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Large asteroid passed close by on 28 Aug 2016 - discovered only one day prior

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Winston

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http://www.virtualtelescope.eu/2016...ncounter-exceptional-image-movie-28-aug-2016/

On 28 Aug 2016, at 01:26 UT, the 35 meters (115 ft) large near-Earth asteroid 2016 QA2 made an exceptionally close encounter with our home planet. At the flyby time, the asteroid was at about 84,000 km (52195 miles) from the Earth's surface! That is 0.22 the average lunar distance.

At Virtual Telescope we managed to cover it around the flyby, getting amazing images.

Below is a stunning video, showing the extremely fast apparent motion of 2016 QA2. The [animated gif] video is 113X faster than the real motion.


The asteroid was only discovered one day prior (27 Aug 2016) to its closest approach:

http://www.minorplanetcenter.net/db...al&utm_source=twitter.com&utm_campaign=buffer

The 2013 Chelyabinsk meteor was estimated to be 20 meters (65.6 ft) large with an atmospheric impact equivalent to approximately 500 kilotons of TNT.

 

SaturnV

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This is a small asteroid. Dangerous are than 1 km in diameter and more. Maybe even entering the atmosphere would collapse. If do not disintegrate Bruce Willis will destroy it.
 

Steven

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I see the string. :tongue:
 

Ravenex

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Extrapolating from the diameter of the mentioned impact an impact by this asteroid would have the energy of a 2.5 megaton blast. Hardly trivial, it could be catastrophic if it impacted a densely populated area, but not a threat to civilization.
 

SaturnV

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Think philosophical. We are composed of atoms survived CATO of supernova. This pathetic asteroid can not change that. Moreover, the death will be instant and painless.
 

farsidius

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I really want to have a good asteroid impact happen during my lifetime. Both the science community and Hollywood have made such big deals about the possibility that I will pass through this world slightly disappointed if it doesn't happen. It doesn't have to hit NY or DC (although that would be a bonus), but somewhere were we can monitor the impact and the immediate aftermath.

COME ON SPACE, I'M WAITING!
 

EXPjawa

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I really want to have a good asteroid impact happen during my lifetime. Both the science community and Hollywood have made such big deals about the possibility that I will pass through this world slightly disappointed if it doesn't happen. It doesn't have to hit NY or DC (although that would be a bonus), but somewhere were we can monitor the impact and the immediate aftermath.

COME ON SPACE, I'M WAITING!
I don't know, I'm a little to close to NYC, globally speaking, to be comfortable with either of those two options. Perhaps if it got Seattle or Portland instead... :p
 

Ravenex

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Neil DeGrasse Tyson has the best vision for asteroid impact:

[video=youtube;xaW4Ol3_M1o]https://www.youtube.com/watch?v=xaW4Ol3_M1o[/video]
 

Winston

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Extrapolating from the diameter of the mentioned impact an impact by this asteroid would have the energy of a 2.5 megaton blast. Hardly trivial, it could be catastrophic if it impacted a densely populated area, but not a threat to civilization.
The Chelyabinsk bolide had a higher velocity, 19.16 ± 0.15 km/s versus this object's 11 km/s velocity. Still, potentially quite consequential if it had entered the atmosphere. Using this calculator:

http://www.purdue.edu/impactearth

NASA data: http://neo.jpl.nasa.gov/ca/

Diameter = 35 m (24 - 55 m; data source: NASA)
Density (common LL5 chondrite type assumed, same as Chelyabinsk) = 3000kg/m^3
Angle = 45 degrees (assumed as compromise for simulation)
Relative Velocity = 11 km/s (data source: NASA)

Projected results:

The projectile begins to breakup at an altitude of 47,100 meters = 154,000 ft
The projectile bursts into a cloud of fragments at an altitude of 12,200 meters = 39,900 ft. (boom!)
The residual velocity of the projectile fragments after the burst is 4.86 km/s = 3.02 miles/s.
The energy of the airburst is 3.28 x 10^15 Joules = 0.78 MegaTons TNT = 780 KiloTons TNT


Chelyabinsk was saved in 2013 by the extremely shallow entry angle of that bolide. The shock wave damage would have been far greater if not for that. On the 1908 Tunguska event:

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

"...modern supercomputer calculations that include the effect of the object's momentum estimate that the airburst had an energy range from 3 to 5 megatons of TNT (13 to 21 PJ), and that more of this energy was focused downward than would be the case from a nuclear explosion."

The downward momentum strongly focuses the blast downward.

"It is estimated that the Tunguska explosion knocked down some 80 million trees over an area of 2,150 square kilometres (830 sq mi), and that the shock wave from the blast would have measured 5.0 on the Richter magnitude scale. An explosion of this magnitude would be capable of destroying a large metropolitan area, but due to the remoteness of the location, no fatalities were documented. This event has helped to spark discussion of asteroid impact avoidance."

