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The NASA-wide CEV Smart Buyer Team (SBT) was assembled in January 2006 and was tasked with the development of a NASA in-house design for the CEV Crew Module (CM), Service Module (SM), and Launch Abort System (LAS). This effort drew upon over 250 engineers from all of the 10 NASA Centers. In 6 weeks, this in-house design was developed. The Thermal Systems Team was responsible for the definition of the active and passive design architecture. The SBT effort for Thermal Systems can be best characterized as a design architecting activity. Proof-of-concepts were assessed through system-level trade studies and analyses using simplified modeling. This nimble design approach permitted definition of a point design and assessing its design robustness in a timely fashion. This paper will describe the architecting process and present trade studies and proposed thermal designs

A method for determining margins in conceptual-level design via probabilistic methods is described. The goal of this research is to develop a rigorous foundation for determining design margins in complex multidisciplinary systems. As an example application, the investigated method is applied to conceptual-level design of the Mars Exploration Rover (MER) cruise stage thermal control system. The method begins with identifying a set of tradable system-level parameters. Models that determine each of these tradable parameters are then created. The variables of the design are classified and assigned appropriate probability density functions. To characterize the resulting system, a Monte Carlo simulation is used. Probabilistic methods can then be used to represent uncertainties in the relevant models. Lastly, results of this simulation are combined with the risk tolerance of thermal engineers to guide in the determination of margin levels.

Phoenix is NASA's first Mars Scouts Mission that will place a soft-lander on the Martian surface at a high northern latitude. Much of the Mars surface environmental flight data from landed missions pertains to the near-equatorial regions. However, orbital observations have yielded very useful data about the surface environment. These data along with a simple, but highly effective one-dimensional atmospheric model was used to develop the Phoenix surface thermal environment. As candidate landing sites were identified, parametric studies including statistical variations were conducted to prescribe minimum nighttime and maximum daytime temperature design Sols (a Martian day). Atmospheric effects such as clouds and ice were considered. Finally, recent candidate landing site imaging conducted by the Mars Reconnaissance Orbiter revealed that the prime site contained a much higher rock density than first thought.