Saturday, February 16, 2013

Too Fragile A Basket

Watch The Skies

Meteor entering Earth's atmosphere, captured by dashboard camera from vehicle outside Chelyabinsk, Russian Federation; 9:26 AM local time, February 15, 2013 (YouTub)

PRESIDENT:  Was that it? Is it over?

TRUMAN:  No, sir. Those were small; the size of basketballs -- Volkswagens...

PRESIDENT:  Well, just how big is it?

OTHER SCIENTIST: Sir, it's seven hundred kilometers in length and --

TRUMAN: (Interrupting)  It's the size of Texas, Mr. President.

PRESIDENT:  My God.  How did we miss this?

TRUMAN:  Sir, the entire budget for tracking near-earth objects last year was 20 million dollars -- million, not billion -- to look for everything that could hit us coming out of the sky. And, excuse me, Mr. President -- but it's a big-ass sky.

-- NASA Director Dan Truman (Billy Bob Thornton)
Armageddon (1998)
Chelyabinsk, Russia is a city once known only to U-2 or SR-71 overflights, or the eyes of Keyhole intelligence satellites; it was known by the then-Soviet military's designation of Chelyabinsk-50 or -65, a center of their nuclear weapons program -- a secret city, difficult to get into and the home of technicians and specialists that tended the warheads stored and maintained in the surrounding countryside.

The area has had three uncontrolled releases of nuclear materials in the past seventy years, and is known as one of the most radioactively-contaminated places on the planet outside Chernobyl.

Now, the warheads are gone (probably). Chelyabinsk is a major transportation hub between European Russia west of the Urals, and Siberian provinces of Sad Vlad The Putin's empire. A town of just over a million people at the eastern foot of the Urals, it resembles a Rust Belt city in Illinois or Ohio -- some genteel decay here and there; important, but not the thriving center it once was.

Yesterday, in the winter sky over Chelyabinsk at 9:26 AM local time, an asteroid which had been pulled into Earth's gravity well, estimated by NASA to be 50 feet in diameter and weighing some fifteen thousand pounds, entered our atmosphere at roughly 40,000 miles an hour.

Since the second half of the 20th century, close monitoring of Earth's atmosphere has led to the discovery that such asteroid airbursts occur rather frequently. A stony asteroid of about [30 feet] in diameter can produce an explosion of around 20 Kilotons, similar to that of the... bomb dropped on Nagasaki, and data released by the U.S. Air Force's Defense support Program indicate that such explosions occur high in the upper atmosphere more than once a year ...Military satellites have been observing these explosions for decades..  (Wikipedia)

Dashboard cameras around the area (what, in a backwater like Chelyabinsk, are so many vehicles doing with dashboard cams?) captured the decent of the small asteroid, heated by friction in a few seconds to several thousands of degrees, shining as brightly as the sun:



Several miles in the air, the super-heated rock exploded.  A resulting pressure wave shattered windows and caused light structural damage in the immediate area; seismographs recorded an earthquake near Chelyabinsk at 2.7 on the Richter scale. 

Some 1,100 people were injured, mostly from flying glass, and most of the damage was to windows and window-frames -- no joke in a Russian city in winter. The most spectacular damage in the city (a collapsed wall at a zinc factory; see below) may have been exacerbated by cut-rate building construction methods.
 


Reports estimate that the asteroid was probably the "stony" type, composed mostly of rock, and it's explosion released energy equal to a 250 - 500 Kiloton nuclear warhead -- roughly 10 times the explosive force of the 'Little Boy' plutonium bomb dropped on Nagasaki in 1945. 

The Nagasaki bomb was a fusion weapon, designed to destroy, and detonated a few hundred meters above the city. The super-heated rock flying over Chelyabinsk was only responding to the laws of physics, and may have exploded high enough in the air that the effects of releasing that much energy were mitigated by distance.   

However -- if the asteroid had instead been composed of nickle-and-iron, it probably wouldn't have exploded in the air. It would have been heavy enough to hit the earth and  release its energy on impact -- and that would have had significantly more force than 250 - 500 Kt. 

An unknown asteroid, falling to earth and causing over a thousand injuries, would have been singular enough.  But it happened just hours before a known and well-publicized asteroid, DA 14, was set to make the closest pass to Earth by a large chunk of rock in anyone's memory: It missed us by only 17,000 miles, well within the Earth's ring of communications and military satellites (out at 25,000 miles).

17K isn't even the width of an Elephant's eyelash in galactic terms -- and DA 14 was three times larger than the object that blew up over Chelyabinsk yesterday -- about as large as the object which caused the Tunguska Event in Siberia, over a thousand miles away and 105 years ago.

On June 30, 1908, a stony asteroid or small comet (which, is still a matter of debate) entered the atmosphere over Siberia and exploded -- in exactly the same manner of the object yesterday at Chelyabinsk.

A few eyewitnesses saw an object streaking east-to-west across the sky, as bright as the sun, followed by one or more explosions. The airburst (like the one at Chelyabinsk) released an estimated 10 to 30 Megatons of energy, as much as the largest strategic nuclear warheads ever made.  Old-growth trees were blown down by the pressure wave in a wide radius around the presumed blast site, and enough dust was blown into the upper atmosphere to be noticeable for months afterward.


