Image credit: Google Earth, NASA/JPL-Caltech › Larger view
From the WSJ (NASA JPL Statement follows):
The meteor that crashed to earth in Russia was about 55 feet in diameter, weighed around 10,000 tons and was made from a stony material, scientists said, making it the largest such object to hit the Earth in more than a century.
Large pieces of the meteor have yet to be found. However, a team from the Urals Federal University, which is based in Yekaterinburg, collected 53 fragments, the largest of which was 7 millimeters, according to Viktor Grokhovsky, a scientist at the university.
Data from a global network of sensors indicated that the disintegration of the Russia fireball unleashed nearly 500 kilotons of energy, more than 30 times the energy of the Hiroshima atomic bomb.
It is the largest reported meteor since the one that hit Tunguska, Siberia, in 1908, according to the U.S. National Aeronautics and Space Administration. The agency’s new gauge of the meteor’s size was a marked increase from its initial estimate.
==============================================================
Here is the NASA JPL statement:
New information provided by a worldwide network of sensors has allowed scientists to refine their estimates for the size of the object that entered that atmosphere and disintegrated in the skies over Chelyabinsk, Russia, at 7:20:26 p.m. PST, or 10:20:26 p.m. EST on Feb. 14 (3:20:26 UTC on Feb. 15).
The estimated size of the object, prior to entering Earth’s atmosphere, has been revised upward from 49 feet (15 meters) to 55 feet (17 meters), and its estimated mass has increased from 7,000 to 10,000 tons. Also, the estimate for energy released during the event has increased by 30 kilotons to nearly 500 kilotons of energy released. These new estimates were generated using new data that had been collected by five additional infrasound stations located around the world – the first recording of the event being in Alaska, over 6,500 kilometers away from Chelyabinsk. The infrasound data indicates that the event, from atmospheric entry to the meteor’s airborne disintegration took 32.5 seconds. The calculations using the infrasound data were performed by Peter Brown at the University of Western Ontario, Canada.
“We would expect an event of this magnitude to occur once every 100 years on average,” said Paul Chodas of NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. “When you have a fireball of this size we would expect a large number of meteorites to reach the surface and in this case there were probably some large ones.”
The trajectory of the Russia meteor was significantly different than the trajectory of the asteroid 2012 DA14, which hours later made its flyby of Earth, making it a completely unrelated object. The Russia meteor is the largest reported since 1908, when a meteor hit Tunguska, Siberia.
Source: http://www.nasa.gov/mission_pages/asteroids/news/asteroid20130215.html
Preliminary information indicates that a meteor in Chelyabinsk, Russia, is not related to asteroid 2012 DA14, which is flying by Earth safely today.
The Russia meteor is the largest reported since 1908, when a meteor hit Tunguska, Siberia. The meteor entered the atmosphere at about 40,000 mph (18 kilometers per second). The impact time was 7:20:26 p.m. PST, or 10:20:26 p.m. EST on Feb. 14 (3:20:26 UTC on Feb. 15), and the energy released by the impact was in the hundreds of kilotons.
Based on the duration of the event, it was a very shallow entry. It was larger than the meteor over Indonesia on Oct. 8, 2009. Measurements are still coming in, and a more precise measure of the energy may be available later. The size of the object before hitting the atmosphere was about 49 feet (15 meters) and had a mass of about 7,000 tons.
The meteor, which was about one-third the diameter of asteroid 2012 DA14, was brighter than the sun. Its trail was visible for about 30 seconds, so it was a grazing impact through the atmosphere.
It is important to note that this estimate is preliminary, and may be revised as more data is obtained.
http://www.nasa.gov/topics/solarsystem/features/asteroidflyby.html
Jet Propulsion Laboratory, Pasadena, Calif.
agle@jpl.nasa.gov
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Hardly a lack of thinking in general, just the lack of correlation between effectiveness at getting elected and concern for anything besides getting elected.
Putting a solar powered rocket on an asteroid isn’t necessary.
If you have that much solar collection surface there, just focus it into a beam and heat the asteroid material direction.
If you don’t, just put a machine with shovels/buckets and begin tossing hunks of asteroid into space.
here is another recent and scary astroid impact Notice how large it was when comparedd to the Earth and the Moon…
.Giant Rogue Asteroid Strikes Jupiter September 10, 2012
Sorry, the URL got truncated. when pasted. Here it is again….
