What was the name of NASA spacecraft that were metallised balloon satellites acting as a passive reflector of microwave signals, the first successful launch of which was on 12 August 1960?
Echoing Reechoed Re-echoed Duck's quack Reechoes Reecho Echo Re-echoes Echo (phenomenon) Echoed Echo (acoustics) Re-echo Reechoing Re-echoing
echo echo acoustics reecho re echoing re echo duck s quack reechoed re echoed reechoes echo phenomenon echoed reechoing re echoes echoing
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Echo