90 degree entry of asteroid 2016 QA2 with otherwise same data as above:

The projectile begins to breakup at an altitude of 47,100 meters = 154,000 ft
The projectile bursts into a cloud of fragments at an altitude of 7,150 meters = 23,400 ft. (boom!)
The residual velocity of the projectile fragments after the burst is 3.64 km/s = 2.26 miles/s.
The energy of the airburst is 3.63 x 10^15 Joules = 0.87 x MegaTons TNT = 870 KiloTons TNT.


An 870 kiloton blast at 23,400 feet with a downward velocity of 2.26 miles/s. Not so good.

For 90 degree entry of asteroid 2016 QA2 at NASA's maximum estimated object diameter of 55 m:

The projectile begins to breakup at an altitude of 47,100 meters = 154,000 ft
The projectile bursts into a cloud of fragments at an altitude of 5,590 meters = 18,300 ft. (boom!)
The residual velocity of the projectile fragments after the burst is 3.27 km/s = 2.03 miles/s.
The energy of the airburst is 1.44 x 10^16 Joules = 3.44 MegaTons.


18,300 ft altitude for a 3.44 megaton blast would be bad enough for a manmade bomb in free fall, let alone for a blast with a downward velocity of 2 miles/s.

And yet this near miss received very little media attention that I've seen, although I only read news on-line.
 
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Winston

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Let's use the median diameter and assume it was a more rare iron composition asteroid instead:

Diameter = 35 m (24 - 55 m; data source: NASA)
Density (Iron) = 8000kg/m^3
Angle = 45 degrees (assumed as compromise for simulation)
Relative Velocity = 11 km/s (data source: NASA)

Energy before atmospheric entry: 1.09 x 10^16 Joules = 2.6 MegaTons TNT

The projectile begins to breakup at an altitude of 6,840 meters = 22,500 ft
The projectile reaches the ground in a broken condition.
The mass of projectile strikes the surface at velocity 8.8 km/s = 5.46 miles/s
The impact energy is 6.95 x 10^15 Joules = 1.66 MegaTons.
The broken projectile fragments strike the ground in an ellipse of dimension 0.183 km by 0.129 km

Transient Crater Diameter: 804 meters ( = 2640 feet )
Transient Crater Depth: 284 meters ( = 932 feet )
Final Crater Diameter: 1 km ( = 0.624 miles )
Final Crater Depth: 214 meters ( = 701 feet )
The crater formed is a simple crater.
The floor of the crater is underlain by a lens of broken rock debris (breccia) with a maximum thickness of 99.1 meters ( = 325 feet ).
 

SaturnV

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То kill us is not a big trouble. But imagine the tragedy of Elon Musk."I'd like to die on Mars, just not impact".On Earth, impact. What personal tragedy.[h=1][/h]
 

boatgeek

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I don't know, I'm a little to close to NYC, globally speaking, to be comfortable with either of those two options. Perhaps if it got Seattle or Portland instead... :p
Hey, there, let's not get too excited about wishing destruction on my neck of the woods! How 'bout Houston? :p
 

Cabernut

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"The asteroid was only discovered one day prior (27 Aug 2016) to its closest approach:"

This is what concerns me... :duck:

For all we know there could be one headed for direct impact TOMORROW!
 

MClark

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I bet most people believe we have a meteor defense in place. I have asked the friends of a 20 something I know and they all agreed it exists. They think ICBM's can shoot out past the moon.

With one day notice it could not be decided bagels or doughnuts for the kick off meeting.

M
 

SaturnV

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Against large asteroids no protection. Even destroyed parts damage will even more and larger perimeter than if it remains intact. Bruce Willis film Armageddon is full unscientific hoax :)The only protection is the displacement of people on other planets and moons :)
 

Peartree

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I bet most people believe we have a meteor defense in place. I have asked the friends of a 20 something I know and they all agreed it exists. They think ICBM's can shoot out past the moon.

With one day notice it could not be decided bagels or doughnuts for the kick off meeting.

M
If we learned anything at all from Hurricane Katrina (and the experts always knew anyway), it's that with one day's notice, evacuation of a large urban area is totally impossible. The mayhem would be ugly in the extreme.
 

Winston

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"The asteroid was only discovered one day prior (27 Aug 2016) to its closest approach:"

This is what concerns me... :duck:

For all we know there could be one headed for direct impact TOMORROW!
Same here which is why I specifically mentioned it in the thread title. With much larger asteroids, they'd be seen soon enough (hopefully) to do a gradual diversion with an Earth defense system. With these smaller ones found at the last minute, diversion would require significant diversion forces such as from a thermonuclear bomb or bombs and their smaller size might make that feasible. But we don't even have that or anyone working to build it from what I know about.

Velocity of approach and time to discern trajectory would present issues, considering that even this one was approaching with a relatively low 11km/s (24,606 mph) velocity. It would probably be best for the diversion system to be a quick launch interceptor with terminal homing.

Then, there's this:

Astronomers say giant comets pose a greater threat to Earth than asteroids

http://www.sciencealert.com/astrono...pose-a-greater-threat-to-earth-than-asteroids

Randomly appearing and approaching at very high velocities and orbit eccentricities, spent (fully outgassed) cores or large debris clusters from same wouldn't produce tails, potentially coming from the sun's direction, so only daytime "visible" (i.e., not visible), etc.
 
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