A progress report on the Advanced Reusable Technologies Project

Rocket-based combined-cycle (RBCC) engines are known as the most promising type of engine with the potential to realize ‘single stage to orbit’ (SSTO). This will dramatically reduce the cost of space round trips and improve the physical experience of astronauts. However, sixty years after this concept was first proposed, no RBCC engine has completed a real flight. The challenges in RBCC development include ejector, scramjet, mode transition, and thermal protection technologies. However, great progress has been made in recent years, suggesting a bright future for these engines. In this paper, we review worldwide progress in the overall layout of RBCC engines. The working process of RBCC engines is introduced to show their distinctiveness among traditional engines. RBCC engines are classified as rectangular section or axisymmetric configuration engines and the development of both types in different countries is reviewed. The engine-airframe integration design and mission planning of RBCC powered aircraft systems are analyzed separately. Even though RBCC powered aircraft and their missions remain conceptual, the design and planning processes are important for RBCC development and space round trips in the future. RBCC study is a typical multi-disciplinary design process. Research addressing the problems encountered by RBCC studies will promote the development of a range of disciplines relevant to aerospace science.

A space elevator is a physical connection from the surface of the Earth to a geo-stationary orbit above the Earth approximately 35,786 km in altitude. Its center of mass is at the geo-stationary point such that it has a 24-hour orbit, and stays over the same point above the equator as the Earth rotates on its axis. The structure is utilized as a transportation and utility system for moving payloads, power, and gases between the surface of the Earth and space. It makes the physical connection from Earth to space in the same way a bridge connects two cities across a body of' water. The space elevator may be an important concept for the future development of space in the latter part of the 21th century. It has the potential to provide mass-transportation to space in the same way highways, railroads, power lines, and pipelines provide mass-transportation across the Earth's surface. The low energy requirements for moving payloads up and down the elevator make it one of only a few concepts that has the potential of lowering the cost to orbit to less than $10 per kilogram. This paper will summarize the findings from a 1999 NASA workshop on Space Elevators held at the NASA Marshall Space Flight Center (MSFC). The workshop was sponsored by the Advanced Projects Office in the Flight Projects Directorate at MSFC, and was organized in cooperation with the Advanced Space Transportation Program at MSFC and the Advanced Concepts Office in the Office of Space Flight at NASA Headquarters. New concepts will be examined for space elevator construction and a number of issues will be discussed that has helped to bring the space elevator concept out of the realm of science fiction and into the realm of possibility. In conclusion, it appears that the space elevator concept may well he possible in the latter part of the 21st century if proper planning and technology development is emphasized to resolve key issues in the development of this advanced space infrastructure concept.

NASA's Integrated Space Transportation Plan — 3 rd generation reusable launch vehicle technology update

A new concept for the low speed propulsion mode in rocket based combined cycle (RBCC) engines has been developed as part of the NASA GTX program. This concept, called the independent ramjet stream (IRS) cycle, is a variation of the traditional ejector ramjet (ER) design and involves the injection of hydrogen fuel directly into the air stream, where it is ignited by the rocket plume. Experiments and computational fluid dynamics (CFD) are currently being used to evaluate the feasibility of the new design. In this work, a Navier-Stokes code valid for general reactive flows is applied to the model engine under ER and IRS cycle operation. Pressure distributions corresponding to ER operation are compared with experimental data. The engine response under IRS cycle operation is examined for different reaction models, grid sizes, and fuel injection schemes. A mode transition study is also discussed. The IRS solutions exhibit a high sensitivity to reaction mechanism. ER results are similar to experimental results, but no experimental data exists for validating IRS results. The CFD results obtained with Jachimowski’s 7-species mechanism indicate that thermally-choked IRS operation is possible and that the thermal throat can be modulated by changes in fuel injection. Results predicting the stability of the flame through the mode transition process cannot be confirmed without additional experimental data. Nomenclature

