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NASA NTRS2013

NASA's Space Launch System: Moving Toward the Launch Pad

The National Aeronautics and Space Administration's (NASA's) Space Launch System (SLS) Program, managed at the Marshall Space Flight Center, is making progress toward delivering a new capability for human space flight and scientific missions beyond Earth orbit. Developed with the goals of safety, affordability, and sustainability in mind, the SLS rocket will launch the Orion Multi-Purpose Crew Vehicle (MPCV), equipment, supplies, and major science missions for exploration and discovery. Supporting Orion's first autonomous flight to lunar orbit and back in 2017 and its first crewed flight in 2021, the SLS will evolve into the most powerful launch vehicle ever flown, via an upgrade approach that will provide building blocks for future space exploration and development. NASA is working to develop this new capability in an austere economic climate, a fact which has inspired the SLS team to find innovative solutions to the challenges of designing, developing, fielding, and operating the largest rocket in history. This paper will summarize the planned capabilities of the vehicle, the progress the SLS program has made in the 2 years since the Agency formally announced its architecture in September 2011, and the path the program is following to reach the launch pad in 2017 and then to evolve the 70 metric ton (t) initial lift capability to 130-t lift capability. The paper will explain how, to meet the challenge of a flat funding curve, an architecture was chosen which combines the use and enhancement of legacy systems and technology with strategic new development projects that will evolve the capabilities of the launch vehicle. This approach reduces the time and cost of delivering the initial 70 t Block 1 vehicle, and reduces the number of parallel development investments required to deliver the evolved version of the vehicle. The paper will outline the milestones the program has already reached, from developmental milestones such as the manufacture of the first flight hardware and the record-breaking testing of the J-2X engine, to life-cycle milestones such as the vehicle's Preliminary Design Review. The paper will also discuss the remaining challenges in both delivering the 70 t vehicle and in evolving its capabilities to the 130 t vehicle, and how the program plans to accomplish these goals. As this paper will explain, SLS is making measurable progress toward becoming a global infrastructure asset for robotic and human scouts of all nations by harnessing business and technological innovations to deliver sustainable solutions for space exploration

Creech, Stephen D.↗

NASA NTRS1998

Field Guide for Designing Human Interaction with Intelligent Systems

The characteristics of this Field Guide approach address the problems of designing innovative software to support user tasks. The requirements for novel software are difficult to specify a priori, because there is not sufficient understanding of how the users' tasks should be supported, and there are not obvious pre-existing design solutions. When the design team is in unfamiliar territory, care must be taken to avoid rushing into detailed design, requirements specification, or implementation of the wrong product. The challenge is to get the right design and requirements in an efficient, cost-effective manner. This document's purpose is to describe the methods we are using to design human interactions with intelligent systems which support Space Shuttle flight controllers in the Mission Control Center at NASA/Johnson Space Center. Although these software systems usually have some intelligent features, the design challenges arise primarily from the innovation needed in the software design. While these methods are tailored to our specific context, they should be extensible, and helpful to designers of human interaction with other types of automated systems. We review the unique features of this context so that you can determine how to apply these methods to your project Throughout this Field Guide, goals of the design methods are discussed. This should help designers understand how a specific method might need to be adapted to the project at hand.

Malin, Jane T.↗

NASA NTRS2002

An Automated Method to Compute Orbital Re-entry Trajectories with Heating Constraints

Determining how to properly manipulate the controls of a re-entering re-usable launch vehicle (RLV) so that it is able to safely return to Earth and land involves the solution of a two-point boundary value problem (TPBVP). This problem, which can be quite difficult, is traditionally solved on the ground prior to flight. If necessary, a nearly unlimited amount of time is available to find the 'best' solution using a variety of trajectory design and optimization tools. The role of entry guidance during flight is to follow the pre- determined reference solution while correcting for any errors encountered along the way. This guidance method is both highly reliable and very efficient in terms of onboard computer resources. There is a growing interest in a style of entry guidance that places the responsibility of solving the TPBVP in the actual entry guidance flight software. Here there is very limited computer time. The powerful, but finicky, mathematical tools used by trajectory designers on the ground cannot in general be converted to do the job. Non-convergence or slow convergence can result in disaster. The challenges of designing such an algorithm are numerous and difficult. Yet the payoff (in the form of decreased operational costs and increased safety) can be substantiaL This paper presents an algorithm that incorporates features of both types of guidance strategies. It takes an initial RLV orbital re-entry state and finds a trajectory that will safely transport the vehicle to Earth. During actual flight, the computed trajectory is used as the reference to be flown by a more traditional guidance method.

