Not yet a reality, but often seriously discussed, is terraforming `aitering an extracterrestrial body to make it capable of supporting  Earth's life forms.
( Not ( ( ( ( ( yet ( a reality ) ) , ) ( ( but ( often seriously ) ) discussed ) ) , ) ( ( is ( ( terraforming ` ) ( ( aitering ( an ( extracterrestrial body ) ) ) ( to ( make ( it ( capable ( of ( supporting ( ( Earth 's ) ( life forms ) ) ) ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (RB Not) (NP (NP (RB yet) (DT a) (NN reality)) (, ,) (VP (PRN (CC but) (ADVP (RB often)) (ADVP (RB seriously))) (VBN discussed)) (, ,)) (VP (VBZ is) (VP (VBG terraforming) (`` `) (S (VP (VBG aitering) (NP (DT an) (JJ extracterrestrial) (NN body)) (S (VP (TO to) (VP (VB make) (S (NP (PRP it)) (ADJP (JJ capable) (PP (IN of) (S (VP (VBG supporting) (NP (NP (NNP Earth) (POS 's)) (NN life) (NNS forms)))))))))))))) (. .)))
Terraforming is a cruel practice that should never exist. 
( Terraforming ( ( is ( ( a ( cruel practice ) ) ( that ( ( should never ) exist ) ) ) ) . ) )
(ROOT (S (NP (NNP Terraforming)) (VP (VBZ is) (NP (NP (DT a) (JJ cruel) (NN practice)) (SBAR (WHNP (WDT that)) (S (VP (MD should) (ADVP (RB never)) (VP (VB exist))))))) (. .)))