What Does It Mean?

There are terms used that are specific to the SIRTF mission. The following definitions are provided to enhance your understanding of the launch activities.

Definitions

Cryo-Telescope Assembly
The Cryo-Telescope Assembly (CTA) is the cold portion of the Observatory, including the cryostat, the telescope assembly, the outer shell group including the thermal radiation shields, the S/C support struts, and the Multiple Instrument Chamber (MIC) which houses the instrument cold assemblies.

Facility
The Facility includes the Observatory and the ground segment.

Observatory
The Observatory is the complete flight system, including the spacecraft, the cryo-telescope assembly, and the three science instruments.

Science Instruments
The Science Instruments (SI's) include the three payload instruments: the Infrared Array Camera (IRAC), the Infrared Spectrograph (IRS), and the Multiband Imaging Photometer for SIRTF (MIPS). The SI's consist of cold assemblies mounted in the CTA and associated warm electronics mounted in the S/C

Spacecraft
The Spacecraft (S/C) refers to the warm portion of the Observatory, including the solar panel, the bus structure, and the components mounted in the bus that provide the Observatory engineering functions. These components include: the solar arrays, the command and data handling unit, the reaction control subsystem, the pointing control subsystem, and the flight software.

Abbreviations

The world of Expendable Launch Vehicles (ELV) uses many terms you may be unfamiliar with. To make the ELV coverage experience more fun and meaningful, we have provided a listing of the most frequently used abbreviations and phrases below.

For a more comprehensive listing of abbreviations, check out the Acronym List provided in the Information Center linked from the Kennedy Space Center home page.