SEARCH · Search NASA
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The possibility and consequences of the extension of human society into space are addressed. The establishment of space colonies, orbital power plants and factories, and space exploration are discussed. The necessity of world cooperation to realize such projects and the development of a global space-centered society are considered.
ABSTRACT In this study we report the spatially resolved, wideband spectral properties of three giant radio galaxies (GRGs) in the COSMOS field: MGTC J095959.63+024608.6, MGTC J100016.84+015133.0, and MGTC J100022.85+031520.4. One of these galaxies, MGTC J100022.85+031520.4, is reported here for the first time, with a projected linear size of 1.29 Mpc at a redshift of 0.1034. Unlike the other two, it is associated with a brightest cluster galaxy (BCG), making it one of the few GRGs known to inhabit cluster environments. We examine the spectral age distributions of the three GRGs using new MeerKAT UHF-band (544–1088 MHz) observations, and L-band (900–1670 MHz) data from the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) survey. We test two models of spectral ageing, the Jaffe–Perola and Tribble models, using the Broadband Radio Astronomy Tools (brats) software, and find that they agree well with each other. We estimate the Tribble spectral age for MGTC J095959.63+024608.6 as 68 Myr, for MGTC J100016.84+015133.0 as 47 Myr, and for MGTC J100022.85+031520.4 as 67 Myr. We find significant disagreements between these spectral age estimates and the estimates of the dynamical ages of these GRGs, modelled in cluster and group environments. Our results highlight the need for additional processes that are not accounted for in either the dynamic age or the spectral age estimations.
We present a new measurement of the Lyα luminosity function (LF) at redshift z = 6.9, finding moderate evolution from z = 5.7 that is consistent with a fully or largely ionized z ~ 7 intergalactic medium. Our result is based on four fields of the LAGER (Lyman Alpha Galaxies in the Epoch of Reionization) project. Our survey volume of 6.1 × 10 6 Mpc 3 is double that of the next largest z ~ 7 survey. We combine two new LAGER fields (WIDE12 and GAMA15A) with two previously reported LAGER fields (COSMOS and CDFS). In the new fields, we identify N = 95 new z = 6.9 Lyα emitter (LAEs) candidates, characterize our survey's completeness and reliability, and compute Lyα LFs. The best-fit Schechter LF parameters for all four LAGER fields are in good general agreement. Two fields (COSMOS and WIDE12) show evidence for a bright-end excess above the Schechter function fit. We find that the Lyα luminosity density declines at the same rate as the UV continuum LF from z = 5.7 to 6.9. This is consistent with an intergalactic medium that was fully ionized as early as redshift z ~ 7 or with a volume-averaged neutral hydrogen fraction of x H I < 0.33 at 1σ.
The Hubble Space Telescope (HST) has contributed significantly to studies of dark energy. It was used to find the first evidence of deceleration at z=1.8 (Riess et al. 2001) through the serendipitous discovery of a type 1a supernova (SN1a) in the Hubble Deep Field. The discovery of deceleration at z greater than 1 was confirmation that the apparent acceleration at low redshift (Riess et al. 1998; Perlmutter et al. 1999) was due to dark energy rather than observational or astrophysical effects such as systematic errors, evolution in the SN1a population or intergalactic dust. The GOODS project and associated follow-up discovered 21 SN1a, expanding on this result (Riess et al. 2007). HST has also been used to constrain cosmological parameters and dark energy through weak lensing measurements in the COSMOS survey (Massey et al 2007; Schrabback et al 2009) and strong gravitational lensing with measured time delays (Suyu et al 2010). Constraints on dark energy are often parameterized as the equation of state, w = P/p. For the cosmological constant model, w = -1 at all times; other models predict a change with time, sometimes parameterized generally as w(a) or approximated as w(sub 0)+(1-a)w(sub a), where a = (1+z)(sup -1) is the scale factor of the universe relative to its current scale. Dark energy can be constrained through several measurements. Standard candles, such as SN1a, provide a direct measurement of the luminosity distance as a function of redshift, which can be converted to H(z), the change in the Hubble constant with redshift. An analysis of weak lensing in a galaxy field can be used to derive the angular-diameter distance from the weak-lensing equation and to measure the power spectrum of dark-matter halos, which constrains the growth of structure in the Universe. Baryonic acoustic oscillations (BAO), imprinted on the distribution of matter at recombination, provide a standard rod for measuring the cosmological geometry. Strong gravitational lensing of a time-variable source gives the angular diameter distance through measured time delays of multiple images. Finally, the growth of structure can also be constrained by measuring the mass of the largest galaxy clusters over cosmic time. HST has contributed to the study of dark energy through SN1a and gravitational lensing, as discussed above. HST has also helped to characterize galaxy clusters and the HST-measured constraints on the current Hubble constant H(sub 0) are relevant to the interpretation of dark energy measurements (Riess et al 2009a). HST has not been used to constrain BAO as the large number of galaxy redshifts required, of order 100 million, is poorly matched to HST's capabilities. As the successor to HST, the James Webb Space Telescope (JWST; Gardner et al 2006) will continue and extend HST's dark energy work in several ways.
