The TSS‐1R Mission: Overview and scientific context

Abstract

Mission BackgroundThe Tethered Satellite System (TSS) program is a binational collaboration between NASA and the Italian Space Agency (ASI) with NASA providing the Shuttle-based deployer and tether and ASI providing a satellite especially designed for tethered deployment. Twelve science investigations (see Table 1) were supported by NASA, ASI, or the Air Force Philips Laboratory. The goals of the TSS-1R mission, which was the second flight of the TSS hardware, were to provide unique opportunities to explore (1) certain space plasma-electrodynamic processes--particularly those involved in the generation of ionospheric currents, and (2) the orbital mechanics of a gravity-gradient stabilized system of two satellites linked by a long conducting tether.TSS-1R was launched February 22, 1996 on STS-75 into a 300-km, circular orbit at 28.5 ø inclination. Satellite flyaway occurred at MEF 3/00:27 and a unique data set was obtained over the next 5 hours as the tether was deployed to a length of 19,695 m. At MET 3/05:11, during a day pass, the tether suddenly broke near the top of the deployer boom. The break resulted from a flaw in the tether insulation which allowed the ignition of a strong electrical discharge that melted the tether. The operations that had begun at satellite flyaway, however, allowed significant science to be accomplished. Instrumentation and MeasurementsThe TSS converted mechanical energy into electrical energy in a classical demonstration of Faraday's law. The configuration was such that the satellite received a positive bias and collected electrons from the ionosphere, which conducted through the tether to the orbiter where the circuit could be closed back to the ionosphere (see Fig. 1 sphere. An electrical schematic is shown in Figure 3 of Dobrowolny and Stone [1994].The TSS was instrumented to control the tether current (as described above) and diagnose the environmental space plasma properties under highly nonequilibrium conditions. The investigations, shown in Table 1

Analysis of chamber simulations of long collecting probes in high-speed dense plasmas

“…This configuration is different than that of Tethered Satellite System missions (TSS-1 and -1R), which used a large (with respect to Manuscript ) spherical collector for electron collection [2]. The relative merits of bare tethers versus endbody electron collection is the subject of some debate [3]- [6].…”

Secondary-Electron-Emission Instability in a Plasma

“…The salient features of the instability are as follows: (i) large-amplitude oscillations bounded by the plasma potential and the beam potential; (ii) frequencies determined by the circuit inductance and the sheath capacitance; (iii) the beam providing the free energy for the instability which can operate at zero dc current to the electrode; (iv) that the instability can arise between two floating electrodes connected by an inductor, one of which is emitting secondary electrons; (v) that the instability excites plasma eigenmodes, e.g., ion acoustic waves or Langmuir wave sidebands. The instability is not only of intrinsic interest in basic plasma physics but may arise on long spacecraft structures bombarded by energetic electrons [14] of Langmuir probes terminated by inductors in electron beams [15] where the oscillations might be mistaken as a beam-plasma instability.…”

Current collection at the shuttle orbiter during the tethered satellite system tether break

“…The orbiter and satellite were in sunlight near the dusk terminator. From Lungmuir probe measurements on the satellite, Gilchrist et al [1998] During the tether break event, currents of •1 A were detected briefly Stone and Bonifazi, 1998], surpassing all currents measured to that point [Thompson et al, 1998]. While the role of the high currents in the tether break is understood [Szalai et al,199õ], a full explanation of how the system supported these currents in each phase of the event has yet to be developed.…”