The NASA SOHO mission has been capturing images of asteroids impacting the Sun. Some of these asteroids were large enough to cause major extinctions of most life on the Earth if they had impacted the Earth instead.
.ASTEROIDS SLAM INTO THE SUN .
“Completely unrelated event” is pushing coincidence a tad too far. Entry vector meaningless, it probably separated quite a while ago, drifted to different track.
In terms of those poor meteor-hunting Russkies, we oughta sit ’em all down to a screening of Stephen King finding his meteor in Creepshow!
I seem to vaguely recall some studies of catastrophic meteorites, that they tend to come in bunches, both on large time scales, but also on millennial time scales. Something to do with gravitational cycles that disturb the Oort cloud, or the asteroid belts as well. This is a very small sample, but the coincidence of two of these things coming so close on a single day does give me some pause as to whether or not we might be entering into a period with more frequent meteorite events.
Anyone know more about such theories/observations?
What really befuddles me is that in the early hours after the meteor had entered the atmosphere over Russia and broken up, we were ‘reliably’ informed that it was about 2m wide and weighed in at approx. 10 tons. Travelling at almost 18,000 mph.
Now, we’re informed that it was actually more like 55 feet wide and weighed in at approx. 10,000 tons. And it was shifting along at ~40,000 mph.
To me there seems to be a cognitive disconnect here. The difference in kinetic energy between a 10t object travelling at 18k mph and that of an object weighing in at 10kt travelling at 40k mph is huge!
It would be nice to know which of the two estimates are most likely to be correct, and also to know why the incorrect one was apparently so wide of the mark.
BTW, I’m not trolling – I really can’t understand it, and would be grateful if someone can let me know what it’s all about.
PS: Thanks to Anthony and WUWT for all the exemplary coverage of this matter.
“nearly 500 kilotons of energy
Especially since we are not dealing with E = mc^2, energy should be expressed in joules and not mass. ”
Answer: 500 kilotons of DYNAMITE equivalent, or at about 20,000 BTU per lbm, that would be 500,000,000*2 or one billion lbm *20,000 BTU each Lbm, or 20 Trillion BTU. That’s a lot, but since a coal plant burns about 10 million lbm/day of coal this is a 1/2 years worth of coal burning.
“A question: How much larger will the UAH anomaly be for February be due to this input?”
Answer to that, considering the SUN’s input is equivalent to about 10,000,000 of said coal plants, we have a MINISCULE rise in atm temp due to this event.
Here are a couple of links with some related information. Caution: Computer Modeling Ahead
History of Asteroid Impacts in Earth Rocks
http://www.nasa.gov/home/hqnews/2012/apr/HQ12-135_Asteroid_Imapcts_Earth_Rocks.htm
Tom Gehrels. A review of comet and asteroid statistics. Earth Planets Space, 51, 1155–1161, 1999. Space Science, University of Arizona, Tucson, Arizona 85721, U.S.A. (Received October 7, 1998; Revised August 12, 1999; Accepted September 15, 1999).
http://www.terrapub.co.jp/journals/EPS/pdf/5111/51111155.pdf
The answer is really pretty simple, early reports are almost always wrong, often catastrophically wrong. This is one of the biggest problems in emergency management in the early hours of an emergency to sort out the early reports and make sense of often mutually exclusive information or conflicting information. You are usually dealing with reports from unsophisticated observers, many of which have built in biases that make them jump to conclusions about what they are seeing. Even sophisticated observers called on by the media to make off the cuff comments on a breaking story often due to the lack of time to double check information, or comments based on faulty initial information occasionally make some really bone headed mistakes. Since the media is usually scientifically and mathematically ignorant they fail at their basic obligation to fact check such early observations and in the rush to get “the scoop” put out blatantly bad info.
The 18,000 mph number makes sense when you realize that that is the required speed for low earth orbit, ( 7.8 km/s or 17 448 mph the media often rounds this up to 18,000 mph in their tv coverage) and either due to lack of understanding or a poorly considered off the cuff remark that speed might have been blurted out by someone not aware that objects in near earth orbit can have approach speeds far higher than that, especially if they come from deep space like a comet. Average impact speeds for meteorites typically is in the 10-70 km/second range ( 22,370 – to 156,585 mph). For objects orbiting the sun, maximum impact speed would be about 72 km/sec (161,060 mph) but could be even higher if the object was not gravitationally bound to the sun and came in from deep space.
http://impact.ese.ic.ac.uk/ImpactEffects/
One observation regarding diverting an impending impact is I have always been puzzled that every solution always seems to be focused on a single means of avoiding impact, when there are actually several different strategies which could be used in combination. To avoid impact you simply have to arrange it so that the near earth object and the earth do not occupy the same space at the same time. You can do that by changing the velocity of the near earth object, but that is a vector quantity composed of both a speed vector and a direction vector. You can either speed it up or slow it down, or you can give it a lateral motion to change its direction. You also can ablate away some of its mass which will change its orbital path around the sun if the ablated mass has escape velocity to get clear of the near earth object.