1. What were the major goals of the project? Under this project, the senior investigator Robert Caldwell (PI) conducted research that addresses outstanding problems in cosmology. This project built on the PI’s ongoing research program in dark energy and cosmic acceleration, cosmology as a probe of fundamental physics, and new gravitational phenomena. Other faculty conducting research under this project were: Stephon Alexander, Marcelo Gleiser, and Devin Walker. Specific results have included predictions of new physics that informs and helps guide Cosmic Frontier observational probes of dark energy, dark matter, and CMB probes pursuing B-mode polarization. 2. What was accomplished under these goals? The project accomplished the primary goals: to extend the state of knowledge of dark energy, inflation, and the phases of the early Universe; to identify new observations and measurements that may help identify the underlying physics of the cosmos; to develop new analysis techniques that enhance the value of exist
The National Aeronautics and Space Administration (NASA) explores the unknown in air and space, innovates for the benefit of humanity, and inspires the world through discovery. Extending the reach of humanity through the human exploration of the Moon, Mars, and beyond is key to that mission. NASA’s Moon to Mars Strategy and Objectives document establishes long-term goals and objectives for crewed deep space exploration; however, satisfying NASA’s Moon to Mars Objectives requires an innovative approach to the definition, management, and execution of NASA’s Moon to Mars Architecture. An architecture offers a high-level unifying structure and defines a system. It provides rules, guidelines, and constraints that define a cohesive and coherent framework that identifies constituent parts, relationships, and connections and establishes how those parts fit and work together. This Architecture Definition Document (ADD) establishes the process for the decomposition of objectives empowers the agency’s success in achieving human exploration of the cosmos. NASA updates this document annually to reflect the maturation of the architecture and the progress NASA and partners make toward achieving exploration objectives. The ADD is not a manifest or requirements document. Instead, it serves as a tool for the programs, projects, and engineers who will implement and execute NASA’s bold ambitions for crewed exploration of deep space. As established in the Moon to Mars Strategy and Objectives, “Why” we explore encompasses three pillars: Science, Inspiration, and National Posture. Ensuring success in all three areas requires an architectural approach that incorporates innovation, collaboration, and partnerships that can be sustained across a multi-decadal effort. This second revision (Rev-B) of the ADD, developed to support NASA’s 2024 Architecture Concept Review (ACR), incorporates several key updates to support the continued evolution of the architecture. Since the last revision of the ADD, NASA has significantly improved the clarity of the objective decomposition, which distills exploration objectives into the characteristics and needs and use cases and functions needed to achieve them. The updated decomposition incorporates findings from internal studies and diverse stakeholder feedback. A model-based systems engineering approach ensures coherence and consistency, removing inconsistency and repetition. Revision B also incorporates advancements to NASA’s Mars architecture, including insight into initial capabilities, systems, and operations necessary to support the Humans to Mars segment. Updates to objective decomposition for Mars add significant detail to the ADD and hint at areas of forward work and future study. An appendix adds greater depth in the future decisions needed for Mars that will drive lunar needs. They are not the only decisions to be made, but they will have huge effects on subsequent decisions. NASA continues to introduce new exploration systems into the architecture. Two new elements — initial surface habitat and lunar surface cargo lander—successfully passed mission concept review in 2024 as a result of extensive analysis, concept refinement, and studies. These elements and their respective reference missions appear in this revision. NASA also continues to apply architecture processes to cross-agency efforts and coordination with external stakeholders by including definitions of architecture technology gaps — essential areas for engagement across and beyond the agency. The technology gaps appendix identifies areas that need attention and innovation to enable future exploration. In publishing this information, NASA communicates the technologies and capabilities that may benefit from partnership with industry, academia, other U.S. government agencies, and international space agencies. Ultimately, NASA established the Moon to Mars Architecture approach to communicate and facilitate humanity’s journey into the universe according to the principles and recurring tenets of NASA’s Moon to Mars Strategy and Objectives. The NASA architecture team thanks their many stakeholders, participants, and partners for their efforts to review and provide feedback. Their support has been critical to the success of this approach.
