Tempest is a reusable crew exploration vehicle (CEV) for transferring crew from the Earth to the lunar surface and back. Tempest serves as a crew transfer module that supports a 4-person crew for a mission duration of 18 days, which consists of 8 days total transit duration and 10-day surface duration. Primary electrical power generation and on-orbit maneuvering for Tempest is provided by an attached Power and Propulsion Module (PPM). Hydrogen (H2)/oxygen (O2) fuel cells and a high energy-density matter (HEDM)/liquid oxygen (LOX) propellant reaction control system (RCS) provide power and reaction control respectively during Tempest's separation from the PPM. Tempest is designed for a lifting entry and is equipped with parachutes for a soft landing. Tempest is part of an overall lunar transportation architecture. The 60,731 lbs combination of Tempest and the PPM are launched atop the notional Centurion C-1 heavylift launch vehicle (HLLV) and delivered to a 162 nmi, 28.5º circular orbit. After separating from the C-1 upper stage, the Tempest/PPM autonomously rendezvous with Manticore, an expendable trans-lunar injection (TLI) stage pre-positioned in the current orbit, and transfer to a lunar trajectory. After entering a 54 nmi polar circular lunar orbit, the Tempest/PPM separate from Manticore. Tempest separates from the PPM and is ferried to/from the lunar surface by Artemis, a reusable lunar lander. Upon return from the lunar surface, Tempest reconnects with the PPM, and the PPM provides the trans-earth injection (TEI) burn required to return to low earth orbit (LEO). Prior to atmospheric entry, Tempest separates from the PPM and subsequently executes a lifting entry trajectory. Crushable thermal foam attached to the lower surface of Tempest serves as an ablative thermal protection system (TPS) and the impact absorber of the parachute landing. Details of the conceptual design process used for Tempest are included in this paper. The disciplines used in the design include: configuration, aerodynamics, propulsion, trajectory, mass properties, environmental control life support system (ECLSS), entry aeroheating and TPS, terminal landing system (TLS), cost, operations, and reliability & safety. Each of these disciplines was computed using a conceptual design tool similar to that used in industry. These disciplines were then combined and optimized for the minimum gross weight of the Tempest CEV. The total development cost including the design, development, testing and evaluation (DDT&E) cost was determined to be $2.9 B FY'04. The theoretical first unit (TFU) cost for the Tempest CEV was $479 M FY'04. A summary of design disciplines as well as the economic results are included. Nomenclature CEV = crew exploration vehicle CER = cost estimating relationship

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1 2 -The President's Vision for Space Exploration presents a need to determine the best architecture and set of vehicle elements in order to achieve a sustained human lunar exploration program. The Lunar Architecture Stochastic Simulator and Optimizer (LASSO), a new simulation-based capability based on discrete-event simulation, was created to address this question by probabilistically simulating lunar transportation architecture based on cost, reliability, and throughput figures of merit. In this study, two competing lunar transportation architectures are examined for a variety of launch vehicle scenarios to determine the best approach for human lunar exploration. Additionally, the two architectures are also compared for varying available ground infrastructure and desired flight rates. It is concluded that an expendable architecture is favored, using man-rated versions of existing evolved expendable launch vehicles (EELVs) for crew launches and developing a heavy-lift launch vehicle for cargo launches.

Entry, descent, and landing (EDL) is a multidimensional, complex problem, which is difficult to visualize in simple plots. The purpose of this work is to develop a systematic visualization scheme that could capture Mars EDL trades as a function of a limited number of variables, such that programmatic design decisions could be effectively made with insight of the design space. Using the Mars Science Laboratory (MSL) as a basis, contour plots have been generated for key EDL figures of merit, such as maximum landed elevation and landed mass as a function of four input parameters: entry mass, entry velocity, entry flight path angle, and vehicle L/D. Additionally, sensitivity plots have been generated in an attempt to capture the effects of varying the fixed input parameters. This set of EDL visualization data has been compiled into a Mars EDL handbook to aid in pre-phase A design space exploration and decision making. Nomenclature DSM = Design Structure Matrix EDL = Entry, Descent, and Landing FPA = Flight Path Angle L/D = Lift to Drag Ratio MER = Mars Exploration Rovers MSL = Mars Science Laboratory PESST = Planetary Entry System Synthesis Tool POST = Program to Optimize Simulated Trajectories TPS = Thermal Protection System

In order to return humans to the Moon, the Constellation Program will be required to operate a complex network of humans and spacecraft in several locations. This requires an early look at how decision-making authority will be allocated and transferred between humans and computers, for each of the many decision steps required for the various mission phases. This paper presents an overview of such a control authority analysis, along with an example based upon a lunar outpost deployment scenario. The results illustrate how choosing an optimal control authority architecture can serve to significantly reduce overall mission risk, when applied early in the design process. *