Of Thunder Gods and Space Science…

When I read comics, I dig when I catch a whiff of science, or at least, when there’s something in there that I can noodle around with and apply some science to. I’m not looking to disprove anything – they are comics after all – I’m looking for stuff that looks cool, and more often than not, when you hold some science up to it, gets a lot cooler.

Case in point: Infinity #4 (Marvel Comics) from last fall. The larger story of isn’t all that important for what I’m talking about here, all you really need to know is that the Avengers are in space, fighting against a tough foe…and they’re losing. By issue #4, they’re orbiting around the planet Hala, the homeworld of the Kree, one of the Marvel Universe’s humanoid alien species. Thor travels down to the planet to parlay with the leader of the enemy forces – the Builders. As he’s getting close to the area where he’ll talk to the Builder, he’s told to ditch Mjolnir, his hammer. Thor whispers a prayer to his father and throws his hammer up into the sky.The parlay starts – and goes…badly. The Builder isn’t so much interested in talking as he is in humiliating Thor – who’s taking it, in a very un-Thor like way. As a reader, we’re in on Thor’s plan – while Thor is belittled and literally slapped around by the Builder we see panels of Thor’s hammer – and it’s trip around Hala’s sun, Pama.

Just as the Builder is at his haughty best, a distinctive “KRAK-A-THOOM!” echoes throughout the region – the sonic boom of Thor’s hammer as it sought to return to Thor’s hand after it’s gravity boosted trip around the sun. Return to Thor’s hand it does, even though it means it punches a hole through the Builder – who’d proven, until this time, really, really hard to beat.

Thor gives the fallen Builder the coup de grace of Mjolnir to head, and there’s cheering. The bad guy’s been defeated. Yay. It’s a turning point in the story, something that gives hope to the opposition, lead by Captain America and the Avengers.

As I said, this scene is one of the things I love about the intersection when comics meet up with science, and makes me want to figure out how it would all work, and what some of the numbers involved are. Sometimes it’s a clean, beautiful thing, and sometimes it’s a complex tangled thing that can only be looked at in pieces. This one tends to be more like the latter. Let me explain:

So for Thor to toss Mjolnir up and around the sun, we have a few things to directly consider, which lead to a few more things that we have to indirectly figure out, and a boatload more than we are left wondering about, but thankfully are outside the scope of this article.

First – getting the hammer off planet. Escape velocity is the name of the game.

The escape velocity is the speed that you need to escape from the gravitational attraction of a more massive body. Comics and science fiction fans are familiar with the idea, and some may know that the escape velocity of earth is 11.2 km/s. By the way, when we launch objects into space, we don’t launch them at, or even try to achieve escape velocity – all we want to do is push them into low earth orbit, and from there, give them another push with an engine. It’s a cheat, because once you’re in low earth orbit, you’re already moving along at 8 km/s – so you just need a little more juice to break free.

But while we’re talking about objects and escape velocity, a question mark that lingers – and will probably linger forever – is did we ever shoot an object from earth into space without the pitstop in low earth orbit. The answer – maybe. During the controversial Operation Plumbbob nuclear tests in 1957, a 900 kg piece of armor plate was propelled off of the top of a test shaft at 66 km/s. The plate was captured on one frame of film, and no one’s saying conclusively that it made it to space, but even a conservative estimate suggests that it had more than enough speed to make it. On a tangent to this tangent, but one that connects back to Thor, the use of nuclear weapons shooting objects into space has been renamed Thunder Well, and has even been suggested as a (admittedly crude) defense against hostile aliens parked in earth orbit.

So back to Thor on Hala, throwing Mjolnir. Just keep in mind; to do something like that on earth, we’re talking about something at least approaching the energy of an atomic bomb.

So what do we need to know to figure out the escape velocity from Hala? Simple – just it’s gravitational acceleration. You know – you learned it back in high school – earth’s is 9.8 m/s². Galileo dropping things? Everything falling at the same rate? Remember? (Take a minute and drop a paper clip and a marker if you don’t – see which one hits the ground first).

Interestingly, we don’t have to worry about the mass of Mjolnir. Escape velocity doesn’t care about mass – only about the energy behind the oomph to get it moving.

So – gravitational acceleration of Hala. Into the wormhole we go.