The Improved Ion Engine

When we have discussed using ion engines to propel space craft in the past, we have talked about an engine that used two plates and electrical currents to propel particles (ions) out the exhaust which has the effect of pushing the craft. The ion engine is an engine that slowly build up speed in space. When it reaches top speed it is one of our fastest, if not the fastest, propulsion unit available. The European Space Agency is responsible for developing a new version of this new engine. It is named the Dual Stage 4 Grid ion thruster or DS4G.

There has been a break through recently in ion engines. The new engine is so fast that it could be used to travel outside the solar system. These are the words of the manager of the new project. So how fast is this new engine? The exhaust of the new engine is able to travel at the speed of 210,000 m/s. The other ion engine exhausts didn't reach a fourth of that. So how was this engine able to achieve these speeds when the other ion engines couldn't? First, you have to understand how an ion engine works. The engine is composed of three grids with micro sized holes in them. The first grid uses a high voltage. There is a chamber attached that has many thousands of charged particles. A low voltage is applied to the last grid. The voltage over the gap creates an electric field and the ions are accelerated out of the back. There is a problem with this procedure however. If too much voltage is applied than the plates began to deteriorate and the ions are bottle necked. Scientists knew that the more voltage that was used the faster the acceleration but were stymied by the deterioration factor.

What good was it to increase voltage and destroy the engine? Well this has been overcome in the new engine. The DS4G uses two pairs of grids instead of three individual ones. The engine is a two stage engine uses two grids and very high voltage in the first stage. This allows the ions to leave the grids without any problems. The other pair of grids is placed much further away and uses low voltage. The difference in the voltage powers the ions out of the exhaust.

This initial four fold + increase in speed is quite a leap forward. We may be able to have regular space travel soon because of this. The thing that is now holding up the practical application is development. While the engine is working perfectly in the lab, it must be tested exhaustively. We certainly don't want any people stranded in space because the engine fails them. Think of the possibilities, trips to Jupiter's moons may someday become routine. The ESA (European Space Agency) is even talking about flying out to the objects that lay beyond Pluto our furthest planet. Scientists were able to get 30K volts difference out of the engine so far, but this could itself be doubled or tripled in the future, increasing the thrust even more. While the engine is still a far cry from what we would need for interstellar flight, it may be perfectly suitable for our needs of flying through the solar system now.

Let's see how good my math is. Mars is 33,900,000 miles from Earth at it's closest point and 54,600,000 miles at the furthermost. We get our ship ready to fly there and it is at the furthermost point away. We know that the engine exhaust is 210,000 meters per second. Lets assume for the sake of simplicity that we can fly straight to Mars and that the ship will be flying at full speed. I know that this is impossible since it takes some time to build up the speed but let's see what we get. It looks to me that if you convert the speed to miles per hour you are talking about flying at 131 mph. I get this by taking 210,000 meters per second and dividing by 39.5 inches, the amount of inches in one meter. This gives me 8,295,000 inches per second of speed. I divide the inches by 12 and I get 691,250 feet per second. There is 5280 feet in a mile so I divide 691,250 by 5280 and I get 130.91856 miles per second.

Next I take the distance of Mars from Earth 54,600,000 and divide it by our speed of 130.91865 miles per second. The trip will last about 58 hours. This was just an exercise. We know that the engine will take a couple of months to achieve full speed but the trip will still be a very short one by current standards. The engine proves itself even more on planets that are further away. It still only takes the same time fo reach full speed so the advantage of top speed is greater the further you go.

By the way, the former ion engine would have resulted in a figure of 908 hours to Mars using the same distances, if the engine could have held together that long. It also would have required longer build up time to reach its full speed. If scientists can find a way to make this engine accelerate faster, perhaps in days instead of months, they would really have something. Can you imagine a one way trip to mars in about 3 days or the moon in a couple of hours.

I would be remiss if I didn't mention the fact that this new engine was developed in only four months. This just goes to show you what the human mind is capable of if it tries. Will this be the dawn of a new space age? Will we finally colonize other planets and moons? When this engine is fully tested and put into production it may just signal a new age for mankind.


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