Final answer:
The Technical Support Services Contract (TSSC) is responsible for hardware and software maintenance within the STARS system, ensuring its optimal operation across multiple air traffic control facilities.
Step-by-step explanation:
The element of the Standard Terminal Automation Replacement System (STARS) that performs hardware and software maintenance, including site adaptation and site support for multiple sites, is known as the "Technical Support Services Contract" (TSSC).
TSSC provides system support for hardware and software issues, adapts the system to the specific requirements of different sites, and generally ensures the smooth operation and reliability of the STARS systems across various air traffic control facilities.