Saturday, October 6, 2007

Physio-economics 101 (a.k.a., Rocket $cience)

Over the last 50 years or so, rocket scientists have come up with all sorts of schemes to reduce the cost of getting around the physics of the problem of getting to orbit. The thing is, rocket scientists should have taken more economics classes when they had the chance.

To understand the problem, in a vastly oversimplified sort of way, we need to go back to the Big Bang. About that time, the laws of physics were cast for the universe we live in. Flash forward about 14 billion years and those same laws drove the evolution of a collection of cosmic dust in the neighborhood we find ourselves in today. That neighborhood, our solar system, came alive when some of that dust collected into the round globe we call the earth. Formed at a comfortable distance from a glowing orb called the sun, our planet evolved into a giant chemistry set, and life arose out of the swamp. Every atom, every molecule, every chemical reaction driven by laws of physics. Or something like that.

The earth pulls everything on its surface down towards its center with a force we generically describe as "gravity." Our planet also has a thin layer of gases that resist attempts to move through them with a property we typically call "friction." Both of these forces conspire to keep our feet firmly planted on the ground, or moving slowly near it. To overcome these forces, and leave behind the surly bonds, we need to gather up a lot of energy and expend it in one way or another such that the object we want to move is accelerated to "orbital velocity."

Rockets are one means of accomplishing this. We ignite some "propellant" that expands out of a nozzle and Newton's first and third laws of motion take care of the rest. Time to get the equations out? F=ma. For every action there is an equal and opposite reaction. The hotter the propellant, the more energy is released, and the more force is created to move the rocket. The burning propellant produces a thrust that accelerates the rocket up, up, and away.

We told you this would be oversimplified! Hang in there.

Again physics helps us burn the propellant in a (usually) contained and controlled fashion and gets us moving in the direction opposite of the one in which we wish to travel. The materials we use in the rocket engines, in the fuel tanks, and in the structures supporting the whole lot, are also bound by the same physical laws set up at the end of the Big Bang. So to deal with the forces involved, we need some minimal amount of material, with some minimal amount of strength to hold the whole thing together, pushing through the friction of the atmosphere and leaving gravity behind. When all of the propellant is gone, what we have left we call the payload.

Enough rocket science. Let's recap. Big Bang. Physical laws set. Stuck on ground. Don't want to be. Get a rocket. Move payload to orbit.

So how much does this all cost? Time to match up economics with the rocket science. The less stuff we need to make for our rocket, in general, the less it will cost us, right? Engineers have worked very hard to develop minimal solutions for rockets. They have optimized the designs to get the most performance they can out of the collection of parts that make up a rocket. They have minimized the amount of material used to build the rockets. And they have tried to minimize the processes used to build the rockets. Optimization, less materials, less process should result in lower costs. But lower relative to what? At some point you just have to conclude that to overcome the physics of the Big Bang, there is some minimal price you have to pay to safely and reliably convert potential energy into kinetic energy and move a pound of payload to orbit. That is the bottom line.

We contend that we are almost there. It is highly unlikely that some new material or process breakthrough, short of the Star Trek transporter, will radically reduce the cost of launching through our atmosphere. So what are we to make of the boasts and claims of the new age rocketeers who hope to radically drop that cost while dealing with the very same physics? Sorry, have to call B.S. on them.

There are only a couple of ways left to cut costs. You can pay your employees less. You can skimp on designs and margins, resulting in a less reliable vehicle. Or you can try and bring reusability into play.

The problem with reusability is that you first have to add more materials to the rocket to give it the capability to repeatedly deal with the physics of launch and recovery. Then you have to almost put it through the same inspection process that a non-reusable system goes through as it is assembled to make sure it is safe and reliable to launch again. So where is the cost savings in all that? Witness the Space Shuttle. The ultimate reusable vehicle. That's how it was sold to the country and to Congress. Yet the reality is far different than its development plan would have led you to expect. Reusability is no panacea.

Is there no hope? Well, we have one thing left in our bag of tricks. Quantity. Today we tend to buy rockets one at a time. Its an artifact of the government budgeting process. Either way you look at it, if you can buy parts in quantity to build rockets that you plan to fly frequently, the price of launch will come down. Way down. Just ask the Russians. Or any other economics major. Imagine how much that SUV would cost if GM bought engine blocks one at a time for each order they get for a car!

So you see, we don't need any new rockets made with 2.0 processes. The ones we already have will do quite well, thank you very much. What we need to do is cut contracts for quantity buys of those rockets. Then rocket makers can buy their parts in quantity. And rocket part makers can spread their overhead over more than one part at a time. And give better prices to the rocket makers. Who, in turn, can give much better prices to their customers. Customers who will now fly more often.

Now why didn't the Emperor think of that? Could it be that he doesn't count economics among the multitude of degrees Congress fawned over? Shame. Because if he had taken those courses when he had the chance we might not be on the side of the dock waving bon voyage to the Chinese.

No comments: