One major problem facing the future exploration of space is the fuel used to propel the spacecraft. More fuel is required for long duration space flights, and with more fuel comes more weight and less space for living quarters. The current fuels used are bulky and weigh down the spacecraft. A new fuel must be used that will reduce the overall weight of the craft, and allow for more space to be utilized for life support systems. This fuel must be small, yet still provide the required amount of power to operate the spacecraft successfully. The very low and highly controllable thrusts levels provided by various electric propulsion technologies will open up entirely new mission categories not otherwise possible. I believe this new fuel is electric propulsion that utilizes electrostatically charged and accelerated nanoparticles as propellant. These field emission thrusters are not practical for launching the spacecraft out of orbit. They will not supply sufficient power to launch a spacecraft out of orbit. Their purpose would be to provide altitude control and acceleration of a spacecraft, either in orbit of earth or on a mission to another planet. These thrusters will be used to propel the spacecraft once in space and maintain the spacecrafts position. Little by little, they should be able to accelerate spacecraft and propel it across the cosmos more efficiently than ever before. They promise to be far more versatile than existing thrusters, capable of getting a crewed mission to Mars, yet also allowing the crew to precisely control the spacecraft's position when it arrives in the Martian orbit. This new electrostatic thruster technology is currently under development. It is termed the nanoparticle field extraction thruster, known as nanoFET. NanoFET is a highly integrated propulsion concept that is a highly efficient, variable specific impulse engine. It can be scaled for multiple uses among the future of space science and exploration. The nanoFET is constructed of highly scalable MEMS/NEMS (microelectromechanical system/ nanoelectromechanical system) structures to feed, extract and accelerate nanoparticles through micron-sized thrusters. MEMS are made up of components between 1 to 100 micrometers in size and MEMS devices generally range in size from 20 micrometers to a millimeter. At these size scales, the standard constructs of classical physics do not always hold true. Due to MEMS' large surface area to volume ratio, surface effects such as electrostatics and wetting dominate volume effects such as inertia or thermal mass. The nanoFET works by transporting conductive nanoparticles along a micro fluidic flow transport system into a small liquid filled reservoir. Particles will contact a conducting plate at the bottom of the reservoir. The particles will become charged and pulled to the top of the liquid by the imposed electric field. An electrostatic force will cause charged nanoparticles to break through the surface tension of the liquid. The nanoparticles would then be accelerated by the vaccum electric field and ejected, causing thrust. The nanoFET’s MEMS/NEMS technology allows for a flat panel thruster design. This desgin incorporates the power proccessing, nanoparticle manufacture, storage, feed, extraction, and acceleration. This design allows for a scalable propulsion system, from watts to megawatts to accompany the many requirements from different mission stages. The nanoFET will also be designed to use different sized nanoparticles to help fulfill the requirments of the mission. Long, thin carbon nanotubes, for instance, give relatively low thrust but make highly efficient use of the available energy. While short carbon nanotubes will generate high thrust, but will be less efficient. It is proposed that no other propulsion system provides this kind of versatility. Another advantage to this system is its unprecedented thrust-to-power ratio for electric propulsion systems. The nanoFET can be adjusted to a specific impulse over a very large range. These impulses can range from 100s to 10,000s. The nanoFET also shows a high efficency over the entire range of specific impulses, over 90%. This system also allows for great flexiblity on the size and type of particles used as propellent. Almost any conductive nanoparticle can be used including: carbon nanotubes, fullerenes, metal nanospheres, and nanowire. It is calculated that a nanoFET could deliver up to 10 times as much thrust as an ion engine of similar size. Compared to an ion, a single nanoparticle ejected at high speed should exert a considerable kick. A short segment of carbon nanotube weighs thousands of times as much as a single xenon ion. Unlike atoms, nanoparticles can be charged very easily. If they are electrically conducting, then you do not need to yank electrons out of them, but merely touch them against an electrode. The larger the charge on the particle, the easier it is to accelerate and so the greater the propulsive force you get from it for the same power consumption. This system also doesn’t have the life limiting factors that are more common in ion thrusters. I believe this new technology will be a great asset in the future of space exploration. This new propulsion system provides superb thrust power with the need of little propellant. This new system will be a completely new innovation and pave the way for the future of space exploration. Utilizing this new propulsion technology will make extended manned missions in space a reality, and cut down costs. With the less space required to house the nanoFET propellent than traditional chemical propellent, the spacecraft will have more room for life support systems. On the other hand, the less space will mean less weight, therefore reducing the amount of chemical propellent needed. Reducing the amount of chemical propellent needed will greatly cut the costs of launching a spacecraft into space, making space travel more affordable. This new innovation has great expectations within the scientific community. It could quite possibly revolutionize space exploration. Providing a lighter, cheaper replacement to chemical fuel to propel a spacecraft through space. The nanoFET is cheap, powerful, small, efficient and versatile. All of these aspects combined create a highly sophisticated propulsion system that is worthy of investigation into its possible use aboard a future spacecraft. I believe this new technology will propel us into the future of space exploration.

Sources 1.http://www.nanowerk.com/spotlight/spotid=1668.php 2.http://www.foresight.org/publications/weekly0093.html#challenge6 3.http://en.wikipedia.org/wiki/MEMS 4.http://uplink.space.com/showflat.php?Cat=&Board=businesstech&Number=689683&page=0&view=collapsed&sb=5&o=0 5.http://www.tmcnet.com/usubmit/2007/03/23/2440012.htm