ARTIFICIAL AURORAL EFFECTS FROM A BARE CONDUCTING TETHER

An electrically floating metallic bare tether in a low Earth orbit wou ld be highly negative with respect to the ambient plasma over most of its length, and would be bombarded by ambient ions. This would liberat e secondary electrons, which, after acceleration through the same volt age, would form a magnetically guided two-sided planar e beam, and res ult in auroral effects (ionization and light emission) upon impact on the atmospheric E layer, at about 120-140 km altitude. This paper exam ines in a preliminary way the feasibility of using this effect as an u pper atmospheric probe. Ionization rates can reach up to 105 cm(-3) s( -1) if a tape, instead of a wire, is used as tether. Contrary to stand ard e beams, the beam from the tether is free of spacecraft charging a nd plasma interaction problems, and its energy flux varies across the cross section, which is quite large; this would make possible continuo us observation from the satellite, with high resolution, both spectral and vertical, of the induced optical emissions. Ground observation mi ght be possible at latitudes around 40 degrees, for night, magneticall y quiet conditions.