Air-Breathing Orbital Navigator for Active Debris Removal

A major challenge for future space development is that Low Earth Orbit is becoming critically congested with space debris. Many solutions have been proffered with the most direct being active removal of the largest objects. There are many challenges encountered when considering Active Debris Removal (ADR). Due to the high.V requirements for multiobject deorbiting missions, conventional propellant based systems become implausible. The ultimate goal of the concept described here is the development of an Air-breathing Planetary Orbiter (APO) spacecraft that can operate on the gases found in virtually every planetary atmosphere, and is designed in such a way that it can also harvest the planetary atmospheres to obtain the fuel required for ADR as well as planetary exploration. At Earth the APO would be employed to deorbit large space debris as well as recover, repair or reposition other space assets. The APO is based on experimental results employing a robust plasma creation and sustainment method referred to as a Rotating Magnetic Field (RMF) generated Field Reversed Configuration (FRC). In experiments, high temperature plasmas (T similar to 40-200 eV) were formed and sustained in gases from Hydrogen to Argon at electrical input powers up to several megawatts. The transverse RMF fully ionized the gas, and in the process generated large azimuthal currents producing the FRC that both confined and heated the ions. An axial magnetic field isolated the plasma from the chamber wall and conducted the plasma exhaust out forming an on-axis plasma jet. In the spacecraft implementation, this process would efficiently convert the incoming atmosphere into the directed thrust and Isp needed for drag makeup. Based on the observed ion temperature, only a fraction of the gas ingested during the orbital transit would be required as the projected Isps ranged from 2.5 to 4 ksec. The burn chamber radius, which is the same as the spacecraft intake aperture, need be no larger than that employed in past RMF FRC experiments (0.4 m). As the APO is electrodeless and magnetically isolated, it is capable of long-term, high-power operation. The ability to operate long-term on caustic atmospheric gases, along with a large intake, minimal drag profile, the APO can perform the multi-target, high.V demands of ADR. The preliminary analysis and design of a prototype APO has been completed based on the drag, power processing, energy, and fuel storage requirements. The results of these analyses, as well as the mission scenario for the removal of a one-ton debris target are discussed.