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.
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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
Related: A problem that is bigger than global warming
D. Patterson says:
February 19, 2013 at 6:09 am
… A Russian political figure denies the existence of the meteorite which fell on Russia and is claiming it was a U.S. weapons test…
>>>>>>>>>>>>>>>>>>>>>
Talk of coincidences. I am reading that when the nuclear power station warning siren goes off. (It is tested every quarter) Made me jump – darn thing is loud.
Exeter is apparently alive and well, and living in Seattle:
Exeter Exeter?
Fortunately, the 500 kT was stretched over a long distance & far overhead, unlike a nuke.
as Pull my finger says, This Island Earth was used in the Mystery Science Theatre 3000.
With marvellous sardonic comments from the two robots watching it with the human. Absolutely wonderful.
In Fred Hoyle’s The Black Cloud, which I read as a child, there is an interesting discussion between Alexandrov, the (appropriately) Russian scientist and some of the others, when Alexandrov points out that the only reliable check in science is prediction. You can make all sorts of correlations after an event but if they’re not made beforehand, they are not significant. A lesson that seems to have been forgotten with the emphasis on peer review these days.
“I can’t say that you are wrong, but there are an awful lot of installations scattered around the world by certain missile-paranoid nations looking for large, fast moving objects. ”
Actually they are looking for small, relatively slow moving objects with very tight conformance parameters. Your Pfp/Pfn is kinda tight. Now if someone when back and post processed that data …
Ruskies, get out & find those pieces! Meteorites on frozen lakes/snow are some of the easiest to find, while the ice/snow lasts. And they’re valuable. Meteorite Men from the Science Channel, book your flight now!
Russians are weird with meteors, the Soviets tried to destroy all records of the Tunguska investigation that was done in the 20s and 30s.
Ha, the Cuba episode was probably one of those big old 1950s Chevies they love backfiring.
My reading of the 1972 event was it only came within 35kn of the surface (this one actually fell to earth) and was about 10 – 14 feet in diameter. So not ‘much larger’.
I am a bit disappointed to read so much niggling and conspiracy theory on what is a fairly straightforward issue.
It is a scientific practice, just poorly explained. They settled on that method of measuring large explosions because the energy release of TNT (which is the reference explosive) was highly uniform and well studied at the time nuclear weapons were being developed, and it was a standard that was easily replicated in the field to calibrate instruments.
As in most new fields of study, one of the on going difficulties is the development of a measurement standard which is both practical and repeatable. Once a practical field reference is found, it then gets adopted as a reference standard until higher precision means allow a more precise measurement standard to be developed (see evolution of the definition of the time base second or the length reference meter).
In this case due to military studies they had a huge amount of reference information both on the chemical energy release of a common easily manufactured explosive which had been in use for a long time but they also had weapons damage effects references from all their conventional weapons studies to help them scale the effects up to the sizes of expected nuclear weapons yields. They also needed to work backwards from predicted explosive yield to the expected physical damage intended at the target to calculate expected weapons effects for a given energy yield. In short they were trying to define how much explosive energy needed to be released in a single point weapon to cause a certain amount of damage over a large area to militarily significant targets. Due to cube square effects you get diminishing returns as the yield goes up as most of the energy is expended moving air around in high in the atmosphere not at ground level where you want the damage effects to occur. In this case height of burst becomes very important because there is a critical altitude of burst that maximizes surface damage due to how the shock wave interacts with the ground and at that altitude create a reinforced shock wave “mach front” at ground level.
In the case of a meteor such as Chelyabinsk the altitude which it undergoes breakup and maximum energy release rate will significantly modify the maximum air blast at ground level under the ground track. If it breaks up too high or too low, the maximum damage area will be smaller than if it breaks up at the ideal altitude to transfer its air blast energy to ground structures.
With regards to the definition of the kiloton energy reference:
The following is a quote from the book “The Effects of Nuclear Weapons” by Glastone 1977 (the same info is in the earlier 1962 edition) Page 13 chapter one. Which was considered the “bible” of weapons effects in the west for many years as it was the first publicly available unclassified document derived directly from nuclear weapons effects tests the U.S. Government conducted for nuclear weapons development.
10^12 calories = 4.184 x 10^9 Joules which rounds to the cited 4.2 E9 Joules in your comment.
Keep in mind that at the time this standard was derived advanced calculations for weapons were still being done on mechanical calculators that took days to work out calculations that can easily be solved on a cheap pocket electronic calculator today. The largest electronic computers of the day still occupied entire rooms and were being used to refine ballistic tables for artillery shells.
Larry
“is there an estimate of the total mass gained by the earth each year from space dust to meteorites, it must run into kilotons per year, of course we should deduct atmospheric losses to space. Is the mass of planet earth increasing or decreasing over time ??” ~Lindsay H
I recall the value being 40~ kilotons of dust and debris swept up by the planet each year.