Zimmerman, Curtis↗

NASA NTRS2020

Multidisciplinary Design Optimization of Low-Boom Supersonic Aircraft with Mission Constraints

Conceptual design of low-boom supersonic aircraft is heavily dictated by aircraft volume and lift distributions. These unique design characteristics make it a challenge to enforce mission requirements (such as static margins and trim requirements) during design optimization. This low-boom design challenge is resolved by using reversed equivalent area targets for low-fidelity low-boom inverse design and a block coordinate optimization (BCO) method for multidisciplinary design optimization (MDO). The corresponding low-boom MDO problem includes aircraft mission constraints on ranges, cruise speeds, trim for low-boom cruise, static margins for takeoff/cruise/landing, takeoff/landing field lengths, approach velocity, and tail rotation angles for trim at takeoff/landing, as well as fuselage volume constraints for passengers and main gear storage. The BCO method is developed to optimally resolve the conflicts between the low-boom inverse design objective and other design constraints. This method is successfully applied to design a low-boom supersonic configuration that carries 40 passengers, flies a low-boom mission with cruise Mach of 1.6 and range of 2,500 nm, and cruises overwater at Mach 1.8 with range of 3,600 nm. The generated configuration satisfies all specified mission constraints and has the potential to match a reversed equivalent area target with ground noise level below 70 PLdB.

Multidisciplinary design optimization↗

NASA NTRS1997

Development and Operation of a Material Identification and Discrimination Imaging Spectroradiometer

Many imaging applications require quantitative determination of a scene's spectral radiance. This paper describes a new system capable of real-time spectroradiometric imagery. Operating at a full-spectrum update rate of 30Hz, this imager is capable of collecting a 30 point spectrum from each of three imaging heads: the first operates from 400 nm to 950 nm, with a 2% bandwidth; the second operates from 1.5 micro-m to 5.5 micro-m with a 1.5% bandwidth; the third operates from 5 micro-m to 12 micro-m, also at a 1.5% bandwidth. Standard image format is 256 x 256, with 512 x 512 possible in the VIS/NIR head. Spectra of up to 256 points are available at proportionately lower frame rates. In order to make such a tremendous amount of data more manageable, internal processing electronics perform four important operations on the spectral imagery data in real-time. First, all data in the spatial/spectral cube of data is spectro-radiometrically calibrated as it is collected. Second, to allow the imager to simulate sensors with arbitrary spectral response, any set of three spectral response functions may be loaded into the imager including delta functions to allow single wavelength viewing; the instrument then evaluates the integral of the product of the scene spectral radiances and the response function. Third, more powerful exploitation of the gathered spectral radiances can be effected by application of various spectral-matched filtering algorithms to identify pixels whose relative spectral radiance distribution matches a sought-after spectral radiance distribution, allowing materials-based identification and discrimination. Fourth, the instrument allows determination of spectral reflectance, surface temperature, and spectral emissivity, also in real-time. The spectral imaging technique used in the instrument allows tailoring of the frame rate and/or the spectral bandwidth to suit the scene radiance levels, i.e., frame rate can be reduced, or bandwidth increased to improve SNR when viewing low radiance scenes. The unique challenges of design and calibration are described. Pixel readout rates of 160 MHz, for full frame readout rates of 1000 Hz (512 x 512 image) present the first challenge; processing rates of nearly 600 million integer operations per second for sensor emulation, or over 2 billion per second for matched filtering, present the second. Spatial and spectral calibration of 66,536 pixels (262,144 for the 512 x 512 version) and up to 1,000 spectral positions mandate novel decoupling methods to keep the required calibration memory to a reasonable size. Large radiometric dynamic range also requires care to maintain precision operation with minimum memory size.

