Close, and nearly cigar

Sunday 17 February 2013, 9.40am HKT


Updated 17 Feb 2013 (number fixes)

asteroids game

Remember this arcade game?
We’re not the one playing it now, are we?
(Image via Engadget)

2.37am local time, 17°C (63°F), chills in the air

IT could’ve been Game Over for us yesterday.

Or to put a positive spin on things, yesterday could’ve been the day all our ‘problems’ are ‘solved.’

The closest we almost got done in by that scumbag esteemed and cordial Asteroid 2012 DA14 was at 19.25 hours GMT on 15 Feb 2013 — travelling at 5 miles a second with just 17,200 miles (27,680 kilometres) to spare between it and the Earth’s surface. The Moon is 239,000 miles (384,633 km) from Earth.

A velocity of 5 miles a second is roughly 18,000 mph (29,000 kmph) — Mach 26, or 26 times faster than the speed of sound.

(In space, there is no sound, and no one can hear you scream…)

gif nasa flyby asteroid 2012 da14

Flyby of Asteroid 2012 DA14 in real time captured in Australia
(Image via NASA)

Funnily enough, astrophysicists use the centre point of Earth to measure distance against Near Earth Objects that do drive-by shootings at our planet. Calculating in this funny way (funny to me at least), Asteroid 2012 DA14 passed 21,160 miles (34,050 km) from centre-point of Earth. That’s a difference of 3,960 miles (6,370 km) — the radius of the Earth — or the distance from London to Columbus (Ohio) or to Dubai (United Arab Emirates).

These astro boys probably think we could actually survive something hitting us anywhere within that 3,960-mille block of Earth. I don’t think so. According to the astro boys, a space rock lawnmowing the hell out of our planet’s surface would still be passing us at 3,960 milles from the centre point of Earth. Then again, what do I know.

Asteroid 2012 DA14 will do another drive-by shooting in 33 years’ time. On 15 Feb 2046, it will pass no closer than 930,000 miles (or 1½ million km) from the centre point of Earth. Just remember to subtract 3,960 milles (9,370 km sorry, it’s 6,370 km) from the astronomers’ figures. Unless of course you actually live in the centre of the Earth.

shuttle vs asteroid 2012 da14

(Image by NASA via Digital Trends)

By the way, Asteroid 2012 DA14 measures 160 feet long (50 metres, the length of an Olympic-sized swimming pool) long and has a mass of 143,000 tons (130,000 metric tonnes).

Interestingly, the last time a space rock of comparable size and mass hit us was the Tunguska event of 1908 in Russia. That time that ‘thing’ blew its load over an 800-square-mile (2,000-square-kilometre) forest with the blast energy of a 10- to 15-megaton nuclear warhead, and flattened everything there. Baby, juice like that is roughly equal to the U.S. “Castle Bravo” hydrogen bomb tested in 1954, or 1,000 times more than the A-bomb lobbed on Hiroshima.

*

ЬДCК IИ THЗ ЦSSЯ

Russian-Meteor-Meme

Back in the USSR — ahem, I meant Russia — we can get a sense of how much more damage if Asteroid 2012 DA14 had hit us with our modern infrastructure.

meteor-gif

(Click on image for animation. Image via thesciencellama)

The Russian meteorite (apparently still officially “an object”) was one galloping sonofabitch Russian mafia hitman. It rammed through into Russian airspace at 33,000 mph (53,000 kmph), or Mach 48, with a heavy contrail — some 12 hours ahead of the flyby time of 2012 D14.

It burnt up in the air over Chelyabinsk, creating a shockwave that shattered windows and stuff. Bits of it landed 80 miles east of Chelyabinsk but made a rather anticlimactic 10-foot puddle in the snow.

Depending on which news service you choose to believe, the injured numbered from 429 (The Guardian newspaper of London) to at least 1,000 (Russian and international news agencies).

russian meteor entry by meteosat-10

The European Meteosat-10 satellite captured the precise moment
the Chelyabinsk object entered Russian airspace
at 02.15 hours GMT on 15 Feb 2013
(Image by EUMETSAT via Gizmodo)

NASA’s Jet Propulsion Laboratory says the Chelyabinsk object before hitting the atmosphere measured 49 feet (15 metres) and had a mass of about 7,000 tons (6,350 metric tonnes). That’s one-third the size of 2012 D14.

