What we remember seeing since our childhood when it comes to space exploration is the gigantic plume of smoke and fire ignition when the rocket first takes off from earth. Much of this type of thing is still needed but once outside of earths gravitational pull the rocket engine with all the smoke and flames is a thing of the past.
These huge rockets have been needed to get through earths gravitational pull and launch the spacecraft into orbit and as far as this phase of the launch sequence we likely will see no change. Once into orbit though there is no need for these powerful rockets and so scientists have been making the switch to electric rocket engines once the craft has reached orbit.
Instead of using chemical reactions to accelerate propellants out the back end these rocket engines are now using solar powered electromagnetic fields. The electric rockets use much less fuel which allow for a compact spacecraft with much smaller launch boosters.
Solar electric propulsion for use in primary propulsion of a space craft was first used with the Dawn space probe. This spacecraft has successfully been exploring the asteroid Vesta and is in fact doing so as I write this. The engines on this craft are only rated at 2.3 kW each or 3 horsepower. The engine on this vessel is about the same size as a lawn mower engine. The build up of thrust took many years because of the small engine to get to the speed that would propel the space craft to the far asteroid.
You can watch a video about the Dawn Space Probe below.
NASA is working on technology that will be ten to 100 times stronger than the Dawn space craft. With the new technology space craft as well as space vehicles will be able to do so much more with much less energy. One day this new technology will allow for more stable logistical points to be established in space to make placing satellites easier as well as a possible planned man mission to Mars.
The plan right now is for a 30 kW solar electric propulsion system that will likely be ready by 2018. They believe they can scale this concept out to 300 kW and even higher which would dramatically cut the costs involved in higher propulsion systems.
The power these systems get is from photovoltaic arrays that are pointed towards the sun. There is a cylinder that the space craft has on it that contains xenon gas that flows from the propellant tank. As the gas flows an electromagnetic field rips electrons from the gas atoms to create a plasma of charged ions. The positive ion’s are accelerated through the action of the electric field that occurs in the middle of the two electrode grids.
The positive ions in the field gets a strong pull from the aft-mounted, negatively charged electrode and moves fast rearward out of the exhaust. This small rush of high-velocity ions allows for incredible efficiency improvements in rocket thrust.
Energy efficiency improvements in space often find real world applications here on earth. As with radiant barrier which is used in space craft to deflect ultra-violet heat from the sun as it hits the ship we now use it in residential and commercial buildings to make these buildings more energy efficient.
I wonder how this new technology might someday offer more energy solutions to produce electricity at a cheaper price here on earth.