Assurance cases are being increasingly acknowledged as a way to build trust in complex systems with autonomous capabilities [1]. An assurance case is a comprehensive, defensible, and valid justification that a system will function as intended for the specific mission and operating environment. Such justifications for systems with autonomous capabilities are often based on various probabilistic quantifications [2]. Due to the dynamic nature of the environmental conditions in which these systems operate, as well as the changing nature of the autonomous systems themselves, these probabilistic quantifications cannot be simply estimated once during design time. Rather, they need to be continually evaluated during systems operations to ensure that the assurance case justifications are valid. We refer to the assurance case that combines both the static and dynamic elements as a Dynamic Assurance Case (DAC). Such complex systems with autonomous capabilities are often deployed with a Ground Control Software (GCS) component to enable remote operation. Whether the system is composed of a single unit or a fleet of units, deployed distributed or in remote environments, GCS acts as a window into the behavior of the deployed system. It receives telemetry from the system, issues commands to the system and provides various functionalities to visualize the system performance. We propose a dynamic assurance framework where the GCS acts as a relay between the autonomous system and its DAC. GCS can be used to measure both unit-specific as well as system-wide probabilistic quantifications using the incoming telemetry. We embed these quantifications throughout the DAC as variables that can be updated by external sources. We use the GCS to periodically update these variables, which allows us to continually evaluate the formally defined assurance case justifications. We demonstrate our dynamic assurance framework in the NASA Ames project Troupe1 that aims at developing a fleet of rovers capable of au- tonomously mapping their environment. The rovers work cooperatively, each collecting data for different parts of the environment. Each rover runs an identical core Flight System (cFS) [4] application. Troupe1 uses OpenC3 Cosmos [5] as the ground system, and AdvoCATE [3] to capture the system DAC. We show how we can measure both rover-specific and system-wide quantifications in Cosmos using its Ruby scripting editor and pass them into the DAC modelled in AdvoCATE. Then, we show how these incoming variables can be embedded in different parts of the DAC and how effects of their updates can be observed
During the last phase of NAG 2-386 we completed three studies. The effects of 14 days of weightlessness; the vastus medialis (VM) from flight rats in COSMOS 2044 was compared with the VM from tail suspended rats and other controls. The type I and II fibers in the mixed fiber portion of the VM were significantly reduced in flight rats and capillary densities paralleled the fiber density changes. The results of this project compared favorably with those in the extensor digitorum longus following seven days of flight in SL 3. The cardiovascular projects focused on the blood pressure changes in head down tilted rats (HDT) and non-head down tilted (N-HDT) rats. Blood pressures (MAP, SP and DP) were significantly elevated through seven days of HDT and rapidly returned to control levels within one day after removal from the HDT position. The N-HDT showed some slight rise in blood pressure but these were not as great and they were not as rapid. The HDT rats were characterized as exhibiting transient hypertension. These results led to some of the microvascular and vascular graduate student projects of Dr. Bernhard Stepke. Also our results refute or, at least, do not agree with previous reports from other laboratories. Each animal, in our blood pressure projects, served as its own control thereby providing more accurate results. Also, our experiments focused on recovery studies which can, in and of themselves, provide guidelines for flight experiments concerned with blood pressure changes. Another experiment was conducted to examine the role of testicular atrophy in whole body suspended (WBS) and tail suspended (TS) rats. We worked in conjunction with Dr. D.R. Deaver's laboratory at Pennsylvania State University and Dr. R. P. Amann at Colorado State University. In the TS rats the testes are retracted into the abdominal cavity, unless a ligature is placed to maintain them in the external scrotal sac. The cryptorchid condition in TS rats results in atrophy of the testes and lowered levels of spermatid formation. Hormonal changes due to testes atrophy must be considered in future experiments where related effects may modify muscle, bone or other tissue changes. Also, some new assessments of past results (published by many researchers) may warrant revised interpretations. The blood pressure studies and the testicular function results were presented and reviewed during an invited lecture at the University of Bordeaux II during the Animals in Space Symposium in March 1993. In summary, each of these three projects complied with the objectives of the proposal and serve to demonstrate the utility of animal models in preparations and interpretations of space flight results. All funding has been expended in accordance with the approved budget.
