In addition to natural and laser guide stars for adaptive optics, it is proposed to use radio-created guide stars or fringes. Heating by intense radio beams either modulators sodium lamp illumination, or creates and modifies plasma in different altitudes. The plasma relaxes by artificial air glow, which is concentrated in few lines, mainly nitrogen and oxygen. Fringes between intense radio beams create plasma fringes, also visible from the telescope. Ionospheric heating was also shown to create patchy artificial aurora. In all cases, the multiplicity of sources or fringes allows multi-conjugate adaptive optics of wide fields of view, and shows promise for long baseline optical interferometry.
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