Officially, Capt. Mark Kelly, who is Giffords' husband of more than three years, is still the commander for the final scheduled flight of the space shuttle program, NASA said. The shuttle Endeavour is scheduled to launch on April 19 on a trip to the International Space Station.
Kelly was named commander in 2009 and has been in training for 17 months. Being chosen to lead the last shuttle flight is a big honor, NASA spokesman Michael Curie said.
Just in case Kelly can't fly as his wife recovers from a gunshot to the head, his spot will be taken by veteran shuttle commander Rick Sturckow (STUR'-koh) who is the agency's deputy chief astronaut.
The Arizona congresswoman remains in critical condition in a Tucson hospital.
Kelly said in a statement released by NASA that he recommended to the space agency that they "take steps now to prepare to complete the mission in my absence if necessary."
"I am very hopeful that I will be in a position to rejoin my (Endeavour) crew members to finish our training," Kelly said in the statement.
As far as NASA is concerned, "Mark is still the commander," chief astronaut Peggy Whitson said. "He is facing many uncertainties now as he supports Gabrielle, and our goal is to allow him to keep his undistracted attention on his family while allowing preparations for the mission to progress."
Curie said NASA hasn't yet determined when exactly it needs to make a decision on whether Kelly, a three-time shuttle flier, will be able to command the mission. But he said naming a backup commander buys some time.
Space shuttle crews usually spend well more than a year training for the intricate duties of a particular mission. Endeavour's 14-day mission would resupply the space station and install a $1.5 billion physics experiment.
The shooting of Giffords put NASA in an uncomfortable position about what to do with the April flight, said American University professor Howard McCurdy, who has written several books about the space program. Removing Kelly from a prestigious job would look like punishing him because of the assassination attempt, but he will be busy helping his wife recover and could be distracted if he flies.
He called Thursday's move "a realistic, carefully thought out compromise."