Into space on seawater

Recently SpaceShipOne made a spectacular flight as the first commercial craft to make it into space. To get there, it rode piggyback on a big jet, and then used a conventional rocket system to push it the rest of the way. That turns out to be a better idea than just blasting off on top of a big expensive rocket. Yet, there may be an even better way.

Outer space is only 62 miles away. If you fly straight up at 62mph, in one hour you will be there! In theory, you could put a cardboard box into space this way because it doesn’t require the use of a supersonic craft. That is, a craft that travels slowly through the atmosphere before accelerating to orbital speed doesn’t need all that extra weight and expense that goes into spaceflight in the conventional manner. By using a powered descent down to the level where the air is thick enough to support gliding, again cardboard would work quite well. Actually, plastic would be a better choice for a space vehicle, but “cardboard” gets the point across better.

Modern rocketry has developed as it has primarily for military reasons. They wanted to get into orbit quickly so the Russians would have trouble watching…except on CBS of course. But when you’re not in such a hurry, there are a variety of viable options available. For example, using a seawater propulsion system. Seawater? That’s right, seawater!

The acceleration from a rocket follows Newton’s law, Force = mass x acceleration. The mass is seawater. The trick is to accelerate it out the tail end of the rocket as fast as you can get it to go. One way is to put the seawater in a tank about half full of compressed air. The compressed air pushes the seawater out the tail end of the rocket and the rocket goes in the other direction. You can buy at toy rocket that does just that. Nice, but not nearly enough power to get us into space. For that, we need to make the water move faster. And for that, we need a particle accelerator. But until now electric rockets haven’t had enough oomph to get off the ground, let alone into outer space. So how can we improve the system?

A nebulizer will make the water into a fog of tiny particles. The tiny drops are then ionized with a high voltage, and accelerated in pulses out the tail end of the rocket. In theory, a good accelerator can get them moving even up near the speed of light. Once in space, the accelerator engine would make a dandy interplanetary propulsion system. But can we get one off the ground?

The problem with previous methods is that they only have one accelerator stage, whereas the method shown has multiple stages. That is, at each stage, the water droplets are accelerated faster and faster. The faster they go, the greater the thrust.

In the drawing, the first water drops are positively ionized. As they approach an accelerator ring, the ring has a negative charge, which pulls on the drops, making them go faster. But as the ionized drops approach the ring, the current shuts off. The drops then coast through the ring. Once on the other side, the ring is ionized again, this time positively, which pushes the drops away.

The other rings work the same way, so that between each ring, the drops are being pushed by the one behind, and pulled by the one in front. The second batch of drops are negatively charged. They are also accelerated, this time by the opposite voltage, but in the same direction. After several such stages, the drops are really moving, and like all rockets, the accelerating mass out the back end cause the rocket (accelerator) to move in the opposite direction.

Aim it straight up, and relax for an hour. Neat huh!

* * *

There are many interesting projects described on the CoolScience website, and in CoolScience publications. See www.coolscience.info. Click on Extraordinary E-books. The CoolScientist is also available for lectures and consulting. Email us at coolscientist@rmrc.org. © 2005 by CoolScience