Dombrowski, Mark↗

NASA NTRS2016

Optimization of NTP System Truss to Reduce Radiation Shield Mass

The benefits of nuclear thermal propulsion are numerous and relevant to the current NASA mission goals involving but not limited to the crewed missions to mars and the moon. They do however also present new and unique challenges to the design and logistics of launching/operating spacecraft. One of these challenges, relevant to this discussion, is the significant mass of the shielding which is required to ensure an acceptable radiation environment for the spacecraft and crew. Efforts to reduce shielding mass are difficult to accomplish from material and geometric design points of the shield itself, however by increasing the distance between the nuclear engines and the main body of the spacecraft the required mass of the shielding is lessened considerably. The mass can be reduced significantly per unit length, though any additional mass added by the structure to create this distance serves to offset those savings, thus the design of a lightweight structure is ideal. The challenges of designing the truss are bounded by several limiting factors including; the loading conditions, the capabilities of the launch vehicle, and achieving the ideal truss length when factoring for the overall mass reduced. Determining the overall set of mass values for a truss of varying length is difficult since to maintain an optimally designed truss the geometry of the truss or its members must change. Thus the relation between truss mass and length for these loading scenarios is not linear, and instead has relation determined by the truss design. In order to establish a mass versus length trend for various truss designs to compare with the mass saved from the shield versus length, optimization software was used to find optimal geometric properties that still met the design requirements at established lengths. By solving for optimal designs at various lengths, mass trends could be determined. The initial design findings show a clear benefit to extending the engines as far from the main structure of the spacecraft as the launch vehicle's payload volume would allow when comparing mass savings verse the additional structure.

Scharber, Luke L.↗

NASA NTRS2023

The Design of the Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) Reentry Vehicle (RV)

This discussion will involve the design and architecture of the Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) Reentry Vehicle (RV). It will describe the structure and modular design of the RV, expounding on its various subsystems, including power and commanding, data handling and recovery, instrumentation, the inflation system, and the aeroshell. The unique launch vehicle architecture for the LOFTID mission, as a massive rideshare payload, required the development of supporting flight systems, including the Payload Adapter Separation System (PASS) and the Reentry Vehicle Payload Adapter Interface Ring (RVPAIR). To do no harm to the primary mission, the LOFTID team also designed and delivered a flightworthy Mass Simulator as risk reduction in the event the RV was not ready in time for the primary mission launch date. Various challenges and design trades will be discussed, along with a brief description of the RV performance in flight.

R J Bodkin↗

NASA NTRSDate not supplied

The Design of the Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) Reentry Vehicle (RV)

R J Bodkin↗

NASA NTRS1990

Lunar astronomical observatories - Design studies

The best location in the inner solar system for the grand observatories of the 21st century may be the moon. A multidisciplinary team including university students and faculty in engineering, astronomy, physics, and geology, and engineers from industry is investigating the moon as a site for astronomical observatories and is doing conceptual and preliminary designs for these future observatories. Studies encompass lunar facilities for radio astronomy and astronomy at optical, ultraviolet, and infrared wavelengths of the electromagnetic spectrum. Although there are significant engineering challenges in design and construction on the moon, the rewards for astronomy can be great, such as detection and study of earth-like planets orbiting nearby stars, and the task for engineers promises to stimulate advances in analysis and design, materials and structures, automation and robotics, foundations, and controls. Fabricating structures in the reduced-gravity environment of the moon will be easier than in the zero-gravity environment of earth orbit, as Apollo and space-shuttle missions have revealed. Construction of observatories on the moon can be adapted from techniques developed on the earth, with the advantage that the moon's weaker gravitational pull makes it possible to build larger devices than are practical on earth.

Johnson, Stewart W.↗

NASA NTRS1982

AGT100 turbomachinery

High-performance turbomachinery components have been designed and tested for the AGT100 automotive engine. The required wide range of operation coupled with the small component size, compact packaging, and low cost of production provide significant aerodynamic challenges. Aerodynamic design and development testing of the centrifugal compressor and two radial turbines are described. The compressor achieved design flow, pressure ratio, and surge margin on the initial build. Variable inlet guide vanes have proven effective in modulating flow capacity and in improving part-speed efficiency. With optimum use of the variable inlet guide vanes, the initial efficiency goals have been demonstrated in the critical idle-to-70% gasifier speed range. The gasifier turbine exceeded initial performance goals and demonstrated good performance over a wide range. The radial power turbine achieved 'developed' efficiency goals on the first build.

