I used to think that exact same question myself. “If we could blow the asteroid into small enough chunks to just burn up in the atmosphere so nothing could hit the ground, wouldn’t that be good enough?”

As others (including Phil himself) have said, the total energy doesn’t change. The problem is that all that stuff burning up in the atmosphere at once is going to dump a *LOT* of heat all across the globe at once. It would be like placing the Earth in a huge blast furnace as the atmosphere superheated to hundreds and hundreds of degrees. It would be a global firestorm.

If it does show up in the sky, I’m sure there will be tons of people assuring us that it’s the Star Wormwood and we’re all doomed. Comets are good like that.

“It would take something about the size of a football field to do us any real damage (and even then it would be local, not global)”

This analogy runs into the same problem that _Armageddon_ did when they said the asteroid was “the size of Texas”.

Namely:
How THICK is a football field?

If we assume a football field is 100 yards long and 160 feet wide, but that it’s only 1 inch thick (about the height of the grass or astroturf on its surface), that’s only 4000 cubic feet. That’s not a very large object at ALL!

In Deep Impact, the idea was to shatter the ICE BALL (Comet) and the small bits (notice the scene) would melt as they entered the atmosphere. Logical assumption Ice+Speed+Atmosphere=Melt, Of course they forgot about +Heat, which would probably cooked most of Canada and melt the Greenland icecap But that is another movie….

Obviously You were groaning too much to actually see the end.

Though using the moon gavity well to sling shot around and pick up speed? Everyone knows, that would send them back in time to 1968, where they could contact the USS. Enterprise, so Kirk could save the day.

For an asteroid of about 10 km in radius (4.188 x 10^12 m^3, which is nowhere near “as big as Texas”) with a density of about 2 g/cm^3 and a closing speed of 5 km/s (which seems reasonable based on what I’ve read), you’re looking at an energy equivalent on the order of 25,000 gigatons of TNT (provided I’ve done the math right, using translational kinetic energy and treating it as a solid, non-rotating body).

Suppose you manage to blow it into 1-meter chunks. Now instead of one massive object, you have 4.188 x 10^12 objects all hitting at around 5 km/s. You still get roughly the same total energy, although spread out over a wider area. However, I can’t imagine dispersing that much energy over any size area in an environmentally benign manner.

Yes, knowing a lot of science can decrease our ignorant enjoyment of SciFi. On the other hand, the closer a writer gets to the real science, the better the story( no distractions). I especially liked FireFly for that very reason. No need for phasers, blasters of exotic origin, FTL, etc. ,,,and they still use projectile weapons. The one major high tech SciFi gadget they proposed was their “gravity drive”, which I expect was included so they could pull high speed turns w/o turning the crew into jelly. If we ever figure out what gives matter mass, this may actually turn out to be possible.

Gary 7

Steve gets it right with the thing being too far out to start glowing from atmospheric friction.

Wait, what?

Friction?

I thought the bulk of the heating when a fast-moving object enters the atmosphere was from compression of the air, not friction. Sure, there’s friction, but that isn’t what causes most of the observed heating.

Do you mean that we couldn’t blow it up to small enough pieces? Or that somehow a huge bunch of really small rocks, that individually would normally burn up in the atmosphere, would somehow still cause a huge amount of damage?

I mean, what if we “vaporize” the asteroid to gazillion chunks a meter across each, would that still pose a problem?

Yeah, they’d still have the same collective mass and the same speed, so therefore they’d have the same energy. Dumping all that energy into Earth’s atmosphere is possibly worse than concentrating it in one place on the surface (unless that place is in the sea).

So I’ve given up trying to be factual in movies, grab some popcorn, sit back and enjoy.

P.S. I would have commented on Blastr, but I’ve been too busy doing stuff with my friends to have time to deal with Facebook or Twitter. Where do people find the time for that kind of stuff? You need either a Facebook or Twitter account to post a comment.

“NASA is notified, and they scramble into action. A team of astronauts hurriedly trains, launches in the Space Shuttle, and lands on the rock hours later.”
Well, let’s just say NASA isn’t exactly nimble.

You could also have added :

I) We won’t have the Space Shuttle soon given it stops flying this year. The program is shutting down and it will be very hard – if its possible at all – to restart if its needed.

