How far is a lightyear? Pretty darned far. 9,460,730,472,580,800 meters, give or take (that is actually the exact defined value, so no lectures about significant figures).

How long would it take to travel that far? If you were walking at a normal pace, you could cover a lightyear in about 270 million years. Clearly we need more speed. What about in a car? The fastest car in the world, according to the top result of a quick Google search, is the Hennessey Venom GT, which managed a staggering 435 km/h. If this car could somehow keep up that speed without ever stopping for gas or maintenance, it would still take nearly 2.5 million years.

Alright, let’s kick things up a notch. During an underground nuclear test in 1957, a steel plate was blasted off the top of the shaft going at least 66 kilometers per second. They don’t know the exact speed because it was only visible in a single frame on the high speed camera. This plate, weighing about a ton, probably burned up in the atmosphere like some sort of crazy reverse asteroid, but if it hadn’t, it could have easily escaped the gravity of the sun and left the solar system (depending on which way it was pointing). That’s fast. But it would still take some 4500 years to go a whole lightyear.

Light is really fast.

But Kerbals are fearless explorers, with an infinite supply of patience. And so, our mission is to send four Kerbals a full lightyear away from their homeworld. We’re going to be utilizing a secret weapon: 100,000x time warp. And rockets. Lots of rockets.

Now, you might be thinking “come on, Kyle, even with a highly efficient multi-stage chemical thruster design augmented with nuclear thermal rockets and ion engines, you can’t possibly get close to that 66 km/s of delta-v.” And you’d be right, of course. So we’re going to abuse the game’s lack of thermodynamics along with the Oberth effect to get a really nice slingshot from very very near to the sun.

Delta-v, or “change in velocity”, is a measure of how powerful a spacecraft is. On Earth, where there is friction to contend with, a full tank of gas will give you a certain range in your vehicle before it runs out. In space, where you can accelerate freely without anything slowing you down, it is more important to know how much you can accelerate your ship before you run out of fuel.

The Oberth effect allows you to squeeze more performance out of your rockets by using them close to an astronomical body. How in the world could that possibly work? Well, consider that kinetic energy is proportional to the square of your velocity. But a rocket with a given amount of delta-v doesn’t care if it’s accelerating you from 0 km/s to 10 km/s, or from 10 km/s to 20 km/s, even though the second instance actually requires three times as much energy. So, to put it plainly, rockets work best when they are already going fast. And the closer you get to a big heavy object, the faster you get. You know, gravity and all that.

Well, what’s the biggest and heaviest object in any planetary system? Why, the central star, of course. And how would you get close enough to pull off this maneuver? That’s where our other orbital mechanics trick comes in: the bi-elliptic transfer.

If your destination orbit is very much larger or smaller than your departure orbit, it may actually be worthwhile (in certain cases) to go the wrong way. And that’s what my brave Kerbonauts are going to do: head out to the edge of the system, dive back down towards the sun, thrust like crazy while skimming the edge of the corona, and then exit the system for good. Oh… what, did you think they were coming back? Hah. This is a one-way trip, I’m afraid.

Time to go to space! First, we need a huge ugly ship full of fuel in a whole bunch of stages.

Then we need to get into orbit.

Once in Kerbin orbit, we need to escape into a heliocentric orbit.

For maximum efficiency, all these transfers are going to be accomplished with a single NTR, pushing the equivalent of 5 full orange tanks of fuel (for those not steeped in Kerbal-lore, the orange tank unit [OTU] is a standard measure of how ridiculously big your spaceship is). This means that everything is very slow. (Once you’re in space, it is best to maximize your specific impulse rather than your thrust)

Here’s where we are, an hour later as I’m writing this post:

The fastest I’ve ever managed to leave the Kerbin system is somewhere around 60 km/s. I’m going to try for something even faster this time, but taking that as the speed, then once I finish all my maneuvers and leave it on 100,000x time acceleration, this mission will take a little over 18 days of realtime to complete. I’m excited! This will be my first time ever going so far. I just hope the game engine doesn’t break before I get there (as it has been known to do when confronted with extremely large numbers).

Stay tuned for day 2…