Tipton, D. L.↗

NASA NTRS1999

Experiments on Evolving Software Models of Analog Circuits

Analog circuits are of great importance in electronic system design since the world is fundamentally analog in nature. While the amount of digital design activity far outpaces that of analog design, most digital systems require analog modules for interfacing with the external world. It was recently estimated that approximately 60% of digital application- specific integrated circuit designs incorporated analog circuits. With challenging analog circuit design problems and few analog design engineers, there are economic reasons for automating the analog design process, especially time-to-market considerations. Techniques for analog circuit design automation began appearing about two decades ago. These methods incorporated heuristics [6], knowledge bases [1], simulated annealing [5], and other algorithms. Efforts using techniques from evolutionary computation began appearing over the last few years. These include the use of genetic algorithms to select electronic component values (for example, the resistance value of a resistor), to select circuit topologies, and to design amplifiers using a limited set of canned topologies [4]. A genetic programming-based analog circuit design system has been demonstrated in which the circuit sizes, component values, and the circuit topologies are determined automatically [3]. The genetic-algorithm systems typically represent circuit structures as vectors of parameters encoded in binary strings, while the genetic programming system manipulates tree data structures.

Lohn, Jason D.↗

NASA NTRSDate not supplied

Development of Thermal Control Devices for Extreme Lunar Environments at Marshall Space Flight Center

NASA’s return to the moon brings many challenges, including issues with sustainable survival on the Lunar surface. One of the key challenges with sustainability is designing adequate thermal control systems that allow for surface systems to survive both during the day and the Lunar Night. The extreme thermal environments on the Lunar surface are a challenging design space for thermal engineers. At equatorial regions, the Lunar noon can be very hot, requiring systems with high heat rejection to the environment. At polar regions, such as those targeted by the return to the moon, the Lunar night temperatures plummet to -200 degrees Celsius or lower. Such temperatures are formidable and require specialized thermal control systems to allow surface assets to surface the long night.

Will Johnson↗

NASA NTRS2004

Risk Assessment and Control through Countermeasure System Iplementation for Long-term Crew Exposure to Microgravity

Experience with the International Space Station (ISS) program demonstrates the degree to which engineering design and operational solutions must protect crewmembers from health risks due to long-term exposure to the microgravity environment. Risks to safety and health due to degradation in the microgravity environment include crew inability to complete emergency or nominal activities, increased risk of injury, and inability to complete safe return to the ground due to reduced strength or embrittled bones. These risks without controls slowly increase in probability for the length of the mission and become more significant for increasing mission durations. Countermeasures to microgravity include hardware systems that place a crewmember s body under elevated stress to produce an effect similar to daily exposure to gravity. The ISS countermeasure system is predominately composed of customized exercise machines. Historical treatment of microgravity countermeasure systems as medical research experiments unintentionally reduced the foreseen importance and therefore the capability of the systems to function in a long-term operational role. Long-term hazardous effects and steadily increasing operational risks due to non-functional countermeasure equipment require a more rigorous design approach and incorporation of redundancy into seemingly non- mission-critical hardware systems. Variations in the rate of health degradation and responsiveness to countermeasures among the crew population drastically increase the challenge for design requirements development and verification of the appropriate risk control strategy. The long-term nature of the hazards and severe limits on logistical re-supply mass, volume and frequency complicates assessment of hardware availability and verification of an adequate maintenance and sparing plan. Design achievement of medically defined performance requirements by microgravity countermeasure systems and incorporation of adequate failure tolerance significantly reduces these risks. Future implementation of on-site monitoring hardware for critical health parameters such as bone mineral density would allow greater responsiveness, efficiency, and optimized design of the countermeasures system.

Gernand, Jeremy M.↗

NASA NTRS1999

ARISE: A Challenging 25-m Space Antenna Design

ARISE (Advanced Radio Interferometry between Space and Earth). Future scientific and communications missions are conceptualizing using very large reflector antennas in space. The antenna dimensions are targeted from lOm to 25m beyond. Frequencies coveting L-band through W-band are being considered. these challenging missions, one may refer to ARISE (Advanced Radio Interferometry between Space and Earth), which is projected to utilize a 25-m dual Gregorian optics operating from 8 GHz to 86 Gl-lz . An artist's renditions Gregorian antenna concept is shown . The objective of this mission is to create a space-based VLBI system (integrated with ground based antennas) for high resolution mapping of black holes. Successful realization of ARISE necessitates development of several technologies . The most crucial technology is that of the deployable 25-m reflector that must work at frequencies as high as 43 and 86 GHz. The current baseline selection for ARISE is an inflatable antenna, under development for several other applications in communications and remote sensing.

