Kennedy K.J.,NASA |
Toups L.D.,NASA |
Rudisill M.,NASA |
Griffin B.,MSFC |
And 16 more authors.
Proceedings of the 12th International Conference on Engineering, Science, Construction, and Operations in Challenging Environments - Earth and Space 2010 | Year: 2010
This paper will describe an overview of the Constellation Architecture Team Lunar Scenario 12.0 (LS-12) surface habitation approach and concept performed during the study definition. The Lunar Scenario 12 architecture study focused on two primary habitation approaches: a horizontally-oriented habitation module (LS-12.0) and a vertically-oriented habitation module (LS-12.1). This paper will provide an overview of the 12.0 lunar surface campaign, the associated outpost architecture, habitation functionality, concept description, system integration strategy, mass and power resource estimates. The Scenario 12 architecture resulted from combining three previous scenario attributes from Scenario 4 "Optimized Exploration", Scenario 5 "Fission Surface Power System" and Scenario 8 "Initial Extensive Mobility" into Scenario 12 along with an added emphasis on defining the excursion ConOps while the crew is away from the outpost location. This paper will describe an overview of the CxAT-Lunar Scenario 12.0 habitation concepts and their functionality. The Crew Operations area includes basic crew accommodations such as sleeping, eating, hygiene and stowage. The EVA Operations area includes additional EVA capability beyond the suitlock function such as suit maintenance, spares stowage, and suit stowage. The Logistics Operations area includes the enhanced accommodations for 180 days such as enhanced life support systems hardware, consumable stowage, spares stowage, interconnection to the other habitation elements, a common interface mechanism for future growth, and mating to a pressurized rover or Pressurized Logistics Module (PLM). The Mission & Science Operations area includes enhanced outpost autonomy such as an IVA glove box, life support, medical operations, and exercise equipment. © 2010 ASCE.
Arnold Sr. W.R.,Defense Group Inc. |
Fitzgerald M.,MSFC |
Rosa R.J.,MSFC |
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013
The advances in manufacturing techniques for lightweight mirrors, such as EXELSIS deep core low temperature fusion, Corning's continued improvements in the Frit bonding process and the ability to cast large complex designs, combined with water-jet and conventional diamond machining of glasses and ceramics has created the need for more efficient means of generating finite element models of these structures. Traditional methods of assembling 400,000 + element models can take weeks of effort, severely limiting the range of possible optimization variables. This paper will introduce model generation software developed under NASA sponsorship for the design of both terrestrial and space based mirrors. The software deals with any current mirror manufacturing technique, single substrates, multiple arrays of substrates, as well as the ability to merge submodels into a single large model. The modeler generates both mirror and suspension system elements, suspensions can be created either for each individual petal or the whole mirror. A typical model generation of 250,000 nodes and 450,000 elements only takes 3-5 minutes, much of that time being variable input time. The program can create input decks for ANSYS, ABAQUS and NASTRAN. An archive/retrieval system permits creation of complete trade studies, varying cell size, depth, and petal size, suspension geometry with the ability to recall a particular set of parameters and make small or large changes with ease. The input decks created by the modeler are text files which can be modified by any text editor, all the shell thickness parameters and suspension spring rates are accessible and comments in deck identify which groups of elements are associated with these parameters. This again makes optimization easier. With ANSYS decks, the nodes representing support attachments are grouped into components; in ABAQUS these are SETS and in NASTRAN as GRIDPOINT SETS, this make integration of these models into large telescope or satellite models easier. © 2013 Copyright SPIE.
Arnold Sr. W.R.,Defense Group Inc. |
Bevan R.M.,MSFC |
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013
Advances in mirror fabrication are making very large space based telescopes possible. In many applications, only monolithic mirrors can meet the performance requirements. The existing and near-term planned heavy launch vehicles place a premium on lowest possible mass, and then available payload shroud sizes limit near term designs to 4 meter class mirrors. Practical 8 meter class and beyond designs could encourage planners to include larger shrouds, if it can be proven that such mirrors can be manufactured. These two factors, lower mass and larger mirrors, present the classic optimization problem. There is a practical upper limit to how large of a mirror can be supported by a purely kinematic mount system handling both operational and launch loads. This paper shows how the suspension system and mirror blank need to be designed simultaneously. We will also explore the concepts of auxiliary support systems which act only during launch and disengage on orbit. We will define required characteristics of these systems and show how they can substantially reduce the mirror mass. © 2013 Copyright SPIE.
Murray S.,Harvard - Smithsonian Center for Astrophysics |
Giacconi R.,Johns Hopkins University |
Ptak A.,Johns Hopkins University |
Rosati P.,European Southern Observatory |
And 13 more authors.