Trees flattened at the Tunguska Event site in Siberia; 
photo taken during the 1927 expedition

Something like Tunguska was a rare event; scientists this week commented that it might only occur every three hundred years.  It isn't unusual for meteorites to enter the atmosphere -- but most are small and unseen,  except on clear nights away from the light pollution of cities, or during annual meteor showers in the summer and fall.

What is unusual, experts say, are events like Chelyabinsk -- "once every hundred years" was the phrase I heard tossed around on news programs -- but they may happen more often than we think.  Earth is a big planet, and three-fifths of its surface is covered by oceans.  An event could happen over the mid-Atlantic, and not be seen by human eyes.

An almost identical event to what happened in Chelyabinsk was seen in Indonesia four months ago, with similar vapor trails, pressure waves and seismic shock reports. 

Smoke trail from the Indonesian meteor, October 2012

Scientists reported recently that they believed it to have been caused by an asteroid roughly the same size and weight as the Chelyabinsk object -- and, the event happened in a sparsely populated area surrounded by a large amount of water, rather than forest.

Scientists have located the larger Near Earth Objects.  Since these rock present the potential for massive damage or extinction of the species, the astronomers take their work seriously. 

Once any asteroid is discovered, the level of hazard any it presents is based on regular observations. Its size, velocity and 'spin' (motion around an internal axis) are determined.  As it approaches the inner Solar System, to become a real threat it must pass through a region in space referred to as a "keyhole".  If it does, then it will be affected by Earth's gravitational pull and possibly drawn in for an impact -- then, or years in the future.

It's a constant dance of mathematics, objects moving through through space and influenced by gravity.  An asteroid orbits the Sun, but so do we -- and what NASA and other astronomers do is constantly refine their calculated odds that an asteroid will arrive at the same place as we will be in our orbit, and when -- or by what margin it will miss us. So far, the chances that any known asteroid will hit us are extremely low. 

The danger is with asteroids too small to see, until they've already hit us -- like the one which exploded yesterday.  And, as Chelyabinsk showed, even something the size of a diesel locomotive can cause real damage.

The problem is, projects to locate any NEO's are underfunded, meaning sizable chunks of rock and iron can come sailing at us out of nowhere. Asteroid 2011-MD, which zipped by in June of last year, was roughly half as large as the Chelyabinsk object.  It did miss us by 3,400 miles -- but it was discovered by NASA only 4 days before its closest approach. 

No industrialized nation has done more than talk about how Humanity might respond if we found a potential planet-killer, capable of producing an Extinction-level Event, was on its way. Human culture is primarily focused on acquisition, dominance, and the continuation of a status quo; making plans for an event seen as improbable just isn't a priority.

 Obligatory cute small animal photo in middle of science blog thing

On tonight's CBS Evening News, Jeffrey Kluger, science editor at Time magazine, said what happened over Russia was rare but nothing new. Asked what could be done about a potential threat, Kluger suggested the technology was available to deflect or change the speed of an asteroid "just a few centimeters per hour, so that when it [approaches Earth], we've already moved past [the point of intersection]".

The CBS anchor asked, That's all it takes? "That's all it takes," Kluger said.

Discovering an object in time to do something (remember, 2011-MD was found only 14 hours away from Earth); building probes -- multiples, because you need redundancy, a second and even third chance with these kinds of odds; then, make a successful rendezvous with the asteroid far enough away from Earth, when your radio signals to the probes will take some time to reach them... it's not as simple as Kluger suggested on CBS.

Total numbers of Near-Earth Asteroids discovered, by method (Wikipedia)

And even Kluger, in an article posted at Time online, says that "drawing-board technology is not the same as actual hardware, and it’s imperative that our good ideas are translated into in-the-hangar spacecraft."

All of the materialistic, political and religious issues we struggle with as a species are an utter waste of time, and an insult to the generations who came before us since Lucy and her kin lived at Olduvai Gorge and looked up at the lights in the night sky.  We need to keep looking up at the Cosmos.

And I agree with the occasionally-quoted remark attributed to Robert Heinlein, that "Earth is too small a basket for Humanity to keep all of its eggs in".   Our destiny is Out There -- even if intergalactic travel at the moment will take hundreds of years, even if all we can do is set up large-scale colonies on the Moon and Mars.

It's really just a matter of making a decision to go. Part of our developing as a technological species means we understand the possibility exists that something -- a meteor, a solar flare; a virus, or changes we've wrought in the Earth's climate  -- can happen.  The whole of humanity could be kicked back into the Stone Age in a matter of minutes.  We deserve better than that.

Tourists on the rim of the Barringer Crater in Arizona -- one-half mile wide,
and created by a nickle-iron asteroid the size of DA 14, which missed us yesterday .

But I'm only a Dog, and not often listened to.

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Und Noch Einmal:  ...and, about the asteroid, DA 14, which just missed us by 17,000 miles last week? 300 feet long, and about 100,000 tons?  Bigger, even than the Tunguska Event object?

Well, it will be back in 2080, when -- unless something else intervenes -- it will hit us traveling at about 18,000 miles an hour.  Don't make any vacation plans for that year.

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