▁power ▁rad iom eters ▁operating ▁from ▁ 0 . 2   M Hz ▁to ▁ 5 . 4   M Hz , ▁one ▁step ▁frequency ▁V - anten na ▁imped ance ▁pro be ▁operating ▁from ▁ 0 . 2 4   M Hz ▁to ▁ 7 . 8 6   M Hz , ▁and ▁one ▁di pole ▁anten na ▁capac it ance ▁pro be ▁operating ▁from ▁ 0 . 2 5   M Hz ▁to ▁ 2 . 2   M Hz . ▁Explorer ▁ 3 8 ▁was ▁designed ▁for ▁a ▁ 1 - year ▁minimum ▁operating ▁lifetime . ▁ ▁The ▁space craft ▁t ape ▁rec order ▁performance ▁began ▁to ▁d eter ior ate ▁after ▁ 2 ▁months ▁in ▁orbit . ▁In ▁spite ▁of ▁several ▁cases ▁of ▁instrument ▁mal function , ▁good ▁data ▁were ▁obtained ▁on ▁all ▁three ▁anten na ▁systems . ▁The ▁small ▁satellite ▁observed ▁for ▁months ▁the ▁" radio ▁sky " ▁in ▁frequencies ▁between ▁ 0 . 2   M Hz ▁and ▁ 9 . 2   M Hz , ▁but ▁it ▁was ▁subject ed ▁to ▁the ▁continuous ▁radio ▁inter ference ▁coming ▁from ▁our ▁planet , ▁both ▁natural ▁( aur ora e , ▁th under st orm s ) ▁and ▁artificial . ▁ ▁Inst ru ments ▁Explorer ▁ 3 8 ▁has ▁ 4 ▁anten nas ▁deployed ▁in ▁orbit : ▁▁▁ 2 ▁V - sh aped ▁anten nas ▁with ▁each ▁of ▁the ▁ 4 ▁branches ▁being ▁ ▁long ▁and ▁used ▁by ▁scientific ▁experiments ; ▁ ▁a ▁ ▁electric ▁di pole ▁anten na