What's in this Report? What's New? This fifth Program Annual Technology Report (PATR) summarizes the Programs technology development activities for fiscal year (FY) 2015. The PATR serves four purposes.1. Summarize the technology gaps identified by the astrophysics community;2. Present the results of this years technology gap prioritization by the PCOS Technology Management Board (TMB);3. Report on newly funded PCOS Strategic Astrophysics Technology (SAT) projects; and4. Detail progress, current status, and activities planned for the coming year for all technologies supported by PCOS Supporting Research and Technology (SRT) funding in FY 2015. .
We present the first results from the ongoing Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) project, which is the largest narrowband survey for z ∼ 7 galaxies to date. Using a specially built narrowband filter NB964 for the superb large-area Dark Energy Camera (DECam) on the NOAO/CTIO 4 m Blanco telescope, LAGER has collected 34 hr NB964 narrowband imaging data in the 3 deg{sup 2} COSMOS field. We have identified 23 Ly α Emitter candidates at z = 6.9 in the central 2-deg{sup 2} region, where DECam and public COSMOS multi-band images exist. The resulting luminosity function (LF) can be described as a Schechter function modified by a significant excess at the bright end (four galaxies with L {sub Lyα∼} 10{sup 43.4±0.2} erg s{sup −1}). The number density at L {sub Ly} {sub α} ∼ 10{sup 43.4±0.2} erg s{sup −1} is little changed from z = 6.6, while at fainter L {sub Lyα} it is substantially reduced. Overall, we see a fourfold reduction in Ly α luminosity density from z = 5.7 to z = 6.9. Combined with a more modest evolution of the continuum UV luminosity density, this suggests a factor of ∼3 suppression of Ly α by radiative transfer through the z ∼ 7 intergalactic medium (IGM). It indicates an IGM neutral fraction of x {sub Hi} ∼ 0.4–0.6 (assuming Ly α velocity offsets of 100–200 km s{sup −1}). The changing shape of the Ly α LF between z ≲ 6.6 and z = 6.9 supports the hypothesis of ionized bubbles in a patchy reionization at z ∼ 7.
This 2-minute animation shows a virtual walk through the large caverns of the Long-Baseline Neutrino Facility, which will house the Deep Underground Neutrino Experiment. To create the caverns for the huge DUNE particle detectors, construction crews will excavate more than 800,000 tons of rock a mile underground at the Sanford Underground Research Facility in South Dakota. Scientists and dignitaries broke ground for this project on July 21, 2017. When construction is complete, DUNE scientists will send an intense neutrino beam through 1,300 kilometers of rock from the Department of Energy’s Fermilab to the DUNE particle detectors to understand the role that neutrinos – the most abundant matter particles in the universe – play in our cosmos. About 1,000 scientists from more than 160 institutions in 30 countries work on the Deep Underground Neutrino Experiment.
