Estimating the Critical Size for a Tungsten Projectile to Reach Earth’s Core via Gravity Alone

Estimating the Critical Size for a Tungsten Projectile to Reach Earth’s Core via Gravity Alone

Ever wondered what it would take to drop something – anything, really – straight into the Earth’s core? I mean, forget rockets and all that jazz for a second. Just good ol’ gravity doing the work. Sounds crazy, right? Well, let’s chew on this thought experiment: how big would a tungsten ball have to be to make it all the way down, dodging fiery doom and all?

Now, before we get ahead of ourselves, let’s be clear: this is purely theoretical. We’re not about to start flinging tungsten at our planet. But it’s a fun way to explore some seriously cool physics.

So, what’s the big challenge? Air. Yep, that pesky atmosphere. Gravity’s pulling our tungsten buddy down, but the air is pushing back – hard. It’s all about overcoming that drag. Think of it like trying to run through water; the faster you go, the harder it gets.

That’s where tungsten comes in. It’s seriously dense stuff – we’re talking about 19.3 grams crammed into every cubic centimeter. This high density is a huge win because it means we can pack a lot of mass into a relatively small package. Less surface area equals less drag.

Okay, so how big are we talking? This is where things get a bit fuzzy. Calculating the exact size is mind-bogglingly complex. You’d need super-detailed models of the atmosphere and some serious number-crunching power. But we can take a stab at a ballpark figure.

See, an object falling through the atmosphere eventually hits what’s called “terminal velocity.” That’s when the air resistance equals the force of gravity, and you stop accelerating. Our tungsten projectile needs to avoid that fate. It needs to punch through the atmosphere like a hot knife through butter, maintaining enough speed to keep going.

Experts will tell you that anything entering the atmosphere slower than orbital velocity (around 7-8 km/s) is in for a rough ride. It’ll probably burn up or slow down to a crawl. So, let’s say our tungsten needs to hit the ground moving at hypersonic speeds – at least five times the speed of sound.

Given all of that, we’re probably looking at a tungsten sphere with a diameter of at least a few meters. Picture a solid ball of tungsten bigger than a car, weighing several tons. That’s a serious chunk of metal!

But even if it makes it through the atmosphere, the journey isn’t over. There’s still almost 3,000 kilometers of mantle to plow through before hitting the liquid outer core. The pressure down there is insane – millions of times the pressure at sea level – and the temperature is scorching.

Tungsten’s high melting point (over 3,400°C) helps, but the pressure will still be a major issue. The impact with the Earth’s surface will also generate a ridiculous amount of heat, so some of the tungsten will probably vaporize. But hopefully, enough of it will survive to keep on trucking towards the core.

So, what’s the bottom line? Getting a tungsten projectile to the Earth’s core using only gravity is a monumental challenge. While we can’t give you an exact size without some serious simulations, we’re likely looking at a sphere several meters in diameter, weighing many tons. It’s a wild idea, but it really makes you appreciate the sheer power of gravity and the challenges of space exploration, doesn’t it? The real size could be much larger, depending on a number of factors.