... A nasty dispute between the Strategic Defense Initiative Organization (SDIO) and the space-science community was narrowly averted early this year when SDI officials backed down on a planned launch of a satellite with a Russian-built nuclear reactor on board. ... Early Soviet space reactors orbited for two to three months, and two Soviet Topaz 1 experiments, one for six and one 12 months, created radiation belts that disrupted the operation of scientific satellites. ...