This chronology covers the 32-year history of orbital debris and near-Earth environmental concerns. It tracks near-Earth environmental hazard creation, research, observation, experimentation, management, mitigation, protection, and policy-making, with emphasis on the orbital debris problem. Included are the Project West Ford experiments; Soviet ASAT tests and U.S. Delta upper stage explosions; the Ariane V16 explosion, U.N. treaties pertinent to near-Earth environmental problems, the PARCS tests; space nuclear power issues, the SPS/orbital debris link; Space Shuttle and space station orbital debris issues; the Solwind ASAT test; milestones in theory and modeling the Cosmos 954, Salyut 7, and Skylab reentries; the orbital debris/meteoroid research link; detection system development; orbital debris shielding development; popular culture and orbital debris; Solar Max results; LDEF results; orbital debris issues peculiar to geosynchronous orbit, including reboost policies and the stable plane; seminal papers, reports, and studies; the increasing effects of space activities on astronomy; and growing international awareness of the near-Earth environment.
ABSTRACT We present a summary of our project that studies galaxies hosting type Ia supernova (SN Ia) at different redshifts. We present Gran Telescopio de Canarias (GTC) optical spectroscopy of six SN Ia host galaxies at redshift z ∼ 0.4–0.5. They are joined to a set of SN Ia host galaxies at intermediate-high redshift, which include galaxies from surveys SDSS and COSMOS. The final sample, after a selection of galaxy spectra in terms of signal-to-noise and other characteristics, consists of 680 galaxies with redshift in the range 0.04 < z < 1. We perform an inverse stellar population synthesis with the code fado to estimate the star formation and enrichment histories of this set of galaxies, simultaneously obtaining their mean stellar age and metallicity and stellar mass. After analysing the correlations among these characteristics, we look for possible dependencies of the Hubble diagram residuals and supernova features (luminosity, colour and strength parameter) on these stellar parameters. We find that the Hubble residuals show a clear dependence on the stellar metallicity weighted by mass with a slope of −0.061 mag dex−1, when represented in logarithmic scale, log 〈ZM/Z⊙〉. This result supports our previous findings obtained from gas oxygen abundances for local and SDSS-survey galaxies. Comparing with other works from the literature that also use the stellar metallicity, we find a similar value, but with more precision and a better significance (2.08 versus ∼ 1.1), due to the higher number of objects and wider range of redshift of our sample.
We study the properties of dark matter halos that contain star-forming galaxies at 1.43 ≤ z ≤ 1.74, using the FMOS-COSMOS survey. The sample consists of 516 objects with a detection of the Hα emission line, which represent the star forming population at this epoch, having a stellar mass range of 10{sup 9.57} ≤ M {sub *}/M {sub ⊙} ≲ 10{sup 11.4} and a star-formation rate range of 15 ≲ SFR/(M {sub ⊙} yr{sup −1}) ≲ 600. We measure the projected two-point correlation function while carefully taking into account observational biases, and find a significant clustering amplitude at scales of 0.04–10 h {sup −1} cMpc, with a correlation length r{sub 0}=5.26{sub −0.62}{sup +0.75} h{sup −1} cMpc and a bias b=2.44{sub −0.32}{sup +0.38}. We interpret our clustering measurement using a halo occupation distribution model. The sample galaxies appear to reside in halos with mass M{sub h}=4.71{sub −1.62}{sup +1.19}×10{sup 12} h{sup −1} M{sub ⊙} on average, which will likely become present-day halos of mass M {sub h} (z = 0) ∼ 2 × 10{sup 13} h {sup −1} M {sub ⊙}, equivalent to the typical halo mass scale of galaxy groups. We then confirm the decline of the stellar-to-halo mass ratio at M {sub h} < 10{sup 12} M {sub ⊙}, finding M {sub *}/M {sub h} ≈ 5 × 10{sup −3} at M {sub h} = 7. 5 × 10{sup 11} M {sub ⊙}, which is lower by a factor of 2–4 than those measured at higher masses (M {sub h} ∼ 10{sup 12–13} M {sub ⊙}). Finally, we use our results to illustrate the future capabilities of Subaru’s Prime-Focus Spectrograph, a next-generation instrument that will provide strong constraints on the galaxy-formation scenario by obtaining precise measurements of galaxy clustering at z > 1.