Collisions with Antarctica from massive objects are less common for a couple of reasons that should seem obvious, namely that most of the remaining material in the solar system lies in the plane of the ecliptic, not all, but most.
When you have orbits that cross in a plane, at some point you will probably get a collision or ejection, when you’re dealing with orbital planes that cross at a more oblique angle, the possible window for collisions shrinks to a line, and I think ejections become more energetically favorable.
As for objects from outside the solar system making it in, the sun has a powerful magnetic field and high speed winds which deflects most of the wispy interstellar gas cloud we’re currently passing through.
If we did plow into something that originated in interstellar space it would be VERY unusual to find it originate from the ecliptic, as the solar system “tipped up” and moving towards Vega.
Usually images depict the solar system moving like a frisbee: — > (towards Vega)
It’s closer to this: \ > (towards Vega)
A comparison of orbits: 2012DA14 and Chelyabinsk.
Wikipedia commons image, image enhanced from a Nasa Blog. View perpendicular to ecliptic.
http://en.wikipedia.org/wiki/File:Orbit_of_2012_DA14_and_Chelyabinsk_meteor_2.jpg
NASA website of Near Earth Orbit object closest approaches. Dynamic table by date. 2012DA14 already scrolled off.
About 1 per day on average, miss distance usually more than 30 Lunar Distances.
http://neo.jpl.nasa.gov/neo/close.html
NASA Near Earth Orbital Object Orbital Parameters.
Sort by MOID (minimum orbital intersection Distance) 2012DA14 is #22 in the list.
http://neo.jpl.nasa.gov/cgi-bin/neo_elem?type=NEA;hmax=all;sort=moid;sdir=ASC;max_rows=20;action=Display%20Table;show=1&from=20
There was an event in the same class as this one (I think) in Brazil in the 1930’s. The problem is that most of the events we hear about like this will be in the Northern Hemisphere because the Southern Hemisphere is mostly water. Any over Antarctica will likely go unnoticed, too. I would be willing to bet there have been several events of this size over the past 100 years, they just haven’t occurred where people noticed them or did any damage.
http://star.arm.ac.uk/impact-hazard/Brazil.html
Somebody else was nodding off in “Current Events”. The reference is to the energy available in a short ton (2,000 lbm) of TNT.
2012DA14 From NEO Earth Close-Approaches table
http://neo.jpl.nasa.gov/cgi-bin/neo_ca?type=NEO&hmax=all&sort=date&sdir=ASC&tlim=current&dmax=0.1AU&max_rows=100&fmt=full&action=Display+Table&show=1
Object: (2012 DA14)
Orbit images http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2012 DA14;orb=1 (java)
Oblique, near ecliptic: http://i49.tinypic.com/osy737.gif
Normal to Ecliptic: http://i49.tinypic.com/10hog3q.gif
Close-Approach (CA) Date (TDB) YYYY-mmm-DD HH:MM ± D_HH:MM
2013-Feb-15 19:25 ± < 00:01
CA Distance Nominal (LD/AU) (most likely Closest Approach Distance)
0.09/0.00023 (Lunar Distance / Astronomical Units)
CA Distance Minimum (LD/AU) (minimum 3-sigma error closest approach)
0.09/0.00023 [It is the same as nominal because the error ellipse is small]
V relative (km/s) [Actual velocity difference with earth at CA]
7.82
V infinity (km/s) [Theoretical velocity difference with earth, if not accelerated by earth's gravity]
6.14
[This is the delta-v needed beyond Earth Escape velocity to achieve rendezvous. I could be wrong about this.]
N sigma [the multiplier of the error ellipse to make it potentially earth grazing)
1.43e+05 [high numbers mean the error ellipse is small relative to the closest approach distance]
H (mag) [Absolute Magnitude]
24.1
Class
ATE* [Aten class,*= potentially hazardous]
Russia’s TU-95 Bear strategic reconnaisance bombers were intercepted by U.S. fighter aircraft as they entered U.S. airspace while flying in a circle around the Hawaiian Islands during their military exercise. This occurred the other day, IIRC about the time of the meteorite fall perhaps.
I assume they concluded that it was a stony meteorite primarily because an iron-nickel meteorite being significantly denser would have had a flatter trajectory and faster transit. Is that correct? I did not see any indication it was either type of meteorite based on viewing actual fragments.
John
The next scary one… we know about… doesn’t come close until 2880, but is big enough that it could seriously disrupt life on earth. The odds are 1 in 300 of it hitting earth if it goes in one projected path, the other projected path has it missing by millions miles. Called 1950 something, was reacquired briefly in 2000 before disappearing again. Anyway, warn your Great*30 grandchildren.
