Elektron
... that the 1964 Elektron satellites, launched in pairs to simultaneously measure the upper and lower Van Allen belts, marked the first time multiple satellites were orbited on a single Soviet rocket?
... that the 1964 <b id="mwB5w"><a href="./Elektron_(satellite_program)" id="mwB50" rel="mw:WikiLink" title="Elektron (satellite program)">Elektron</a></b> satellites, launched in pairs to simultaneously measure the upper and lower <a href="./Van_Allen_radiation_belt" id="mwB54" rel="mw:WikiLink" title="Van Allen radiation belt">Van Allen belts</a>, marked the first time multiple satellites were orbited on a single Soviet rocket?