navy combat veteran and retired nasa astronaut mark kelly, notably the husband of former congresswoman gabby giffords, announced he is running for senate in arizona in 2020 as a democrat. the announcement was made via a campaign video that was posted on social media this morning with the title "my next mission." we get the story tonight from nbc's cynthia mcfadden. >> reporter: tonight it's official, retired astronaut mark kelly is running for john mccain's senate seat in arizona. making the announcement in a highly polished video. >> you know, it becomes pretty obvious pretty early when you get into space that we're all kind of in this together. >> reporter: trained as an engineer, kelly became a navy fighter pilot and nasa astronaut. >> these missions are very, very challenging and very rewarding. >> reporter: he met his wife gabby giffords when he was about to turn 40.