The National Aeronautics and Space Administration, commonly referred to as NASA, does not track or research Unidentified Flying Objects. However, the astronauts of the Apollo 16 mission did photograph an object during their return from the moon in 1972.
It is a common misconception that Unidentified Flying Objects, or UFOs, are synonymous with alien spacecraft. A UFO is simply anything viewed in the sky that cannot be identified as a known object.
NASA explains that close investigation of UFO photographs and video often leads to the objects' identification and declassification as UFOs. An example of this occurred during the Apollo 16 mission to the moon when American astronauts John Young, Thomas Mattingly and Charles Duke recorded an object that resembled commonly accepted ideas of an alien spacecraft. However, upon investigation of the footage, a group of space image science analysts concluded the object was the floodlight boom of the astronauts' own spacecraft.