Tests of a 40% scale model of the inlet to a rocket-based combined-cycle (RBCC) engine were conducted in the NASA Lewis Research Center's 1-Foot by 1-Foot Supersonic Wind Tunnel at Mach numbers from 4 to 6. The full-scale RBCC engine is currently being tested at the NASA Lewis Plum Brook Station Hypersonic Tunnel Facility (HTF). The RBCC engine flowpath is divided into three rectangular channels by two struts. Each strut in the full-scale engine contains three small rocket chambers which exhaust out of the trailing edge. The leading edges of the struts begin ahead of the cowl lip to provide transverse compression surfaces within the inlet. Two non-compressi ve outer sidewalls represent planes of symmetry. Objectives of the sub-scale inlet tests included determining the starting and performance characteristics of a baseline leading edge strut configuration, and an alternate configuration. The effects of precompression plate boundary layer ingestion and freestream Reynolds number were also investigated. Detailed pilotpressure surveys at the strut trailing edge station were used to establish the inlet performance and also guide the design of ramjet fuel injectors for the full-scale engine. These measurements, surface static pressures, and oil flow visualization were used to validate an inlet CFD analysis. A remotely-actuated plug was used to simulate combustion back-pressure during the tests. Pilot-pressure surveys were obtained by traversing a remotely-actuated, 12-tube rake across the flowpath. Inlet performance for Mach 4 through 6 is summarized for all configurations tested. Results indicate that the untapered strut configuration generally sustained higher back-pressure, and had lower distortion than the tapered strut configuration. In addition, the untapered strut configuration self-started at all Mach numbers tested. The untapered strut configuration was subsequently chosen for the full-scale engine. Pilot-pressure surveys, and surface static pressure distributions have been published previously for the untapered strut configuration at the HTF test Mach numbers of 5 and 6. This report presents summary performance data for all the strut configurations at Mach numbers 4, 5, and 6.

Personal computers of the past were limited to running computational fluid dynamics codes in serial mode. With the advent of multicore technology and suitable compilers, personal computers nowadays can execute codes in a parallel fashion similar to that of supercomputers and cluster computer systems. This article investigated what performance can be achieved when executing an aerodynamic code on an Intel quad core based personal computer with an OpenMP compiler in a Windows environment. The code solved the Euler equations to find the flowfield around a NACA0012 aerofoil on an O-type boundary fitted structured grid system. A speedup of up to 350% was obtainable in double precision accuracy. The reduced computation time means that, for small scale problems, more accurate Euler codes can replace commonly used transonic small disturbance codes. For larger problems, this information serves as a reference for developers of hybrid MPI/OpenMP algorithms for cluster computer systems. References Advanced Micro Devices (AMD), AMD FireStream 9170: Industry's First GPU with Double-Precision Floating Point, 2007, http://ati.amd.com/products/streamprocessor/specs.html Allmaras, S. R., Venkatakrishnan, V., and Johnson, F. T., Farfield Boundary Conditions for 2-D Airfoils, AIAA Paper 2005-4711, AIAA, 2005. Bailey, D., Barszcz, E., Barton, J., Browning, D., Carter, R., Dagum, L., Fatoohi, R., Fineberg, S., Frederickson, P., Lasinski, T., Schreiber, R., Simon, H., Venkatakrishnan, V., and Weeratunga, S., The NAS Parallel Benchmarks, National Aeronautics and Space Administration (NASA), Contractor Report 203186, USA, 1994, http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19970014936_1997021577.pdf Dong, S., and Karniadakis, G. E., Dual-Level Parallelism for High-Order CFD Methods, Parallel Computing, 30, Jan. 2004, pp. 1--20. Hirsch, C., Numerical Computation of Internal and External Flows (Volume 2): Computational Methods for Inviscid and Viscous Flows, John Wiley and Sons, Great Britain, 1992. Hoffmann, K. A., Computational Fluid Dynamics for Engineers, Engineering Educational System, Texas, USA, 1989. Intel, Tera-scale Computing Research Program, c.2007, http://www.intel.com/research/platform/terascale/ Jin, H., Frumkin, M., and Yan, J., The OpenMP Implementation of NAS Parallel Benchmarks and its Performance, National Aeronautics and Space Administration (NASA), Technical Report NAS-99-011, Moffett Field, USA, 1999. Liu, Y., and Vinokur, M., Nonequilibrium Flow Computations 1: An Analysis of Numerical Formulations of Conservation Laws, National Aeronautics and Space Administration (NASA), Contractor Report 177489, California, USA, 1988, http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880021000_1988021000.pdf Lock, R. C., Test Cases for Numerical Methods in Two-Dimensional Transonic Flows, Advisory Group for Aerospace Research and Development (AGARD), Report Number 575, 1970. Ly, E., Improved Approximate Factorisation Algorithm for the Steady Subsonic and Transonic Flow over an Aircraft Wing, Proceedings of the 21st Congress of the International Council of the Aeronautical Sciences (ICAS98), ICAS and AIAA, Melbourne, Australia, 1998, Paper A98-31699. Ly, E., and Gear, J. A., Time-Linearized Transonic Computations Including Shock Wave Motion Effects, Journal of Aircraft, 39, 6, Nov/Dec. 2002, pp. 964--972. Ly, E., and Nakamichi, J., Time-Linearised Transonic Computations Including Entropy, Vorticity and Shock Wave Motion Effects, The Aeronautical Journal, Nov. 2003, pp. 687--695. Ly, E., and Norrison, D., Automatic Elliptic Grid Generation by an Approximate Factorisation Algorithm, ANZIAM Journal, 48 (CTAC2006), pp. C188--C202, July 2007, http://anziamj.austms.org.au/ojs/index.php/ANZIAMJ/article/view/48. Ly, E., and Norrison, D., Generating Elliptic Grids in Three Dimensions by a Method of False Transients, ANZIAM Journal, 49 (EMAC2007), pp. C170--C183, Nov. 2007, http://anziamj.austms.org.au/ojs/index.php/ANZIAMJ/article/view/313. Nvidia, The Era of the Personal Supercomputer, 2007, http://www.nvidia.com/content/events/siggraph_2007/supercomputing.html Pope, S. B., A Perspective on Turbulence Modeling, Modeling Complex Turbulent Flows, Kluwer Academic Publishers, The Netherlands, 1999. Pulliam, T., Kutler, P., and Rossow, V., Harvard Lomax: His Quiet Legacy to Computational Fluid Dynamics, 14th AIAA Computational Fluid Dynamics Conference, Norfolk, VA, 28 June-1 July, 1999, http://people.nas.nasa.gov/ pulliam/mypapers/lomax_la.ps Steger, J. L., and Warming, R. F., Flux Vector Splitting of the Inviscid Gasdynamic Equations with Application to Finite Difference Methods, National Aeronautics and Space Administration (NASA) Technical Memorandum 78605, California, USA, 1979, http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790020779_1979020779.pdf Thompson, J. R., Warsi, Z. U. A., and Mastin, C. W., Numerical Grid Generation: Foundations and Applications, Elsevier Science Publishing Co. Inc., New York, USA, 1985. Van Leer, B., Flux-Vector Splitting for the Euler Equations, Proceedings of the 8th International Conference on Numerical Methods in Fluid Dynamics, Aachen, West Germany, 1982.

