A Harvesting Planetary Orbiter to Enable Deep Space Missions to the Jovian Planets

To create a more efficient propulsion system for in-space transportation the NEP and NTP systems are now being developed to facilitate the human exploration of Mars. They are, however, unlikely to meet the challenge of deep space without significant advances in efficiency and the ability to use in-situ resources. The concept outlined in this paper is the development of a planetary orbiter spacecraft that can operate on virtually any gas, and is designed in such a way that it can also harvest the planetary atmospheres to obtain the fuel required for the return transit. It is based on experimental results employing a robust plasma creation and sustainment methodology referred to as a Rotating Magnetic Field (RMF) generated Field Reversed Configuration (FRC). In the experiments a Hydrogenic gas was partially ionized and accelerated out of a magnetized cascaded arc source with directed velocities of 35 km/s that is characteristic of the conditions that would confront a Harvesting Planetary Orbiter (HarPO) in the atmospheres of the Jovian planets. The transverse RMF fully ionized the gas, and in the process generated large azimuthal currents which produced an FRC that confined and heated the ions. The stationary, axial guide magnetic field confined the plasma within the chamber wall and conducted the plasma exhaust to form an on-axis plasma jet. In the spacecraft implementation, this system would efficiently process the incoming atmosphere into the necessary thrust and Isp for drag makeup. Based on the ion temperature measurements in the experiments, only a fraction of the gas ingested during the orbital transit would be required as the projected Isp is 12 ksec. The plasma chamber radius, which is the same as the spacecraft intake aperture, need be no larger than that employed in past RMF FRC experiments (0.4m). Given that the HarPO is electrodeless and magnetically insulated, it quite capable of long-term operation on the lighter elements, so that the array of HarPO's could also be employed as the main thrusters for the transits to and from the outer planets. The analysis and design of a prototype HarPO has been completed based on the drag, power processing, energy and fuel storage requirements that would be encountered in the Jovian atmospheres. The results from this analysis, as well as the architectures for a Neptune and Jupiter mission will be described.