II) The Space Shuttle won’t be able to go beyond Low Earth Orbit anyhow (right?)

III) No, NASA hasn’t got any sceret super-Spaceplanes that like Shuttles but even better conveniently locked away in hanger somewhere ready to fly at a weeks notice.

Sadly.

In Armageddon, given the size of the asteroid involved, they’d need a nuke that could detonate with the same energy output as the sun. I’m rather glad we don’t have a weapon like that.

Actually, pedantic nit-pick mode on (well you did ask for feedback!) that needs qualifying I think – after all nuclear weapons esp. fusion bombs *do* produce the output of the Sun – or a tiny fraction of it or its surface. Right?

The output of the Sun for how long or how much of it’s surface? That’s an immediate question I wonder about with that.

I’m also glad we don’t have anything like that – but gladder still that our global enemies lack such weaponry too!

Such minor nits aside though – great article, BA.

http://www.space.com/4711-flying-saucers-saturn-explained.html

to send it rocketing towards Earth like that?

When you wrote :

… no asteroid is actually flying saucer shaped!

you forgot to note that some moons *are*, BA!

See :

http://www.dailymail.co.uk/sciencetech/article-1367617/Saturns-UFO-moons-Bizarrely-shaped-Pan-Atlas-baffle-scientists.html

&

http://astrobob.areavoices.com/2010/11/23/how-to-make-a-flying-saucer-saturn-style/

Plus given the number of asteroids in our solar system, I think its’ likely that some will turn out to be “Flying Saucer” shaped, we just haven’t encountered any yet. That’s probably a good thing given the conspiracy theorists (eg. likes of Hoagland) and what they’d most likely make of such a find.

I probably shouldn’t mention that one of the professional robotic networks is called SkyNet. Seriously.

I knew there was one named spaceguard after a reference in Arthur C.Clarke’s Rama series, I didn’t know there was one named after the Terminator franchise. An unfortunate chocie of name. Yikes!

“In a few weeks’ time, an asteroid hundreds of miles across will hit the Earth, wiping out all life.”
This part always makes me laugh. Objects hundreds of miles across are bright. .. [SNIP] … more likely we’d find it would pass several times in its orbit before it would hit us. For example, we know of no objects more than a few miles across that can hit us in the next century.

That’s true enough for asteroids – but, I gather, not so much for comets esp. unpredictable long period comets or one’s on their first pass through the inner solar system.

So if we cross out asteroid and replace it with *comet* the Hollywood scenario there is plausible if highly unlikely methinks.

I reckon that would have been worth mentioning – and I’m pretty sure I remember you doing so in your (second) book.

The reason you don’t want to land on the asteroid to push it is due to a number of factors.

1) It’s much much harder to land on something without crashing than to simply orbit nearby.

2) There may be debris and irregular surfaces that make it impossible to correctly align the lander (in fact, this is most likely)

3) It’s harder to remotely communicate with a probe when the radio signal gets blocked by the mass of the meteoroid.

4) The spin rate and axis of rotation of these types of objects changes frequently and unpredictably. Even the effect of light hitting its surface can cause jets of evaporating material to alter its rotation.

5) The object might just be a loose collection of dust and rubble without any sufficiently hard surface to push against. If you started pushing a rocket into it you might just end up unintentionally drilling down into a rubble pile.

All in all, the gravity tug option is much more predictable and less prone to complications.

The probe has to use some kind of thrust to maintain its position, near enough to the asteroid so its gravity affects it, but without crashing into it. Suppose you use low-thrust ion engines to do the job, (perhaps two of them at an angle so the reaction mass doesn’t hit the asteroid and push it when you’re trying to pull it).

Am I right so far?

So why not just land the probe on the asteroid and point the engines outward, effectively turning the asteroid-plus-probe into a low-power rocket? Is using gravity more efficient somehow? The asteroid’s spin might be an issue (so land at a pole), but my (probably faulty) intuition tells me that applying the thrust directly will be at least as efficient as applying it indirectly.

The artist also didn’t show the shock wave that would be at the front of the thing & there are flames that look like a piece of burning wood instead of a narrow streak. Artistic license has to enter into it there. Gotta make it look like what people think of when they think “flames”…

Who did the illustration, Phil? Blastr?