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The Aerospace Testing Seminar
During the 1960s, national security space programs suffered repeated failures, with some programs having more than others. The disparity among different programs prompted the Air Force to institute a critical examination of satellite design, development, and manufacturing processes. The goal was to identify improvements that could reduce the orbital failure rate of Air Force satellites.
The study revealed a wide diversity of philosophies, methods, and requirements. Each program developed its own test protocols based upon the experience of the contractor, Aerospace, and Air Force personnel working on the project. In some cases, the absence of a centralized "lessons learned" feedback mechanism resulted in the same failures and failure modes repeated on different programs. Aerospace began to document failures and the associated lessons learned in an effort to avoid repetition of failures. One clear lesson that emerged was the importance of perceptive testing, applied in a consistent and reproducible manner.
The Air Force asked Aerospace to conduct a forum for discussing test practices across the industry. The meeting, the first Aerospace Testing Seminar, took place in Palo Alto, California, in 1973 and was supported by an advisory board composed of Air Force and Aerospace personnel. In hindsight, the striking feature of this event was the level of disclosure about design, testing, and manufacturing processes among organizations that were essentially competitors.
The testing practices used by the various contractors in attendance were considered, and a first step was taken toward establishing a standard set of test requirements for use in the acquisition of Air Force space systems. A testing document was selected as a baseline for the development of a comprehensive environmental test standard. Another outcome of this symposium was a request that Aerospace develop a military standard to establish a testing baseline for all Air Force space systems. The result of that effort was MIL-STD-1540 "Test Requirements for Space Vehicles," issued in 1974. The second Aerospace Testing Seminar was held in 1975 to present details of the newly developed military standard and to continue the dialog fostered by the first seminar.
Since that time, the Aerospace Testing Seminar has become a regular event held every 18 months. The planning board has grown to 50 members, representing a wide spectrum of the aerospace industry, including major contractors, Air Force, NASA, JPL, Naval Research Laboratories, Sandia National Laboratories, and The Aerospace Corporation. The European Space Agency and several European contractors are also represented. The 22nd seminar took place in March 2005, jointly sponsored by Aerospace, the Air Force Space and Missile Systems Center, and the Institute of Environmental Sciences and Technology. The only event of its kind in the United States, the seminar now attracts participants from all across the world.
The 22nd seminar provided four days of conferences under the general theme of "testing relevance into the next generation." A review of the session and paper titles provides a quick snapshot of the most pressing issues facing the aerospace testing field. The event included a full day of tutorials in areas such as force-limited vibration testing, satellite structural testing, thermal testing, and high-frequency structural dynamics. Many aerospace organizations, including Air Force program offices, rely on these tutorials as a means of expanding the education of their staff on testing practices.
Conference sessions were divided into six general topics. A session on testing philosophies and standards discussed vibroacoustic test specifications, a new verification standard, and an environmental test thoroughness index. A session on testing strategies and management included presentations on the use of thermal vacuum chambers and testing of an advanced synthetic-aperture radar satellite. New thermal cycler designs, test fixtures in arc-jet facilities, and options for replacing base shake tests were among the topics covered in a session on innovations in test facilities and equipment. The test perceptiveness and effectiveness presentations covered lessons learned from EMC testing of the Mars Rovers, mechanical qualification tests, and suitable satellite complexity indicators for evaluating flight failures. A session on instrumentation, data acquisition, and evaluation considered topics ranging from a comparison of pyroshock test-prediction methods to videogrammetry based on microcameras to techniques for deriving a motor current drive waveform. The modeling, analysis, and simulation session explored analytical impact models and experimental test validation, the use of air bearing simulator for attitude control systems, and static qualification logic for launch vehicle structures.
Papers presented by Aerospace researchers covered topics such as burst testing of graphite-epoxy composite tubes, attenuation of transient vibrations using a tuned vibration absorber, application of new and revised national security space development test standards, evaluating the effect of protoqualification acoustic test duration on mission reliability, development of an advanced environmental test thoroughness index, and improved vibroacoustic test specification and practice.
In an interesting replay of history, the Air Force recently asked Aerospace to help develop a series of updated environmental test standards. In response, Aerospace published a Technical Operating Report that will soon be released as MIL-STD-1540E—the latest version of the standard that evolved from the first testing seminar 30 years ago. In fact, Aerospace researchers at the 22nd seminar delivered papers discussing the vibration, acoustics, shock, thermal, and electromagnetic compatibility requirements in MIL-STD-1540E. And again, members of the planning board reviewed the draft MIL-STD and provided extensive comments to help make this baseline industry document more relevant in the drive to make future space systems more reliable than ever.
The 23rd Aerospace Testing Seminar will take place October 10–12, 2006. The theme will be "New Dimensions." For details, visit http://www.aero.org/conferences/ats/.
