Dr David Bearden
Under constrained budgets and rigid schedule, NASA, DoD and the space industry have greatly increased their utilization of small low-cost spacecraft to conduct science investigations and technology demonstrations. Recent failed or impaired small planetary science satellites such as Mars Polar Lander (MPL), Mars Climate Orbiter (MCO), and near-misses turned successful such as Mars Global Surveyor (MGS), and Near Earth Asteroid Rendezvous (NEAR) have fueled the ongoing debate about NASAs Faster, Better, Cheaper (FBC) approach to scientific missions. Several noteworthy failures of NASA earth-orbiting and DoD missions of a similar class such as Lewis and Space Tether EXperiment (STEX) have occurred as well. While recent studies have observed that FBC results in lower absolute costs and shorter development times relative to traditional missions, these benefits have been achieved at the expense of increasing performance risk. In the wake of these failures, NASA has adjusted their risk posture and adopted a Mission Success First criteria, but there are some who wonder if missions initiated under the FBC framework that are already in the late stages of development or awaiting launch may have a similar fate.
Critical to risk management within a constrained environment is identification of when performance requirements and technology-utilization decisions reach a threshold that, while ostensibly achievable within the allocated budget or schedule, leads to failures due to unprepared for circumstances. Risks may not manifest themselves ahead of time or in obvious or typical ways. However, when examined after the fact, loss or impaired performance is often found to be the result of mismanagement or miscommunication in lethal combination with a series of improbable events which, in their own right, would not have resulted in loss of the mission. These missteps, which often occur when the program is operating near the budget ceiling or under tremendous schedule pressure, result in failure due to lack of sufficient resources to test, simulate or review work and processes in a thorough manner.
With a decade of experience and over two dozen scientific spacecraft developed, a significant data set exists with which to conduct a thorough examination. This study takes an objective look at FBC missions using a complexity index to compare development time and system costs. Typical complexity drivers include both general programmatic knowledge (e.g., heritage, amount of redundancy, contractor experience) and demonstrable objective subsystem technical parameters (e.g., mass, power, performance, pointing accuracy, downlink data rate, technology choices). The key question addressed is when does a mission become too fast and too cheap that it is prone to failure? A comparison of the relative failure rates of recent NASA and DoD small satellites is presented with conclusions regarding dependence on system complexity. Furthermore, a process is proposed under which a new mission in the formative stage may be compared against missions of the recent past to balance risk with cost and schedule. While it remains debatable whether allocation of additional resources (cost, schedule) would have increased the probability that a given mission might have succeeded, this much is clear: When a mission fails, it appears that it is within a discernable regime where resources may be insufficient.