IF ALL had gone well with the US space program this year—as of course it has not—science, and medicine in particular, might have obtained considerably more data about the extraterrestrial environment and human ability to cope with it. In a late December editorial entitled 1986: A Vintage Year for Space Science, the director of the National Aeronautics and Space Administration (NASA) Marshall Space Flight Center, Huntsville, Ala, opined: If all goes as planned, it appears that the coming year will be an extraordinarily good one for space science ( Science 1985;230:1327). Adding to that outlook, although not specifically mentioned in the editorial, was NASA's plan to average more than one space shuttle mission a month during 1986. But, just like the actual dark clouds that threaten space launches, figurative clouds were gathering over the agency. Subsequent testimony suggests bureaucratic problems and cost concerns. Then, 28 days into the new year, seven

Computational Fluid Dynamics (CFD) analysis results and experimental data are presented for the Pennsylvania State University's (PSU) Propulsion Engineering Research Center (PERC) rocket based combined cycle (RBCC) rocket-ejector experiments. The PERC RBCC experimental hardware was tested in direct-connec t configuration operating in diffusion and afterburning (DAB) combustion. Two of the test points had similar experimental hardware but significantly different rocket and air flow rates resulting in significantly different plume-to-air mixing characteristics. At the design point mass flow rates the plume-to-air mixing was diffusion dominated. At a test point with mass flow rate below the design point, the mixing rate was enhanced due to recirculation of plume gases. The objective of this paper is to provide insight into the fluid dynamics responsible for this change in ejector mode mixing characteristics of the RBCC. The plume-to-air mixing of the two test points is measured experimentally with Raman Spectroscopy specie distribution. CFD analysis is used to interpret the experimental data and illustrate the fluid dynamics of the two different mixing processes. Experimental data and CFD analysis of intermediate mass flow rates are used to illustrate the transition from diffusion dominated mixing to recirculation dominated mixing. Nomenclature AR = area ratio d = duct height, 12.7 cm (5 in.) h = horizontal position PC = chamber pressure x = axial position

