ALBERT

Description: NASA's Human Exploration and Development of Space (HEDS) Enterprise is defining architectures and requirements for human exploration that radically reduce the costs of such missions through the use of advanced technologies, commercial partnerships and innovative systems strategies. In addition, the HEDS Enterprise is collaborating with the Space Science Enterprise to acquire needed early knowledge about Mars and to demonstrate critical technologies via robotic missions. This paper provides an overview of the technological challenges facing NASA as it prepares for human exploration. Emphasis is placed on identifying the key technologies including those which will provide the most return in terms of reducing total mission cost and/or reducing potential risk to the mission crew. Top-level requirements are provided for those critical enabling technology options currently under consideration.

Description: Through the application of advanced technologies, mission concepts, and new ideas in combining capabilities, architectures for missions beyond Earth orbit have been dramatically simplified. These concepts enable a stepping stone approach to discovery driven, technology enabled exploration. Numbers and masses of vehicles required are greatly reduced, yet enable the pursuit of a broader range of objectives. The scope of missions addressed range from the assembly and maintenance of arrays of telescopes for emplacement at the Earth-Sun L2, to Human missions to asteroids, the moon and Mars. Vehicle designs are developed for proof of concept, to validate mission approaches and understand the value of new technologies. The stepping stone approach employs an incremental buildup of capabilities; allowing for decision points on exploration objectives. It enables testing of technologies to achieve greater reliability and understanding of costs for the next steps in exploration.

Description: A human mission to Mars will occur at some time in the coming decades. When it does, it will be the end result of a complex network of interconnected design choices, systems analyses, technical optimizations, and non-technical compromises. This mission will extend the technologies, engineering design, and systems analyses to new limits, and may very well be the most complex undertaking in human history. It can be illustrated as a large menu, or as a large decision tree. Whatever the visualization tool, there are numerous design decisions required to assemble a human Mars mission, and many of these interconnect with one another. This paper examines these many decisions and further details a number of choices that are highly interwoven throughout the mission design. The large quantity of variables and their interconnectedness results in a highly complex systems challenge, and the paper illustrates how a change in one variable results in ripples (sometimes unintended) throughout many other facets of the design. The paper concludes with a discussion of some mission design variables that can be addressed first, and those that have already been addressed as a result of ongoing National Aeronautics and Space Administration (NASA) developments, or as a result of decisions outside the technical arena. It advocates the need for a 'reference design' that can be used as a point of comparison, and to illustrate the system-wide impacts as design variables change.

Description: As we venture back to the Moon with a longer term goal of future Mars missions, lunar missions can provide an important testbed for technologies, systems and operations that directly feed forward to future Mars needs. Gateway missions can provide good in-space transportation feed forward to human Mars missions. Modest operations on the Moon such as the GER (Global Exploration Roadmap)-class missions, can provide key Mars human performance and surface mission capability development and risk reduction. A human return to the Moon can, if done correctly, serve as an excellent down payment to Mars.

Description: Human space mission designers stretching back to von Braun and beyond have envisioned the moon as a waypoint to the more challenging missions to Mars. The moon is seen as a potential proving ground for technologies, equipment and operations, and a venue upon which to learn the art of surface exploration. Mars missions are years in duration with very limited Earth return opportunities, but the moon provides the opportunity to perfect exploration concepts while being only a few days from Earth. Though the environment and gravity differ from Mars, and will thereby not provide a perfectly analogous environment, the remoteness, limited logistics, and harsh conditions on the Moon provide an environment that can be used to stress many systems that will be used or will be extensible to hardware and operations that will be used on Mars. This paper begins by describing the systems, or options for systems, that together comprise a human Mars architecture. With this human Mars operational concept as a basis of comparison, each of these systems is analyzed in the context of a range of potential exploration missions that first targets lunar exploration experience, examining how the lunar experience can be best used to prepare for the eventual human mission to Mars. The paper concludes with a concise summary of specific areas that have the strongest applicability between exploration experience on the lunar surface and extensibility to human Mars exploration.

