A Successful Strategy for Satellite Development and Testing - Inpe

and environment for testing the attitude control system, providingsolar illumination in vacuum for fully extended solar arrays, andfitting large systems into a relatively confined vacuum chamber).But even in light of these acknowledged limitations, Aerospacefound an increasing trend away from applying flight-like testingmethodologies where they were previously considered routine,such as in unit and subsystem performance testing and softwarecompatibility with hardware in the loop. Similarly, intersegmenttesting between the ground and space segments was often eliminatedentirely or greatly reduced in scope.The decision to omit or scale back these tests must be accompaniedby a clear assessment of the attendant risks. Where thereis significant risk exposure by not being able to test appropriately,mitigation strategies can be developed early in the life cycle.Aerospace found these risks were not always well understood, andconsequently, mitigation strategies were not effectively applied.Aerospace found that best practices for flight-like testing hadnot been codified in the industry. There was a general lack ofpractical guidance for determining how well or poorly the testingwas conducted. This was particularly true for “day in the life” operationaltesting.Traditionally, issues and problems uncovered during satellitedevelopment and testing would result in design and processchanges, which would in turn be scrutinized for insights thatvery often improve the development and verification process. Asa third-party observer, Aerospace could look across contractorboundaries and identify key lessons and practices, which couldthen be used to help prioritize the reintroduction of industry-widespecifications and standards. With the cancellation of these standardsin the mid-1990s, contractors were left on their own to accommodatetechnological changes and lessons learned into theirown processes—with variable success.A Leap in ComplexityWhile verification rigor had dropped, overall satellite complexityrose, often exponentially, as a result of advances in electronicstechnology and software. Not only were these systems usingmore parts, but the parts themselves were often far more complex,requiring much more stringent design verification and qualificationpractices. The greater use of field-programmable gate arrays(FPGAs) and application-specific integrated circuits (ASICs),with millions of embedded transistors on a single device, poses aneven greater testing challenge.Not only does increasing complexity pose a challenge tothe verification process, but it also implies an increase in thelikelihood of latent design and workmanship defects. Given theincreases in complexity, the corresponding pressures on the verificationprocesses, and the increased failure potential, the industryand government had embarked on a path of conflicted logic thatresulted in numerous problems that were often not detected untillate in development cycle, or even on orbit.Under acquisition reform, the government did not always specifyrequirements for qualifying the parts used in space systems.The manufacturers assumed responsibility for piece-part qualification,based on the application and the performance requirementsat the system level. This led to problems for several reasons.Acquiring qualified parts had become more difficult as suppliersfocused on commercial markets at the expense of the militaryspace market (which, although relatively small, typically requiresCumulative success rate (percent)Environmental test thoroughness1009080706050TraditionalacquisitionpracticesHigher-riskacquisitionpractices401980 1985 1990 1995 2000Year of launchOut of a sample of more than 450 vehicles manufactured in the United States,those developed using traditional acquisition practices show a consistentlyhigher success rate in the first year of operations. In contrast, vehicles developedusing higher-risk acquisition approaches show markedly lower successrates in the first year of operations.U.S. space asset loss (millions of dollars)100908070605030002500200015001000500Pre - 1995NRO programsPost - 1995Landsat 6NOAA 13UFO-1MarsObserverSMC programsAcquisition reform in the national security space arena reduced verificationrigor, as illustrated in the drop in environmental test thoroughness.3 Titan IV’sMilstar/NRO/DSP2 Delta III’sMars Climate Orbiter090 91 92 93 94 95 96 97 98 99YearThis chart shows the value in dollars of U.S. space assets lost during the 1990s.Recent independent studies have shown that reducing technical verificationrigor and diminishing the role of independent technical oversight in the developmentof government and commercial space systems results in greater problems,as evidenced by higher failure rates and cost and schedule overruns.