Performance goals for data archive systems need to be established early in the design process to ensure stability and
acceptable response throughput. Load testing is one technique used to measure the progress towards these performance
goals. Providing resources for load-test planning is critical, and this planning must include feasibility studies, tool
analyses, and generation of an overall load-test strategy. This strategy is much different for science data archives than
other systems, including commercial websites and high-volume data centers. This paper will provide an overview of the
load testing performed on the Spitzer Space Telescope's science archive, which is part of Science Operations System at
the Spitzer Science Center (SSC). Methods used for planning and conducting SSC load tests will be presented, and
advanced load-testing techniques will be provided to address runtime issues and enhance verification results. This work
was performed at the California Institute of Technology under contract to the National Aeronautics and Space
The Spitzer Science Center (SSC) Software Science Operations System (SOS) is a large, complex software system.
Over 1.2 million lines of code had been written for the SOS by time of launch (August 2003). The SSC uses a defect
tracking tool called GNATS to enter defect reports and change requests. GNATS has been useful beyond just tracking
defects to closure. Prior to launch a number of charts and graphs were generated using metrics collected from GNATS.
These reports demonstrated trends and snapshots of the state of the SOS and enabled the SSC to better identify risks to
the SOS and focus testing efforts. This paper will focus primarily on the time period of Spitzer's launch and In Orbit
Checkout. It will discuss the metrics collected, the analyses done, the format the analyses was presented in, and lessons
learned. This work was performed at the California Institute of Technology under contract to the National Aeronautics
and Space Administration.
The Spitzer Space Telescope was successfully launched on August 25th, 2003. After a 98 day In Orbit Checkout and
Science Verification period, Spitzer began its five and one half year mission of science observations at wavelengths
ranging from 3.6 to 160 microns. Results from the first two years of operations show the observatory performing
exceedingly well, meeting or surpassing performance requirements in all areas. The California Institute of Technology
is the home for the Spitzer Science Center (SSC). The SSC is responsible for selecting observing proposals, providing
technical support to the science community, performing mission planning and science observation scheduling,
instrument calibration and performance monitoring during operations, and production of archival quality data products.
This paper will provide an overview of the Science Operations System at the SSC focusing on lessons learned during
the first two years of science operations and the changes made in the system as a result. This work was performed at the
California Institute of Technology under contract to the National Aeronautics and Space Administration.
The Multiband Imaging Photometer for Spitzer (MIPS) provides long wavelength capability for the mission, in imaging bands at 24, 70, and 160 microns and measurements of spectral energy distributions between 52 and 100 microns at a spectral resolution of about 7%. By using true detector arrays in each band, it provides both critical sampling of the Spitzer point spread function and relatively large imaging fields of view, allowing for substantial advances in sensitivity, angular resolution, and efficiency of areal coverage compared with previous space far-infrared capabilities. The Si:As BIB 24 micron array has excellent photometric properties, and measurements with rms relative errors of 1% or better can be obtained. The two longer wavelength arrays use Ge:Ga detectors with poor photometric stability. However, the use of 1.) a scan mirror to modulate the signals rapidly on these arrays, 2.) a system of on-board stimulators used for a relative calibration approximately every two minutes, and 3.) specialized reduction software result in good photometry with these arrays also, with rms relative errors of less than 10%.