Description: Many human space exploration mission architecture assessments have been performed over the years by diverse organizations and individuals. Direct comparison of metrics among these studies is extremely difficult due to widely varying assumptions involving projected technology readiness, mission goals, acceptable risk criteria, and socio-political environments. However, constant over the years have been the physical laws of celestial dynamics and rocket propulsion systems. A finite diverse yet finite architecture trade space should exist which captures methods of human exploration - particularly of the Moon and Mars - by delineating technical trades and cataloging the physically realizable options of each. A particular architectural approach should then have a traceable path through this "trade tree". It should be pointed out that not every permutation of paths will result in a physically realizable mission approach, but cataloging options that have been examined by past studies should help guide future analysis. This effort was undertaken in two phases by multi-center NASA working groups in the spring and summer of 2004 using more than thirty years of past studies to "flesh out" the Moon-Mars human exploration trade space. The results are presented, not as a "trade tree", which would be unwieldy, but as a "menu" of potential technical options as a function of mission phases. This is envisioned as a tool to aid future mission designers by offering guidance to relevant past analyses.

Description: Even after more than thirty years of scientific investigation, serious concerns regarding human physiological effects of long-duration microgravity exposure remain. These include loss of bone mineral density, skeletal muscle atrophy, and orthostatic hypertension, among others. In particular, "Safe Passage: Astronaut Care for Exploration Missions," states "loss of bone density, which apparently occurs at a rate of 1% per month in microgravity, is relatively manageable on the short-duration missions of the space shuttle, but it becomes problematic on the ISS [International Space Station]. ...If this loss is not mitigated, interplanetary missions will be impossible." While extensive investigations into potential countermeasures are planned on the ISS, the delay in attaining full crew complement and onboard facilities, and the potential for extending crews tours of duty threaten the timely (〈 20 years!) accumulation of sufficient data for countermeasures formulation. Indeed, there is no guarantee that even with the data, a practical or sufficiently robust set of countermeasures will be forthcoming. Providing an artificial gravity (AG) environment by crew centrifugation aboard deep-space human exploration vehicles, long a staple technique of science fiction, has received surprisingly limited engineering assessment. This is most likely due to a number of factors: the lack of definitive design requirements, especially acceptable artificial gravity levels and rotation rates, the perception of high vehicle mass and performance penalties, the incompatibility of resulting vehicle configurations with space propulsion options (i.e., aerocapture), the perception of complications associated with de-spun components such as antennae and photovoltaic arrays, and the expectation of effective crew micro-gravity countermeasures. These perception and concerns may have been overstated, or may be acceptable alternatives to countermeasures of limited efficacy. This study was undertaken as an initial step to try to understand the implications of and potential solutions to incorporating artificial gravity in the design of human deep-space exploration vehicles. Of prime interest will be the mass penalties incurred by incorporating AG, along with any mission performance degradation.

Description: In an on-going effort to make human Mars missions more affordable and sustainable, NASA continues to investigate the innovative leveraging of technological advances in conjunction with the use of accessible Martian resources directly applicable to these missions. One of the resources with the broadest utility for human missions is water. Many past studies of human Mars missions assumed a complete lack of water derivable from local sources. However, recent advances in our understanding of the Martian environment provides growing evidence that Mars may be more "water rich" than previously suspected. This is based on data indicating that substantial quantities of water are mixed with surface regolith, bound in minerals located at or near the surface, and buried in large glacier-like forms. This paper describes an assessment of what could be done in a "water rich" human Mars mission scenario. A description of what is meant by "water rich" in this context is provided, including a quantification of the water that would be used by crews in this scenario. The different types of potential feedstock that could be used to generate these quantities of water are described, drawing on the most recently available assessments of data being returned from Mars. This paper specifically focuses on sources that appear to be buried quantities of water ice. (An assessment of other potential feedstock materials is documented in another paper.) Technologies and processes currently used in terrestrial polar regions is reviewed. One process with a long history of use on Earth and with potential application on Mars - the Rodriguez Well - is described and results of an analysis simulating the performance of such a well on Mars are presented. These results indicate that a Rodriguez Well capable of producing the quantities of water identified for a "water rich" human mission are within the capabilities assumed to be available on the Martian surface, as envisioned in other comparable Evolvable Mars Campaign assessments. The paper concludes by capturing additional findings and describing additional simulations and tests that should be conducted to better characterize the performance of the identified terrestrial technologies for accessing subsurface ice, as well as the Rodriguez Well, under Mars environmental conditions.

