Alexander (Alex) Sonnenberg WG12 passed away on Wednesday, June 20 in a tragic wingsuit BASE jumping accident in the HauteSavoie region of the French Alps. Patriotic and compassionate, he would do anything to help his fellow man—especially wounded veterans—who needed him most.

As NASA Astronaut Scott Kelly writes: “Five years ago my fiancé, Amiko, was taking her first tandem skydive and when I learned one of the instructors was a former U.S. Navy senior chief petty officer in SEAL Team 6, I said “that’s our guy.” We then became quick friends. Later, he also took my daughter Samantha on her first jump. He will be missed by countless people in ways that are difficult to describe. He loved life, loved his friends and was loved in return—one of the greatest people I have ever known. Always checking in and always there for anyone in need with a helping hand—no ask was too large.

He and his then girlfriend, Amina Belouizad—recently married—came to Baikonur, Kazakhstan to see me off the planet before my year in space. He supported Amiko and my kids during the strenuous travel and schedule of events leading up to my spaceflight. He intentionally sat with my daughter Charlotte, twelve years old at the time, at a dinner held in a Mongolian yurt in Baikonur the day before launch to talk with her and to be sure she understood while he was there for the experience and to support me, he was also there for her. Seeing a loved one off to space is physically and emotionally exhausting on your immediate family. Alex, despite having gone more than 20 hours without sleep the night of my launch, when the other guests went off to bed, recognized the toll on Amiko and knew she would be restless. “Hey, let’s grab a beer,” he said, nodding to her with a quick, slight lift of his chin and a smile in his always optimistic way. He sat with her, and they talked when he could have been sleeping, putting her at ease and letting her know she was not alone, then, nor would be for the next year before my return to Earth.

He supported me and my family while I was in space in ways small and large. When he learned I had a pair of special workout shoes that didn’t make it to space when a cargo ship blew up, he made arrangements to send not one but two pairs of shoes plus a few other items, including a Pink Floyd Dark Side of the Moon t-shirt that he likely got from his dresser drawer—he had a fondness for graphic t-shirts. He stepped in to help Amiko’s son whose car was totaled and mentored him on career paths as he would be graduating from high school while I was in space. Alex’s friendship to me and my family did not end in space. Having returned from my yearlong mission two years ago, retiring from NASA, I now travel a lot, making it difficult to stay in touch with friends back at home in Houston, TX. Alex still always made an extra effort to catch up with Amiko and I whether by phone or email and was always eager to plan a meet up in person the moment he knew we were home again, no matter how briefly.

A patriot and an American hero in every sense of the word. He was awarded the Bronze Star Medal, five Joint Service Commendation Medals (two with Valor) and the Navy Achievement Medal. After 13 years of service in the Navy, he attended The University of Pennsylvania Wharton School of Business where he obtained an MBA in Finance and Entrepreneurial Management. Thoughtful to the core, Alex was also a board member of One More Wave—a non-profit organization that promotes ocean therapy for disabled veterans. Enthusiastic about adventure sports and the outdoors, he was an avid skydiver, BASE jumper and wingsuit pilot with more than 1,800 jumps. Despite admitting to being scared of jumping off cliffs, he challenged himself and seemed fearless. Alex, my friend, may you get some epic jumps wherever you are. You are already missed more than you could ever know.”