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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.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

Search for Terrestrial Planets with SIM Planet Quest

SIM is an astrometric mission that will be capable of 1 microarcsec relative astrometric accuracy in a single measurement of approx.1000 sec. The search for terrestrial planets in the habitable zone around nearby stars is one of the main science goals of the project. In 2001, NASA through the peer review process selected 10 key projects, two of which had as its goal, the search for terrestrial planets around nearby stars. The two teams, one led by G. Marcy (UC Berkeley) and one lead by M. Shao (JPL), have an extensive preparatory science program underway. This paper describes the status of this activity as well as the technology status of SIM's narrow angle astrometry capability, to reach 1 uas in a single epoch measure and its ability to average multiple epoch measurements to well below 1 uas.

extrasolar planets↗
NASA NTRS1999

NASA's Terrestrial Planet Finder: The Search for (Habitable) Planets

One of the primary goals of NASA's Origins program is the search for habitable planets. I will describe how the Terrestrial Planet Finder (TPF) will revolutionize our understanding of the origin and evolution of planetary systems, and possibly even find signs of life beyond the Earth.

terrestrial planet finder↗
NASA NTRS1979

Geophysical observations pertaining to solid-state convection in the terrestrial planets

Observational evidence for solid-state convection in the interiors of the terrestrial planets is reviewed. For the earth, the motion of the lithospheric plates constitutes clear evidence of large-scale convection in the mantle. Although Mars has been found to lack evidence of plate tectonics, the morphology of the Tharsis uplift and the elevation dichotomy between the northern and southern hemispheres may be evidence of mantle convection at one time. Measurements of lunar heat flow and seismic Q imply a convective mechanism limited to the lower mantle. Evidence for internal convection on Mercury consists of its dipole magnetic field and the 3/2 resonance between its rotational motion and its orbital motion, both of which can also be explained by other processes. The limited radar imagery of Venus has not yet provided conclusive evidence of either the presence or absence of convection features. It is concluded that although interior convection in terrestrial planets is implied by rheological, energy and momentum considerations, only on earth is the lithosphere thin enough to provide conclusive evidence of convection.

Phillips, R. J.↗
NASA NTRS2006

Adaptive Nulling for the Terrestrial Planet Finder Interferometer

A description of adaptive nulling for Terrestrial Planet Finder Interferometer (TPFI) is presented. The topics include: 1) Nulling in TPF-I; 2) Why Do Adaptive Nulling; 3) Parallel High-Order Compensator Design; 4) Phase and Amplitude Control; 5) Development Activates; 6) Requirements; 7) Simplified Experimental Setup; 8) Intensity Correction; and 9) Intensity Dispersion Stability. A short summary is also given on adaptive nulling for the TPFI.

adaptive nulling↗
NASA NTRS2004

NASA's Terrestrial Planet Finder Missions

NASA has decided to move forward with two complementary Terrestrial Planet Finder (TPF) missions, a visible coronagraph and an infrared formation flying interferometer. These missions are major missions in the NASA Office of Space Science Origins Theme. The primary science objectives of the TPF missions are to search for, detect, and characterize planets and planetary systems beyond our own Solar System, including specifically Earth-like planets.

Terrestrial Planet Finder (TPF)↗
NASA NTRS2004

Terrestrial Planet Finder Coronagraph : technology and mission design studies

The Terrestrial Planet Finder (TPF) coronagraph study involves exploring the technologies that enable a coronagraph style instrument to image and characterize earth-like planets orbiting nearby stars. Testbeds have been developed to demonstrate the emerging technologies needed for this effort and an architecture study has resulted in designs of a facility that will provide the environment needed for the technology to function in this role. A broad community of participants is involved in this work through studies, analyses, fabrication of components, and participation in the design effort. The scope of activities - both on the technology side and in the architecture study side - will be presented in this paper. The status and the future plans of the activities will be reviewed.