Hot dust-obscured galaxies (hot DOGs), selected from Wide-Field Infrared Survey Explorer’s all-sky infrared
\nsurvey, host some of the most powerful active galactic nuclei known and may represent an important stage in the
\nevolution of galaxies. Most known hot DOGs are located at z > 1.5, due in part to a strong bias against identifying
\nthem at lower redshift related to the selection criteria. We present a new selection method that identifies 153 hot
\nDOG candidates at z ~ 1, where they are significantly brighter and easier to study. We validate this approach by
\nmeasuring a redshift z = 1.009 and finding a spectral energy distribution similar to that of higher-redshift hot
\nDOGs for one of these objects, WISE J1036+0449 ( LBol ~= 8 x 10^46 erg s^-1). We find evidence of a broadened
\ncomponent in Mg II, which would imply a black hole mass of MBH ~= 2 x 10^8 M(solar) and an Eddington ratio of
\nLambdaEdd ~= 2.7. WISE J1036+0449 is the first hot DOG detected by the Nuclear Spectroscopic Telescope Array, and
\nobservations show that the source is heavily obscured, with a column density of NH = 2-15 x 10^23 cm^-2 . The
\nsource has an intrinsic 2–10 keV luminosity of ~ 6 x 10^44 erg s^-1, a value significantly lower than that expected
\nfrom the mid-infrared/X-ray correlation. We also find that other hot DOGs observed by X-ray facilities show a
\nsimilar deficiency of X-ray flux. We discuss the origin of the X-ray weakness and the absorption properties of hot
\nDOGs. Hot DOGs at z ~< 1 could be excellent laboratories to probe the characteristics of the accretion flow and of
\nthe X-ray emitting plasma at extreme values of the Eddington ratio.

Abstract20 July 1969: approximately 240 000 mi away from Earth, two astronauts named Neil Armstrong and Edwin E. Aldrin Jr. landed on the moon. 20 October 2020: approximately 200 million miles away from Earth, the National Aeronautics and Space Administration (NASA) managed to land a spacecraft on an asteroid named Bennu and collect a sample from its surface. Sometime 2030s: approximately 34 million miles away from Earth, NASA is looking to successfully send humans to Mars. So, why is all this important? The effects of climate change are apparent on Earth today—temperatures around the world higher than normal, a rising sea level, natural disasters increasing in frequency and strength—and these effects continue to become ever more apparent as time goes on; thus, there is a need for solutions, which outer space has become one that is simultaneously grown in seriousness over the years. Colonizing space, traveling to distant planets and inhabiting them, these are definite possibilities for humans, as evidenced above by the remarkable progress NASA has made; however, one of the biggest obstacles NASA is dealing with in bringing those possibilities into fruition is their food system—all the actors and interactions within a food chain, meaning those who grow the food, those who process the food, those who transport the food, those who sell the food and finally, those who consume and dispose of the food. The shelf life of NASA's current food system will not last past 18 months in the unique environment of space, where there are the hazards of galactic cosmic rays, solar radiation and microgravity. Recognizing this—essentially recognizing that achieving such aforementioned feats would require a food system that can last much longer—NASA and others have constantly been researching and experimenting with their food system, ranging from how its food is grown, processed and preserved to the focus of this literature review: how it is packaged. Henceforth, the purpose of this literature review is to chronologically look at and discuss the major materials and technologies used in NASA's space food packaging of the past—the 1960s–1970s—look at and discuss those of the present—the 1980s–2000s—and finally, look ahead and discuss those of the future, entailing materials and technologies currently being worked on or considered for future use in NASA space missions. At that, here's to 60 years of activity in space.

