5. The physical size of SPS and its characteristics create a number of problems such as flux tube blockage, IR sources, photoelectrons, and spacecraft charging that give rise to local rather than global consequences. (H, U) 6. Enhancement of airglow, especially the nitrogen (N2, ^2+) airglow due to enhanced precipitation of energetic Ar+ ions into the atmosphere. (Note that this enhancement appears to be much larger than the effects discussed in Sections 2 and 3 above.) (H, U) 4.6 CONCEIVABLE ATMOSPHERIC EXPERIMENTS 4.6.1 High-Altitude Injection of Gases, Plasmas, and Electron/Ion Beams (Pongratz) + Here we examine experiments that could explore the phenomenology of the Ar engine burns. Two target-of-opportunity experiments may be relevant: 1. A Japanese Space Shuttle/Spacelab ion beam experiment (Dr. Obayashi), to be conducted in 1984-85. 2. GREYHOUND, which is proposed by N. J. Stevens of NASA-Lewis as a test of ion engines (see also Section 4.6.3, Item 3). The ideal experiment would involve a full-scale Ar+ engine and should be conducted on long- and short-field lines. Long-term studies of possible ion acceleration should be possible. The energy and pitch angle distributions of energetic ions should be measured as a function of distance (parallel and perpendicular to the magnetic field lines) from the engine burn. Electrostatic and possibly electromagnetic waves generated by the ion engine pulses should be monitored. Wave frequencies between the lower hybrid resonance and ion cyclotron frequencies, and below, would be the relevant ambient plasma parameters, which should be monitored before, during, and after the ion engine pulses. Most likely a mother/daughter satellite configuration would be required. The planning and construction of this experiment could take more than six years and several hundred million dollars. Long-term ion energization studies may require optical techniques, and here the use of Ca+ ions would provide a tracer of mass close to that of argon but which could be traced optically. However, we know of no technology for producing large quantities of Ca+ in space. 4.6.2 Relevance of SCATHA (P78-2) to SPS (Chiu) SCATHA (Spacecraft Charging At High Altitudes) is an integrated satellite to study spacecraft-environmental interactions at geosynchronous orbit, sponsored jointly by the USAF and NASA. It has relevance for SPS assessment in the following areas:
RkJQdWJsaXNoZXIy MTU5NjU0Mg==