A Fact-Check for the Four-Color World

Friday, April 01, 2005

Superman/Batman: Kiss My Asteroid

To follow up on my look at the new Krypton, I'm going to take on some of the science that's brought to the table in Jeph Loeb's first Superman/Batman arc, "Public Enemies."

Brief summary: A Kryptonite asteroid the size of Australia is headed straight for Earth. President Luthor has gone crazy after becoming a Kryptonite drug junkie, so he tells the world that the asteroid is Superman's fault, and they believe him. Lots of fighting ensues, and eventually the day is saved by an one-time Loeb character from a few years earlier, who builds a giant robot spaceship that smashes the asteroid into little pieces.

At the end of issue one, Luthor is shown standing in front of a giant screen that shows the asteroid (then labelled "Asteroid 921 Wormwood," but later called "Asteroid X") somewhere beyond Saturn. It's said that the asteroid is a week away from reaching Saturn's orbit.

In the upper left corner of the screen, it shows "Pluto" and its moon "Phobos." Phobos is indeed a moon...of Mars. Pluto's moon is Charon, named for the ferryman of the River Styx from Roman mythology. It was also discovered on the day I was born.

(Continuity sidebar: The DCU Pluto probably shouldn't have a moon at all. Before Loeb's "Our Worlds at War" event, the planet Pluto was stolen by Brainiac 13 and made into the new Warworld. After this was discovered, Green Lantern then constructed a replacement Pluto out of spare asteroids (there was a reason given for this, but it was bad science too). When Pluto was missing, Charon should have drifted off with no planetary gravity to hold it in place. Maybe GL found it and brought it back.)

This provides some good comparison for the Kryptonite asteroid. Charon is 728 miles in diameter, a little more than half of Pluto's 1413 mile diameter. Both dwarf measly little Phobos, which is still only 17 miles across at its widest. It's incredibly tiny. Our moon (ten brownie points to the person who knows the name of our moon) is a bit larger: 2160 miles in diameter.

The Kryptonite asteroid (not meteor; an asteroid becomes a meteor when it enters the atmosphere) is said to be the size of Brazil at one point, and the size of Australia later on. Neither nation is round, but they have similar land areas (Autralia = 3.1 million mi2; Brazil = 3.3 million mi2). A circle with an area of 3.2 million mi2 would have a diameter of a little more than 2000 miles.

Thus, the Kryptonite asteroid was about 80% of the size of our moon. Or about three times the volume of Pluto. Maybe it's just me, but I think "The asteroid is almost as big as our moon" sounds a lot more threatening than the Aussie comparison.

This shows why the attempt to destroy the asteroid with nuclear bombs (in #2) failed. Imagine trying to blow up the moon with a handful of nukes. They wouldn't make a dent. On the other hand, it makes one wonder how the Superman/Batman robot-ship managed to successfully break it up. It may be hard and it may be fast, but compared to the asteroid, it's really tiny.

Let's say the ship was 500 feet tall, being shot at an asteroid 2000 miles across. In terms of size, that's like shooting a bullet at a sphere 1/3 of a mile in diameter (or about 6 football fields across). That's one seriously powerful projectile to not only affect that sphere, but to break it up into tiny pieces.

The largest asteroid yet discovered is 2001 KX76, which has a diameter of about 900 miles at the most. The Kryptonite asteroid is thus at least twelve times as large as the biggest real-world asteroid. Of course, the size of this asteroid could be due to its unnatural origin. It is a chunk of a destroyed planet, after all. And potentially a rather large planet, as discussed in my previous post.

Krypton is also a very distant planet, as detailed previously. 2.2 million light years away from Earth (or 13 quintillion miles). This means that one way or another, that Kryptonite asteroid had to travel 2.2 million light years to get here. But how?

In the second Superman/Batman arc, introducing the new Supergirl, we were told a little more about the asteroid (and for now, we'll assume the information given is accurate). Kara's father built a spaceship and locked its navigational system onto Kal's ship. However, her ship never actually launched. It got buried in a huge chunk of Kryptonite, and Kara was kept alive in a state of suspended animation while the rock made its way to Earth.