The Visible Infrared Imaging Radiometer Suite (VIIRS) is a key instrument onboard the Suomi NPP (S-NPP) and the NOAA-20 satellites that provides state-of-the-art Earth observations for ocean, land, aerosol, and cloud applications. VIIRS Reflective Solar Band (RSB) Sensor Data Records (SDR, or Level 1b products) are calibrated and produced independently by The National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (NASA) VIIRS science teams. Multiple versions of S-NPP and NOAA-20 VIIRS SDRs are available to date. This study evaluates the long-term calibration stability, biases, and inter-channel consistency of S-NPP and NOAA-20 VIIRS SDRs generated by NOAA and NASA over Deep Convective Clouds (DCC) to support downstream applications, especially climate data record studies. Five VIIRS RSB SDRs were analyzed in this study: (1) NOAA version 2 S-NPP VIIRS reprocessed SDRs (NOAA-NPP-V2, 2012–2020), (2) NASA Collection 1 S-NPP VIIRS SDRs (NASA-NPP-C1, 2012–2021), (3) NASA Collection 2 S-NPP VIIRS SDRs (NASA-NPP-C2, 2012–2021), (4) NOAA constant F-factor calibrated NOAA-20 VIIRS SDRs (NOAA-N20-ConstF, 2018–2021), and (5) NASA Collection 2 NOAA-20 VIIRS SDRs (NASA-N20-C2, 2018–2021). The DCC time series analysis results indicate that the calibrations of the three S-NPP VIIRS RSB SDRs are generally stable, with trends within ±0.1%/year for all RSBs, except for M3–M4 (all three S-NPP SDRs) and I3 (NASA-NPP-C1 only). The calibration of NASA-NPP-C2 SDRs is more uniform at individual detector levels. NOAA-NPP-V2 and NASA-NPP-C1 SDRs exhibit non-negligible time-dependent detector level degradation in M1–M4 (up to 1.5% in 2020–2021), causing striping in the SDR imagery. The biases between NOAA and NASA S-NPP VIIRS RSB SDRs are from 0.1% to 2.4%. The calibrations of the two NOAA-20 VIIRS RSB SDRs are also generally stable, with trends within ±0.16%/year. Small downward trends were observed in the visible and near-infrared (VIS/NIR) bands, and small upward trends were observed in the shortwave infrared (SWIR) bands for both NOAA and NASA NOAA-20 SDRs. The biases between NOAA and NASA NOAA-20 VIIRS RSB SDRs are nearly constant over time and within ±0.2% for VIS/NIR bands and ±0.7% for SWIR bands. There exists large inter-satellite biases between S-NPP and NOAA-20 VIIRS SDRs, especially in the VIS/NIR bands (up to 4.5% for NOAA SDRs and up to 7% for NASA SDRs). In addition, the DCC reflectance of S-NPP VIIRS RSB spectral bands is more consistent with that of the SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) than that of NOAA-20. Bands M4 and M9 seem out of family in all five S-NPP and NOAA-20 RSB SDRs evaluated.

Public communication strategy for NASA’s planetary protection program: Expanding the dialogue

The Hierarchical Data Format (HDF) has been a data format standard in National Aeronautic and Space Administration (NASA)'s Earth Observing System Data and Information System since the 1990s. Its rich structure, platform independence, full-featured application programming interface (API), and internal compression make it very useful for archiving science data and utilizing them with a rich set of software tools. However, a key drawback for long-term archiving is the complex internal byte layout of HDF files, requiring one to use the API to access HDF data. This makes the long-term readability of HDF data for a given version dependent on long-term allocation of resources to support that version. Much of the data from NASA's Earth Observing System have been archived in HDF Version 4 (HDF4) format. To address the long-term archival issues for these data, a collaborative study between The HDF Group and NASA's Earth Science Data Centers (ESDCs) is underway. One of the first activities was an assessment of the range of HDF4-formatted data held by NASA to determine the capabilities inherent in the HDF format that were used in practice and for use in estimating the effort for full implementation across NASA's ESDCs. Based on the results of this assessment, methods for producing a map of the layout of the HDF4 files held by NASA were prototyped using a markup-language-based HDF tool. The resulting maps allow a separate program to read the file without recourse to the HDF API. To verify this, two independent tools based solely on the map files were developed and tested.

The National Aeronautics and Space Administration (NASA) was created in 1958 to develop America's non-military space effort. But the early leaders of a self-consciously elite science and technology agency rarely saw Earth as a part of 'space' or solar system exploration. This is clear when examining NASA's relations with earthly applications in the late 1950s and 1960s and with fast-emergent environmentalism in the 1970s and 1980s. NASA consistently misread the importance of the most popular science-based political movement of the late twentieth century. NASA was advised from 1959 onwards that earthly concerns - and practical worldly benefits - were necessary to create broad and enduring support for space explorations. Despite this, NASA leaders consistently underestimated, ignored or spun-off Earth 'applications' in the formative period of America's civilian space programme. Power and prestige-focused human spaceflight, Moon and Mars missions, and human settlement of the solar system, became NASA's enduring 'human spaceflight culture'.

Feasibility Study for a Commercial Space Station in Low Earth Orbit