Brad St. Germain

Utilizing Lunar Architecture Transportation Elements for Mars Exploration

In 2004, President Bush announced a new U.S. Vision for Space Exploration that includes plans to return humans to the moon followed by human missions to Mars. While human Mars missions have been studied and analyzed for decades, the current technical and political environment presents mission designers with new objectives and constraints. Given the significant investment required to develop new launch vehicles, habitat systems, and supporting technologies for the preparatory lunar campaign, it is likely that those systems will serve as the centerpiece of any future Mars exploration architecture. This paper summarizes the efforts of SpaceWorks Engineering’s advanced design team to develop a viable Mars architecture based on Project Constellation launch vehicles and related lunar transportation technologies. All-chemical LOX/LH2 transfer vehicles are used. No in-situ resource utilization (propellant manufacture) has been assumed. An overall concept of operations is outlined. Details are provided on element masses, Earth-Mars transfer times, development and operations costs, and estimated mission reliability. Throughout this internally-funded effort, emphasis has been placed on maturing design tools and multidisciplinary processes in order to develop a useful national capability should formal studies of Mars architectures be undertaken.

Critical Flight Conditions of Operational Rocketback Trajectories

This paper presents recent work that the U.S. Air Force has conducted to better understand the range of potential rocketback trajectories that could meet future launch needs. Various vision architectures were considered to meet a variety of reference mission requirements. These trajectories were compared against each other to determine ranges of critical flight conditions of interest for detailed aerodynamic analysis. Computational Fluid Dynamics (CFD) analysis is presented to show where the most uncertainty in flight conditions appears. This analysis presents a starting point for determining the flight conditions requiring flight testing to validate CFD models.

A Stochastic Process for Prioritizing Lunar Exploration Technologies

*† ‡ Obtaining an affordable and sustainable exploration scenario requires the development of new technologies. Limited technology maturation budgets require that strategic decision makers must choose which set of potentially beneficial technologies to fund. Methods are needed which allow managers to make informed decisions based on engineering analysis. The Abbreviated Technology Identification, Evaluation, and Selection (ATIES) methodology is such one such method. ATIES uses a systematic aggregation of decision-making techniques and probabilistic methods. As a demonstration of this process, this study applies ATIES to a candidate lunar exploration architecture scenario. The baseline architecture consists of chemical propulsion in-space stages and Space Shuttle derived Earth-to-Orbit (ETO) transportation. The Mission Scenario Analysis Tool (MSAT) is used to determine various architecture level metrics across the entire exploration campaign. Four notional architecture-enhancing technologies are examined using ATIES and MSAT: an advanced Liquid Oxygen (LOX) / Liquid Hydrogen (LH2) rocket engine, composite propellant tanks fully compatible with cryogenic liquids, enhanced Automated Rendezvous and Docking (AR&D), and new lightweight Environmental Control and Life Support System (ECLSS) for the Crew Exploration Vehicle (CEV). These four technologies are assessed individually and in combinations to quantify their impact and rank their relative benefit.

Starsaber: A Small Payload-Class TSTO Vehicle Concept Utilizing Rocket-Based Combined Cycle Propulsion

37th AIAA/ASME/SAE/ASEE Joint Propulsion Conference And Exhibit Salt Lake City, UT, July 8-11, 2001.

Lunar Lander Designs for Crewed Surface Sortie Missions in a Cost-Constrained Environment

The authors have performed a parametric study of lunar lander vehicle designs to transport a crew of 2 between the Earth-Moon L1 or L2 libration points and the lunar surface for a 14-day sortie mission. The trade space of lunar lander designs includes different propellant options and staging configurations. The propellant combinations considered are: oxygen and hydrogen, oxygen and methane, oxygen and kerosene, and nitrogen tetroxide and hydrazine. The staging configurations considered are: a single-stage lander, a two-stage lander with ascent and descent stages, and a two-stage lander with inspace and lander stages. Lander masses and dimensions are presented for each combination of propellant type and staging configuration. The resultant lander masses ranged from 30t to 60t. For each configuration, the Design, Development, Test, and Evaluation (DDT&E) and Theoretical First Unit (TFU) costs, as well as lander vehicle contribution towards the probability of loss of mission, are also presented. DDT&E costs ranged from

Probabilistic Examination of Lunar Landers

6.0B to

REACTIONN: A Nuclear Electric Propulsion Mission Concept to the Outer Solar System

7.5B, while TFU costs ranged from

Global Humanitarian Supply Delivery with Reusable Launch Vehicles

500M to

An Evaluation of Two Alternate Propulsion Concepts for Bantam-Argus: Deeply-Cooled Turbojet+Rocket and Pulsed Detonation Rocket+Ramjet

800M. The total loss of mission for all concepts ranged from 1.9% to 3.2%.

Tanker Argus: Re-supply for a LEO Cryogenic Propellant Depot

*† ‡ SpaceWorks Engineering, Inc. (SEI) has developed a new analysis model specifically tailored to the conceptual level design and evaluation of lunar ascent and descent systems. Entitled Moonraker, the model includes over two hundred input variables that can be used to describe the entire system configuration, from subsystem components to high level mission assumptions. The weight estimation and sizing process is based on physical equations and a set of historical mass estimating relationships developed through extensive research. Moonraker’s output consists of a three-level weight breakdown structure (WBS) for each vehicle stage that has been analyzed, as well as geometry information (surface area, volume). The result of a verification exercise of the Moonraker model against an Apollo Lunar Excursion Module (LEM) is addressed. Later, an examination of an all-new lunar lander design created in Moonraker and based on a relevant mission scenario is discussed. The design process outlined for this all-new concept acknowledges uncertainty in the performance modeling of future technologies, and seeks to effectively deal with this uncertainty through probabilistic methods.