In case you missed, this is the background on tonight's launch: http://www.spacex.com/news/2015/12/21/background-tonights-launch http://www.spacex.com/news/201

In case you missed, this is the background on tonight's launch: http://www.spacex.com/news/2015/12/21/background-tonights-launch http://www.spacex.com/news/2015/12/21/background-tonights-la...