Scott Kelly

Scott Kelly recounts that while flying a Navy jet off Virginia Beach, his back-seat Radar Intercept Officer was convinced they had flown past a UFO; on investigation it turned out to be a novelty 'Bart Simpson' balloon.

it turns out it was Bart Simpson, a balloon

Retired astronaut Scott Kelly recounts that his brother, astronaut and Senator Mark Kelly, as commander of Space Shuttle mission STS-124 (2008), saw an unexplained object in the payload bay before closing the bay doors, initially feared it was a tool or bolt that could jeopardize reentry, but a photograph revealed it was actually the International Space Station, roughly 80 miles away.

when they blew up the picture they realized that this is not a bolt or a tool in the payload Bay - it was actually the International Space Station, that was 80 miles away

Scott Kelly states that during his 20 years in NASA's astronaut office, he was never officially or unofficially briefed on, or involved in any discussion of, anything considered a UAP or UFO, and is not aware of any NDA restricting astronauts from discussing UAP sightings.

in my experience of being in the astronaut office for 20 years there was never any formal or informal discussions at all about uaps or UFOs, or anyone reporting anything that would suggest something from beyond our planet