AIP Conference Proceedings | Year: 2010
Sensitive surveys of the X-ray universe have been limited to small areas of the sky due to the intrinsically small field of view of Wolter-I X-ray optics. High angular resolution is needed to achieve a low background per source, minimize source confusion, and distinguish point from extended objects. WFXT consists of three co-aligned wide field X-ray telescopes with a 1° field of view and a≲10″ (goal of 5″) angular resolution (HEW) over the full field. Total effective area at 1 keV will be >5000cm-2. WFXT will perform three extragalactic surveys that will cover most of the sky to 100-1000 times the sensitivity of the ROSAT All Sky Survey, ≳2000deg 2 to deep Chandra or XMM-Newton sensitivity, and ≳100deg 2 to the deepest Chandra sensitivity. WFXT will generate a legacy X-ray dataset of a half million clusters and groups of galaxies to z≈2, also characterizing the physics of the intracluster gas for a significant fraction of them, thus providing an unprecedented data set for cosmological applications; it will detect >107AGN to z>6, again obtaining spectra for a substantial fraction, to study the growth of supermassive black holes; it will detect >105normal/starburst galaxies; and it will detect and characterize star formation regions across the Galaxy. WFXT is the only X-ray survey mission that will match, in area and sensitivity, the next generation of wide-area optical, IR and radio surveys. © 2010 American Institute of Physics.
Additive manufacturing, or 3-D printing, is a key technology for enhancing space vehicle designs and manufacturing and enabling more affordable exploration missions. The technology has the potential to influence spacecraft built for leaving Earth and spaceships and landers for visiting other destinations. Future plans include performing engine tests with liquid oxygen and methane—key propellants for Martian landers since methane and oxygen production might be possible on the Red Planet. "We manufactured and then tested about 75 percent of the parts needed to build a 3-D printed rocket engine," said Elizabeth Robertson, the project manager for the additively manufactured demonstrator engine at NASA's Marshall Space Flight Center in Huntsville, Alabama. "By testing the turbopumps, injectors and valves together, we've shown that it would be possible to build a 3-D printed engine for multiple purposes such as landers, in-space propulsion or rocket engine upper stages." Over the last three years, the Marshall team has been working with various vendors to make 3-D printed parts, such as turbopumps and injectors, and test them individually. To test them together, they connected the parts so that they work the same as they do in a real engine. Only they are not packaged together in a configuration that looks like the typical engine you see on a test stand. "In engineering lingo, this is called a breadboard engine," explained Nick Case, the testing lead for the effort. "What matters is that the parts work the same way as they do in a conventional engine and perform under the extreme temperatures and pressures found inside a rocket engine. The turbopump got its "heartbeat" racing at more than 90,000 revolutions per minute (rpm) and the end result is the flame you see coming out of the thrust chamber to produce over 20,000 pounds of thrust, and an engine like this could produce enough power for an upper stage of a rocket or a Mars lander." Seven tests were performed with the longest tests lasting 10 seconds. During the tests, the 3-D printed demonstrator engine experienced all the extreme environments inside a flight rocket engine where fuel is burned at greater than 6,000 degrees Fahrenheit (3,315 degrees Celsius) to produce thrust. The turbopump delivers the fuel in the form of liquid hydrogen cooled below 400 degrees Fahrenheit (-240 degrees Celsius). These tests were performed with cryogenic liquid hydrogen and liquid oxygen, propellants that are mainstays of spaceship propulsion systems. Even if methane and oxygen prove to be the Mars propellant of choice, the propellant combination of cryogenic liquid hydrogen and oxygen tests the limits of 3-D printed hardware because it produces the most extreme temperatures and exposes parts to cryogenic hydrogen, which can cause embrittlement. In addition to testing with methane, the team plans to add other key components to the demonstrator engine including a cooled combustion chamber and nozzle and a turbopump for liquid oxygen. "These NASA tests drive down the costs and risks associated with using additive manufacturing, which is a relatively new process for making aerospace quality parts," said Robertson. "Vendors who had never worked with NASA learned how to make parts robust enough for rocket engines. What we've learned through this project can now be shared with American companies and our partners." To make each part, a design is entered into a 3-D printer's computer. The printer then builds each part by layering metal powder and fusing it together with a laser – a process known as selective laser melting. The 3-D printed turbopump, one of the more complex parts of the engine, had 45 percent fewer parts than similar pumps made with traditional welding and assembly techniques. The injector had over 200 fewer parts than traditionally manufactured injectors, and it incorporated features that have never been used before because they are only possible with additive manufacturing. Complex parts like valves that normally would take more than a year to manufacture were built by in a few months. This made it possible to get the parts built and assembled on the test stand much sooner than if they had been procured and made with traditional methods. Marshall engineers designed the fuel pump and its components and leveraged the expertise of five suppliers to build the parts using 3-D printing processes. "This new manufacturing process really opened the design space and allowed for part geometries that would be impossible with traditional machining or casting methods," said David Eddleman, one Marshall's propulsion designers. "For the valve designs on this engine, we used more efficient structures in the piece parts that resulted in optimized performance." All data on materials characterization and performance for these parts will be available in NASA's Materials and Processes Technical Information System, called MAPTIS, which is available to approved users. To learn more about MAPTIS or request access, visit: maptis.nasa.gov/ NASA propulsion engineer Nick Case explains how engineers configured engine parts to make and test additively manufactured engine parts as a system. Credit: NASA/MSFC Explore further: NASA performs first J-2X powerpack test of the year