is ▁data . ▁The ▁E URE CA ▁satellite , ▁deployed ▁by ▁ST S - 4 6 ▁Atl ant is ▁in ▁ 1 9 9 2 ▁and ▁retrieved ▁by ▁ST S - 5 7 ▁Ende av our ▁in ▁ 1 9 9 3 , ▁was ▁also ▁used ▁for ▁de br is ▁study . ▁ ▁The ▁solar ▁arrays ▁of ▁Hub ble ▁were ▁returned ▁by ▁miss ions ▁ST S - 6 1 ▁Ende av our ▁and ▁ST S - 1 0 9 ▁Columbia , ▁and ▁the ▁impact ▁cr aters ▁studied ▁by ▁the ▁E SA ▁to ▁validate ▁its ▁models . ▁Material s ▁returned ▁from ▁Mir ▁were ▁also ▁studied , ▁not ably ▁the ▁Mir ▁Environment al ▁Effect s ▁Pay load ▁( which ▁also ▁tested ▁materials ▁intended ▁for ▁the ▁I SS ). ▁ ▁G abb ard ▁diag rams ▁ ▁A ▁de br is ▁cloud ▁resulting ▁from ▁a ▁single ▁event ▁is ▁studied ▁with ▁scatter ▁plots ▁known ▁as ▁G abb ard ▁diag rams , ▁where ▁the ▁per ige e ▁and ▁ap og ee ▁of ▁fragments ▁are ▁pl otted ▁with ▁respect ▁to ▁their ▁orb ital ▁period . ▁G abb ard ▁diag rams ▁of ▁the ▁early ▁de br is ▁cloud ▁prior ▁to ▁the ▁effects ▁of ▁perturb ations , ▁if ▁the ▁data ▁were ▁available , ▁are ▁re construct ed . ▁They ▁often ▁include ▁data ▁on ▁newly ▁observed , ▁as ▁yet ▁un catalog ued ▁fragments . ▁G abb ard ▁diag rams ▁can ▁provide ▁important ▁ins ights ▁into ▁the ▁features ▁of ▁the ▁fragment ation , ▁the ▁direction ▁and ▁point ▁of ▁impact . ▁ ▁De aling ▁with