▁weeks ▁each ▁time . ▁ ▁Rock o ons ▁ ▁The ▁rock oon ▁( a ▁port man te au ▁of ▁ro cket ▁and ▁bal lo on ) ▁was ▁a ▁solid ▁fuel ▁ro cket ▁that , ▁rather ▁than ▁being ▁immediately ▁lit ▁while ▁on ▁the ▁ground , ▁was ▁first ▁carried ▁into ▁the ▁upper ▁atmosphere ▁by ▁a ▁gas - filled ▁bal lo on . ▁Then , ▁once ▁separated ▁from ▁the ▁bal lo on ▁at ▁its ▁maximum ▁height , ▁the ▁ro cket ▁was ▁automatically ▁ign ited . ▁This ▁achieved ▁a ▁higher ▁alt itude , ▁since ▁the ▁ro cket ▁did ▁not ▁have ▁to ▁move ▁through ▁the ▁lower ▁th icker ▁air ▁layers ▁that ▁would ▁have ▁required ▁much ▁more ▁chemical ▁fuel . ▁ ▁The ▁original ▁concept ▁of ▁" rock o ons " ▁was ▁developed ▁by ▁C md r . ▁Lee ▁Lewis , ▁C md r . ▁G . ▁Hal v ors on , ▁S . ▁F . ▁S inger , ▁and ▁James ▁A . ▁Van ▁Allen ▁during ▁the ▁Aer ob ee ▁ro cket ▁firing ▁cru ise ▁of ▁the ▁ ▁on ▁March ▁ 1 , ▁ 1 9 4 9 . ▁ ▁From ▁July ▁ 1 7 ▁to ▁July ▁ 2 7 , ▁ 1 9 5 6 , ▁the ▁Naval ▁Research ▁Labor atory ▁( N RL ) ▁ship board ▁launched ▁eight ▁De acon ▁rock o ons ▁for ▁solar ▁ult rav io let ▁and ▁X - ray ▁observations ▁at ▁~ 3 0 ° ▁N ▁~ 1 2 1 . 6 ° ▁W , ▁south west ▁of ▁San ▁Clement e ▁Island , ▁ap