Rahmat-Samii, Yahya↗

NASA NTRS2011

Low-Thrust Orbit Transfer Design for DAWN Operations at VESTA

Upon arrival at the asteroid Vesta, scheduled for July of 2011, the Dawn spacecraft will target a series of four distinct mapping orbits, each providing a unique opportunity to observe Vesta. The unknown, and potentially complex, Vesta gravity field presents challenges for designing low-thrust transfers between these mapping orbits while maintaining spacecraft safety from Vesta occultation of the Sun. This paper provides a description of the orbit transfers designed for Vesta operations along with a discussion of the constraints and methods used to design these transfers. The effect of alternate gravity fields on the viability of the designs and the design method is also considered

low thrust↗

NASA NTRS2000

New Human-Computer Interface Concepts for Mission Operations

The current climate of budget cuts has forced the space mission operations community to reconsider how it does business. Gone are the days of building one-of-kind control centers with teams of controllers working in shifts 24 hours per day, 7 days per week. Increasingly, automation is used to significantly reduce staffing needs. In some cases, missions are moving towards lights-out operations where the ground system is run semi-autonomously. On-call operators are brought in only to resolve anomalies. Some operations concepts also call for smaller operations teams to manage an entire family of spacecraft. In the not too distant future, a skeleton crew of full-time general knowledge operators will oversee the operations of large constellations of small spacecraft, while geographically distributed specialists will be assigned to emergency response teams based on their expertise. As the operations paradigms change, so too must the tools to support the mission operations team's tasks. Tools need to be built not only to automate routine tasks, but also to communicate varying types of information to the part-time, generalist, or on-call operators and specialists more effectively. Thus, the proper design of a system's user-system interface (USI) becomes even more importance than before. Also, because the users will be accessing these systems from various locations (e.g., control center, home, on the road) via different devices with varying display capabilities (e.g., workstations, home PCs, PDAS, pagers) over connections with various bandwidths (e.g., dial-up 56k, wireless 9.6k), the same software must have different USIs to support the different types of users, their equipment, and their environments. In other words, the software must now adapt to the needs of the users! This paper will focus on the needs and the challenges of designing USIs for mission operations. After providing a general discussion of these challenges, the paper will focus on the current efforts of creatin(y an effective USI for one specific suite of tools, SERS (The Spacecraft Emergency Response System), which has been built to enable lights-out operations. SERS is a Web-based collaborative environment that enables secure distributed fault management.

Fox, Jeffrey A.↗

NASA NTRS1999

Performance of a 2.5 THz Receiver Front-End for Spaceborne Applications

The OH radical plays a significant role in a great many of the known ozone destruction cycles, and has become the focus of an important radiometer development effort for NASA's Earth Observing System Chem I satellite, which will monitor and study many tropospheric and stratospheric gases and is scheduled for launch in 2002. Here we describe the design, fabrication, and testing of a receiver front end used to detect the OH signals at 2.5 THz. This is to be the first Terahertz heterodyne receiver to be flown in space. The challenges of producing the necessary high-performance mixers are numerous, but for this application, there is the added challenge of designing a robust receiver which can withstand the environmental extremes of a rocket launch and five years in space. The receiver front-end consists of the following components: a four-port dual-polarization diplexer, off-axis elliptical feed mirrors, mixers for horizontal and vertical polarization, support structures allowing simple and rugged alignment, low noise IF amplification from 7.7 to 21.1 GHz, and mixer DC bias circuitry. The front-end design, alignment, and operation will be covered in depth, followed by a discussion of the most recent results in receiver noise and dual-mode horn beam patterns. JPL MOMED mixers are employed, and have resulted in receiver noise temperatures of 14,500 K, DSB with LO frequency 2.522 GHz and IF of 12.8 GHz. Horn beam patterns correspond well with theory, with no significant sidelobes above the -25 dB level. Considering the high-quality beam of this receiver, these results are competitive with the best reported in the literature.

Gaidis, Michael C.↗

NASA NTRS2013

Designing Scenarios for Controller-in-the-Loop Air Traffic Simulations

Well prepared traffic scenarios contribute greatly to the success of controller-in-the-loop simulations. This paper describes each stage in the design process of realistic scenarios based on real-world traffic, to be used in the Airspace Operations Laboratory for simulations within the Air Traffic Management Technology Demonstration 1 effort. The steps from the initial analysis of real-world traffic, to the editing of individual aircraft records in the scenario file, until the final testing of the scenarios before the simulation conduct, are all described. The iterative nature of the design process and the various efforts necessary to reach the required fidelity, as well as the applied design strategies, challenges, and tools used during this process are also discussed.

ATD1↗