 Most of the mission 's delays were caused by external tank issues on STS @-@ 133 Discovery . When Mark 's twin brother Scott Kelly went to the ISS on October 7 , 2010 , STS @-@ 134 was scheduled to go to the station during Scott 's mission . The potential rendezvous in space of the Kelly brothers would have been a first meeting of blood relatives in space . The delay of the launch of STS @-@ 134 ended the possibility of that happening . 
