▁the ▁Canadian ▁Space ▁Agency . ▁Tri D AR ▁had ▁previously ▁flow n ▁on ▁ST S - 1 2 8 ▁and ▁ST S - 1 3 1 , ▁ab o ard ▁Space ▁Sh utt le ▁Disc overy . ▁Tri D AR ▁provides ▁guidance ▁information ▁that ▁can ▁be ▁used ▁for ▁rende z vous ▁and ▁dock ing ▁operations ▁in ▁orbit , ▁planet ary ▁land ings ▁and ▁vehicle ▁ins pection / navigation ▁of ▁robot ic ▁ro vers . ▁It ▁does ▁not ▁rely ▁on ▁any ▁reference ▁markers , ▁such ▁as ▁reflect ors , ▁position ed ▁on ▁the ▁target ▁space craft , ▁instead ▁using ▁a ▁las er - based ▁ 3 D ▁sensor ▁and ▁a ▁thermal ▁im ager . ▁Ge ometric ▁information ▁contained ▁in ▁success ive ▁ 3 D ▁images ▁is ▁matched ▁against ▁the ▁known ▁shape ▁of ▁the ▁target ▁object ▁to ▁calculate ▁its ▁position ▁and ▁orientation ▁in ▁real - time . ▁ ▁The ▁sensor ▁was ▁emp la ced ▁on ▁the ▁exterior ▁air lock ▁tr uss ▁next ▁to ▁a ▁Tra ject ory ▁Control ▁System ▁( T CS ) ▁sensor . ▁The ▁Tri D AR ▁hardware ▁was ▁installed ▁in ▁Atl ant iss ▁payload ▁bay ▁on ▁ 6 ▁April ▁ 2 0 1 1 . ▁On ▁ST S - 1 3 5 , ▁Tri D AR ▁was ▁used ▁to ▁demonstrate ▁technology ▁for ▁autonom ous ▁rende z vous ▁and ▁dock ing ▁in ▁orbit . ▁ ▁Down - mass ▁payload ▁ST S - 1 3 5 ▁returned ▁to ▁Earth ▁carrying ▁several ▁items ▁of ▁down mass ▁payload . ▁ ▁The ▁failed ▁am mon ia ▁P