The Road to Launch and Operations of the Spitzer Space Telescope

Spitzer Space Telescope, the fourth and final of NA SA's Great Observatories, and the cornerstone to NASA's Origins Program, launched on 25 August 2003 into an Earth -trailing solar orbit to acquire infrared observations from space. Spitzer has an 85cm diameter beryllium telescope, which operates near absol ute zero utilizing a liquid helium cryostat for cooling the telescope. The helium cryostat , though designed for a 2.5 year lifetime, through creative planning now has an expected lifetime of 5.5 years. Spitzer has completed its in orbit checkout/science verification phases and the first 2 1/2 years of nominal operations , becoming the first mission to execute astronomical observations from a solar orbit. Spitzer was designed to probe and explore the universe in the infrared utilizing three state of the ar t detector arrays providing imaging, photometry, and spectroscopy over the 3 -160 micron wavelength range. Spitzer is achieving major advances in the study of astrophysical phenomena across the expanses of our solar system to both the earliest formations o f our universe to it s outer edge. Many technology areas critical to future infrared missions have been successfully demonstrated by Spitzer. These demonstrated technologies include lightweight cryogenic optics, sensitive detector arrays, and a high perfo rmance thermal system, combining passive radiation with cryogenic cooling, which effectively cool ed the telescope in space after its warm launch. Although Spitzer has seen great success, its road to launch and operations was filled with many pot holes an d stumbling blocks. These were driven by historical issues (e.g. the mid stream transition from the cheaper/faster/better paradigm, an extremely long development phase, software inheritance issues , and an inexperienced development staff ). A competing cha llenge was Spitzer’s unique need to be fully flight ready before launch (i.e. no cruise period for completion of the implementation typical to planetary missions ). The se challenges were further magnified by t he finite life of the cryogen system combined w ith the occurrence of all mission critical events within the first few hours after launch rather than the months or years typical in deep space missions. This paper describes how the project was able to overcome these stumbling blocks along with changes in philosophies, experiences, and lessons learned. It will describe how projects must invest early or else heavily later in the development phase to achieve a successful operations phase. The result for the Spitzer Space Telescope was a successful launch o f the observatory followed by an extremely successful In Orbit Checkout/Science Verification phase and a subsequent successful operational phase.