel it with nukes.
...
#3
First step: get rid of the space nuclear test ban.

#1 -- yes, that's the case to consider. But there is no reason not to try to create an EARLY warning system.

#2 -- nonsense.
Like I said before, most of meteorites are VERY fragile - naturally. This is from my personal experience, not from books. But you don't have to take my word, refer to meteorite catalogs: 1. Monica Grady; 2. V.Buchwald; 3. R.Hutchinson.

To shatter 15-meter H-chondtrity body into 1000 pieces - the classic Russian RPG-29 would be quite enough. For a guy like DA14 (50 to 100 m in diameter) - a light American armor-piercing bomb (like what they used at Midway) is sufficient.
NO nukes, all you need is 500 lbs of TNT and Lieutenant Commander McClusky.

#3 -- I strongly disagree, again.
No need to go into politics that DEEP. First thing is a detection/warning system, the space nuclear test ban is no problem here. The second thing is also different - it's a guidance system with VERY smart computer to deliver a DIRECT hit. Near miss does not work for any warhead - TNT or nuke - there is no shock wave in space.

#### Robotbeat

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##### Re: Meteor Strikes Chelyabinsk, Russia
« Reply #379 on: 02/19/2013 12:14 PM »
DLR: Don't read into what I'm saying. I'm saying Oort cloud objects won't be dealt with until at least the latter part of the 21st century, not that we couldn't build the tech needed earlier. To say anything else would be highly optimistic.
« Last Edit: 02/19/2013 12:17 PM by Robotbeat »
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