This is pretty scant information to draw solid conclusions from, but it seems that one conclusion is unavoidable at this time, and that is the implication that the navigational system on Kara's ship guided the asteroid to Earth. How? We don't know.

And that raises certain questions. Did the nav system calculate the future position of Earth, and point the asteroid in that direction to start with? Or did the ship somehow continually adjust the course of its moon-sized chassis? For such a small ship, it has a lot of power to move and guide a small planet. Did the asteroid simply drift through space, carrying the ship with it, or did the ship somehow move both itself and the asteroid at some faster-than-light speed?

Birthright all but demands that the answer to the last question involves the use of some sort of faster-than-light travel. Kara spent some time in suspended animation, but her trip to Earth only took about 35 years more than Clark's. Light from Krypton would take at least two million years to reach Earth. There couldn't be too much difference between the ships' speeds, or else they would have arrived millions of years apart instead of just 35. And since I'm wary of the thought of both ships taking millions of years to reach Earth at less-than-light speed, they both must have travelled considerably faster-than-light.

Last time, I used the example of Kal's trip taking 10 years. If that were the case, then Kara's would have taken about 45 years. That would mean that the asteroid was travelling at 33 trillion mph (the speed of light is 670 million mph). And the shorter the time that Kal's journey was, the faster Kara's asteroid must have been moving. If Kal's trip took under a month (which would have his ship moving at a speed that would cross the whole Milky Way Galaxy in about two days), then Kara's ship was moving at about 43 trillion mph, or about 63,000 times the speed of light. This asteroid was really moving.

If Kara's ship was having to propel a small planet at realistically high speeds, it would have taken a phenomenal amount of energy (both to speed it up, and to slow it down at the end). But since we're playing with science fictional warp speeds, anything's possible. Maybe it's just as easy to warp speed a planet as it is to do it with a small ship, so we can ignore the power problem.

On the other hand, once the asteroid/ship 'drops out of warp,' it's pretty much stuck at a constant velocity. It can't slow down as it approaches Earth unless the ship has a means of decelerating a moon's worth of mass. And since the ship wasn't designed to do anything like that, I think it's a really big cheat to assume that it could.

Constant velocity means we can make some other calculations. When the asteroid is first shown, it is said that it is 7.21 days away from Saturn, but we're never told how long it will take to get from Saturn to Earth. And it did apparently get close enough that lots of chunks of it landed on Earth.

If the asteroid had just passed Pluto, then the time from Saturn to Earth would be 51 hours. I don't think the story moves that quickly, and without anyone mentioning the immediate doom. And besides, the 'time to Saturn' suggests to me that Saturn would be the next planet it would pass.

So let's say it had just passed Uranus. That would mean it was travelling at 5.3 million mph, and would reach Earth 6.3 days after passing Saturn. That's fairly reasonable within the context of the story, but a shorter time would quickly get questionable. If it was already halfway between Uranus and Saturn, then the time to Earth would be 12.6 days. That seems about right to me. The events of the story move too fast for me to think there was a waiting period of three or four weeks.

One wonders why DCU scientists didn't notice a radioactive moon hurtling at Earth at over two million miles per hour any earlier than they did. It would've passed Neptune's orbit over two weeks earlier. I'll give them the benefit of the doubt, and assume that the ship dropped out of warp shortly before it was discovered.

At one point in the story, we're shown a future Superman living on a barren Earth that had been hit by the asteroid. Aside from the question of how Superman survived on a Kryptonite-irradiated planet even though no one else did, what's wrong with this picture?

Imagine an asteroid 80% the size of the moon, hitting the Earth at a speed of 2.6 million mph. That's twice as fast as the fastest comet (you could travel from the Earth to the moon in under 6 minutes). What do you think is going to be left of the Earth? In a word, rubble. That kind of collision doesn't just destroy life, it destroys planets.

And that brings us to the end of another overly-long analysis. Questions? Comments? Snide remarks?