NASA’s Astrophysics Division (APD) funds development of cutting-edge technology to enable its missions to achieve ambitious and groundbreaking science goals. These technology development efforts are managed by the Physics of the Cosmos (PCOS), Cosmic Origins (COR), and Exoplanet Exploration (ExE) Programs. The NASA Strategic Astrophysics Technology (SAT) Program was established in 2009 as a new technology maturation program to fill the gap in the Technology Readiness Level (TRL) range from 3 to 6. Since program inception, 100 SAT grants have been openly competed and awarded, along with dozens of direct-funded projects, leading to a host of technologies advancing their TRLs and/or being infused into space and suborbital missions and ground-based projects. We present the portfolio distribution in terms of specific technology areas addressed, including optics, detectors, coatings, coronagraphs, starshades, lasers, electronics, cooling systems, and micro-thruster subsystems. We show an analysis of the rate of TRL advances, infusion success stories, and other benefits such as training the future astrophysics workforce, including students and postdoctoral fellows hired by projects. Finally, we present APD’s current strategic technology maturation priorities for investment, enabling a range of future strategic astrophysics missions
“Dark energy” is a phenomenon of unknown origin that pervades the vacuum of space and is causing the present-day expansion of the universe to accelerate. Understanding the nature of dark energy is one of the most fundamental challenges to modern physics, having the potential to revolutionize our theories of both gravity and elementary particle physics. The effects of dark energy are currently only accessible to astronomical survey experiments that probe large volumes of the cosmos. One of the most powerful forms of experiment for studying dark energy is the cosmological “redshift survey,” which maps the large-scale structure of the universe as traced by the positions of galaxies, quasars, and intergalactic hydrogen clouds. The signature of dark energy and other cosmological parameters is imprinted on this large-scale structure as it evolves over cosmic time. This project focused on maximizing the accurate extraction of information from redshift surveys by improving the algorithms and statistics applied across the chain of inference from raw pixels to high-level cosmological parameter estimation. At the low level, this project developed new techniques for calibrating and analyzing high-background, low signal-to-noise data from astronomical survey spectrographs to provide reliable three-dimensional maps of galaxies and quasars throughout the universe. At the high level, this project developed new statistical frameworks for understanding the completeness of redshift surveys and the underlying demographics of the galaxies that they observe, thereby allowing for a more accurate connection between survey results and theoretical models. This work contributes to maximizing the scientific reach of existing and planned surveys, and opens new potential feasibility for more ambitious surveys in the future.
Recent developments in compact object astrophysics, especially the discovery of merging neutron stars by LIGO, the imaging of the black hole in M87 by the Event Horizon Telescope, and high- precision astrometry of the Galactic Center at close to the event horizon scale by the GRAVITY experiment motivate the development of numerical source models that solve the equations of general relativistic magnetohydrodynamics (GRMHD). Here we compare GRMHD solutions for the evolution of a magnetized accretion flow where turbulence is promoted by the magnetorotational instability from a set of nine GRMHD codes: Athena++, BHAC, Cosmos++, ECHO, H-AMR, iharm3D, HARM-Noble, IllinoisGRMHD, and KORAL. Agreement among the codes improves as resolution increases, as measured by a consistently applied, specially developed set of code performance metrics. We conclude that the community of GRMHD codes is mature, capable, and consistent on these test problems.
Recent developments in compact object astrophysics, especially the discovery of merging neutron stars by LIGO, the imaging of the black hole in M87 by the Event Horizon Telescope, and high- precision astrometry of the Galactic Center at close to the event horizon scale by the GRAVITY experiment motivate the development of numerical source models that solve the equations of general relativistic magnetohydrodynamics (GRMHD). In this work we compare GRMHD solutions for the evolution of a magnetized accretion flow where turbulence is promoted by the magnetorotational instability from a set of nine GRMHD codes: Athena++, BHAC, Cosmos++, ECHO, H-AMR, iharm3D, HARM-Noble, IllinoisGRMHD, and KORAL. Agreement among the codes improves as resolution increases, as measured by a consistently applied, specially developed set of code performance metrics. Thus, we decide that the community of GRMHD codes is mature, capable, and consistent on these test problems.