Description: In an on-going effort to make human Mars missions more affordable and sustainable, NASA continues to investigate the innovative leveraging of technological advances in conjunction with the use of accessible Martian resources directly applicable to these missions. One of the resources with the broadest utility for human missions is water. Many past studies of human Mars missions assumed a complete lack of water derivable from local sources. However, recent advances in our understanding of the Martian environment provides growing evidence that Mars may be more "water rich" than previously suspected. This is based on data indicating that substantial quantities of water are mixed with surface regolith, bound in minerals located at or near the surface, and buried in large glacier-like forms. This paper describes an assessment of what could be done in a "water rich" human Mars mission scenario. A description of what is meant by "water rich" in this context is provided, including a quantification of the water that would be used by crews in this scenario. The different types of potential feedstock that could be used to generate these quantities of water are described, drawing on the most recently available assessments of data being returned from Mars. This paper specifically focuses on sources that appear to be buried quantities of water ice. (An assessment of other potential feedstock materials is documented in another paper.) Technologies and processes currently used in terrestrial Polar Regions are reviewed. One process with a long history of use on Earth and with potential application on Mars - the Rodriguez Well - is described and results of an analysis simulating the performance of such a well on Mars are presented. These results indicate that a Rodriguez Well capable of producing the quantities of water identified for a "water rich" human mission are within the capabilities assumed to be available on the Martian surface, as envisioned in other comparable Evolvable Mars Campaign assessments. The paper concludes by capturing additional findings and describing additional simulations and tests that should be conducted to better characterize the performance of the identified terrestrial technologies for accessing subsurface ice, as well as the Rodriguez Well, under Mars environmental conditions.

Description: Propulsion technology development efforts at the NASA Johnson Space Center continue to advance the understanding of the quantum vacuum plasma thruster (QThruster), a form of electric propulsion. Through the use of electric and magnetic fields, a Q-thruster pushes quantum particles (electrons/positrons) in one direction, while the Qthruster recoils to conserve momentum. This principle is similar to how a submarine uses its propeller to push water in one direction, while the submarine recoils to conserve momentum. Based on laboratory results, it appears that continuous specific thrust levels of 0.4 - 4.0 N/kWe are achievable with essentially no onboard propellant consumption. To evaluate the potential of this technology, a mission analysis tool was developed utilizing the Generalized Reduced Gradient non-linear parameter optimization engine contained in the Microsoft Excel platform. This tool allowed very rapid assessments of "Q-Ship" minimum time transfers from earth to the outer planets and back utilizing parametric variations in thrust acceleration while enforcing constraints on planetary phase angles and minimum heliocentric distances. A conservative Q-Thruster specific thrust assumption (0.4 N/kWe) combined with "moderate" levels of space nuclear power (1 - 2 MWe) and vehicle specific mass (45 - 55 kg/kWe) results in continuous milli-g thrust acceleration, opening up realms of human spaceflight performance completely unattainable by any current systems or near-term proposed technologies. Minimum flight times to Mars are predicted to be as low as 75 days, but perhaps more importantly new "retro-phase" and "gravity-augmented" trajectory shaping techniques were revealed which overcome adverse planetary phasing and allow virtually unrestricted departure and return opportunities. Even more impressively, the Jovian and Saturnian systems would be opened up to human exploration with round-trip times of 21 and 32 months respectively including 6 to 12 months of exploration at the destinations. Finally, interstellar trip times are assessed at milli-g acceleration levels.