Eastern Earth Globe Russian Meteor1

Distance between Earth and 2012 DA14 is about correct,
but length of meteor trail is NOT to scale
(Image via AlicesAstroInfo.com)

According to NASA scientists, the trajectory of the Chelyabinsk object was different from the trajectory of Asteroid 2012 D14, making the two objects and events completely unrelated. In videos of the event, the Chelyabinsk object is seen to pass from left to right in front of the rising sun, which means it was travelling from north to south. Asteroid 2012 D14’s trajectory is in the opposite direction (from south to north).

*

THE BIGGER PICTURE

asteroid comeback

(Image via m4f)

The truth is, we could’ve been double-penetrated yesterday. As it turned out, the smaller bugger had a field day with us instead, thankfully.

The boffins say 2012 DA14 wasn’t going to hit us. They also say direct hits are pretty slim too. They say most bodies enter the Earth’s atmosphere at a 45° angle, so they are likely to burn themselves out in the air (the best scenario) because of the high heat generated by the compression of air in front of the flying body, or explode in an airburst (the worst scenario) with reduced destructive power over the ground surface (or the city below).

And then came the Chelyabinsk meteorite.

asteroid buddy

(Image via images.nonexiste.net)

The bollocks explanation from the scientists boils down to energy.

From the various articles I’ve read, a space object about the size, density, velocity and entry angle of 2012 DA14 carries 3 or 4 megatons of kinetic energy on entry into the Earth’s atmosphere. If the wretched thing exploded 10 kilometres from ground surface, the airburst energy would be around 3 megatons. The “Little Boy” A-bomb dropped on Hiroshima was rated only 16 kilotons (the rating of most modern artillery-fired tactical nuclear shells). Three-megaton blast magnitude is around 130–140 Hiroshima A-bombs.

I think the boffins sometimes are just a little too much on the optimistic side. They seem to forget that flying objects will have bits flaking off of them and make a mess of things as they fly through the atmosphere. Airbursts send bits flying off at high speed to clusterf*ck everything on the ground too.

Look at the Tunguska meteor of 1908. It blew up around 10 kilometres in the air over an uninhabited forest region. It wiped out EVERYTHING in 2,000 square kilometres. Hong Kong is only 1,104 sq. km (468 sq. miles). London is only 1,670 sq. km (600 sq. miles).

I don’t pretend to know much about physics. I had to resit my O- and A-level physics, but my physics is good up to hospital labtech territory. If the entry angle is shallow (i.e. less than 45°), then the asteroid will meet greater air resistance and more likely to explode at higher altitudes. If the entry angle is straight down (i.e. 45° to 90°), then it’s less air resistance and the impact more localised.

That’s dynamite on paper. The reality is that lots of asteroids or meteors in the last 10,000 years also rammed through into Earth’s atmosphere at shallow entry angles but carried tens of times more destructive power than the Tunguska event. There HAVE BEEN bodies of denser matter (like iron) or higher mass hitting our planet at shallow angles that DIDN’T disintegrate midair. You can imagine chunks breaking off and mowing down everything in their high-speed paths. There HAVE BEEN bodies coming straight down whose results WEREN’T localised at all — think of that big crater in Arizona as an example.

I remember Sir Patrick Moore, the famous British astronomer, saying on TV back in the early 1980s that if we’re unlucky enough to be hit by a ‘hot’ asteroid of over 200,000 tons (as opposed to a ‘cold’ one like 2012 D14), the Earth would explode like a lit cigarette touching a balloon.

meteor dinosaurs

(Image via kroblues)

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© The Naked Listener’s Weblog, 2013. Updated 17 Feb 2012. (B13061)

Faux Cyrillic text via Fake Cyrillic Generator by The World of Stuff.

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