As news media and city officials watch from the balcony of the city baseball stadium in Lancaster, California, a crane gently positions an F/A-18 Hornet aircraft for mounting on a steel pedestal. The F/A-18 was recently retired by NASA's Dryden Flight Research Center, Edwards, California, after being flown as a safety chase and support aircraft over the past nine years. The aircraft is now mounted nose skyward on the 28-foot-tall pedestal in front of the Lancaster Municipal Stadium, know as ''The Hangar.'' The stadium is the home field of the Lancaster Jethawks, a Class-A farm team of the Seattle Mariners.