Each object will have a minimum energy strategy to avoid collision. In one case the minimum energy solution might be to slow it down. In another the minimum energy solution might be to speed it up or tweak it sideways.
The deep impact mission shows we can rendezvous with an asteroid and arrange for it to “run over” a slower moving object with today’s technology.
One idea I never see advanced is to use a strategy like the Deep impact mission, and position a space craft so it could distribute a plume of sand like particles, or even multiple very small “smart impactors” ahead of the object, and let it run over and impact the thousands of small particles or smart impact module. Each individual impact would be too weak to break up the object and create the multiple body problem or divert it much, but the combined effect (like a car driving through a hail storm) would both transfer energy and ablate mass from the object. Like the gravity tug idea, it would be a way to slow the object and change its orbital elements by changing its mass. The optimum strategy might be to use multiple missions in succession each applying a small change in the objects velocity. Some sort of manageable impact scheme like this would allow you to slow the objects speed of motion with out changing its direction vector significantly, and would work even if the object was spinning as the small dust particles or smart impact modules would always impact on the forward face of the object determined by its orbital motion. Then with a gravity tug you could pull it to one side to augment the change caused by changing its orbital speed.
Maybe we should think about a multifaceted attack rather than any single strategy. It would also give us a more fail safe solution.
The impacting objects could take many forms, inert material, pellets of CO2, small spinning disks of light material, even high energy materials like small pellets of explosive materials where you would get benefit from both the chemical energy of the impactor and its kinetic energy of motion. Which would be more effective multiple impacts from small pellets of explosive materials, tens of thousands of small sand like particles squirted out in a stream along the orbital path or one or more spinning disks of plastic that would simultaneously vaporize across the entire front of the object as it impacted the asteroid. Perhaps a series of smart impactors each guiding a balloon filled with a gas or explosive gas mixture.
Bottom line is how do you transfer the most momentum to the object without breaking it up due to a violent impact. Would you get more bang for your buck by letting it run into a hail storm of BB’s which each would form thousands of craters and eject material from the surface or let it run into a large gas filled balloon (or even several such balloons) and change its velocity by the over pressure across the front face as it slams into the gas bag.
Larry
The technology and capabilities required to capture and maneuver asteroids is on the drawing boards,..For those who have not had a detailed look at the USA’s 21st century expectation (Bush Snr. era) of humanity’s expansion into space, this is well worth exploring.
http://makezineblog.files.wordpress.com/2012/09/space-plan-scan-touched-up-001.pdf
Thank you to all who responded to “500 kilotons of energy“. My physics students would never have gotten away with that sort of thing!
How is this meteor unrelated to the asteroid? How is it ruled out?
How is that possible within hours of the event?
It maybe the case, that it’s all just a big coincidence. We have other asteroids making a close approach, and we know nothing about the debris that precedes or follows them. Learning nothing by being too big headed from this close approach is feckless.
Mechanics of moving an asteroid like 2012DA14 away from an Earth collision.
An asteroid tractor (Tug) uses the mutual gravitation between the Tug and the asteroid as the tractor force. The trick is that the rocket exhaust needs to be in two or three thrusters pointing past the asteroid rather than at the asteroid. All that is necessary is that the Tug is close enough to the gravitationally weak asteroid so that the gravitational pull is enough force to do the job.
So how big does this Tug need to be? How much propellant is needed to move a 130,000 ton asteroid to miss the Earth? 1 ton? 10 tons? 100 tons? 1000 tons?
If you have 20 years, all you need is 0.1 ton. 100 kg! What is more, we can do it with off-the-shelf hardware. It can be done with a “Dawn”-like space probe with three small tri-pod ion thrusters instead of one thruster on the centerline — and lots of time. I’m amazed how little mass is necessary.
The goal is to apply a force F to move the asteroid mass m1 one Earth Radius R in a time span of T years.
