Air-quality regulators planned to sample the air around the Santa Susana Field Lab late Thursday for contamination that may have been released when the Topanga Fire roared through the hilltop lab. Thursday was supposed to be the day of the final rocket test at the field lab, ending testing operations at the hilltop site. Instead, it was at the center of a massive brush fire that stretched miles through the rugged area. Several vacant buildings at the site were burned, and an office and machine shop were damaged by the flames. But hazardous waste and radioactive facilities were not affected,...