Mark Kelly retiring from NASA to be with wife

Congresswoman Gabrielle Giffords and astronaut Mark Kelly.

Astronaut Mark Kelly says he is retiring from NASA and the U.S. Navy to be with his wife, Rep. Gabrielle, as she continues her long recovery from a gunshot wound.

In a Facebook posting, Kelly says he has reached a "crossroads" in his life and is focused on spending time with his wife and daughters.

"Gabrielle is working hard every day on her mission of recovery. I want to be by her side," Kelly said. "Stepping aside from my work in the Navy and at NASA will allow me to be with her and with my two daughters. I love them all very much and there is no doubt that we will move forward together."

Kelly, who served in Operation Desert Storm and captained the Space Shuttle Endeavour's final mission during a 25-year career, said the decision to retire was not easy.

"Public service has been more than a job for me and for my family," he said.

Kelly added that after taking some time off, he will explore "new opportunities" to serve the country again.

Meanwhile, Giffords and Kelly announced Tuesday that they have a deal for a joint memoir. It is to be an intimate chronicle of everything from their careers and courtship to the Jan. 8 tragedy when a gunman shot Giffords in the head as she met with constitutents in Tucson, Arizona. Six people were killed in the attack and 12 others besides the congresswoman were wounded.

Gabrielle Giffords has deal for a memoir

"Since Jan. 8, it's been really touching to us to see how much support there is for Gabby and her recovery, and how much interest there is in how she's doing and her story," said Kelly.