R = Earth Radius: 6378000 m
Time of force = T = 20 years (thrusting time).
Time of force = T = 6.31E+08 sec
Acceleration to move R in T = a = 3.20E-11 m/sec^2 __ (from R = 0.5*a*T^2)
Mass of 2012DA14 = m1 = 1.30E+08 kg
F = ma = 4.16E-03 N = kg-m/sec2 __ About 0.001 pound force.
(a big mass * a puny acceleration = feather weight force)
How big does the Tug need be to have at least that gravitational force?
Gravitational constant = G = 6.67E-11 N-m2/kg2
Radius of 2012DA14 = r1 = 15 m __ (actual dimensions 20 m wide x 40 m long)
Tug Standoff = r1b = 45 m __ (3 times radius so that jets point over the rim)
F from accel due to gravity = G*m1*m2/r^2
If F = 0.00416 N = kg-m/sec2
minimum mass of tug at r1b = F*r1b^2/(G*m1) = m2 = 972.0 kg __(less than Dawn)
So a one ton tug 45 m from the center of a 130,000 asteroid has a can pull at 0.00416 N. If it tugs for 20 years, that’s enough for a miss.
This is a tiny force, so an Ion drive, like the Dawn and Deep Space 1 probes is ideal for minimum propellant needs.
g = 9.81 9.81 m/s²
ion Drive Specific Impulse = Isp = 3000 sec ( 4000 sec is possible)
Ion thruster exhaust velocity = Ve = 29430 m/sec
Fthrust = Isp * mdot * g = Ve * mdot
Fthrust = 0.00416 N = kg-m/sec2 (required thrust for the job above)
Propellant rate = Fthrust/ Ve = mdot = 1.41E-07 kg/sec or 0.141 milligram/sec.
Propellant mass = mdot * T = mf = 89.3 kg
Delta-V of asteroid = a*T = deltaVa = 2.02E-02 m/sec = 20 mm/sec after 20 years of tug.
Time is your friend. The amount of fuel needed goes as m1/T^2.
Check math:
Change momentum of propellant = Ve*mf = 2.63E+06 kg-m/sec
Change momentum of Asteroid = deltaVa*m1 = 2.63E+06 kg-m/sec
Thrust of Dawn: 0.09000 N 20x what is needed
mass of Dawn (full) 1240 kg ( 640 kg is propellant.)
power of Dawn 1300 W
Whew! Truly impressive calculations Stephen! Back when I was into physics I used to gobble that stuff up! :> Nowadays it mainly just makes my eyeballs hurt. LOL!
Question though… and it’s quite possible that it’s all covered inside there ….
You talk about enough thrust to move the asteroid by an Earth radius. I would think that, 20 years away, you’d have to move it just an extremely tiny fraction of such a distance — because the operative factor wouldn’t be the distance moved as much as the slight change in angular direction. If I’m a bullet flying along and pointing at something 500 million miles away and you simply sneeze in my general direction as I pass you by, I would think that the .0000001% shift in angle your sneeze would impart would produce an endpoint at that 500 million mile point that would be VERY significantly different than it would have been without the sneeze.
Is that all accounted for in your equations already?
😕
MJM
You can see it for yourself when you watch the Russian videos on YouTube. Notice how the meteor passed overhead at Chelyabinsk, leaving behind the large trail of smoke and blasted the windows and buildings in the bright morning sunlight. Other videos showed a landscape in morning twilight as the meteor came to Earth in the far distance ahead where the Sun was about to come over the horizon. These videos show us how the meteor traveled from the East, where the Sun was coming over the horizon for the morning, to the West which was in the twilight darkness of the earlier morning. This East o west transit above the Earth was confirmed by the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO). They are responsible for operating a network of infrasound monitoring stations around the world to detect violations of the Nuclear Test Ban Treaty. Their network detected the meteor’s impact with the atmosphere and bolide explosion as it passed over Alaska and transited westwards into Russia where it exploded in the atmosphere and impacted the ground in fragments.
This pathway and speeed through the Earth’s atmosphere tracks backwards towards the Sun. In other words, to pass over Alaska and impact in Russia at the observed velocity, the meteor had to approach the Earth from Sunward to strike the Earth’s atmosphere and dive into Russia along the morning terminator between morning and night.
