Nandini's Niche

The title of this post is quite redundant, of course. In any case, here’s an update. During a slump, my blogging takes earth-shattering occurrences to get jolted back to life – and I guess this certainly qualifies: an asteroid is right now – that’s right, as you read this, if you’re reading today – doing the cosmic equivalent of threading a needle. For all that Apollo Asteroid “2004 XP14″ sounds like a new release from Microsoft, this smokin’ piece of rock hurtles by today at just 1.1 times the distance to the moon away! It’s a bullet that’s passing through the sleeve of our collective shirts without grazing our arm. Whee haa.

I’m currently reading A short History of Nearly Everything, Bill Bryson’s definitive work of genius. Here’s what it has to say about asteroid impacts. I might as well warn you to forget everything you know from Armageddon and Deep Impact.

An asteroid or comet traveling at cosmic velocities would enter the Earth’s atmosphere at such a speed that the air beneath it couldn’t get out of the way and would be compressed, as in a bicycle pump. As anyone who has used such a pump knows, compressed air grows swiftly hot, and the temperature below it would rise to some 60,000 Kelvin, or ten times the surface temperature of the Sun. In this instant of its arrival in our atmosphere, everything in the meteor’s path—people, houses, factories, cars—would crinkle and vanish like cellophane in a flame.

One second after entering the atmosphere, the meteorite would slam into the Earth’s surface. The meteorite itself would vaporize instantly, but the blast would blow out a thousand cubic kilometers of rock, earth, and superheated gases. Every living thing within 150 miles that hadn’t been killed by the heat of entry would now be killed by the blast. Radiating outward at almost the speed of light would be the initial shock wave, sweeping everything before it.

For those outside the zone of immediate devastation, the first inkling of catastrophe would be a flash of blinding light—the brightest ever seen by human eyes—followed an instant to a minute or two later by an apocalyptic sight of unimaginable grandeur: a roiling wall of darkness reaching high into the heavens, filling an entire field of view and traveling at thousands of miles an hour. Its approach would be eerily silent since it would be moving far beyond the speed of sound. …

Within minutes, over an area [of the whole of USA], nearly every standing thing would be flattened or on fire, and nearly every living thing would be dead. People up to a thousand miles away would be knocked off their feet and sliced or clobbered by a blizzard of flying projectiles. Beyond a thousand miles the devastation from the blast would gradually diminish.

But that’s just the initial shockwave. No one can do more than guess what the associated damage would be, other than that it would be brisk and global. The impact would almost certainly set off a chain of devastating earthquakes. Volcanoes across the globe would begin to rumble and spew. Tsunamis would rise up and head devastatingly for distant shores. Within an hour, a cloud of blackness would cover the planet, and burning rock and other debris would be pelting down everywhere, setting much of the planet ablaze. It has been estimated that at least a billion and a half people would be dead by the end of the first day. …

The amount of soot and floating ash from the impact and following fires would blot out the sun, certainly for months, possibly for years, disrupting growing cycles. In 2001 researchers at the California Institute of Technology analyzed helium isotopes from sediments left from [a mid-sized asteroid thought to have caused dinosaurs to become extinct] and concluded that it affected Earth’s climate for about ten thousand years.

We can only guess how well, or whether, humanity would cope with such an event.
And in all likelihood, remember, this would come without warning, out of a clear sky.

But let’s assume we did see the object coming. What would we do?

Everyone assumes we would send up a nuclear warhead and blast it to smithereens. The idea has some problems, however. First, … our missiles are not designed for space work. They haven’t the oomph to escape Earth’s gravity and, even if they did, there are no mechanisms to guide them across tens of millions of miles of space. Still less could we send up a shipload of space cowboys to do the job for us, as in the movie Armageddon; we no longer possess a rocket powerful enough to send humans even as far as the Moon. The last rocket that could, Saturn 5, was retired years ago and has never been replaced. Nor could we quickly build a new one because, amazingly, the plans for Saturn launchers were destroyed as part of a NASA housecleaning exercise.

Even if we did manage somehow to get a warhead to the asteroid and blasted it to pieces, the chances are that we would simply turn it into a string of rocks that would slam into us one after the other in the manner of Comet Shoemaker-Levy on Jupiter—but with the difference that now the rocks would be intensely radioactive. Tom Gehrels, an asteroid hunter at the University of Arizona, thinks that even a year’s warning would probably be insufficient to take appropriate action. The greater likelihood, however, is that we wouldn’t see any object—even a comet—until it was about six months away, which would be much too late. Shoemaker-Levy 9 had been orbiting Jupiter in a fairly conspicuous manner since 1929, but it took over half a century before anyone noticed.

This book is a constant revelation… exhilarating, really. Just this morning, I was very, very pissed off to find out that a mind-bendingly amazing piece of information was left out of all our Biology text books in school. I remember learning drearily by heart the parts of an animal cell in junior college. I remember being remotely puzzled while learning about mitochondrial DNA and RNA – why on earth do we have two sets of DNA in every cell in our body, one in the nucleus and one in the mitochondrion? Anyway. My puzzlement faded, I suppose, because I had more presing things on my mind, like trying not to flunk the test tomorrow etc., and I had put that strange piece of info simply out of my mind.

Here’s what the teacher never hinted at: mitochondria are practically separate organisms! Not only that, they’re invading organisms. Here’s the illuminating quote from A Short History Of Nearly Everything:

One reason life took so long to grow complex was that the world had to wait until the simpler organisms had oxygenated the atmosphere sufficiently. … It took about two billion years, roughly 40 percent of Earth’s history, for oxygen levels to reach more or less modern levels of concentration in the atmosphere. But once the stage was set, and apparently quite suddenly, an entirely new type of cell arose—one with a nucleus and other little bodies collectively called organelles (from a Greek word meaning “little tools”). The process is thought to have started when some blundering or adventuresome bacterium either invaded or was captured by some other bacterium and it turned out that this suited them both. The captive bacterium became a mitochondrion. This mitochondrial invasion (or endosymbiotic event, as biologists like to term it) made complex life possible. (In plants a similar invasion produced chloroplasts, which enable plants to photosynthesize.)

Mitochondria manipulate oxygen in a way that liberates energy from foodstuffs. Without this niftily facilitating trick, life on Earth today would be nothing more than a sludge of simple microbes. Mitochondria are very tiny—you could pack a billion into the space occupied by a grain of sand—but also very hungry. Almost every nutriment you absorb goes to feeding them.

We couldn’t live for two minutes without them, yet even after a billion years mitochondria behave as if they think things might not work out between us. They maintain their own DNA. They reproduce at a different time from their host cell. They look like bacteria, divide like bacteria, and sometimes respond to antibiotics in the way bacteria do. In short, they keep their bags packed. They don’t even speak the same genetic language as the cell in which they live. It is like having a stranger in your house, but one who has been there for a billion years.

Would it have killed educators to put nifty stuff like this in our text books? I suppose it would get in the way of – oh – blind memorisation.