Another good use for all the AGW waste money, other than something to change the course of NEOs (although I think a well placed ICBM would do the trick) is planting some sort of monitoring device on these meteors and asteroids. More power for observing, no waste on propulsion.
Observations as opposed to Hansenesque advocacy, multiple arrested biased adjustments? You decide.
Near-Earth Asteroid Delta-V for Spacecraft Rendezvous
http://echo.jpl.nasa.gov/~lance/delta_v/delta_v.rendezvous.html
The table is ordered in increasing delta-v required for rendezvous.
2012 DA14 is #5040 on the list with a delta-v of 7.282 km/sec. (from Low Earth orbit)
There are 2400 NEO’s that take less than 6.3 km/sec delta-v to rendezvous with Mars,
1600 NEO that take less than the 6.0 km/sec delta-v to rendezvout with the Moon.
Chart: Rocket Mass Ration vs Delta-V (normalized to exhaust velocity).
http://en.wikipedia.org/wiki/File:Rocket_mass_ratio_versus_delta-v.png
A Centaur RL-10 has an exhaust velocity of 4.55 km/sec.
So a delta-v of 7.282 would be a 7:1 mass ratio from low-earth orbit.
Approximate cost per kg to LEO is $25,000/kg
http://www.futron.com/upload/wysiwyg/Resources/Whitepapers/Space_Transportation_Costs_Trends_0902.pdf
So approximate cost to rendezvous 2012DA14 is a minimum of $175,000 / Kg payload.
An ICBM would not have much effect.
Put a basketball in a pool, put a firecracker on the side as close to the water line as you can get it, set it off… how far did the ball move?
Nuclear weapons are far more impressive when you’re the size of a person compared to when you’re the size of a house or even larger, particularly when said house is hurtling through a near-vacuum at 10~20 km/s.
A large portion of the damage from a nuclear weapon is due to the presence of an atmosphere, remove the effects of the massive blast of air and you get a very diffuse particle beam. This is why the Casaba-Howitzer devices were looked at for Orion type propulsion, focusing the energy from a nuclear detonation into a jet would be far more effective than just setting them off next to the plate.
The most effective currently plausible technology which could prevent an impact with sufficient warning is to scale up something like the Dawn probe. Have it fly near the object and maintain a position relative to it, such that the tug of gravity from the probe is enough to change the course of the object.
It doesn’t take a large input if you get to it early enough, hence the value of early warning systems.
While the meteor’s kinetic energy due to its velocity is easily understood, don’t forget that it could also have been rotating. There would be additional kinetic energy in the form of angular momentum. Likely only a few percent more ( rough calculation, could be wrong ) but as the objects become larger, even a small angular rotation speed can double the kinetic energy.
Talk about scary, try this meteorite story. Russians searching for meteorite fragments beware.
.My Lucky Meteor – Joe Dirt (1/8) Movie CLIP (2001) HD .
It has already been imagined for some decades. There have been a variety of methods described for dealing with the problem. It’s not just the simple case of a body spinning on just one axis. The greater and more common problem is the case of the body tumbling in more than one axis. The solutions must be varied to meet the complicatoins arising from different time scales, different body sizes, and different compositions of the body. On longer time scales with smaller bodies, tumbling and vectoring of the orbit can be handled by positioning a spacecraft and/or a smaller rock or asteroid of sufficient mass in close enough proximity to ever so slightly alter the orbital path with mutual gravitational attraction.
The problem of keeping solar collectors aimed properly towards the Sun has a number of possible solutions. It has often been proposed to use orbital solar collectors in orbit to beam electrical poweer down to the Earth through the atmosphere to deliver electrical power to the Earth. The same idea without the attenuation of an atmosphere can be doe at the location of an asteroid. The solar collectors collect the solar energy at the spacecraft adjacent to the tumbling asteroid and microwaves the energy to the electrical devices and propulsion systems installed on the tumbling asteroid. The propulsion systems need not be of any great size. Some would seem to be little more than what was needed to propel a small scale model on the Earth, if there is sufficient time to accumuate the necessary kinetic energy versus the mass fo the asteroid. The propellant would likely be the asteroidal matter being vaporized and accelerated different forms and combinations of electrically powered magnetiic, ion, and/or plasma soultions. The propulsive systems could be small enough to fit on a tabletop to the sizes of current jet engines. Even something as quixotic as the future age equivalent of a counter rotating asteroidal monorail could be used to stablize tumbling and propelling mass off the asteroid. The bottomline ist that all you need to do is apply a very small amount of force for long periods of time to alter the orbital path of an asteroid. It only takes some thinking, moderate space travel resources, and the will to try doing it.
The biggest deficit at the present time is a lack of will and thinking to accomplish the task.