These are inaccurate markings on this museum display. The aircraft was indeed operated at NAS Pax with the Naval Research Laboratory's (NRL) air component. In 2004 the NRL air component was formally designated a squadron, Scientific Development Squadron One VXS-1. It was given a tail code and squadron patch. Squadron's and units aboard NAS Patuxent River used to be charged with maintaining the upkeep of the Pax museum aircraft, and when the S-2D was brought in for a fresh paint job, someone decided to mark the bird up in VXS-1 markings instead of maintaining the aircraft's actual markings from it's time in service with NRL.