The asteroid, on the other hand, is approaching the Earth from behind the Earth’s orbital path, if I’m correctly informed. If so, the asteroid would impact the Earth from that general direction. This would generally mean an impact sometime roughly between noon and midnight from the point of view of observers on the ground. Since this metwor made its impact in a trajectory generally perpindicular to the trajectory of the asteroid and any companion meteors, the meteor cannot be a companion of the asteroid.
The meteor’s approach from sunward also explains why optical telescopes would have been unable to see it approach the Earth. Radio telesopes would have had difficulty detecting the meteor due to its small size and unusal approch from sunward.
D.J. Hawkins
“The reference is to the energy available in a short ton (2,000 lbm) of TNT.”
Err, yes. I know that. My gripe is that the language is sloppy, and I would prefer a statement from a scientific authority just adds those three letters “TNT”
Sloppy language is a breeding ground for confusion, and the case of global warming … erm …. climate change (cough) disruption clealy shows.
@michaeljmcfadden
You talk about enough thrust to move the asteroid by an Earth radius. I would think that, 20 years away, you’d have to move it just an extremely tiny fraction of such a distance
No matter how long you tug, at the end of time T, you must move the path one earth radius R from a dead center hit (worst case) to a grazing miss. If T is 20 years, you must move it R at the end of 20 years. If T is 1 year, you still need to move it R in 1 year — but with a velocity that will move it 20R in 20 years.
You can see this best in the DeltaV. If I have 20 years (630 million seconds), then as the asteroid streaks by, we’ve added only 20 mm/sec lateral DeltaV (average 10 mm/sec over 20 years under constant weak acceleration.)
If you only had 1 year, you would need to add 400 mm/sec DeltaV to make the miss. 20 times more kinetic energy in 1/20 of the time, so 400 times the power and thrust needed in the 20 year case.
I was wrong about this: The amount of fuel needed goes as m1/T^2.
The fuel rate (mdot) goes as m1/T^2.
But total fuel goes as m1/T
I got into this because I couldn’t believe some commentators on TV saying that NASA had the capability today to deflect asteroids. I knew about the gravitaional tractor concept, but I had in my mind that it had to be a twenty-ton monster. That it would be impractical to carry enough fuel to do the job and that somehow you would need to use the asteroid for reaction mass material with all the complications that entailed on a spinning rock with little gravity….. We don’t have that today!
Well, I’ll be… we DO have the capability today! KISS. A ton of pure Xenon expelled at 30 km/sec is far better than mining and pitching rocks.
A slightly reconfigured Dawn spacecraft, a dozen angled thrusters for redundancy, a bigger propellant tank and a Delta-IV or Atlas-V Centaur booster is all you would need to move a 1.5 million ton asteroid enought to miss Earth — that and 25 years warning before potential impact.
Aside: Dawn is an unsung hero of a spacecraft. Check it’s timeline and its traverse. Launched Sep 2007. A gravity assist from a Mars fly by Feb. 2009. Hitched a ride on asteroid Vesta as it orbited Vesta July 2011 to Sept 2012. Thrusted away from Vesta for a Ceres encounter and orbit in Feb. 2015 for 5 month study there. Ion Thursters on about half of the time during those 7 years.
Correction: If you only had 1 year, you would need to add 400 mm/sec DeltaV to make the miss. 20 times more kinetic energy</b. in 1/20 of the time, so 400 times the power and thrust needed in the 20 year case.
That ain’t right! It is 20 times the delta-V, 400 times the kinetic energy, 400 times the propellant flow, 400 times the Thrust. 400 times the electrical power. 20 times the total fuel. (I’m racking my brain how it is not at the same time 8000 times the power: 400 times kinetic energy in 1/20 the time. I think the kinetic energy value is a red herring )
My blunder is in thinking that the propellant is the source of the energy, like it is in a bi-propellant (O2+H2) chemical rocket. In an ion-drive, the propellant is inert — all power must come from an electrical generation source like solar panels, which quickly become the limiting factor in available power. As solar panel’s power goes by Area, but the panel structural total mass goes up by A^b, where b is greater than 1.0 probably less than 1.5.
michaeljmcfadden says:
February 18, 2013 at 7:36 pm
What *would* the effect have been if it was a fairly vertical hit on downtown Manhattan?
_____________________________
Noted astronomical artist Chesley Bonestell reckoned it would look like this:
http://chazhuttonsfsm.tumblr.com/post/682410910/chesley-bonestell-what-would-happen-if-a-very
http://apod.nasa.gov/apod/ap130221.html
Astronomy Picture of the Day had a bit about gravity tugs for asteroids.