ELECTRICAL POWER REQUIRED FOR A 39 DAY TREK TO MARS TOP
StarTravel has been used to perform a general heliocentric orbital transfer analyses to determine velocity increment (dV) and flight time (dT) required for traveling from Earth to Mars in 39 days as proposed in NASA's new budget. This combination MathCAD and StarTravel analysis uses an iterative solution based on the number (N) of 200 killowatt VASIMR rocket motors required to achieve the dV for Mars orbital insertion. A solution for traveling to Mars in 39 days is achieved when the equations of motion for gravity-free and drag-free space flight predict a total flight distance equal to the distance traveled along the elliptical transfer orbit predicted by StarTravel.

In summary, the following analysis predicts that at minimum a 9 megawatt power source is needed to energize a cluster of 45 VASIMR (200kw) rocket motors to achieve the thrust required for traveling to Mars in 39 days. This power source estimate is in line with previous statements by Dr. Franklin Chang Diaz who stated, in a paper called The VASIMR Rocket that appeared in the November 2000 issue of Scientic American, that a 10 megawatt nuclear reactor is required for a 39 day journey from Earth to Mars. In addition, on September 29, 2009 Dr. Franklin Chang Diaz stated the following. "In fact, with the power close to what a nuclear submarine generates, you could use VASIMR to fly humans to Mars in 39 days." Therefore, while AeroRocket believes the VASIMR rocket motor represents a great leap forward in space propulsion technology, we do not believe President Obama knows or has been informed that a high density nuclear reactor is required for his unfunded 39 day journey to the red planet. Without Presidential authority, NASA does not have the political will to design and operate a 10 megawatt high density nuclear powered spacecraft and that canceling the Constellation Moon project essentially ends America's ability to conduct manned flights beyond low Earth orbit until a non-nuclear power source for VASIMR can be developed. Therefore, without a Presidential vision for space travel it will be many decades before America will travel beyond low Earth orbit. Unless the present policy is changed America's manned missions beyond low Earth orbit will come to an end with the cancellation of the Constellation Moon project.
 

BASIC ELECTRO-HYDRODYNAMIC THRUSTER (EHDT) DESIGN TOP
The ion engine design represented here is based on the concept of the Electro-Hydrodynamic Thruster (EHDT) which consists of a small diameter wire loop called the Sharp Edge Electrode (+V) separated from a three-sided sheet of aluminum foil called the Smooth Edge Electrode (-V). Where, either balsawood or plastic insulation material are used to separate the positive and negative electrodes. To start the process, Nitrogen and Oxygen gases in the vicinity of the positively charged wire loop are ionized when electrons from the supplied air are attracted to the positively charged electrode. The relatively small mass of positively charged ions are accelerated through the air gap between the two electrodes transferring linear momentum to the neutrally charged air. Neutrally charged air moves with the positively charged ions during the momentum transport process down the axis of the ion engine providing a very small thrust. Finally, positively charged ions are neutralized upon impact with the Smooth Edge Electrode and exit the Smooth Edge Electrode contributing to total ion engine thrust.

For the ion engine illustrated above the small diameter loop is replaced by a Sharp Edge Electrode disk having two very sharp internal and external circular edges for ionizing Nitrogen and Oxygen as air flows through the ion engine. In addition, the aluminum foil electrode is replaced by a very smooth aluminum cylinder having a uniformly rounded inlet edge that prevents coronal discharge and allows closer positive and negative electrode spacing. The illustration above displays the Smooth Edge Electrode as machined from a tube of aluminum in close proximity to the Sharp Edge Electrode. To power the ion engine a high voltage transformer from a Plasma Globe was used to supply 5kV to the positive Sharp Edge Electrode disk. A properly sized high voltage diode (8kV, 10 mA) was used to rectify voltage from 5kV AC supplied by the Power Globe transformer to 5 kV DC required by the positive electrode.

The potential advantage of the Smooth Edge Electrode is the elimination of a cathode neutralizer normally required to neutralize the positively charged plume of ions as the plume exits the ion engine by supplying a stream of electrons to the plume. Also, it may be the basic shape of these electrodes prevents the erosive effects normally observed on ion engine electrodes over long periods of time. This project is simply a demonstration for the use of the acceleration electrodes depicted in these illustrations.

ION ENGINE DESIGN FOR TRAVEL IN OUTER SPACE TOP
The high voltage transformer from the Plasma Globe pictured above is to weak to provide any meaningful ion engine thrust. In other words a standard design EHDT device powered by one of these Plasma Globe high voltage transformers could never levitate or even move around by itself on the end of a tether. To overcome these severe power limitations a second Plasma Globe high voltage transformer was added to excite a make-shift electron gun for an added source of electrons to ionize the fuel (Oxygen, Nitrogen and Argon) in the air. The addition of an electron gun worked rather well increasing sheet deflection and therefore ion engine thrust by a factor of approximately 5. Ion engine thrust was determined by applying the linear momentum equation for an inertial control volume of a free-jet impinging on the vertical sheet of paper. Ion engine thrust was also determined by measuring the amount of force required to deflect the vertical sheet of paper on the end of two threads as illustrated in Figure-1.

If this were an ion engine meant to operate in space the surrounding air will be replaced by Argon (Ar) injected at the front of the ion engine. Also, the ion engine design illustrated above will be enclosed by a circular cylinder so the ionized fuel (Argon) can circulate through and around the electrodes. Then, you would be off to the races, although rather slowly at first because ion engine thrust is on the order of only a few milliNewtons. A preliminary electrostatic thruster analysis indicates this design provides a specific impulse (Isp) of about 7,000 seconds. More work needs to be done on the preliminary ion engine design presented here to finalize the AeroRocket ion engine design. A final ion engine design is presented in Figure-12 that more closely resembles a design intended to operate in space. If this information proves useful or interesting please send an email to let us know.

Using the electrostatic equations on page 590 of Rocket Propulsion Elements, 6th Edition the rocket motor thrust for this ion engine is 1.832 mN and the specific impulse is 19,000 seconds.