space↗
NASA NTRS2004

Integrated Modeling Approach for the Terrestrial Planet Finder Mission

Because of the complexity of the Terrestrial Planet Finder (TPF) design concepts, the project will rely heavily on the use of engineering and science simulations to predict on-orbit performance. Furthermore, current understanding of these missions indicates that the 3m to 8m class optical systems need to be as stable as picometers in wavefront and sub-milli arcsec in pointing. These extremely small requirements impose on the models a level of predictive accuracy heretofore never achieved, especially in the area of microgravity effects, material property accuracy, thermal solution convergence, and all other second order modeling effects typically ignored. New modeling tools and analysis paradigms are developed which emphasize computational accuracy and fully integrated analytical simulations. The process is demonstrated on sample problems using the TPF Coronagraph design concept. The TPF project is also planning a suite of testbeds through which various aspects of the models and simulations will be verified.

terrestrial planet finder↗
NASA NTRS2002

Selected mission architectures for the Terrestrial Planet Finder (TPF): large, medium, and small

Four teams incorporating scientists and engineers from more than 50 universities and 20 engineering firms have assessed techniques for detecting and characterizing terrestrial planets orbiting nearby stars. The primary conclusion from the effort of the past two years is that with suitable technology investment starting now, a mission to detect terrestrial planets around 150 nearby stars could be launched within a decade.

Terrestrial↗
NASA NTRS1979

Subsolidus convective cooling histories of terrestrial planets

The subsolidus convective cooling histories of terrestrial planets evolving from hot initial states are investigated quantitatively. A simple analytic model simulating average heat flux from a vigorously convecting mantle and incorporating a mantle viscosity proportional to mantle temperature and a lithosphere which thickens as the planet cools is employed. Heat flux from the convecting mantle is calculated on the basis of a power law relation between Nusselt number and Rayleigh number. The temperature distribution in the lithosphere is assumed to be linear throughout the cooling history of the planet. Cooling histories have been determined for the earth, Mars, Mercury and the moon and the mantle temperature decreases, mantle viscosity increases and decreases of heat flux to the surface and to the base of the lithosphere and of Nusselt and Rayleigh numbers are illustrated for each planet. It is found that primordial heat can contribute substantially to the present surface heat flux of a planet.

Schubert, G.↗
NASA NTRS1983

The geology of the terrestrial planets

Knowledge regarding the geology of the terrestrial planets has increased considerably during the last four years. The present investigation provides a brief summary of work during these years on the geology of Mercury, Venus, moon, and Mars. Following the Mariner 10 encounter with Mercury in 1974, the geologic history of the planet was broadly outlined by Strom (1979). McCauley et al. (1981) recognized several facies of ejecta around Caloris. Hostetler and Drake (1980) showed that unless Mercury received more than 60-70 percent of its thermal energy from tidal interactions, it must have undergone early, almost global melting. Knowledge of the Venusian surface has increased substantially over the last few years both through improvement of earth-based observations and in connection with the Pioneer Venus mission. A topographic map of Venus is presented. Attention is also given to the composition and character of lunar highlands, the evolution of different maria, photographs obtained of almost the entire planet Mars, and Martian craters and volcanism.

Carr, M. H.↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Terrestrial Planets: Building Blocks and Differentiation

The session "Terrestrial Planets: Building Blocks and Differentiation: included the following topics:Magnesium Isotopes in the Earth, Moon, Mars, and Pallasite Parent Body: High-Precision Analysis of Olivine by Laser-Ablation Multi-Collector ICPMS; Meteoritic Constraints on Collision Rates in the Primordial Asteroid Belt and Its Origin; New Constraints on the Origin of the Highly Siderophile Elements in the Earth's Upper Mantle; Further Lu-Hf and Sm-Nd Isotopic Data on Planetary Materials and Consequences for Planetary Differentiation; A Deep Lunar Magma Ocean Based on Neodymium, Strontium and Hafnium Isotope Mass Balance Partial Resetting on Hf-W System by Giant Impacts; On the Problem of Metal-Silicate Equilibration During Planet Formation: Significance for Hf-W Chronometry ; Solid Metal-Liquid Metal Partitioning of Pt, Re, and Os: The Effect of Carbon; Siderophile Element Abundances in Fe-S-Ni-O Melts Segregated from Partially Molten Ordinary Chondrite Under Dynamic Conditions; Activity Coefficients of Silicon in Iron-Nickel Alloys: Experimental Determination and Relevance for Planetary Differentiation; Reinvestigation of the Ni and Co Metal-Silicate Partitioning; Metal/Silicate Paritioning of P, Ga, and W at High Pressures and Temperatures: Dependence on Silicate Melt Composition; and Closure of the Fe-S-Si Liquid Miscibility Gap at High Pressure and Its Implications for Planetary Core Formation.

Source record↗
NASA NTRS2004

Terrestrial Planet Finder

Integrating and testing the proposed Terrestrial Planet Finder imposes constraints on the design. Some of these will be discussed including the dimensions of existing test facilities, the effects of gravity, ambient vibrations and the size of GSE optics.

Smith, Andrew↗
NASA NTRS2005

The Terrestrial Planet Finder coronagraph dynamics error budget

The Terrestrial Planet Finder Coronagraph (TPF-C) demands extreme wave front control and stability to achieve its goal of detecting earth-like planets around nearby stars. We describe the performance models and error budget used to evaluate image plane contrast and derive engineering requirements for this challenging optical system.

coronagraph↗
NASA NTRS1988

Wrinkle ridge assemblages on the terrestrial planets

The morphological and dimensional similarities of the structures within the wrinkle ridge assemblages observed on terrestrial planets are investigated, including structures that occur in mare basalts on the moon and in smooth plains on Mars and Mercury. These structures can be classified as either arches or ridges on the basis of morphology, and ridges can be subdivided onto first-, second-, and third-order ridges on the basis of dimensions. Using ridge structures on the Columbia Plateau (U.S.) as analogs, a basis for a structural interpretation of the wrinkle ridge assemblages on the terrestrial planets is established. It is shown that the anticlinal ridges of the Columbia Plateau are appropriate analogs to the first-order ridges, supporting tectonic interpretations for the ridges.

Watters, Thomas R.↗
NASA NTRS2006

Status of the Terrestrial Planet Finder Interferometer (TPF-I)

The interferometric version of the Terrestrial Planet Finder (TPF-I) has the potential to find and characterize earth-sized planets in the habitable zones of over 250 nearby stars and to search for life using biomarkers in the atmospheres of any planets found. The scientific case for such a mission continues to be strengthened by on-going progress in the detection of planets via indirect means. This paper summarizes the status of TPF-I, illustrative scientific requirements for the mission, and its enabling technologies.

Terrestrial Planet Finder (TPF)↗
NASA NTRS1978

The origin and relative abundances of C, N and the noble gases on the terrestrial planets and in meteorites

Relative concentrations of noble gases and C and N are evaluated for the terrestrial planets. Comparisons between amounts of volatile materials in carbonaceous chondrites and on Earth and Mars are presented as support for the accretion model of planetary formation. However, attention is given to the large differences in the C/noble gas ratios on various bodies in the solar system, e.g. the Sun, Venus, Earth, Mars, stressing that the data are too incomplete to provide a reliable model for the sources of volatile and noble elements on the terrestrial planets.

Bogard, D. D.↗
NASA NTRS2000

The Stability of Terrestrial Planets in Systems with a Planet in the Asteroid Region

If a planetary-mass body were present in the asteroid belt, the orbits of the terrestrial planets and those of the giant planets would be more closely coupled. A greater exchange in angular momentum could affect the stability of the terrestrial planets. To study this effect, we have simulated several systems consisting of the Solar System planets and a 0.1 - 10 Earth mass object on the orbit of a main belt asteroid. An integration with Ceres at five Earth masses remained stable for a billion years. Ceres at ten Earth masses, however, caused the system to become unstable at 25 - 50 million years. When additional mass was given to both Ceres (bringing it up to five Earth masses) and Mars (one Earth mass), the systems self-destructed within 40 million years. Systems with Pallas at five Earth masses became unstable at 150 - 170 million years. Vesta at five Earth masses caused the system to become unstable in as little as 13 million years, but systems with Vesta at two Earth masses remained stable for 100 million years.

Lissauer, Jack J.↗